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This study evaluated the productivity and nutrient concentrations of organic cherry tomatoes and leguminous green manures grown in intercropping systems in rotation with maize. The experimental des...

This study was designed to investigate the effects of

Made available in DSpace on 2021-06-25T10:21:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Stable isotopes (e.g., 15N) can be used to develop best practices for fertilizer management in cereal crops under tropical conditions. The objectives of this study were to determine the N contribution from fertilizer and soil to wheat and corn grown in rotation and the residual N contribution from fertilizer applied to wheat and carried over to corn under Brazilian savannah conditions. This study was established in a no-till system on Rhodic Haplustox soil in a randomized complete block design with four replications. The N treatments applied to the wheat crops were 0, 20, 40, 60, 80 and 160 kg (urea-15N) ha−1. The residual effects of N on the succeeding corn crop were evaluated. During the corn phase, two additional treatments were included: a control (0 N) and a treatment with 160 kg N ha−1. Regression analysis showed that the highest estimated wheat yield (5415 kg ha−1) was observed with the application of 114 kg N ha−1. Significant effects from the residual N were observed in the corn shoot biomass and straw N uptake. On average, the recovery rate of the urea N fertilizer was 34% for wheat, and the residual urea N fertilizer use in corn (when applied to wheat) was less than 5% of the amount initially applied. The effect of the residual N was not enough to meet the N demands of the succeeding corn crop. The results of this study provide producers and the scientific community with good estimates of nitrogen use efficiency for wheat and corn. Department of Plant Health Rural Engineering and Soils College of Engineering Sao Paulo State University (UNESP), Avenida Brasil, 56 - Centro Goiano Federal Institute, Rio Verde Campus Department of Soil Water and Climate Southwest Research and Outreach Center University of Minnesota Center for Nuclear Energy in Agriculture University of Sao Paulo Department of Plant Health Rural Engineering and Soils College of Engineering Sao Paulo State University (UNESP), Avenida Brasil, 56 - Centro FAPESP: 18/08485-7 CNPq: 312359/2017-9

The extraction and quantification of leaf pigments are easy, fast, and cheap procedures; on the other hand, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy associated with chemometrics tools could offer new insights into leaf biochemical composition. We aimed to boost the classic leaf pigment quantification, adding leaf biochemical information derived from DRIFT spectroscopy + principal component analysis, using the same leaf pigment extract produced by the classical quantification method. We performed a dose-response experiment using P as the limiting nutrient, and maize (Zea mays L.) as a plant-test. After 45 d of growth, we evaluated the effects of P fertilization in total maize shoot biomass, P shoot accumulation, leaf pigment quantification by UV-Vis, and the evaluation of biochemical variations by DRIFT spectroscopy analysis associated with a chemometric approach in the same leaf extract used for pigment quantification. P fertilization raised biomass accumulation (∼7.4×), P uptake (∼2.3×), and total chlorophyll a and b contents (∼2.1×). DRIFT spectroscopy analysis of extracted pigments revealed an elevated content of proteins and polysaccharides at high P availability. At low P availability, we found a low efficiency of N metabolism suggested by the accumulation of inorganic N forms. DRIFT spectroscopy applied together with the classic leaf pigment extraction and quantification method is a novel and promising tool for plant nutrition studies as a DRIFT spectroscopy metabolic profile protocol.

A possible way to improve phosphate rock (PR) agronomic performance is through the addition of elemental sulfur (S0). We used 32P isotope dilution method to assess the P taken up by crops treated w...

A adubação fosfatada corresponde à fração mais onerosa do custo de produção da cultura da soja. A obtenção de cultivares de soja eficientes na absorção e utilização de fósforo em condição sub-ótima de disponibilidade deste elemento contribui para aumentar o potencial produtivo da cultura. Trinta e dois cultivares de soja [Glycine max (L.) Merrill], recomendados para o cerrado, de ciclo precoce, semiprecoce, semitardio e tardio, foram avaliados em um Latossolo Vermelho Amarelo, distrófico, do cerrado, objetivando avaliar a eficiência de absorção e utilização de P, utilizando-se parâmetros fisiológicos, químico/isotópico, bioquímico e microbiológicos. Dois experimentos foram instalados em casa de vegetação no CENA/USP, utilizando-se o delineamento em blocos casualizados com três repetições. No primeiro experimento avaliou-se a atividade da fosfatase ácida, biomassa da parte aérea e concentração de fósforo na folha diagnóstica. No segundo experimento avaliaram-se os cultivares de soja quanto à eficiência na absorção de P, utilizando como indicadores de absorção a razão de eficiência radicular e atividade específica de 32P através da técnica de diluição isotópica de 32P e, como indicador de eficiência de utilização, o índice de utilização de fósforo. Constataram-se diferenças entre os cultivares de soja, demonstrando que em condições sub-ótimas de disponibilidade de P, os cultivares de soja apresentam comportamentos diferentes quanto à eficiência na absorção e utilização de fósforo. Os cultivares precoces, semiprecoces, semitardios e tardios apresentaram diferenças genotípicas na eficiência de absorção e utilização de fósforo não somente entre os grupos, mas também dentro dos grupos examinados. Os cultivares BRAS 97-7371 e IAC PL-1 destacaram-se entre os cultivares estudados na eficiência de absorção e utilização de P. A técnica da diluição isotópica de 32P mostrou-se eficaz correlacionando-se negativamente com a atividade da fosfatase ácida. As variáveis percentagem de colonização micorrízica e razão de eficiência radicular não foram consistentes, e pouco contribuiu na avaliação dos cultivares quanto a absorção de fósforo. The phosphate fertilization represents the most costly fraction of soybean crop production. The obtention of soybean cultivars efficient in absorption and utilization of phosphorus in soil of low available P status contributes for increasing productive potential of the crop. Thirty two soybean [Glycine max (L.) Merrill] cultivars (recommended for cerrado) of early, semi-early, semi-late and late cycle were grown in Dystrophic red-yellow latosol (Typic Dystrarox) cerrado soil to evaluate their efficiency to absorb and utilize phosphorus by physiological, chemical/isotopical, biochemical and microbiological parameters. Two experiments were carried out in green house at CENA/USP (Centro de Energia Nuclear na Agricultura/University of S. Paulo), Brazil, using random bloc design with three replicates. In the first experiment acid phosphatase, shoot biomass and P content in the diagnostic leaf were considered for the cultivars evaluation. In the second experiment the root efficient ratio and the 32P isotopic dilution technique were used as uptake indicators and P utilization index for P utilization efficiency. There were differences among the cultivars, showing that they behave differently in ability to absorb P in soil of low available P status. The early, semi-early, semi-late and late cultivars presented genotypic differences on uptake and utilization of P efficiency not only among the groups, but also within the examined group. The BRAS 97-7371 and IAC PL-1 cultivars were the best on the ability to absorb poorly available P and its utilization among the evaluated cultivars. The 32P isotopic dilution technique showed efficient and correlated negatively with acid phosphatase activity. The variables mycorrhizal colonization percentage and root efficiency ratio were not consistent and little contributed for the comparison of soybean cultivars on the P uptake efficiency.

The primary goal of this study was to evaluate the phosphorus uptake and use efficiency in Brazilian soybean cultivars, besides root morphology and architecture characteristics related to phosphorus uptake, carrying out two greenhouse experiments. The experiment 1 was completely randomised, with 56 treatments (soybean cultivars) and 3 replicates. Experiment 2 was completely randomised design with three replicates, and the ten cultivars (greater and lower efficiency) were selected for this assay according to their ability to absorb phosphorus less available determined in experiment 1. The study was carried out at Center of Nuclear Energy in Agriculture, University of São Paulo, Brazil, between February 2011 and August 2012. The isotopic dilution technique was used in the first experiment to assess the phosphorus availability in the soil and to determine the ability of plants to access labile phosphorus by measuring the specific activity of plants grown in soil labeled with radioactive phosphorus. Nine cultivars showed greater phosphorus uptake and used efficiency. The second experiment evaluated the root morphology and architecture. The cultivars with greater uptake efficiency have root morphology and architecture characteristics that favour acquisition of phosphorus from soil compartments that are inaccessible to other cultivars. Phosphorus uptake by plants was not affected by soybean seeds phosphorus content. Identification of these cultivars is very important because it could enable soybean farming in low fertility soils, reducing fertiliser dependence. Made available in DSpace on 2018-12-07T23:51:49Z (GMT). No. of bitstreams: 1 Bruno2542018JEAI43230.pdf: 435564 bytes, checksum: 8818d17221e6b5d294cdf8c34da8c0d0 (MD5) Previous issue date: 2018-12-07

Recent research has shown the need for an in-depth knowledge of zinc biofortification of cereal and oilseed grains due to its importance to human nutrition. However, little is known about t...

