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This study tested the hypothesis that enhanced-efficiency fertilizers, such as urea treated with NBPT, are a feasible substitute for ammonium nitrate–based fertilizers for green sugarcane cultivation. The experimental design included six N sources applied over sugarcane straw at two sites in Central-South Brazil. Treatments included ammonium nitrate, urea, and four urea-based fertilizers treated with different rates of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) at two rates of N (50 and 100 kg ha−1), plus an additional control. Nitrogen status in the plant, the activity of glutamine synthetase (GS) and nitrate reductase (NR) in the leaves, and sugarcane stalk yield and quality were evaluated. At site 1, N rates increased the SPAD index, stalk yield, N uptake, and sugar yield. At site 2, N rates increased GS activity, N content, the SPAD index, and N uptake, but stalk and sugar yield were not increased due to large variability in these parameters. All N sources resulted in similar yields at both sites. These results were compared with those in the literature. Among 27 studies surveyed, the average sugarcane yield was 97.8 or 97.4 Mg ha−1 under ammonium nitrate or urea fertilization, respectively, and these averages did not differ by the Kruskal-Wallis test. The results of this study demonstrate that enhanced-efficiency fertilizers have the potential to reduce NH3 emissions from urea-based fertilizers in green sugarcane fields without affecting sugarcane yield.

Made available in DSpace on 2020-12-12T02:00:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Sugarcane (Saccharum spp) crop has high social, economic and environmental importance for several regions throughout the world. However, the increasing demand for efficiency and optimization of agricultural resources generates uncertainties regarding high mineral fertilizer consumption. Thereby, organomineral fertilizers are to reduce the conventional sources consumption. Thus, this study was carried out to evaluate the agronomic and economic sugarcane performancies and the residual effect of P and K under mineral and organomineral fertilization. Growth and technological parameters, leaf and soil nutrients concentration in surface and subsurface layers were analyzed from sugarcane planting (plant cane) until the first ratoon. Agronomic and economic sugarcane efficiency were evaluated. At the first ratoon, resin-extractable P provided by mineral and organomineral fertilizers were, respectively, 15 and 11 mg kg−1 in the 0.0–0.2 m, and 28 and 31 mg kg−1 in 0.2–0.4 m layer. However, exchangeable K in the 0.0–0.2 m layer was 1.88 and 1.58 mmolc kg−1 for mineral and organomineral fertilizers, respectively. The yield gains over the control reached with mineral and organomineral fertilizers were, respectively, 10.99 and 17 Mg ha−1 at the lowest fertilizer rate; and 29.25 and 61.3 Mg ha−1 at the highest fertilizer rate. Agronomic and economic organomineral fertilizer efficiencies are more pronounced in plant cane. Summing two harvests, the organomineral is 7% more profitable than mineral fertilizer. São Paulo State University (UNESP) College of Agricultural Sciences Dep. of Crop Science Lageado Experimental Farm, P.O. Box: 237 Sugarcane Technology Center (CTC), P.O. Box: 162 Agronomic Institute of Campinas (IAC) Soils and Environmental Resources Center, Av. Barão de Itapura 1481 São Paulo State University (UNESP) College of Agricultural Sciences Dep. of Crop Science Lageado Experimental Farm, P.O. Box: 237

Best management practices for N fertilization should increase yields while reducing negative environmental effects such as losses by ammonia (NH3) volatilization and emission of greenhouse gases, especially nitrous oxide (N2O). We studied the impact on sugarcane of two N sources (UR: urea and CAN: calcium ammonium nitrate) in three N rates (30, 60, and 90 kg N ha−1 in the plant cane cycle and 60, 120, and 180 kg N ha−1 in ratoons) on a sugarcane field grown on a Red Latosol soil in southeastern Brazil. We measured sugarcane yields and N2O, CO2 and CH4 emissions in three crop cycles (plant cane, 2nd and 3rd ratoons), and NH3 in two crop cycles (2nd and 3rd ratoons). The accumulated emission of N2O from UR was significantly higher in comparison with those of CAN in all three crop cycles. The average emission factors for UR were 0.8% (plant cane), 1.1% (2nd ratoon) and 0.8% (3rd ratoon) and the corresponding figures for CAN were 0.4%, 0.7% and 0.5%, respectively. The N2O intensity was higher for UR (20.3 mg N–N2O kg−1 sugarcane stalk) than CAN (16.2 mg N–N2O kg−1 sugarcane stalk). The NH3 volatilization losses for CAN were less than 1% compared to 5–16% of the N applied as UR. Stalk yield increased with N application, but no difference was observed between UR and CAN. We concluded that CAN has the potential to reduce both NH3 and N2O losses compared with urea and is the preferred N source for sugarcane.

