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The objective was to evaluate the agronomic performance of black wattle seedlings (Acacia mearnsii) grown on substrates with increasing proportions of biochar based on anaerobic sewage sludge (ASS-biochar). In addition, the present study proposed appropriate ranges for the main physical-hydraulic and chemical attributes of these substrates. Made available in DSpace on 2022-03-10T02:03:53Z (GMT). No. of bitstreams: 1 Artigo-Agronomic-performance-and-optimal-ranges.pdf: 1807745 bytes, checksum: 88e79f479691a66dfe768a2557af74e2 (MD5) Previous issue date: 2021 Published online: 21 August 2021.

Efficient water use in agriculture is a global demand, and in this context, the implementation of a sprinkler irrigated rice system has become a reality. Besides saving water, proper management of a sprinkler irrigated system can maintain high levels of productivity. This study aimed to determine the effect of soil water tension on rice crop production, in both vegetative and reproductive stages, as well as to evaluate the effect of soil water availability and physicochemical attributes on biometric and reproductive characteristics associated to rice grain yield under sprinkler irrigation. The experiment was carried out at the Lowland Experimental Station, Embrapa Clima Temperado, Capão do Leão ? Rio Grande do Sul, Brazil, during two growing seasons, in an area irrigated by a lateral-move sprinkler irrigation system. The following irrigation managements were evaluated: irrigation, when the mean soil water tension was i) 10?kPa; ii) 20?kPa; iii) 40?kPa; iv) 40?kPa on vegetative and 20?kPa on reproductive stages and v) 40?kPa on vegetative and 10?kPa on reproductive stages. Under sprinkler irrigation, rice plant development was impaired as soil water tension increased, evidenced by a reduction in plant heights. Soil water tension of 10?kPa was adequate to manage the sprinkler irrigation in rice, especially in the reproductive stage and when using cultivars developed for flooded environments. Rice development and yield were affected by increasing soil bulk density and acidity. Rainwater represented approximately 40 % of the water used by sprinkler irrigated rice during the crop cycle, contributing with the reduction of irrigation water use. Made available in DSpace on 2020-12-02T09:07:05Z (GMT). No. of bitstreams: 1 Pinto-etal-2020.pdf: 567113 bytes, checksum: b82ff96fafd1b2026d3b539a67485f7c (MD5) Previous issue date: 2020

The aim of this study was to determine the impact of harvesting traffic by evaluating the spatial variability of soil physical attributes on a clayey Oxisol under sugarcane cultivation using different row spacing. Two areas of sugarcane production (RB855156 genotype) were planted in autumn 2013, both using conventional planting systems. Treatments were either sugarcane cultivated using: (i) single-row spacing (SR) of 1.50 m; or (ii) double-row spacing (DR) of 0.40 × 1.50 m. Areas using SR spacing occupied a total of 6 ha areas using DR spacing occupied a total of 2 ha. Assessments of soil physical attributes were performed during the summer of 2016 after the second harvest. Soil measurements in each area were done at 100 points using a grid design with dimensions of 10 m long by 5 m wide. Soil sampling was taken from the 0.00-0.10 m layer, from points distributed along the planted row and the machine?s wheel track. The following soil physical attributes were assessed: bulk density, total porosity, macroporosity, microporosity, soil penetration resistance, and water contentat field capacity. Bd and PR in the single-row spacing showed critical values for adequate sugarcane root development. The highest spatial variability of PR and Ma was found in double-row spacing, however, this spacing arrangement promoted a better soil physical conditions. Made available in DSpace on 2020-12-22T09:03:42Z (GMT). No. of bitstreams: 1 Panzieira-et-al.2020.pdf: 1390910 bytes, checksum: fdac74b0945a53bba592ce1add243526 (MD5) Previous issue date: 2020

O objetivo foi avaliar as propriedades físico-hídricas de diferentes substratos e seus efeitos no desenvolvimento de mudas de alface em sistema floating. O estudo foi realizado em casa de vegetação durante os meses de janeiro e fevereiro de 2017. O delineamento foi de blocos casualizados, com 16 tratamentos, representandos por 13 proporções de substratos à base de composto orgânico, casca de arroz carbonizada e vermiculita e três substratos comerciais. Foram avaliadas as características físico-hídricas (fração granulométrica, densidade seca, porosidade total, espaço de aeração, água facilmente disponível, água disponível, água remanescente e capacidade de retenção de água), pH e condutividade elétrica dos substratos. O número de folhas, altura das plantas, comprimento do sistema radicular, massa fresca de raiz e parte aérea e massa seca de raiz e parte aérea foram avaliados aos 25 dias após a emergência. O espaço de aeração e a água remanescente são as variáveis físico-hídricas aprioritárias que devem ser avaliadas em substratos que serão utilizados em sistema floating. As formulações com 33,33% de composto orgânico, 43,33 a 53,33% de casca de arroz carbonizada, e 23,33 a 13,33% de vermiculita apresentaram os melhores desempenhos entre os substratos estudados para a produção de mudas de alface em sistema floating. Made available in DSpace on 2020-12-10T09:04:42Z (GMT). No. of bitstreams: 1 3937-Texto-do-artigo-17081-1-10-20201106.pdf: 548763 bytes, checksum: 07423ede9c51e21f99faedb1b58ba5e3 (MD5) Previous issue date: 2020