Made available in DSpace on 2019-10-04T12:37:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-05-20 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) United States Institute of Peace Studies regarding the residual effects of sewage sludge in soil several years after the first and only application are still scarce, especially for tropical areas under forestry management. In these soils, the residual effects can represent a neglected phenomenon, since silvicultural management experiences a longer crop rotation cycle compared to most common agricultural cycles. Consequently, under forestry management, sewage sludge applications can represent an event occurring just once over cycles of several years. This study aimed to evaluate the long-term effects of residual sewage sludge application in infertile tropical soils under Eucalyptus plantations in terms of both the main chemical features (pH, soil organic matter, N, P, S, K, Ca, Mg, and cation-exchange capacity) and the potentially toxic elements (As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Se, and Zn) concentrations/behaviors of soil. Residual effects were evaluated in four areas (Sao Paulo State, Brazil) after 10.0, 12.2, 12.4, and 17.2 years from the first and only application, respectively. Differences in terms of treatments were evaluated by analysis of variance: correlations and similarity analyzed by principal component and cluster analysis, respectively. The results showed that soil organic matter, main macronutrients (N and P), and cation-exchange capacity contents were generally higher in sewage sludge-treated soils while potentially toxic element contents tended to increase at increasing sewage sludge doses. In most of the investigated treatments, the potentially toxic element concentrations were usually below both the soil natural background concentrations and quality reference values. Principal component and cluster analysis revealed that differences among areas were primary due to differences in applied sewage sludge type and amount. The effects of residual sewage sludge application on soil, in terms of both the pros and cons, can be detected even many years after the first and only application. Studies on the long-term effects of sewage sludge should be mandatory for both monitoring the pedoenvironment and for guiding policymakers and producers on the best practices for their reuse and management. (C) 2019 Elsevier Ltd. All rights reserved. Univ Sao Paulo, Dept Forest Sci, Coll Agr Luiz de Queiroz, Av Padua Dias 11, BR-13418900 Piracicaba, SP, Brazil Univ Sao Paulo, Ctr Nucl Energy Agr, Av Centenario 303, BR-73416000 Piracicaba, SP, Brazil Inst Forest Sci & Res IPEF, Private Bag 530, BR-13400970 Piracicaba, SP, Brazil Univ Sao Paulo, Dept Soil Sci, Coll Agr Luiz de Queiroz, Av Padua Dias 11, BR-13418900 Piracicaba, SP, Brazil Univ Sao Paulo, Dept Exact Sci, Coll Agr Luiz de Queiroz, Av Padua Dias 11, BR-13418900 Piracicaba, SP, Brazil Sao Paulo State Univ, Dept Plant Protect, Rural Engn & Soils, Sch Engn, BR-15385000 Ilha Solteira, SP, Brazil Univ Sassari, Dipartimento Architettura Design & Urbanist, Via Colombo 1, I-08100 Nuoro, Italy Univ Sassari, Desertificat Res Ctr, Viale Italia 39, I-07100 Sassari, Italy Sao Paulo State Univ, Dept Plant Protect, Rural Engn & Soils, Sch Engn, BR-15385000 Ilha Solteira, SP, Brazil FAPESP: 2004/15097-0 FAPESP: 2018//13152-7 CNPq: 485205/2012-2 CNPq: 312728/2017-4 CAPES: 001

This study was designed to investigate the effects of Azospirillum brasilense and Bradyrhizobium sp. co-inoculation coupled with N application on soil N levels and N in plants (total N, nitrate N-NO3− and ammonium N-NH4+), photosynthetic pigments, cowpea plant biomass and grain yield. An isotopic technique was employed to evaluate 15N fertilizer recovery and derivation. Field trials involved two inoculations—(i) single Bradyrhizobium sp. and (ii) Bradyrhizobium sp. + A. brasilense co-inoculation—and four N fertilizer rates (0, 20, 40 and 80 kg ha−1). The co-inoculation of Bradyrhizobium sp. + A. brasilense increased cowpea N uptake (an increase from 10 to 14%) and grain yield (an average increase of 8%) compared to the standard inoculation with Bradyrhizobium sp. specifically derived from soil and other sources without affecting 15N fertilizer recovery. There is no need for the supplementation of N via mineral fertilizers when A. brasilense co-inoculation is performed in a cowpea crop. However, even in the case of an NPK basal fertilization, applied N rates should remain below 20 kg N ha−1 when co-inoculation with Bradyrhizobium sp. and A. brasilense is performed.

Selecting pyrolysis parameters for recycling P-rich and hazardous biowastes, such as bones, into fertilizers is still a challenge. Our objective was to improve pyrolysis procedures of pig bones for the production of P fertilizers. Bone chars were produced by pyrolysis at 400, 550, or 800 °C with no gas addition; 550 and 800 °C under N2; 800 °C under steam flux, using calcination at 800 °C as control treatment. Synchrotron-based X-ray diffraction and X-ray absorption near edge structure spectroscopy at the P and Ca K- and L-edges showed that these bone chars were largely composed of hydroxyapatite. Hydroxyapatite crystallization was inhibited by pyrolysis conducted in the absence of oxygen at 400, 550, or 800 °C, either under no gas or under N2 flux. The clogging of pores by lack of organic compounds removal was hypothesized to cause low surface area of 400 °C bone char, resulting in a fertilizer with citric-acid soluble P as low as calcination, while 550 and 800 °C bone chars obtained in absence of oxygen showed greater porosity, surface area, and citric acid-soluble P than steamed or calcined samples at 800 °C. Although extractable phosphate in water and neutral-ammonium-citrate showed trends comparable to those from citric acid, it was negligible for all heated materials. Since it is possible to produce bone chars with different chemical, physical and crystallographic properties by managing pyrolysis conditions, bone chars can be designed to increase their suitability as P fertilizers for different purposes, such as high solubility or slow P release.

This work aimed to evaluate the nitrogen transfer, the yield and the nutrient contents of organic cherry tomatoes intercropped with legumes in two successive years. The randomized block experimenta...

Made available in DSpace on 2018-11-26T17:41:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Suzano Pulp and Paper Company S.A. Fertilization of Eucalyptus plantations using sewage sludge on unfertile tropical soils represents an alternative to using mineral N and P fertilizers. A 44-month field experiment was conducted to study the effects of increasing application of sludge, and its interactions with mineral N and P fertilizers, on wood volume. Four rates of sludge (0, 8,15 and 23 Mg ha(-1), dry base), N (0, 47, 95 and 142 kg ha(-1)) and P (0, 28, 56 and 84 kg ha(-1) of P2O5) were combined in a 4 x 4 x 4 factorial scheme in a totally randomized block design. Response surface and age-shift modeling was used to establish an initial recommendation for mineral fertilization of the Eucalyptus plantations treated with sludge and to analyze the implications of increased growth on the duration of the forest cycle in a tropical climate. The results showed that from 8 to 44 months after planting, the sludge application (with or without N and P) yielded a statistically larger wood volume (P < 0.05), compared to application of N and P fertilizers only. The response surface modeling showed the following outcomes: i) application of sludge based on N criterion reduced the need for N and P fertilizers by 100%; and ii) an increase in wood volume by 7% could be achieved, compared to NPK fertilizers only, if 2/3 of the recommended P was applied. The cultivation time to produce 150 m(3) ha(-1) of wood volume was 45 months for the control and was reduced by two, three, four, or five months, respectively, through application of recommended P, sludge dose, sludge plus one third of P, and sludge plus two thirds of P. On the whole, sewage sludge could represent an excellent unconventional N and P fertilizer source for wood production on unfertile tropical soils. (C) 2017 Elsevier Ltd. All rights reserved. Univ Sao Paulo, Dept Plant Nutr, Ctr Nucl Energy Agr, BR-13400970 Piracicaba, SP, Brazil Fed Univ Grande Dourados, Sch Engn, BR-79804070 Dourados, MS, Brazil EMBRAPA Cerrado, BR-73310970 Planaltina, DF, Brazil Univ Sao Paulo, Luiz de Queiroz Coll Agr, BR-13418900 Piracicaba, SP, Brazil Suzano Papel & Celulose SA, BR-18200000 Itapetininga, SP, Brazil Univ Florida, Inst Food & Agr Sci, Indian River Res & Educ Ctr, Ft Pierce, FL 34945 USA Sao Paulo State Univ, Sch Engn, Dept Plant Protect Rural Engn & Soils, BR-15385000 Ilha Solteira, SP, Brazil Univ Sassari, Dipartimento Architettura Design & Urbanist, Via Colombo 1, I-08100 Nuoro, Italy Univ Sassari, Desertificat Res Ctr, Viale Italia 39, I-07100 Sassari, Italy Sao Paulo State Univ, Sch Engn, Dept Plant Protect Rural Engn & Soils, BR-15385000 Ilha Solteira, SP, Brazil FAPESP: 2004/15097-0 FAPESP: 2015/09690-5 CNPq: 313374/2014-7

It can be expected that the thermal diffusivity of a magnetic fluid varies from time to time after applying a magnetic field because of the growth of the inner structure of a magnetic fluid such as chain-like clusters. In this study, time series variation of the thermal diffusivity of a magnetic fluid caused by applying a magnetic field was investigated experimentally. For the measurement of time series variation of thermal diffusivity, we attempted to apply the forced Rayleigh scattering method (FRSM), which has high temporal and high spatial resolution. We set up an optical system for the FRSM and measured the thermal diffusivity. A magnetic field was applied to a magnetic fluid in parallel and perpendicular to the heat flux direction, and the magnetic field intensity was 70 mT. The FRSM was successfully applied to measurement of the time series variation of the magnetic fluid from applying a magnetic field. The results show that a characteristic configuration in the time series variation of the thermal diffusivity of magnetic fluid was obtained in the case of applying a magnetic field parallel to the heat flux direction. In contrast, in the case of applying a magnetic field perpendicular to the heat flux, the thermal diffusivity of the magnetic fluid hardly changed during measurement.

Although silicon (Si) fertilization in rice ( Oryza sativa ) plants have already been studied, most of the Brazilian studies have focused on the acidity correction effects of sources and the application rate, but not on Si supply. Moreover, beneficial effects are rarely linked to other Si-accumulation plants such as pearl millet ( Pennisetum glaucum ), which is extensively grown in low soluble Si of Cerrado soils. The objective of this study was to evaluate the Si sources and application rates on the yield and quality of two commonly cultivated grain crops (rice and pearl millet) in Cerrado soils. The experiments were conducted on two crops (rice and pearl millet) and two soil types (Rhodic Haplustox-LV and Quartzipsamment-RQ) in a completely randomized factorial scheme with four replicates, four Si rates (0; 200; 400, and 800 kg ha -1 Si); and three sources (calcium and magnesium silicate, wollastonite, and silicic acid). All plots receiv ed the same quantities of Ca and Mg to equilibrate these levels in both soils. Ca and Mg silicate and wollastonite produced linear increases in soluble Si (0.5 mol L -1 acetic acid), in LV, RQ, and in Si uptake by rice and pearl millet. Increases in shoot dry weight were observed in rice and pearl millet from maximum rates of 542, 550 and 480 kg ha -1 Si in RQ, respectively. Ca and Mg silicate levels were higher than wollastonite in the dry weight of both plants.