Maize-forage grasses intercropping systems have been increasingly adopted by farmers because of their capacity to recycle nutrients, provide mulch, and add C to soil. However, grasses have been shown to increase nitrous oxide (N2O) emissions. Some tropical grasses cause biological nitrification inhibition (BNI) which could mitigate N2O emissions in the maize cycle but the reactions of the N cycle and the microbial changes that explain the N2O emissions are little known in such intercropping systems. With this in mind, we explored intercropping of forage grasses (Brachiaria brizantha and Brachiaria humidicola) with distinct BNI and yield potential to increase N cycling in no-till maize production systems compared to monocrop with two N rates (0 and 150 kg ha−1) applied during the maize season. These grasses did not strongly compete with maize during the period of maize cycle and did not have a negative effect on grain yield. We observed a legacy of these grasses on N mineralization and nitrification through the soil microbiome during maize growth. We observed that B. humidicola, genotype with higher BNI potential, increased net N mineralization by 0.4 mg N kg−1 day−1 and potential nitrification rates by 1.86 mg NO3-N kg−1 day−1, while B. brizantha increased the soil moisture, fungi diversity, mycorrhizal fungi, and bacterial nitrifiers, and reduced saprotrophs prior to maize growth. Their legacy on soil moisture and cumulative organic inputs (i.e., grass biomass) was strongly associated with enhanced mineralization and nitrification rates at early maize season. These effects contributed to increase cumulative N2O emission by 12.8 and 4.8 mg N2O-N m−2 for maize growing after B. brizantha and B. humidicola, respectively, regardless of the N fertilization rate. Thus, the nitrification inhibition potential of tropical grasses can be outweighed by their impacts on soil moisture, N recycling, and the soil microbiome that together dictate soil N2O fluxes.

The use of sugarcane straw is a promising option to enhance bioenergy production. But the implications of straw removal for soil greenhouse gas (GHG) emission are not yet fully understood due to scarcity of studies under Brazilian conditions. Four field experiments were designed to assess soil N2O and CH4 emissions derived from nitrogen (N) fertilization under scenarios of sugarcane straw removal in Sao Paulo state, Brazil. Our focus was also to derive the direct N2O emission factor (EF) that represents the regional conditions of sugarcane production, taking into account the data obtained from this study and those from the literature. In each field study, four straw removal rates (no removal (NR); low removal (LR)—removal of 5 Mg ha−1; high removal (HR)—removal of 10 Mg ha−1; and total removal (TR)—removal of 15 Mg ha−1) were arranged in a randomized block design. This study shows a clear evidence that CH4 fluxes are very low for all assessed sites regardless of straw removal rates, indicating a predominance of CH4 consumption by the soil. Cumulative N2O emissions ranged from 0.20 to 4.09 kg ha−1 year−1 and were significantly affected by straw removal in two sites, indicating that straw removal reduces N2O emissions. The average direct N2O EFs obtained from this study and from the literature were 0.28, 0.44, 0.70, and 0.56% for TR, HR, LR, and NR treatments, respectively, which are consistently lower than the EF of 1% suggested by the IPCC. Based on our regional-specific EF (Tier 2), the direct N2O emissions derived from N fertilization under scenarios of straw removal showed a reduction of at least 50% in relation to IPCC approach. Our findings are a step forward in providing regional-specific data to reduce the high level of uncertainty concerning N2O emission assessments of sugarcane ethanol in Brazil, but further studies are needed to evaluate how straw removal for bioenergy production and the associated changes in soil organic carbon stocks affect the GHG balance of sugarcane.

Sugarcane straw is a source of carbon (C) and nitrogen (N), which affect soil temperature and moisture and therefore soil nitrous oxide (N2O) emissions from fertilized fields. The use of a nitrification inhibitor (NI) with N fertilizers is an option to reduce N2O production; however, sugarcane straw may interfere with the efficiency of a NI to reduce these losses. We conducted two laboratory studies over nearly 100 days to evaluate the following: (i) the implications of sugarcane straw removal and N fertilization under different temperatures on N2O emissions and (ii) the efficiency of a NI to reduce N2O emissions as determined by straw rates. In the first experiment, the treatments were as follows: N (0 and 100 kg ha−1), straw (0 and 8 Mg ha−1), and soil temperature (20 and 30 °C); in experiment 2, we included another straw rate (16 Mg ha−1) and NI dicyandiamide (DCD) (10 kg ha−1). Straw increased N2O emissions from N fertilizer by 37-fold and 3-fold in experiments 1 and 2, respectively. The N2O emissions were 62% higher at 20 °C than at 30 °C, whereas the opposite was observed for CO2 emissions. There was a synergistic effect of straw, which increased the dissolved organic C by more than 50% in the topsoil layer and was positively correlated with N2O emissions. The NI strongly reduced N2O emissions (> 63%) regardless of the straw rate, with no effect on soil respiration. The use of NI is an important strategy to mitigate N2O emissions from N fertilization in sugarcane fields where harvest residues are preserved.