Avaliou-se o efeito da retenção de água de substratos para plantas formulados a partir de diferentes proporções de lodo de esgoto (LETE) solarizado, na produção de mudas de acácia-negra (Acacia mearnsii). O experimento foi conduzido em casa de vegetação e no Laboratório de Física do Solo da Embrapa Clima Temperado. O LETE utilizado foi coletado em leitos de secagem de uma Estação de Tratamento de Esgoto aeróbio de Rio Grande - RS. Os tratamentos consistiram de cinco doses de LETE solarizado, combinadas com cinza de casca de arroz e vermiculita em diferentes proporções (20:40:40, 30:35:35, 40:30:30, 50:25:25 e 60:20:20) e dois substratos comerciais (Beifort® S10 B e Mec Plant®). O delineamento experimental foi de blocos casualizados. Foram avaliadas as características físico-hídricas: água facilmente disponível, água tamponante, água remanescente e capacidade de retenção de água. As variáveis de crescimento avaliadas foram: massa fresca da parte aérea e do sistema radicular. O substrato com 20% de LETE solarizado, 40% vermiculita e 40% cinza de casca de arroz apresentou a melhor condição físico-hídrica para o desenvolvimento de mudas de acácia-negra. Made available in DSpace on 2019-12-13T18:11:28Z (GMT). No. of bitstreams: 1 2019BambergCienciaRural.pdf: 540161 bytes, checksum: ff96713c084d9f2247defbd0d9ce1a51 (MD5) Previous issue date: 2019

Made available in DSpace on 2019-12-30T18:10:48Z (GMT). No. of bitstreams: 1 SeminaCiAgMittelmannProduction.pdf: 363245 bytes, checksum: 39152185b5b3d0a8133d04e3c3e2af64 (MD5) Previous issue date: 2019

Made available in DSpace on 2019-11-27T00:40:12Z (GMT). No. of bitstreams: 1 CarlosReisserAlex3707Textodoartigo1563811020191126.pdf: 925338 bytes, checksum: 32af2144e06cca6d5170ccbb2df0cb3b (MD5) Previous issue date: 2019

O objetivo deste trabalho foi determinar a influência da tensão de água e de atributos físicos e químicos do solo sobre a produtividade do arroz irrigado por aspersão, em terras baixas no Rio Grande do S l. Na safra 2011/2012, foram avaliados os efeitos das tensões de água no solo de 20 e 40 kPa, durante todo o ciclo da cultura, bem como as de 40 e 20 kPa nas fases vegetativa e reprodutiva, respectivamente. Na safra 2012/2013, foram avaliadas as tensões de 10, 20 e 40 kPa, durante todo o ciclo da cultura, e as de 40 e 10 kPa nas fases vegetativa e reprodutiva, respectivamente. Em ambas as safras, utilizou-se a cultivar de arroz irrigado BRS Pampa. O gasto com água na irrigação por aspersão representou 48% do gasto com a irrigação por inundação. A produtividade do arroz correlacionou-se positivamente com a microporosidade e com os teores de fósforo e potássio disponíveis no solo; e negativamente com a macroporosidade e a saturação por alumínio. A avaliação conjunta da tensão de água e de atributos físicos e químicos do solo permite avaliar com mais propriedade a variabilidade na produtividade de arroz irrigado por aspersão em terras baixas no Rio Grande do Sul. A irrigação por aspersão possibilita melhor uso da água proveniente da precipitação pluvial, com efeitos positivos sobre a economia de água. Made available in DSpace on 2017-04-12T12:47:14Z (GMT). No. of bitstreams: 1 WalkyriaProdutividadedearrozirrigado.pdf: 648665 bytes, checksum: 6219a06dc97fd5958f4a718d5d34e471 (MD5) Previous issue date: 2017-04-12