Cover plants are intended to cover the soil, protecting it from erosion, nutrient leaching, and providing nutrients through recycling or biological fixation. The objectives of this study were to evaluate the dry biomass productivity and total accumulation of nutrients in the cover crops shoots and in the upland rice grown in succession; and evaluate the effect of the isolated and combined use of cover crops and urea on upland rice crop, grown under no-tillage system. The field experiment was conducted at Selviria-MS, Brazil, in an Oxisol (Rhodic Ilaplustox), cerrado (savannah) phase. The experimental design was randomized blocks, in a 5x3 factorial scheme. The treatments were four cover crops species: sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan L.), green velvet bean (Mucuna prurens), millet (Pennisetum glaucum L.), and spontaneous vegetation (fallow in off-season) combined with 20 kg N ha-1 applied at sowing, 20 kg N ha-1 applied at sowing + 60 kg N ha-1 at plus topdressing, and without mineral N fertilizer application. The millet recycled large amounts of K, Mg, S, and micronutrients, but negatively influenced the rice grain yield grown in succession. There was no response to topdressed mineral N fertilizer when the crop was grown in rotation to legume cover crops. Upland rice under no-tillage showed a positive response to the N fertilization at seeding and when it is grown in rotation with the use of millet or fallow in the off-season. Upland rice also showed a response to N fertilization applied at topdressing.

The main aims of this study were to evaluate the P uptake of Brazilian wheat cultivars and to identify the root traits involved in P uptake capacity. Two greenhouse studies were carried out. An isotopic dilution technique with 32P as a tracer was used in the first experiment. The root morphology and architecture was evaluated in the second experiment. The results indicated differences in P uptake between the cultivars. The cultivars with higher values of P uptake exhibited total root shallow, which enhances root proliferation in P-rich surface soil. Twenty-one cultivars showed potentially greater phosphorus uptake efficiency, and we observed the importance of root traits for improving the P uptake ability.

Large areas of land are nowadays contaminated by heavy metals and, it is therefore, important to monitor their levels in soils. Vegetables act as transfer mechanisms of such contaminants from soils to higher levels in the food chain. In this study, we aimed to evaluate the effectiveness of chemical extractants by the L-value method for Cd phytoavailability using the 109Cd radionuclide. In a greenhouse experiment, rocket plants (Eruca sativa L.) were cultivated in pots with samples from Typic Hapludox and Typic Quartzipsamment soils. Cadmium concentrations ranging from 0 to 16 mg kg-1 were added to a 200 mL solution containing 148 kBq 109Cd. The available Cd in the soil was extracted by DTPA, Mehlich-1, Mehlich-3, and a mixture of organic acids (acetic, citric, lactic, and oxalic acids). Cd concentrations were determined by atomic absorption spectrophotometry, and 109Cd radionuclide activity was measured by low-level β-counting. The dry matter yield was not influenced by Cd rates, but the Cd content and accumulation in shoots had a positive linear correlation. Generally, Cd was extracted in higher quantities by Mehlich-1 followed by DTPA, Mehlich-3, and organic acids. A linear correlation was found between the chemical extractants and Cd accumulation in shoots for both soils. According to the L Ratio, the extractants based on strong acids and chelating agents presented low efficiency regarding Cd phytoavailability. The organic acids, which presented values close to the L-value, may provide a promising method for evaluating environmental contaminants.

The purpose of this study was to evaluate the efficiency of superphosphate fertilizer in remediating a contaminated soil with potentially toxic elements. For this, different phosphorus doses were used in a number of lettuce plants. The element concentrations determined in their leaves were compared with those found in control lettuce plants. Instrumental neutron activation analysis was the analytical technique used to determine element concentration in lettuce leave samples. The application of 250 mg kg−1 of P was the most effective treatment to reduce the concentrations of Br, Ca, Cd, Cl, Co, Cr, Fe, K, Mg, Mn, Sb and Zn in lettuce leaves.

Three assays were developed from April 3, 1995 to October 10, 2005. The work with corn was conducted in a greenhouse, using velvet bean (Mucuna aterrima) and sunn hemp (Crotalaria juncea) as green manure with 15N labeling of either shoots or roots, in two soils with contrasting textural classes. The mineralization of N from legume plants incorporated into the two soils was investigated too. This work included two green manures: velvet bean and sunn hemp, and the common bean (Phaseolus vulgaris) residues. Nitrogen from the velvet bean accounted for a greater proportion of the soil inorganic N; shoots were responsible for most of N accumulated. Common bean residues caused immobilization of inorganic N. The leguminous species added were intensively and promptly mineralized, preserving the soil native nitrogen. One hundred days after emergence of the corn, velvet bean provided higher accumulation of nitrogen in the soil, higher absorption by corn plants and accumulation in the aerial part. The green manure decomposition was more intense in the medium textured soil. In this soil, highest nitrogen losses were also observed. The sugarcane (Saccharum spp.) was cultivated for five years in the field and was harvested three times; 15N recovery was evaluated in the first two harvests. The combination of inorganic fertilizer and green manure resulted in higher sugarcane yields than either N source applied separately; however, in the second cutting the yields were higher where sunn hemp was used than in plots with ammonium sulfate. The recovery of N by the first two consecutive harvests accounted for 19% to 21% of the N applied as sunn hemp and 46% to 49% of the N applied as ammonium sulfate. Very little inorganic N was present in the 0-40 cm soil layer with both N sources.

The increasing ethanol production brings many advantages to Brazil. However, it generates high quantities of vinasse from 10 to 15 l per liter of alcohol produced. This residue is applied as a fertilizer in sugarcane crops but, it presents a potential risk to soil quality when high doses of vinasse are applied in the same area over years. So, one solution would be to transport it to distant locations, but this would mean an increase in costs. Thus, concentrated vinasse, wherein the volume is reduced by evaporation process, becomes a viable alternative and is being increasingly used by sugarcane mills in Brazil. The aim of this study was to evaluate the net nitrogen mineralization and potential nitrogen mineralization of soil that received three doses of concentrated and not concentrated vinasse. The not concentrated vinasse is a good alternative to be applied, but higher doses promote N losses by denitrification due to the high water content. The highest values of potential nitrogen mineralization and, lowest values of constant of mineralization in the treatments with concentrated vinasse indicate that this residue releases N at a slower speed than in treatments with not concentrated vinasse, suggesting that there will be N availability in the subsequent crops.

The sugar and alcohol sector has invested heavily in technologies to increase the productivity of sugarcane and consequently the gross income of sugar and alcohol; among these practices irrigation and fertilization stands out. The objective of this study is to evaluate the agro industrial and sugarcane yield (plant cane and first ratoon cycle) grown in the Sudoeste Goiano, Brazil, as affected by water replacement and nitrogen (N) rates; and to evaluate the residual effect from N rates on sugarcane ratoon grown under water replacement levels. The study was carried out with pots filled with a mixture of 120 kg of Oxisol (Rhodic Hapludox) and cattle manure, in a proportion of 3:1 v/v, respectively. A completely randomized design was used, 3x4, with three repetitions, analyzed in split plots. The treatments were combinations of three levels of replacement water (75, 50 and 25% of available water) and four N rates (0, 60, 120 and 180 kg ha-1, equivalent to pots), which were also the same doses for the treatment residual N rate. In both cycles, at harvesting the stem yield and the total recoverable sugar (TRS) were determined for calculation of gross income of sugar and alcohol. The plant cane was not affected significantly by any of the factors evaluated. Interactions between the residual N doses and water replacements influenced the TRS and the gross income of sugar and alcohol in ratoon cane, proving that the N applied on a cycle can be leveraged by another; the stem productivity was affected only by water replacements. Key words: Residual nitrogen, sugar yield, alcohol yield, irrigation, stem productivity.

Background and aims Phosphorus (P) is a mobile nutrient in the plant so growth depends on its internal remobilization and a plant’s ability to respond to its availability in the growing media. This study was conducted to evaluate the influence of P status and rootstocks on the patterns of P uptake and remobilization in orange trees. Methods Sweet orange trees on Cleopatra mandarin (CM) or Rangpur lime (RL) rootstocks were grown for nine months in nutrient solution (NS) that was either P-deficient (DNS) or was P-sufficient (SNS). After this period, half of the trees were reciprocally transferred between DNS and SNS (from D to S and S to D), while the others remained in their initial P availability. Results Trees on RL had more shoot and root growth, accumulated more P and had greater efficiency of P absorption and transport to the shoot (PAE) than those on CM. The major source of P for growth was previously stored P even with an adequate current P supply to the roots. This suggested the dominance of P remobilization over P uptake and the requirement that trees had sufficient stored P to meet P demand of new growth. Trees on CM had greater concentrations of remobilized P in new shoots than trees on RL. Conclusion Trees grafted on rootstocks less able to take up P (CM) were more dependent on the internal reserves of P for new growth than rootstocks with higher PAE (RL).

In low fertility tropical soils, boron (B) deficiency impairs fruit production. However, little information is available on the efficiency of nutrient application and use by trees. Therefore, this work verified the effects of soil and foliar applications of boron in a commercial citrus orchard. An experiment was conducted with fertigated 4-year-old ‘Valencia’ sweet orange trees on ‘Swingle’ citrumelo rootstock. Boron (isotopically-enriched 10B) was supplied to trees once or twice in the growing season, either dripped in the soil or sprayed on the leaves. Trees were sampled at different periods and separated into different parts for total B contents and 10B/11B isotope ratios analyses. Soil B applied via fertigation was more efficient than foliar application for the organs grown after the B fertilization. Recovery of labeled B by fruits was 21% for fertigation and 7% for foliar application. Residual effects of nutrient application in the grove were observed in the year after labeled fertilizer application,...