It is likely more critical than ever to have access to proven indicators of the plant availability of P given the awareness of the implications of its management in crop production and the surrounding environment. Methods of assessing P availability will vary regionally, but commonly achieve good correlation to plant response. Continued improvement in the delivery of P sources to crops is in turn encouraging research that is improving our understanding of how to assess the behavior of P in soil.

Vinasse is a major byproduct of the sugarcane biofuel industry, recycled in the fields. However, there is evidence that the application of vinasse with mineral nitrogen (N) fertilizers in sugarcane enhances the emission of greenhouse gases (GHGs). Therefore, strategies are needed to decrease the environmental impacts caused by both inputs. We carried out three sugarcane field experiments by applying N fertilizer (ammonium nitrate) with types of vinasses (concentrated-CV and standard-V) in different combinations (vinasses with N fertilizer and vinasses one month before or after mineral N fertilization). The gases nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) were measured in one experiment fertilized in the beginning (fall/winter = dry season) and two experiments fertilized in the end (spring = rainy season) of the harvest season. Sugarcane fields were sinks rather than sources of CH4, while total carbon emitted as CO2 was similar between seasons and treatments. The effect of mineral fertilization and vinasses (CV and V) on N2O emissions was highly dependent on soil moisture (rain events). The N2O-N fertilizer emission factor (EF) varied from 0.07% to 0.51%, whereas the average EF of V and CV were 0.66% and 0.34%, respectively. On average across the three experiments, the combination of vinasse (CV or V) with N fertilizer increased the N2O emissions 2.9-fold compared to that of N fertilizer alone. For CV + N, the EF was 0.94% of the applied N and 0.23% of the ammonium nitrate-N, and for V + N (EF = 0.47%), increased emissions were observed in two out of three experiments. The strategy of anticipating or postponing vinasse application by one month with respect to mineral N reduced the N2O emissions by 51% for CV, but not for V. Therefore, to avoid boosting N2O emissions, we suggest applying vinasses (CV and V) before or after mineral N fertilization.

Nitrous oxide (N2O) emission estimates are important to ascertain the greenhouse gas balance of ethanol produced from sugarcane. We quantified N2O emissions in the presence of sugarcane crop residues, N fertilizer (ammonium sulfate), and a nitrification inhibitor (NI, dicyandiamide). Two field experiments were conducted to evaluate the implications of N fertilizer application during dry and wet seasons at two locations in southeast Brazil. Treatments consisted of four levels of crop residue (0, 5, 10, and 15 Mg ha−1) and three of N fertilizer (0 and 120 kg ha−1 and 120 kg ha−1 plus NI). N2O emission was measured using the closed chamber method and sugarcane yield via mechanical harvest. N2O emissions were higher in wet than in dry seasons following N fertilizer application, albeit affected by crop residue and NI in both. Retaining crop residues on the soil increased N2O emission and sugarcane yield. The N2O emission factor from N fertilizer ranged from 0.12% to 1.44% of N applied. NI reduced N2O emissions (by 87% and 63% in dry and wet seasons, respectively). Sugarcane yield varied from 42 to 92 Mg ha−1 of fresh matter stalk and emission intensity from 3.7 to 22.9 kg of CO2eq. Mg of stalk−1. The lowest greenhouse gas intensity was recorded with 5 Mg ha−1 crop residue and 120 kg ha−1 N supplemented with NI. Therefore, partial crop residue removal and NI addition to N fertilizer may be effective strategies to improve the sustainability index of biofuel from sugarcane and reduce N2O emissions and intensity.