The knowledge of field management zones based on soil attributes can be helpful for the implementation of site-specific management. This work had the objective of analyzing the spatial dependence of soil attributes of the 0-0.20 m and 0.20-0.40 m layers of an Entisols Quartzipsamments, in Petrolina, Northeast Brazil, which has been cultivated with micro sprinkler irrigated grapevines. In a rectangular grid with 168 points spaced by 4.0 x 3.5 m, soil samples were collected from each layer to determine soil bulk density, contents of clay, silt and sand, soil water contents at field capacity and wilting point. All data sets were submitted to classic statistical and geostatistical analyses. For the 0-0.20 m layer, the distributions of soil bulk density, clay content and soil water content at field capacity presented a spatial dependence structure, with ranges of 10.0 m, 8.3 m and 7.2 m, respectively. In the 0.20-0.40 m layer, spatial dependence was found for soil density, sand content (6.6 m for both attributes) and soil water content at field capacity (6.8 m range). Distributions of silt and sand contents and soil water content at wilting point presented no spatial dependence in the upper layer as well as the clay and silt contents and soil water content at wilting pointing in the deeper layer. By constructing the soil attribute contour maps, distinct management zones were defined as well as their extension. Practical uses for irrigation scheduling purposes were proposed.

O estudo da relação entre as propriedades do solo é de grande importância na área agronômica objetivando um manejo racional dos recursos naturais do meio ambiente e um aumento na produtividade agrícola. Tradicionalmente este estudo tem sido realizado usando modelos de regressão estática os quais não levam em consideração a estrutura espacial envolvida. Este trabalho teve o objetivo de avaliar a relação entre uma variável de determinação mais cara e demorada (por exemplo, nitrogênio total do solo) e outras de mais barata e rápida determinação (p.e., carbono orgânico do solo, pH, etc.). Duas importantes classes de modelos (espaço de estados linear e redes neurais) são usadas para predição e comparadas aos modelos de regressão uni- e multivariados aqui usados como referência. Para tal, em uma área experimental cultivada com aveia, situada em Jaguariúna, SP (22º41? S e 47º00? W), amostras de um solo classificado como Latossolo foram coletadas na camada arável ao longo de uma transeção espacial de 194 m, eqüidistantes de 2 m. Os modelos de rede neural recorrente e de espaço de estados padrão tiveram uma melhor performance preditiva da variável nitrogênio total do solo quando comparados aos modelos de regressão padrão. Entre os modelos de regressão padrão o Autoregressivo Vetorial teve um melhor desempenho preditivo da variável nitrogênio total do solo.

The assessment of the relationship among soil properties (such as total nitrogen and organic carbon) taken along lines called transects is a subject of great interest in agricultural experimentation. This question has been usually approached through standard state-space methods by some authors in the soil science literature. Important limitations of the mentioned procedures used in practice are pointed out and discussed in this paper, specially those related to the model parameters, meaning and practical interpretation. In the standard state-space approach, based on an autoregressive structure, it does not present any parameters that express the variables relationship at the same point in space, but only at lagged points. Also, its model parameters (in the transition matrix) have a global meaning and not a local one, not expressing more directly the soil heterogeneity. Therefore, the objective here is to propose an alternative state-space approach, based on dynamic (space-varying parameters) regression models in order to avoid the mentioned drawbacks. Soil total nitrogen and soil organic carbon samples were collected on a Typic Haplustox. Samples were taken along a line (transect) located in the middle of two adjacent contour lines. The transect samples, totaling 97, were collected in the plow layer (0-0.20 m) at points spaced 2 meters appart. Results show the comparative advantages of the proposed method (based on an alternative state-space approach) in relation to the standard state-space analysis. Such advantages are related to a more adequate incorporation of soil heterogeneity along the spatial transect resulting in a better model fitting, and greater flexibility of the model's building process with an easier interpretability of the local model coefficients. Made available in DSpace on 2017-09-19T00:11:21Z (GMT). No. of bitstreams: 1 TimmStateSpace6393.pdf: 204064 bytes, checksum: 4e9d017a9ff149f88364c1d94299f406 (MD5) Previous issue date: 2006-10-02

The effects of soil water spatial variability previous to irrigation and of the field capacity on the estimation of irrigation water depth are evaluated. The experiment consisted of a common bean (Phaseolus vulgaris L.) crop established on a Kandiudalfic Eutrudox of Piracicaba, SP, Brazil, irrigated by central pivot, in which soil water contents were evaluated with a depth neutron gauge, in a grid of 20x4 points with lag of 0.5 m. In a given situation, the 80 calculated irrigation water depths presented a coefficient of variation of 29.3%, with an average water value of 18 mm, maximum of 41 mm and minimum of 9 mm. It is concluded that the only practical way of irrigation is the use of an average water depth, due to the inherent variability of the soil, and that the search for better field capacity values does not imply in better water depth estimates. Made available in DSpace on 2018-09-18T00:32:35Z (GMT). No. of bitstreams: 1 ScientiaAgricolav.58n.3p.5495532001.pdf: 4581215 bytes, checksum: 0cc02ad21c9303ebf658f275fadfc1bb (MD5) Previous issue date: 2001-12-19