O objetivo deste trabalho foi avaliar o efeito do modo de aplicação do superfosfato triplo (SFT), do fosfato natural reativo de Gafsa e da mistura entre essas fontes no aproveitamento do fósforo (P) por plantas de milho e de soja. Os experimentos foram realizados em casa de vegetação, e as plantas foram cultivadas em vasos com Latossolo Vermelho-Amarelo distrófico. As fontes fosfatadas foram aplicadas isoladamente ou em misturas (proporção 1:1), à dose de 90 mg kg-1 de P, de modo não localizado ou localizado no solo. Para a quantificação do P absorvido pelas plantas das diferentes fontes, empregaram-se tratamentos com o solo e com o SFT marcados com 32P. O aproveitamento do fósforo do superfosfato triplo aplicado de forma localizada (9,8%) foi superior ao da não localizada (7%). A aplicação não localizada do fosfato natural reativo proporcionou maior aproveitamento do fósforo (3,8%), em comparação à localizada (0,5%). Em comparação à aplicação isolada do fosfato de Gafsa, o aproveitamento do fósforo pelas plantas de milho e soja aumentou quando essa fonte foi aplicada como mistura compactada; em presença do superfosfato triplo, a aplicação do fosfato natural reativo de Gafsa de modo não localizado proporcionou maior aproveitamento do P pelas plantas de soja. O aproveitamento do fósforo do fosfato natural de Gafsa aumenta quando aplicado ao solo com o superfosfato triplo, e esse efeito depende do método de aplicação das fontes fosfatadas. The objective of this work was to evaluate the effects of methods of applying triple superphosphate (TSP), Gafsa reactive phosphate rock and mixtures between these sources on phosphorus (P) utilization by maize and soybean plants. The experiments were carried out in a greenhouse, and the plants were grown in pots containing Typic Haplustox soil. The phosphorus sources were applied isolatedly or mixed (1:1 ratio) in a P rate of 90 mg kg-1, in a non-localized or in a localized manner in the soil. To quantify plant-absorbed phosphorus from the different sources, treatments with soil and TSP labeled with 32P were used. Phosphorus utilization from triple superphosphate applied locally was superior (9.8%) to the P utilization of this source applied non locally to the soil (7%). Inversely, better results with Gafsa phosphate rock occurred with P applied non locally to soil (3.8%), compared to the values obtained when the fertilizer was applied locally (0.5%). The phosphorus utilization from the Gafsa phosphate rock by maize and soybean plants increased when it was applied as compacted triple superphosphate and Gafsa phosphate rock mixture. In the presence of triple superphosphate, the soil-incorporated application of Gafsa phosphate rock led to greater utilization of phosphorus by soybean plants. The utilization of Gafsa phosphate rock phosphorus increases when it is applied together with triple superphosphate; and this effect depends on the methods of application of these phosphate sources.

The availability of phosphorus (P) from " Patos de Minas" phosphate rock (PR) can be improved if it is applied mixed with a water-soluble P source. The objective of this study was to evaluate 32P as a tracer to quantify the effect of the ratio of mixtures of triple superphosphate (TSP) with PR and the rates of application on P availability from PR. Two experiments were conducted in a greenhouse utilizing corn (Zea mays L.) plants as test crop. In the first experiment, the P sources were applied at the rate of 90 mg P kg-1 soil either separately or as compacted mixtures in several TSP:PR ratios (100:0, 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100 calculated on the basis of the total P content). In the second experiment, the TSP was applied alone or as 50:50 compacted mixtures with PR applied at four P rates (15, 30, 60 and 90 mg P kg-1) while the sole PR treatment was applied at the 90 mg kg-1 P rate . The mixture of PR with TSP improved the P recovery from PR in the corn plant and this effect increased proportionally to the TSP amounts in the mixture. When compared with the plant P recovery from TSP (10.52%), PR-P recovery (2.57%) was much lower even when mixed together in the ratio of 80% TSP: 20% PR. There was no difference in PR-P utilization by the corn plants with increasing P rates in the mixture (1:1 proportion). Therefore, PR-P availability is affected by the proportions of the mixtures with water soluble P, but not by P rates. A disponibilidade de fósforo do fosfato natural de Patos de Minas (FN) pode ser melhorada se aplicado junto com uma fonte de P solúvel em água. O objetivo desse estudo foi usar o 32P como traçador para quantificar o efeito das doses e das proporções das misturas de superfosfato triplo (SFT) com FN no aumento da disponibilidade de P do FN. Dois experimentos foram desenvolvidos em casa-de-vegetação com plantas de milho (Zea mays L.) como cultura teste. No primeiro experimento as fontes de fósforo, na dose de 90 mg kg-1 de P, foram aplicadas sozinhas ou em misturas compactadas e em várias proporções de SFT com FN (80:20, 60:40, 50:50, 40:60 e 20:80) calculadas com base no teor de P total, enquanto que no segundo, o superfosfato triplo foi aplicado tanto sozinho como em misturas compactadas com o fosfato natural de Patos e em quatro doses de P (15, 30, 60 e 90 mg kg-1) na proporção de 50:50 e o FN sozinho na dose de 90 mg P kg-1. A mistura do FN com o SFT melhorou o aproveitamento do P do FN pelo milho e esse efeito foi crescente com o aumento da proporção do SFT na mistura. Se comparado com o aproveitamento do P do SFT (10,52%) pelas plantas o aproveitamento do P do FN (2,57%) foi baixo, mesmo na proporção de 80% SFT: 20% FN. Não houve diferença no aproveitamento do P do PR entre as doses da mistura na proporção de 1:1. Portanto, a disponibilidade de P do FN é afetada pela proporção das misturas com a fonte solúvel de P, mas não pelas doses deste nutriente.

O nitrogênio é o nutriente mineral extraído em maior quantidade pelo milho, o que mais influencia a produtividade de grãos e o único absorvido como cátion (NH4+) ou anion (NO3-). Os objetivos deste trabalho foram investigar o acúmulo pelos grãos de milho do nitrogênio aplicado ao solo sob as formas amoniacal e nítrica, do nitrato de amônio, comparado à amídica, da uréia, marcados com 15N; determinar o estádio de desenvolvimento da planta de milho em que se atinge o máximo aproveitamento do N do fertilizante pelos grãos e; quantificar o N do solo exportado pelos grãos de milho. O estudo foi desenvolvido no Polo Regional do Desenvolvimento dos Agronegócios do Noroeste Paulista (APTA), em Votuporanga (SP), em um Latossolo Vermelho. O delineamento experimental foi o de blocos casualizados com 13 tratamentos e quatro repetições, dispostos em esquema fatorial 6 x 2 + 1 (testemunha, sem aplicação de N). Utilizou-se uma dose equivalente a 120 kg ha-1 de nitrogênio, compreendida pelas fontes uréia-15N e nitrato de amônio, com enriquecimento no cátion NH4+ (15NH4+NO3-) ou no anion NO3- (NH4+15NO3- ), aplicado em seis parcelamentos de 20 kg ha-1 de N, em microparcelas distintas, desde a semeadura até o estádio fenológico 7 (grãos pastosos). O nitrogênio aplicado sob a forma amoniacal ou nítrica foi acumulado equitativamente pelo milho. O milho acumulou mais nitrogênio da uréia do que do nitrato de amônio. O N aplicado ao milho no estádio de oito folhas expandidas promoveu maior acúmulo deste nutriente nos grãos. Nitrogen is the most absorbed mineral nutrient by corn crop and most affects grains yield. It is the unique nutrient absorbed by plants as cation (NH4+) or anion (NO3-). The objectives of this work were to investigate the N accumulation by corn grains applied to the soil as NH4+ or NO3- in the ammonium nitrate form compared to amidic form of the urea, labeled with 15N; to determine the corn growth stage with highest fertilizer N utilization by the grains, and to quantify soil nitrogen exported by corn grains. The study was carried out in the Experimental Station of the Regional Pole of the Sao Paulo Northwestern Agribusiness Development (APTA), in Votuporanga, State of Sao Paulo, Brazil, in a Red Latosol. The experimental design was completely randomized blocks, with 13 treatments and four replications, disposed in factorial outline 6x2 + 1 (control, without N application). A nitrogen rate equivalent to 120 kg N ha-1 as urea-15N or as ammonium nitrate, labeled in the cation NH4+ (15NH4+NO3-) or in the anion NO3- (NH4+15NO3- ), was applied in six fractions of 20 kg N ha-1 each, in different microplots, from seeding to the growth stage 7 (pasty grains). The forms of nitrogen, NH4+-N and NO3--N, were accumulated equitably by corn grains. The corn grains accumulated more N from urea than from ammonium nitrate. The N applied to corn crop at eight expanded leaves stage promoted largest accumulation of this nutrient in the grains.