Made available in DSpace on 2021-06-25T12:31:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-02-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Intercropping upland rice with forage grasses is a potential strategy for enhancing the sustainability of agriculture in the tropical region by increasing food production, land use per unit area, nitrogen (N) cycling, and profitability. However, little is known about the appropriate N management and N use efficiency of upland rice in these complex systems. Thus, our aim was to verify the feasibility of intercropping upland rice with tropical forage grasses combined with different N management applications at sowing and sidedressing. A field experiment was carried out in three growing seasons with three intercropping systems (monocropped upland rice, upland rice intercropped with palisade grass, and upland rice intercropped with guinea grass) combined with six N applications to upland rice [0-0 (control), 100-0, 80-20, 50-50, 20-80, and 0-100 kg N ha(-1) at sowingsidedressing]. Dry matter (DM) and accumulated N were measured in upland rice and forage grasses. In addition, components of rice yield production, industrial yield, production cost, land equivalent ratio, relative N yield, relative crowding coefficient, aggressivity of upland rice with forage grasses, forage crude protein (CP) concentration, estimated animal stocking rate, and estimated meat production were determined. Despite competition between rice and forage grasses, intercropping systems had superior benefits in terms of production and land use per unit area, N cycling, and profitability compared with monoculture. Forage DM production, CP, estimated animal stocking rate, and estimated meat production increased when N fertilizer was applied at sidedressing to rice (20-80, 50-50 and 0-100 kg N ha(-1)). Rice intercropped with guinea grass produced a greater amount of biomass, indicating that this forage species may be more advantageous in tropical regions. Net profit, total aboveground biomass, total N content, land equivalent ratio, and relative N yield were greater in intercropping systems fertilized with N. UNESP, Dept Crop Sci, Coll Agr Sci, Botucatu, SP, Brazil NIOO KNAW, Dept Microbial Ecol, Netherlands Inst Ecol, Wageningen, Netherlands Fed Univ Jatai, UFJ, Campus Riachuelo, Jatai, Go, Brazil UNESP, Dept Anim Nutr & Breeding, Sch Vet Med & Anim Sci, Botucatu, SP, Brazil ARS, USDA, NCSU Campus, Raleigh, NC USA Agron Inst Campinas IAC, Soils & Environm Resources Ctr, IAC, Campinas, SP, Brazil UNESP, Dept Crop Sci, Coll Agr Sci, Botucatu, SP, Brazil UNESP, Dept Anim Nutr & Breeding, Sch Vet Med & Anim Sci, Botucatu, SP, Brazil

Made available in DSpace on 2021-06-25T12:25:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-11-05 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Intercropping grain with forage crops bridges the gap between agriculture and sustainability. In tropical regions, forage grasses are increasingly being adopted as winter pasture intercropped and in rotation with maize to maximize food production. However, current recommendations for nitrogen (N) fertilizer application are based on monocropped maize (Zea mays), and the best N management approach for intercropping systems remains unclear. A field experiment was carried out in three growing seasons with three intercropping systems [monoculture maize, intercropped with palisadegrass (Urochloa brizantha), and intercropped with guineagrass (Megathyrus maximus)] combined with six different split applications of N to maize (0-0, 100-0, 70-30, 50-50, 30-70, and 0-100 kg N ha(-1) at seeding-sidedressing) with four replicates. We measured dry matter (DM) and accumulated N in maize and forage grasses, as well as maize production components and yields. Additionally, land equivalent ratio, relative crowding coefficient, aggressivity of maize with forage grasses, forage crude protein (CP) concentration, estimated animal stocking rate, and estimated meat production and economic outcomes. Greatest maize yield was 8.7 Mg ha(-1) for monocropped maize. However, favorable maize yield was also obtained in intercropping systems. Although no difference was observed between intercropping systems, applying all N at sidedressing of maize negatively affected maize and forage yields and, consequently, land use and economic evaluation. For both intercropping systems, estimated meat and land use were 114 and 10% higher when N fertilizer was applied than the control (0-0 kg N ha(-1)), on average. Maize-forage grass intercropping is a viable alternative production system for improving yields and land use. In addition, estimated meat production and revenue can be enhanced with palisadegrass or guineagrass. At least half of the N fertilizer must be applied early in the growing season of maize to maximize production of the entire system. Sao Paulo State Univ, Dept Soil Sci, Coll Agr Sci, Botucatu, SP, Brazil Sao Paulo Agcy Agribusiness Technol, Agencia Paulista Tecnol Agronegocios, Dept Dev Decentralizat, Andradina, Brazil Netherlands Inst Ecol, Dept Microbial Ecol, NIOO KNAW, Wageningen, Netherlands Sao Paulo State Univ, Sch Vet Med & Anim Sci, Dept Anim Nutr & Breeding, Botucatu, SP, Brazil Sao Paulo State Univ, Coll Agr Sci, Botucatu, SP, Brazil ARS, USDA, NCSU Campus, Raleigh, NC USA Soils & Environm Resources Ctr, Inst Agron Campinas, IAC, Campinas, Brazil Brazilian Agr Res Corp, Corn & Sorghum Res Ctr, EMBRAPA, Sete Lagoas, Brazil Sao Paulo State Univ, Dept Soil Sci, Coll Agr Sci, Botucatu, SP, Brazil Sao Paulo State Univ, Sch Vet Med & Anim Sci, Dept Anim Nutr & Breeding, Botucatu, SP, Brazil Sao Paulo State Univ, Coll Agr Sci, Botucatu, SP, Brazil FAPESP: 2003/09914-3 FAPESP: 2003/01968-7