O conhecimento da variabilidade da nutrição de plantas e da produtividade em áreas cultivadas pode fornecer importantes subsídios na racionalização do uso de insumos e auxiliar no manejo da fertilidade do solo. O objetivo deste trabalho foi avaliar a variabilidade da nutrição mineral de plantas de milho por meio do fracionamento de um talhão cultivado comercialmente em células de manejo e verificar as relações com a produtividade. O estudo foi realizado na Fazenda Alto Alegre, em Planaltina (GO), em área de 373 hectares de Latossolo Vermelho-Amarelo Distroférrico, cultivado com milho na safra 2003/04. Traçado um polígono da área, procedeu-se sua divisão em 80 células de manejo de quatro hectares cada uma. A amostragem de folhas em cada célula seguiu uma diagonal com 12 pontos para compor uma amostra composta. Realizou-se a análise dos macro e micronutrientes nas folhas. A produtividade para cada célula foi obtida por meio de colhedora equipada com GPS. Na análise da variabilidade dos resultados foram considerados os parâmetros estatísticos descritivos. O teste ausência de correlação foi realizado com o nível de significância de 5%. A variabilidade da concentração dos nutrientes na folha indicadora do milho foi considerada baixa para N, P, K, S e Mg; e média para Ca, Cu, Fe, Mn e Zn. A variabilidade da produtividade de milho revelou diferenças de produção para cada célula analisada. Os coeficientes de correlação entre os nutrientes e a produtividade foram significativamente diferentes de zero (p

A new Cockcroft–Walton (CW)-type high-voltage DC generator with RF air-core transformer used as a step-up transformer has been developed. The design concept of the air-core transformer is shown, which is operated on the resonance condition between the inductance of the secondary coil and the stray capacitance of CW circuit with the conical-type coil structure. Adapting the RF air-core transformer to CW circuit with DC-300 kV 100 mA, excellent performances have been demonstrated. In the new CW circuit, it results in downsizing of capacitors to operate at higher frequency than conventional ones, and reduction of the volume by approximately 40% has been shown in the typical DC generator with 1 MV 100 mA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(1): 18–26, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20500

O conhecimento da variabilidade da fertilidade do solo em áreas cultivadas pode trazer importantes subsídios para a racionalização de uso dos corretivos e fertilizantes do solo. O objetivo deste estudo foi determinar a variabilidade da fertilidade do solo por meio do fracionamento de um talhão comercial em pequenas células de manejo. O experimento foi realizado na Fazenda Alto Alegre em Planaltina - GO, numa área de 373 ha de um Latossolo cultivada com milho na safra 2003/04. Traçado um polígono da área, procedeu-se à divisão em 80 células de manejo de quatro hectares cada. A amostragem do solo seguiu uma diagonal com doze pontos para formar a amostra composta representativa dentro de cada célula. As coordenadas desses pontos foram obtidas e arquivadas. Realizou-se a análise da textura do solo e da fertilidade do solo. A produtividade de cada célula foi obtida por meio da colhedora equipada com Sistema de Posicionamento Geográfico (GPS) e monitor de rendimento de grãos. Na análise da variabilidade espacial dos dados, foram considerados parâmetros estatísticos descritivos. A medida de correlação linear de Pearson a 5 e 1 % dos atributos de fertilidade com a produtividade do milho e altitude foi realizada. A variabilidade foi considerada alta para o P disponível, Cu e Zn; média, para matéria orgânica, S, Ca, Mg, acidez potencial, soma de bases, capacidade de troca de cátions a pH 7,0, saturação por bases, B, Fe e Mn, e baixa, para pH e K. Os coeficientes de correlação linear foram significativos e positivos para a matéria orgânica e boro versus produtividade do milho. Contudo, para Cu, manganês e Zn foram significativos e negativos. Em estudos de escala de campo, normalmente não é possível isolar ou medir todos os fatores bióticos e abióticos que influenciam a produção da cultura. Entretanto, verificou-se que o conhecimento da variabilidade da fertilidade e produtividade pode fornecer importantes subsídios para a racionalização do uso de insumos. Insights on the variability of soil fertility in cultivated areas can contribute significantly to a rationalized use of fertilizers and soil amendments. The objective of this study was to determine the soil fertility variability through the fractionation of a commercial corn field into small management cells. The study was carried out on the farm Alto Alegre, Planaltina, GO, Brazil, on an Oxisol previously under Cerrado (savannah) in an area of 373 ha under corn in the 2003/2004 growing season. A polygon was outlined and divided into 80 management cells of 4 ha each. The soil was sampled at twelve points along the plot diagonal to constitute a representative composite sample within each cell. The coordinates of these points were obtained and recorded. The soil samples were analyzed for texture and soil fertility. The yield for each cell was obtained with a harvester equipped with a Global Positioning System (GPS) and grain yield monitor. Descriptive statistics parameters were considered in the analysis of data variability. It was carried out Pearson's simple linear correlation analysis at 5 and 1% significance level for soil fertility versus corn grain yield and altitude data. The variability was considered high for soil available phosphorus, copper and zinc concentrations; medium for soil organic matter, sulphur, calcium, and magnesium concentrations, potential acidity, sum of bases, CEC, base saturation, boron, iron as well as manganese concentration, but low for soil pH and potassium concentration. Linear correlation coefficients (LCC) were significant and positive for soil organic matter and boron content versus corn yield. However, the LCC for copper, manganese and zinc content were significant and negative. Although it is normally not possible to isolate or measure all biotic and abiotic factors that affect the yield in field scale studies, knowledge on soil fertility variability and grain yield can contribute to a rationalization of agricultural investments.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:46:00Z No. of bitstreams: 1 S0100-06832006000400013.pdf: 138417 bytes, checksum: 571c7bb52955cc2d66572ad6540c5fda (MD5) Made available in DSpace on 2013-08-22T18:46:00Z (GMT). No. of bitstreams: 1 S0100-06832006000400013.pdf: 138417 bytes, checksum: 571c7bb52955cc2d66572ad6540c5fda (MD5) Previous issue date: 2006-08-01 Made available in DSpace on 2013-09-30T18:13:52Z (GMT). No. of bitstreams: 2 S0100-06832006000400013.pdf: 138417 bytes, checksum: 571c7bb52955cc2d66572ad6540c5fda (MD5) S0100-06832006000400013.pdf.txt: 40779 bytes, checksum: f0a6cad0dcd9404e5a9723a5af8f4429 (MD5) Previous issue date: 2006-08-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:30:23Z No. of bitstreams: 2 S0100-06832006000400013.pdf: 138417 bytes, checksum: 571c7bb52955cc2d66572ad6540c5fda (MD5) S0100-06832006000400013.pdf.txt: 40779 bytes, checksum: f0a6cad0dcd9404e5a9723a5af8f4429 (MD5) Made available in DSpace on 2014-05-20T13:30:23Z (GMT). No. of bitstreams: 2 S0100-06832006000400013.pdf: 138417 bytes, checksum: 571c7bb52955cc2d66572ad6540c5fda (MD5) S0100-06832006000400013.pdf.txt: 40779 bytes, checksum: f0a6cad0dcd9404e5a9723a5af8f4429 (MD5) Previous issue date: 2006-08-01 O não revolvimento do solo com cultivo de adubos verdes na entressafra e o manejo da adubação nitrogenada alteram, geralmente, a dinâmica e a recuperação do N no sistema solo-planta. O objetivo deste trabalho foi avaliar a quantidade de N nativo do solo absorvido pelo milho em plantio direto, sob diferentes doses de N, em sucessão à crotalária (Crotalaria juncea), ao milheto (Pennisetum americanum) e à vegetação espontânea (pousio) em um Latossolo Vermelho no Cerrado. O estudo foi desenvolvido na fazenda experimental da Faculdade de Engenharia de Ilha Solteira-UNESP, Selvíria-MS, nos anos agrícolas 2001/02 e 2002/03. O delineamento experimental foi o de blocos casualizados com 15 tratamentos e quatro repetições, dispostos em esquema fatorial, 5 x 3, sendo cinco doses de N, na forma de uréia (0, 30, 80, 130 e 180 kg ha-1) e três sistemas de cobertura do solo (crotalária, milheto e o solo em pousio na entressafra). A quantidade de N nativo do solo absorvida pelo milho foi calculada pela diferença entre total de N acumulado na planta de milho, na época da maturação fisiológica, e o somatório do N proveniente da uréia, do milheto ou da crotalária determinados pelo método isotópico com 15N. O solo forneceu a maior quantidade de N para o milho, comparada à do fertilizante inorgânico conjuntamente à dos adubos verdes. As doses de N e os sistemas de cobertura do solo influenciaram significativamente a absorção de N nativo do solo pelo milho. In untilled soils with green manure cultivation in during the dry season and the management of the nitrogen fertilization usually change the dynamics and the recovery of the nitrogen in the soil-plant system. The objective of this study was to evaluate the amount of native soil nitrogen absorbed by corn under no-tillage and submitted to different N rates in succession to sunnhemp (Crotalaria juncea), millet (Pennisetum americanum) and fallow in a Red Latosol in the Cerrado. The experiment was carried out on an Experimental Farm of the Faculty of Engineering, São Paulo State University (UNESP-Ilha Solteira), which is situated in Selvíria, state of Mato Grosso do Sul, Brazil, during the 2001/02 and 2002/03 growing seasons. The experiment was set up in a randomized complete block design, with 15 treatments and four replications in a 5 x 3 factorial scheme, which consisted of the combination of five urea-N rates (0, 30, 80, 130 and 180 kg ha-1 of N) and three preceding cover crops (sunnhemp, millet and fallow ground). The amount of soil native N absorbed by corn was calculated by the difference between the total N accumulated in the corn plant at physiologic maturation stage and the amount of N coming from urea, millet or sunnhemp as determined by the 15N isotopic method. The soil supplied greater N amounts to corn than the inorganic fertilizer and green manures combined. The N rates and cover crop systems significantly influenced the uptake of soil native nitrogen by corn plants. USP CENA UNESP FEIS Departamento de Solos e Engenharia Rural USP ESALQ Programa de Pós-Graduação em Irrigação e Drenagem UNESP FEIS Departamento de Solos e Engenharia Rural