Made available in DSpace on 2020-12-12T02:50:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-03 Intercropping forage grasses with upland rice is an alternative cropping system to improve agroecosystem diversification and could potentially enhance sustainability in tropical regions. However, nitrogen (N) immobilization and nutrient competition between rice and forage grasses could reduce rice grain yield and decrease overall productivity. Therefore, fertilizer N requirements of upland rice intercropped with forage grasses needs to be better defined. Field experiments were carried out during three growing seasons on a Typic Haplorthox soil in São Paulo state of Brazil. The experimental design was a randomized block design with a 3 × 4 factorial scheme with four replications. Treatments were cropping system [monocropped rice (Oryza sativa L.), rice intercropped with palisadegrass (Urochloa brizantha), and rice intercropped with guineagrass (Megathyrsus maximus) and sidedress N application rate (0, 40, 80, and 120 kg N ha−1). Intercropped grasses were sown between upland rice rows 30 days after rice emergence. On average, intercropping of rice with palisadegrass or guineagrass decreased rice shoot dry matter and grain yield by 11% and milled rice productivity by 10% compared with monocropped rice. Grain yield, grain protein, and milled productivity of rice increased as N application rate increased. Forage dry matter production (first and second cut) and crude protein (second cut) were greatest in the rice + palisadegrass intercropping system. Production of both forage grasses increased with up to 80 kg N ha−1 in the first cut and increased linearly with N in the second cut. Intercropping of rice with palisadegrass or guineagrass with 80 kg N ha−1 application resulted in the greatest land equivalent ratio (1.96 and 1.55, respectively). Relative N yield was greatest at 120 kg N ha−1 (220 and 173%, respectively). Although rice monocropping had greatest grain yield, intercropping systems with forage grasses were more favorable from both economic and environmental perspectives by enhancing plant diversification, nutrient cycling with forage grasses, land use production per unit area, and profitability throughout the year. UNESP Department of Soil Science College of Agricultural Science NIOO-KNAW Department of Microbial Ecology Netherlands Institute of Ecology USDA Agricultural Research Service NCSU Campus IAC Soils and Environmental Resources Center Instituto Agronômico de Campinas UNESP Department of Soil Science College of Agricultural Science

Made available in DSpace on 2020-12-12T01:48:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In tropical regions, one of the primary difficulties in the sustainability of no-till systems is the maintenance of soil cover throughout the year. Intercropping corn (Zea mays L.) with tropical perennial grasses is an innovative approach to overcome this difficulty. However, the use of sidedress nitrogen (N) fertilization in this intercropping system remains incompletely studied. The effects of using sidedress N application rates (0, 50, 100 and 200 kg ha−1 N) on monocropped corn or corn intercropped with palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R. Webster ‘Marandu’] or guineagrass [Megathyrsus maximum (Jacq.) R. Webster ‘Mombaça’] with respect to leaf nutrient concentration, agronomic characteristics, revenue and land use efficiency were investigated over three growing seasons in the Brazilian Cerrado region on a clay soil, kaolinitic, thermic Typic Haplorthox. In general, the intercropping systems of corn with palisade or guineagrass did not cause reductions in the leaf nutrient concentration, agronomic characteristics, kernels attributes, shoot dry matter and corn yield compared to that observed in the monocropped system. High sidedress N application rates promoted higher concentrations of nutrients in leaves (primarily N and P), corn yield, forage production and crude protein concentration in the off-season. Corn monocropped or intercropped with palisadegrass and guineagrass using 113, 156 and 187 kg ha−1 N resulted in the highest corn yields (9.2, 8.8 and 9.7 Mg ha−1, respectively). In addition, using these N application rates, corn intercropped with palisadegrass and guineagrass and subsequent meat production estimated on pastures resulted in the highest net profits (US$ 1196 and 1093 ha−1, respectively), whereas monocropped corn without N addition resulted in the lowest net profits (US$ 304 ha−1). Thus, forage produced during the off-season can be used for animal grazing or fodder during the dry season, increasing revenue. Corn intercropped with palisade grass with the addition of 200 kg ha−1 N resulted in a higher land equivalent ratio and relative N yield (1.21 and 123%, respectively). In summary, sidedress N fertilization in intercropped systems can increase crop and forage yields and revenue, improving land-use efficiency in tropical agriculture. São Paulo Agency of Agribusiness Technology (APTA) Department of Crop Science College of Agricultural Science São Paulo State University (UNESP) Department of Animal Nutrition and Breeding School of Veterinary Medicine and Animal Science UNESP College of Agricultural Science UNESP Corn and Sorghum Research Center Brazilian Agricultural Research Corporation (EMBRAPA) USDA – Agricultural Research Service, 3218 Williams Hall, NCSU Campus, Box 7619 Soils and Environmental Resources Center Instituto Agronômico de Campinas (IAC) Department of Crop Science College of Agricultural Science São Paulo State University (UNESP) Department of Animal Nutrition and Breeding School of Veterinary Medicine and Animal Science UNESP College of Agricultural Science UNESP FAPESP: 2003/01968-7 FAPESP: 2003/09914-3

Enhanced efficiency fertilizers (EEF) are of interest for sugarcane (Saccharum spp.) production due to the potential to reduce N losses, and improve crop yield and environmental conditions. This study was conducted to determine the effect of urea with N‐(n‐butyl) thiophosphoric triamide (NBPT) or dicyandiamide (DCD) on NH3 volatilization and sugarcane yield. The NH3 volatilization, the foliar concentration of N and S, and yield of stalk and pol were monitored in two field trials testing six N sources (urea; urea + NBPT; urea + DCD; ammonium sulfate [AS]; ammonium nitrate [AN]; ammonium sulfate nitrate), and three N rates (50, 100, and 150 kg ha−1). The N losses from urea totaled 22 and 18% in Sites 1 and 2, respectively. Treating urea with NBPT reduced NH3 volatilization by 60%. Sugarcane yield increased 8.8; 11.6; and 16.0 Mg ha−1 (Site 1), and 4.5, 9.3, and 14.2 Mg ha−1 (Site 2) with the application of 50, 100, and 150 kg ha−1 N as compared to control, respectively. All N sources increased yields, demonstrating similar efficiency for sugarcane production. Green harvesting sugarcane cultivated in sandy soils with low organic matter concentration is highly responsive to N, showing similar efficiency between EEF and conventional N fertilizers.

Made available in DSpace on 2020-12-12T01:28:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Human activities are pushing earth beyond its natural limits, so recycling nutrients is mandatory. Microalgae are highly effective in nutrient recovery and have strong potential as a sustainable wastewater treatment technology. Here, nutrients from black water (toilet wastewater) were recovered as microalgal biomass, which was dried and assessed as a fertilizer in pot experiments compared with inorganic fertilizer. We deciphered the effects of microalgal biomass as a biofertilizer on plant growth and quality and the biological processes linked to greenhouse gas (GHG) emissions. In addition, we elucidated the assembly of the active microbiome in bulk soil and rhizosphere during barley development. Microalgal biomass application and inorganic fertilizer (NPK) resulted in similar plant productivity (16.6 g pot−1). Cumulative nitrous oxide (N2O) emissions were 4.6-fold higher in the treatment amended with microalgal fertilizer (3.1% of applied N) than that with inorganic fertilizer (0.5% of applied N). Nitrification by bacteria was likely the main pathway responsible for N2O emissions (R2 = 0.7, p ≤ 0.001). The application of nitrogen fertilizers affected the structures of both the active bacterial and protozoan communities, but these effects were less obvious than the strong plant effect, as the recruited microbiota varied among different plant developmental stages. Both treatments enriched similar bacterial and protozoan taxonomic orders but with different distributions through time across the plant developmental stages. Furthermore, the bacterial community showed a clear trend of resilience from the beginning of the experiment until harvest, which was not observed for protozoa. Our results indicate that the use of microalgal biomass as a fertilizer is a viable option for recycling nutrients from wastewater into plant production. Microbial Ecology Department Netherlands Institute of Ecology (NIOO), Droevendaalsesteeg 10, 6708PB KWR Watercycle Research Institute, Groningenhaven 7, 3433, PE Soils and Environmental Resources Center Agronomic Institute of Campinas (IAC), Av. Barão de Itapura 1481 Maranhão State University Department of Agroecology Department of Environmental and Civil Engineering São Paulo State University (UNESP), Avenida Engenheiro Luiz Edmundo Carrijo Coube, 14-01 Department of Terrestrial Ecology Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10 Department of Aquatic Ecology Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10 Ecology and biodiversity Institute of Environmental Biology Utrecht University, Padualaan 8 Department of Environmental and Civil Engineering São Paulo State University (UNESP), Avenida Engenheiro Luiz Edmundo Carrijo Coube, 14-01