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:46:54Z No. of bitstreams: 1 S0100-204X2006000300015.pdf: 1049103 bytes, checksum: 9c33904675e800143e48a59a5e5a8be2 (MD5) Made available in DSpace on 2013-08-22T18:46:54Z (GMT). No. of bitstreams: 1 S0100-204X2006000300015.pdf: 1049103 bytes, checksum: 9c33904675e800143e48a59a5e5a8be2 (MD5) Previous issue date: 2006-03-01 Made available in DSpace on 2013-09-30T19:36:29Z (GMT). No. of bitstreams: 2 S0100-204X2006000300015.pdf: 1049103 bytes, checksum: 9c33904675e800143e48a59a5e5a8be2 (MD5) S0100-204X2006000300015.pdf.txt: 43241 bytes, checksum: be9f8fdceb252d47df5c82bedea0f1f9 (MD5) Previous issue date: 2006-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:09:49Z No. of bitstreams: 2 S0100-204X2006000300015.pdf: 1049103 bytes, checksum: 9c33904675e800143e48a59a5e5a8be2 (MD5) S0100-204X2006000300015.pdf.txt: 43241 bytes, checksum: be9f8fdceb252d47df5c82bedea0f1f9 (MD5) Made available in DSpace on 2014-05-20T15:09:49Z (GMT). No. of bitstreams: 2 S0100-204X2006000300015.pdf: 1049103 bytes, checksum: 9c33904675e800143e48a59a5e5a8be2 (MD5) S0100-204X2006000300015.pdf.txt: 43241 bytes, checksum: be9f8fdceb252d47df5c82bedea0f1f9 (MD5) Previous issue date: 2006-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) O objetivo deste trabalho foi definir a melhor dose e época de aplicação, e a eficiência de utilização do N, utilizando-se uréia marcada com 15N, pelo milho cultivado sob plantio direto, em sucessão à crotalária (Crotalaria juncea), ao milheto (Pennisetum americanum) e à vegetação espontânea (pousio), em um Latossolo Vermelho no Cerrado. O delineamento experimental foi o de blocos ao acaso, com 24 tratamentos e quatro repetições, em esquema fatorial incompleto, 3x3x2 + 6: três doses de N (80, 130 e 180 kg ha-1); três sistemas de cobertura do solo (crotalária, milheto e pousio); duas épocas de aplicação do N (estádio quatro ou oito folhas); e seis tratamentos adicionais (três sem aplicação de N e três que receberam 30 kg ha-1 de N na semeadura). O cultivo do milho em sucessão à crotalária proporciona maior quantidade na planta e aproveitamento pela planta do N proveniente do fertilizante e maior produtividade de grãos. A aplicação do N ao milho com quatro folhas proporciona maior produtividade de grãos, comparada à aplicação com oito folhas, quando em sucessão ao milheto. The objective of this work was to evaluate the best rate and time for N application, and N utilization using urea-15N, by corn crop grown under no-tillage system, in succession to sun hemp (Crotalaria juncea L.), millet (Pennisetum americanum) and to the spontaneous vegetation (fallow ground), in a Rhodic Hapludox soil in Cerrrado. The experimental design was randomized complete blocks, with 24 treatments and four replications, in an incomplete factorial 3x3x2 + 6: three N rates (80, 130 and 180 kg ha-1 N); three preceding cover crops (sun hemp, millet and fallow ground); two N application time (four leaves or eight leaves stage); and six additional treatments (three without N application and three that received 30 kg ha-1 N at seeding). The corn grown in succession to sun hemp provided higher amount of N derived from fertilizer, N utilization efficiency and grain yield. Application of N to corn four leaves stage provides higher grain yield, compared to the application to eight leaves stage, in succession to millet. Universidade de São Paulo Centro de Energia Nuclear na Agricultura Universidade Estadual Paulista Júlio de Mesquita Filho Universidade Estadual Paulista Júlio de Mesquita Filho

Eucalyptus plantation in Brazil is generally set on low fertility soils, therefore phosphorus (P) fertilization is mandatory and increases the cost of plantation operation. Using species that more efficiently uptake phosphorus from less soluble sources is an interesting option. However, little is known about eucalyptus regarding its ability of using less soluble forms of phosphorus. The use of P by eucalyptus (E. urophylla, E. grandis, and E. urophylla ´ E. grandis) was studied in greenhouse using a loamy-textured, hipodystrophic Typic Haplustox from the Cerrado region, and 32P isotopic method. The P sources tested were triple superphosphate (TSP), phosphate rock (PR) and the triple superphosphate mixed with PR (TSP+PR). The effectiveness of P sources in terms of increasing dry matter yield was TSP = (TSP + PR) > PR, and the P uptake followed the order (TSP + PR) > TSP > PR for both species plus the hybrid. The increase in P uptake from PR due to TSP influence was 217.3% for E. urophylla, 235.7% for E. grandis, and 28.7% for E. urophylla ´ E. grandis, indicating an enhancement effect of TSP on the effectiveness of PR. The hybrid E. urophylla ´ E. grandis was the most efficient genotype on P soil use and E. grandis most exigent in P fertilizer. Como geralmente os solos usados para plantações de eucalipto no Brasil são de baixa fertilidade, a adubação fosfórica é indispensável, incrementando o custo da plantação. Espécies mais eficientes no uso de fósforo (P) de fontes pouco solúveis poderiam ser uma opção interessante. Porém, pouco se conhece ainda sobre o comportamento de eucalipto em relação à capacidade de usar fósforo de fontes com diferente solubilidade em água. O uso de P por eucalipto (E. urophylla, E. grandis, and E. urophylla ´ E. grandis), foi estudado em experimento de casa de vegetação usando solo da Região de Cerrado, Latossolo Vermelho Amarelo hypodistrófico, e o método isotópico com 32P. As fontes de P usadas foram superfosfato triplo (SFT), rocha fosfórica (RF) e a mistura de superfosfato triplo com rocha fosfórica (SFT+RF). A eficácia das fontes de P em termos do aumento do rendimento de matéria seca seguiu a ordem SFT = (SFT + RF) > RF e de P absorvido a ordem (SFT + RF) > SFT > RF por ambas as espécies e o híbrido de eucalipto. O incremento na absorção de P de RF, influenciada pela mistura com SFT foi de 217,3% em E. urophylla, 235,7% em E. grandis e 28,7% em E. urophylla ´ E. grandis, indicando o efeito benéfico do SFT sobre a efetividade da RF. O híbrido E. urophylla ´ E. grandis foi o genótipo mais eficiente no uso de P do solo e E. grandis o mais exigente em P do fertilizante.

A conceptual model of water and solute transport pathways was developed and applied to a pasture hillslope in the southwestern Brazilian Amazon basin using select field measurements. Infiltration-excess or Horton overland flow (HOF), saturation overland flow (SOF), and groundwater in both the near-stream zone and upslope were sampled on a hillslope draining a 3Ð9 hectare pasture for a total of ten storms during the first half of the rainy season (October–November) in 2002. A Soil Conservation Service SCS curve number model of HOF and an annual water balance of both upslope and near-stream zones were used to calculate the contribution of each flowpath to solute export. HOF occurred in rainstorms greater than 5 mm and accounted for ¾8% of annual rainfall. Flow generated in the near-stream zone was ¾8% of annual rainfall. Sub-surface flow from upslope groundwater dominated annual runoff (¾19–30% of annual rainfall). Solutes fell into three categories according to flowpath. HOF from upslope positions dominated the export of total phosphorus (TP) and total dissolved phosphorus (TDP, 51–72% of total annual export). The near-stream zones controlled the export of K (58–65%), total dissolved nitrogen (TDN, 76–80%), and total nitrogen (TN, ¾75%) owing to relatively high solute concentrations and the large volume of water that flowed through the near-stream zone. Na and Si export was via groundwater from upslope (50–67% of annual export). The flux calculations were based on a small number of storms and are preliminary estimates designed to identify broad patterns in solute export via different hydrologic pathways. Additional processes, especially N removal at the groundwater-stream interface and in the stream channel, may affect actual export rates at the watershed scale. Whereas HOF production is negligible in Amazon forests, it represents a significant pathway for additional loss of elements, especially phosphorus, from mature pasture systems. The evidence presented here shows that biogeochemical perturbations and enhanced solute fluxes continue for decades following deforestation for pasture. Copyright  2006 John Wiley & Sons, Ltd.

A new Cockcroft–Walton (CW)-type high-voltage DC generator with RF air-core transformer used as a step-up transformer has been developed. The design concept of the air-core transformer is shown, which is operated on the resonance condition between the inductance of the secondary coil and the stray capacitance of CW circuit with the conical-type coil structure. Adapting the RF air-core transformer to CW circuit with DC-300 kV 100 mA, excellent performances have been demonstrated. In the new CW circuit, it results in downsizing of capacitors to operate at higher frequency than conventional ones, and reduction of the volume by approximately 40% has been shown in the typical DC generator with 1 MV 100 mA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(1): 18–26, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20500