Made available in DSpace on 2020-12-12T02:18:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 High grain yields of upland rice (Oryza sativa L.) can be achieved in no-tillage systems. However, managing nitrogen (N) fertilization for rice in succession to forage grasses is a challenge because forage residues change N cycling and increase microbial immobilization of N, thereby reducing N availability to the subsequent cash crop. In the present study, two field experiments were conducted to determine if applying all or part of the N fertilizer on preceding palisade grass (Urochloa brizantha) and ruzigrass (Urochloa ruziziensis) or their desiccated residues immediately before rice seeding can supply N to the subsequent rice crop. Forage biomass yield (8–16 Mg ha− 1), N accumulation, and N supply to the subsequent upland rice were highest when all of the N fertilizer was applied on forage grasses at 50, 40 or 35 days before rice seeding (DBS), as opposed to the conventional split application at rice seeding and at tillering. On average, the grain yield of upland rice was 54% higher in succession to palisade grass compared with ruzigrass. The grain yield of rice was higher when N was applied to palisade grass at 35 DBS and ruzigrass at 50 DBS, reaching 5.0 Mg ha− 1 and 3.7 Mg ha− 1, respectively. However, applying N to ruzigrass was less effective for increasing upland rice yields since the yields did not differ from the treatments with the conventional split application. Adjusting the time of N application to forage grasses to increase the grain yields of subsequent upland rice is a sustainable alternative that can promote the economic viability of upland rice production. Department of Crop Science College of Agricultural Sciences São Paulo State University (UNESP), Av. Universitaria, 33789, Lageado Experimental Farm Department of Microbial Ecology Netherlands Institute of Ecology, Droevendaalsesteeg 10 Ecology and biodiversity Institute of Environmental Biology Utrecht University, Padualaan 8 Federal University of Jataí (UFJ), R. Riachuelo, 1530, Samuel Grahan Agronomic Institute of Campinas (IAC), Av. Barao de Itapura, 1481, Botafogo Department of Crop Science College of Agricultural Sciences São Paulo State University (UNESP), Av. Universitaria, 33789, Lageado Experimental Farm

Disturbances in soil can cause short-term soil changes, consequently changes in microbial community what may result in long-lasting ecological effects. Here, we evaluate how multiple pulse disturbances effect the dynamics and resilience of fungal community, and the co-occurrence of fungal and bacterial communities in a 389 days field experiment. We used soil under sugarcane cultivation as soil ecosystem model, and organic residue (vinasse - by-product of sugarcane ethanol production) combined or not with inorganic (organic residue applied 30 days before or together with mineral N fertilizer) amendments as disturbances. Application of organic residue alone as a single disturbance or 30 days prior to a second disturbance with mineral N resulted in similar changes in the fungal community. The simultaneous application of organic and mineral N as a single pulse disturbance had the greatest impact on the fungal community. Organic amendment increased the abundance of saprotrophs, fungal species capable of denitrification, and fungi described to have copiotrophic and oligotrophic lifestyles. Furthermore, the changes in the fungal community were not correlated with the changes in the bacterial community. The fungal community was neither resistant nor resilient to organic and inorganic disturbances over the one-year sampling period. Our findings provide insights on the immediate and delayed responses of the fungal community over one year to disturbance by organic and inorganic amendments.

Recycling residues is a sustainable alternative to improve soil structure and increase the stock of nutrients. However, information about the magnitude and duration of disturbances caused by crop and industrial wastes on soil microbial community structure and function is still scarce. The objective of this study was to investigate how added residues from industry and crops together with nitrogen (N) fertiliser affect the microbial community structure and function, and nitrous oxide (N2O) emissions. The experimental sugarcane field had the following treatments: (I) control with nitrogen, phosphorus, and potassium (NPK), (II) sugarcane straw with NPK, (III) vinasse (by-product of ethanol industry) with NP, and (IV) vinasse plus sugarcane straw with NP. Soil samples were collected on days 1, 3, 6, 11, 24 and 46 of the experiment for DNA extraction and metagenome sequencing. N2O emissions were also measured. Treatments with straw and vinasse residues induced changes in soil microbial composition and potential functions. The change in the microbial community was highest in the treatments with straw addition with functions related to decomposition of different ranges of C-compounds overrepresented while in vinasse treatment, the functions related to spore-producing microorganisms were overrepresented. Furthermore, all additional residues increased microorganisms related to the nitrogen metabolism and vinasse with straw had a synergetic effect on the highest N2O emissions. The results highlight the importance of residues and fertiliser management in sustainable agriculture.

Sugarcane is a widespread bioenergy crop in tropical regions, and the growing global demand for renewable energy in recent years has led to a dramatic expansion and intensification of sugarcane agriculture in Brazil. Currently, extensive areas of low-intensity pasture are being converted to sugarcane, while management in the remaining pasture is becoming more intensive, i.e., includes tilling and fertilizer use. In this study, we assessed how such changes in land use and management practices alter emissions of greenhouse gases (GHG) such as CO2, N2O and CH4 by measuring in situ fluxes for one year after conversion from low-intensity pasture to conventional sugarcane agriculture and management-intensive pasture. Results show that CO2 and N2O fluxes increased significantly in pasture and sugarcane with tillage, fertilizer use, or both combined. Emissions were highly variable for all GHGs, yet, cumulatively, it was clear that annual emissions in CO2-equivalent (CO2-eq) were higher in management-intense pasture and sugarcane than in unmanaged pasture. Surprisingly, tilled pasture with fertilizer (management-intensive pasture) resulted in higher CO2-eq emissions than conventional sugarcane. We concluded that intensification of pasture management and the conversion of pasture to sugarcane can increase the emission factor (EF) estimated for sugarcane produced in Brazil. The role of management practices and environmental conditions and the potential for reducing emissions are discussed.