The phosphate fertilization represents the most costly fraction of soybean crop production. Efficient soybean cultivars for P absorption and utilization in soils of medium available P are highly desirable and might contribute for increasing crop production potential. Thirty two soybean [Glycine max (L.) Merr.] cultivars recommended for 'Cerrado' and differing in growth cycle (early, semi-early, semi-late, and late) were grown in a dystrophic Typic Haplustox Cerrado soil to evaluate the acid phosphatase activity, P content in the diagnostic leaf, and shoot biomass. There were differences among the soybean cultivars within all maturation groups in acid phosphatase activity and shoot biomass. The diagnostic-leaf P-content showed significant differences on semi-late and late maturation groups' cultivars. The acid phosphatase activity correlated positively with the plant shoot biomass from semi-early (r = 0.46) and late (r = 0.47) cultivars, and negatively (r = -0.40) with the P content in the diagnostic leaf of late maturation cultivars. The occurrence of soybean cultivars with high and low acid phosphatase activity within the same maturation groups indicates the existence of different mechanisms involving P mobilization in the soil and internal plant P remobilization. A adubação fosfatada corresponde à fração mais onerosa do custo de produção da cultura da soja. A obtenção de cultivares de soja eficientes na absorção e utilização de fósforo (P) em condição de média disponibilidade deste nutriente pode contribuir para aumentar o potencial produtivo da cultura. Trinta e dois cultivares de soja [Glycine max (L.) Merr.], de ciclo precoce, semiprecoce, semitardio e tardio, recomendados para o cerrado, foram cultivados em Latossolo Vermelho-Amarelo distrófico típico, do cerrado, objetivando avaliar a atividade da fosfatase ácida, concentração de P na folha diagnóstico e biomassa da parte aérea. Ocorreram diferenças entre os cultivares dentro de todos os ciclos de maturação na atividade da fosfatase ácida e na biomassa da parte aérea. Cultivares de ciclos semitardio e tardio apresentaram diferenças significativas quanto à concentração de fósforo na folha diagnóstico. A atividade da fosfatase ácida correlacionou-se positivamente com a biomassa da parte aérea nos cultivares dos ciclos semiprecoce (r = 0,46) e tardio (r = 0,47) e, negativamente (r = -0,40), com a concentração de P na folha-diagnóstico, nos cultivares do ciclo tardio. A ocorrência de cultivares de soja com alta e baixa atividade da fosfatase ácida dentro do mesmo ciclo de maturação sinalizam a existência de diferentes mecanismos envolvidos na mobilização de P no solo e remobilização interna deste nutriente na planta entre os grupos de cultivares.

Nitrogen (15N) released from sunnhemp (Crotalaria juncea), velvet bean (Mucuna aterrima) and from Phaseolus bean residues was evaluated after incubation of the plant material in an Eutrudox and a Paleudalf, in a greenhouse experiment with pots containing 6 kg of air dried soil. Dry matter equivalent to 13 Mg ha-1 of Phaseolus bean residues and the same amount of above ground parts of the leguminous species, associated to 2.7 and 2.2 Mg ha-1 of roots of sunnhemp and velvet bean respectively, were incorporated into the soil. A completely randomized experimental design was adopted, with treatments arranged in a 2 ´ 3 + 1 factorial, replicated three times. The treatments were the following: two soils (Eutrudox and Paleudalf) and three plant materials: two green-manures (sunnhemp or velvet bean), and Phaseolus bean residues, besides one control without plant incorporation into the soil. For the green-manure treatments there were two sub-treatments for each legume species, with 15N labeling of either shoots or roots. Soil moisture was maintained relatively constant during the experiment al period and the treatments were sampled weekly during 49 days. Total mineral nitrogen in the soil, as well as that derived from the legume plants were determined by isotope dilution. Nitrogen from the velvet bean accounted for a greater proportion of the soil inorganic N; shoots were responsible for most of N accumulated. Dry bean residues caused immobilization of inorganic N. The leguminous species added were intensively and promptly mineralized preserving the soil native nitrogen. Mineralization of the legume plant N was greater in the Paleudalf soil than in the Eutrudox. Estudou-se a mineralização do nitrogênio derivado das leguminosas adubo verde (mucuna-preta e crotalária juncea) e de restos culturais de feijoeiro, marcados com 15N, incorporados em dois solos, Latossolo Vermelho eutroférrico textura argilosa, A moderado (LVef) e Argissolo Vermelho-Amarelo distrófico textura arenosa/média, A moderado (PVad). O trabalho foi desenvolvido em casa de vegetação, em vasos com 6 kg de terra fina seca ao ar. Incorporou-se aos solos o equivalente a 13 Mg ha-1 de material seco de palha de feijão e mesma quantidade da parte aérea das leguminosas associadas a 2,7 e 2,2 Mg ha-1 de raízes de mucuna-preta e crotalária juncea respectivamente. Adotou-se um delineamento experimental inteiramente casualizado com três repetições e os tratamentos originaram-se de um fatorial 2´ 3 + 1 e foram os seguintes: dois solos (LV ef e PV ad) e incorporação de três tipos de leguminosas, sendo dois adubos verdes (mucuna-preta e crotalária juncea), e resíduo cultural de feijoeiro, além de uma testemunha sem adição de material vegetal. Os tratamentos com adubos verdes foram divididos em subtratamentos com marcação isotópica independentes da parte aérea e raízes. Os solos foram incubados por 49 dias fazendo-se sete amostragens em intervalos de sete dias. A palha de feijão causou imobilização do N-mineral no solo. A mucuna-preta contribuiu em maior proporção do nitrogênio mineral do solo, principalmente a parte aérea. O N do material vegetal das leguminosas foi mineralizado mais intensamente, preservando o nitrogênio presente no material orgânico original dos solos. A mineralização das leguminosas foi maior no solo Argissolo Vermelho-Amarelo.

One of the main factors limiting agricultural production in tropical climate regions is mainly related to the presence of exchangeable aluminum (Al3+) in highly weathered acid soils. Four methods of Al3+ determination extracted with neutral 1 mol L¹ KCl solution were evaluated: three colorimetric methods (aluminon plus ascorbic acid, and eriochrome cyanine R by FIA) and the usual titrimetric method with back-titration. Surface samples from 20 soils of different Brazilian regions, with active acidity (0.01 mol L¹ CaCl2 pH) ranging from very high to medium (3.82 to 5.52), were used. The variance analysis revealed significant interaction among Al3+ determination methods and soil. Mean methods comparisons within each soil (Tukey, P < 0.05) indicated that, for most of the soils, the methods differed among each other, although there were high correlations between the obtained values. Al3+ values determined for soil samples by titration varied between 0.15 and 14.71 mmol c dm³. The colorimetric methods showed higher values than the titration method, mainly for those with aluminon (up to 18.75 mmol c dm-3). The Al3+ contents of colorimetric methods correlated quadraticaly with the titration values, for the soil samples with Al3+ > 10 mmol c dm³. Among colorimetric methods, in operational terms, the eriochrome with FIA method presented analytical performance up to 50 samples per hour, easiness and sensibility for routine Al analysis in soil samples. However, due to the specificity, the titration/back-titration method should be used, despite the moroseness, when the Al3+ ions are the objective. Um dos principais fatores que afetam a produção agrícola em regiões de clima tropical, é a presença de alumínio trocável (Al3+) em solos ácidos altamente intemperizados. Foram avaliados quatro métodos de determinação de alumínio trocável em solução neutra de KCl 1 mol L¹: três métodos colorimétricos (aluminon, aluminon + ácido ascórbico e eriocromo cianina R por FIA) e o método titulométrico usual com retrotitulação ácida. Para obtenção dos extratos de KCl, foram usadas amostras superficiais de 20 solos de diferentes regiões brasileiras, com acidez ativa (pH em CaCl2 0,01 mol L¹) variando de muito alta a média (3,82 a 5,52). A análise de variância revelou interação significativa entre os métodos de determinação e amostras de solos. O teste de médias (Tukey, P < 0,05) de métodos dentro de amostras evidenciou, para a maioria das amostras de solos, que os métodos analíticos diferenciaram entre si, embora tenha havido forte correlação entre os valores obtidos. Os valores de Al3+ determinados por titulação variaram de 0,15 a 14,71 mmol c dm³. Os métodos colorimétricos apresentaram valores superiores aos da titulação, notadamente aqueles com aluminon (até 18,75 mmol c dm³). Os teores de Al3+ dos métodos colorimétricos se relacionaram quadraticamente com os teores obtidos por titulação, em amostras de solos com Al3+ > 10 mmol c dm³. Dentre os métodos colorimétricos, o reagente eriocromo cianina R, em sistema FIA, mostrou-se operacionalmente confiável e eficiente para a análise de Al, de amostras de solos, em rotina, com freqüência analítica de 50 determinações por hora. Todavia, devido à especificidade, o método titulométrico com retrotitulação deve ser usado, não obstante a morosidade, quando o objetivo é a determinação do íon Al3+.

Foram estudados os efeitos da aplicação de composto de lixo urbano, proveniente da usina de compostagem São Matheus da cidade de São Paulo, na dose de 30 g dm-3 (60 t ha-1), na presença e ausência de calcário dolomítico e adubos minerais, sobre os teores de carbono orgânico, de nitrogênio total e de fósforo e enxofre disponíveis de 21 solos ácidos e cinco solos alcalinos, onde o calcário foi substituído por gesso. O experimento foi realizado em condições de casa de vegetação com os solos nas parcelas em blocos ao acaso, com três repetições e os tratamentos em subparcelas. O acúmulo de matéria orgânica, em virtude da aplicação do composto, foi evidente em solos com teores iniciais de carbono orgânico > 12 g dm-3 e de nitrogênio > 1,3 g dm-3, porém com relação C/N < 12. Nos demais solos, o acúmulo foi decorrente da interação entre a estabilidade da matéria orgânica do composto, da matéria orgânica nativa e as propriedades físicas e químicas dos solos. A aplicação do composto aumentou os teores de nitrogênio total e de enxofre disponível em todos os solos, porém o fósforo disponível somente foi aumentado nos solos ácidos. A aplicação do composto de lixo urbano como fertilizante orgânico é viável, porém seus efeitos sobre as propriedades químicas do solo devem ser monitorados. A green house experiment was conducted to investigate the effects of the application of solid urban waste compost at a rate of 30 g dm-3 (60 t ha-1), on 21 acid and five alkaline soils in relation to their organic carbon, total nitrogen, available phosphorous and sulfur contents. Compost from the São Matheus Treatment Plant (São Paulo, Brazil) was applied with or without dolomitic lime and mineral fertilizers. In alkaline soils, lime was substituted by gypsum. The experiment was carried out with soils in the plots, in a completely randomized block design with three replicates, and treatments in the sub-plots. Compost application caused evident organic carbon accumulation in soils with initial organic carbon contents > 12 g dm-3 and nitrogen > 1.3 g dm-3, but a C/N ratio < 12. In the other soils, organic carbon accumulation was a consequence of the interaction between the stability of compost organic matter, original organic matter, and physical and chemical soil properties. Residue application increased the contents of total nitrogen and available sulfur in all soils, but available phosphorous only increased in acid soils. The use of solid urban waste compost as organic fertilizer in agricultural areas is viable under the condition, however, that its effects on chemical properties are properly monitored.

[PT] O presente trabalho foi conduzido no período de novembro de 2006 a junho de 2010, com objetivo de avaliar a produção de cana-de-açúcar, em três ciclos agrícolas consecutivos, após pré-cultivo de espécies adubos verdes. Os adubos verdes Crotalária-júncea, e Guandu IAC-fava larga apresentaram a maior produção de material vegetal fresco e seco. Para a produção de colmos e açúcar, com exceção ao tratamento mucuna-cinza que apresentou um comportamento semelhante à testemunha sem adubo verde, todos os adubos verdes aumentaram a produtividade, produzindo, na média de três cortes, 25% mais que o tratamento sem adubo verde. Os adubos verdes reduziram a ocorrência de plantas daninhas até o primeiro corte com destaque para as mucunas verde e cinza. Não foram observadas alterações na infecção natural por micorrizas, nem na infestação por broca da cana nos tratamentos com adubos verdes em relação à testemunha., [EN] This work was carried out to evaluate the sugarcane yield after a pre-cultivation of green manure species from November 2006 to June 2010. Sunn hemp and pigeon pea IAC-fava larga showed a higher production of fresh and dried plant material. For the production of stalks and sugar, except for the gray velvet beans treatment, that showed a behavior similar to the treatment without green manure. All the treatments with green manure increased yield, producing an average of 25% more than the treatment without green manure. Green manures had an effect on weed control with emphasis on green and gray velvet beans until the first cut of sugarcane. No changes were observed in the natural infection by mycorrhizal fungi, nor infestation by the sugarcane borer in the treatments with green manure in relation to the control., Ao CNPq pelo apoio (bolsa de produtividade em pesquisa do primeiro autor).

O uso agrícola do composto de lixo, como fertilizante orgânico, além de melhorar as propriedades do solo, representa uma alternativa importante para gestão de resíduos sólidos domiciliares. Foram estudados os efeitos da aplicação do composto de lixo, proveniente da cidade de São Paulo (Usina de compostagem São Matheus), na dose de 30 g dm-3 (60 t ha-1), na presença e ausência de calcário dolomítico e adubos minerais, sobre os teores de cátions trocáveis (K+, Ca2+, Mg2+ e Na+); a capacidade de troca de cátions (CTC) e a saturação por bases (V%) de 21 solos ácidos e 5 solos alcalinos. Nos solos alcalinos o calcário foi substituído por gesso. O experimento foi conduzido em condições de casa de vegetação em delineamento em blocos ao acaso, com parcelas em faixas e três repetições. Nos solos ácidos, a aplicação do composto de lixo promoveu aumentos nos teores trocáveis de potássio, cálcio, magnésio e sódio, em média, de 195%, 200%, 86% e 1200%, e elevação da CTC em 42%, refletindo na V%, com aumento médio de 39%. Nos solos alcalinos, esses efeitos foram menos pronunciados, refletindo porém, em média, em aumentos da CTC em 8,4% e da V% em 2%. Os maiores efeitos sobre as propriedades químicas avaliadas foram conseqüências das aplicações do composto + adubo + calcário, nos solos ácidos, e do composto + adubo + gesso, nos solos alcalinos. A aplicação agrícola do composto de lixo urbano é viável, porém seus efeitos sobres as propriedades químicas do solo devem ser monitorados. The use of urban organic solid waste compost as organic fertilizer is an important alternative to solid waste management. This waste has been applied to agricultural lands because of the benefits in relation to soil chemical properties. A greenhouse experiment was conducted to investigate the effects of the application of urban waste compost, at the rate of 30 g dm-3 (60 t ha-1), on the contents of exchangeable cations (K+, Ca2+, Mg2+, and Na+), on cation exchangeable capacity (CEC), and on base saturation (BS%) of 21 acid and 5 alkaline soils. The organic compost (collected at the São Matheus Plant Treatment, São Paulo, Brazil) was applied with or without dolomitic lime and mineral fertilizers. For alkaline soils, lime was substituted by gypsum. The experiment was carried out on a split-plot, completely randomized block design with three replicates. The compost application increased the exchangeable content of potassium, calcium, magnesium, and sodium on average of 195%, 200%, 86%, and 1200%, respectively, and elevated the CEC by 42% in acid soils. Consequently the BS% was increased 39%. A lower, but significant, increase on CEC was observed in alkaline soils in response to the compost application. Average CEC and BS% increases were of 8.4% and 2%, respectively. The highest effects on the evaluated soil properties were verified for compost + fertilizer + lime and compost + fertilizer + gypsum applications in acid and alkaline soils, respectively. It is concluded that the use of urban waste compost in agricultural lands is viable only if its effects on chemical properties are properly monitored.

In a multi-strata agroforestry system in the central Amazon near Manaus, we studied the root activity distribution of different fruit trees and a legume cover crop in comparison to monocultures and a secondary forest site. Uptake of applied 32P, 33P and 15N from 0.1, 0.6 and 1.5 m depth was compared in both the dry and wet season. The results obtained with 32P were similar to those with 15N but showed a higher variability, probably due to the lower mobility of P than N in soil and thus the labeling of a smaller soil volume with 32P. During the dry season, topsoil root activity measured with 15N was around 80% for all species with the exception of the palm tree Bactris gasipaes Kunth., which had a higher uptake from 0.6 m (50%) than from 0.1 m (30%). The subsoil (1.5 m) root activity was higher, when Bactris was not regularly cut for heart of palm harvest but grown for fruit production. Additionally, relative subsoil root activity of Theobroma increased and topsoil root activity of both Bactris and Theobroma decreased when intercropped in comparison to the monoculture. During the rainy season, the topsoil tree root activity slightly increased attributable to increasing water availability near the soil surface. The lowest isotope enrichment was noted for the secondary forest trees despite their low above ground biomass. The magnitude of the isotope enrichment was related to the foliar P and less pronounced to the foliar N contents, indicating higher nutrient cycling for nutrient-rich plant species. Despite the significant subsoil root activity (1.5 m) there was little evidence that large amounts of nutrients below 1 m depth can be recycled by the investigated tree species. More important may be a rapid recycling of nutrients from 0–1 m depth.

Separate assessment of nutrient uptake by individual plants in mixed cropping with trees is impossible without tracer techniques. The different 15N-to-14N isotope ratio of atmospheric and soil N can be used to study the contribution of biologically fixed N to the nutrition of associated trees. In most cases, the assessment of nutrient uptake distribution is an appropriate way of evaluating how to improve the transfer of biologically fixed N. Radioisotopes (e.g., 32P), stable isotopes (e.g., 15N) and rare elements (e.g., Sr) can be used to determine relative root activity distribution by applying the tracer to different soil depths or distances from trees. A broadcast application of the tracer instead of point application makes it possibe to calculate uptake values per unit area. The direct determination of nutrient pathways with such robust experiments offers considerable advantages for improving nutrient use efficiency and complementarity in multistrata agroforestry systems.

Desenvolveu-se, na Estação Experimental de Piracicaba - Instituto Agronômico (SAA-SP), de março/94 a setembro/95, um experimento para avaliar o potencial de fornecimento de nitrogênio de adubos, verde e mineral, aplicados, de forma exclusiva ou combinada, na cultura do milho. Em uma primeira fase, produziram-se, simultaneamente, mucuna-preta sem marcação isotópica no campo e adubo verde marcado com 15N em casa de vegetação e, na segunda, a mucuna-preta foi incorporada ao solo, cultivando-se, em seguida, milho. O experimento constou dos seguintes tratamentos: testemunha, 15N-mucuna-preta (4,4 t ha-1 de matéria seca e 25,8 g kg-1 de N), 15N-uréia (50 e 100 kg ha-1 de N) e as possíveis combinações de mucuna-preta e uréia marcadas ou não com 15N. Esses foram dispostos em delineamento experimental de blocos ao acaso com quatro repetições. O solo forneceu a maior parte do N acumulado nas plantas de milho, seguido, em ordem decrescente, pela uréia e mucuna-preta. A contribuição da uréia para o N acumulado nas plantas de milho foi proporcional à dose aplicada. O aproveitamento de nitrogênio da uréia pelo milho foi maior que o da mucuna-preta, sendo os melhores efeitos proporcionados pela combinação das duas fontes. An experiment was carried out at the Instituto Agronômico (SAA-SP) Experimental Station, in Piracicaba-SP, from March/94 to April/95, to evaluate the potential of velvet bean (Mucuna aterrima) green manure and urea, applied alone or combined, to supply nitrogen to corn crop. The experiment consisted of a preliminary phase for the production of velvet bean under field conditions and for the production of green manure labeled with 15N under greenhouse conditions. The green manure was later incorporated to the soil and corn was grown. The treatments were: control; 15N labeled green manure (4.4 t ha-1 of dry matter and 25.8 g kg-1 of N); 15N labeled urea (50 and 100 kg ha-1 of N); and the combinations of green manure and urea labeled or not with 15N. The experimental design was a randomized block with four replicates. Most of the accumulated N by corn was supplied by the soil, followed by urea and velvet bean. Urea contribution to accumulated N in corn was proportional to the applied rate. Utilization of urea N by corn was greater than that of green manure, with the best effects provided by the combination of the two sources.