The application of vinasse, an organic byproduct of ethanol production, can enhance greenhouse gas emissions from N fertilizers, especially nitrous oxide (N2O). The objective of this work was to test the efficiency of the nitrification inhibitor (NI) 3,4 dimethylpyrazole phosphate (DMPP) in reducing N2O emissions from urea (UR) and ammonium nitrate (AN) applied with or without standard (V) or concentrated vinasse (CV). Two laboratory studies were conducted with repacked soil columns from a sugarcane field. Based on usual field rates, UR and AN were added at a rate equivalent to 100 kg N ha−1, V was added at 100 m3 ha−1 (51 kg N ha−1), and CV was added at 20 m3 ha−1 (Exp. 1: 35 kg N ha−1 and Exp. 2: 56 kg N ha−1). N2O emissions were measured for 75 and 61 days after the input of fertilizers and vinasses. When mineral fertilizers were compared, the N2O-N emission factors (EFs) were: 0.08% (AN) and 1.44% (UR). Combined with N fertilizers, vinasses (CV and V) greatly enhanced the N2O emissions from soil (ranging from 0.76% to 1.5% in one study and 1.37% to 6.27% in the other). In addition, CV + N fertilizer emitted more N2O than V + N fertilizer or N fertilizer alone. However, NI reduced N2O emissions by 80% on average for vinasses (CV and V) plus N fertilizer (AN and UR) and UR alone, but not for AN alone. Since both vinasses and mineral N fertilizers are standard inputs for sugarcane production and high N2O emissions are observed when they are applied in the same area, NI should be considered for mitigation of soil N2O emissions from sugarcane used for bioenergy.

Nitrogen use in agriculture directly impacts food security, global warming, and environmental degradation. Forage grasses intercropped with maize produce feed for animals and or mulch for no-till systems. Forage grasses may exude nitrification inhibitors. It was hypothesized that brachiaria intercropping increases N recycling and maize grain yield and reduces nitrous oxide (N2O) emissions from soil under maize cropping. A field experiment was set up in December 2016 to test three cropping system (maize monocropped, maize intercropped with Brachiaria brizantha or with B. humidicola) and two N rates (0 or 150 kg ha-1). The grasses were sown with maize, but B. humidicola did not germinate well in the first year. B. brizantha developed slowly during the maize cycle because of shading but expanded after maize was harvested. The experiment was repeated in 2017/2018 when B. humidicola was replanted. N2O and carbon dioxide (CO2) emissions, maize grain yield and N content were measured during the two seasons. After the first maize harvest, the above- and below-ground biomass, C and N content of B. brizantha grown during fall-winter, and the biological nitrification inhibition potential of B. brizantha were evaluated. Maize yield responded to N fertilization (5.1 vs. 9.8 t ha-1) but not to brachiaria intercropping. B. brizantha recycled approximately 140 kg N ha-1 and left 12 t dry matter ha-1 for the second maize crop. However, the 2017/18 maize yields were not affected by the N recycled by B. brizantha, whereas N2O emissions were higher in the plots with brachiaria, suggesting that part of the recycled N was released too early after desiccation. Brachiarias showed no evidence of causing nitrification inhibition. The strategy of intercropping brachiarias did not increase maize yield, although it added C and recycled N in the system., Highlights • N recycled by brachiaria mulch did not increase maize yield. • B. brizantha mulch increased N2O emissions with no effect on maize yield. • There was no evidence of nitrification inhibition by B. brizantha or B. humidicola.

Nitrogen loss as ammonia (NH3) is a major problem when urea is topdressed over crop residues. The treatment of urea with N-(n-butyl) thiophosphoric triamide (NBPT) temporarily inhibits urease activity and reduces NH3 volatilization loss under many agro­ecological conditions. However, the amount of straw on the soil in green sugarcane trash blanketing (GCTB) systems affects the success of NBPT in reducing NH3 loss. We hypothesized that an increase in the NBPT concentration in urea above the current level (530 mg NBPT kg−1 urea) in Brazil is necessary to reduce the NH3 volatilization and to improve the efficiency of urea in GCTB systems. We evaluated the NH3 loss from urea treated with NBPT under field conditions in GCTB systems. Six field trials were conducted across the State of Sao Paulo, the main sugarcane-growing region in Brazil. The treatments were urea, ammonium nitrate, urea treated with NBPT at concentrations of 530, 850, 1500, and 2000 mg kg−1, and a control plot without N fertilizer. The amount of volatized NH3 was assessed through a closed semi-static collector containing two acid-trap foam disks, and analyzed by colorimetry using flow injection analysis. NBPT concentrations above 530 mg kg−1 delayed the time of maximum rate of loss and also reduced cumulative NH3 loss. Ammonia emissions were linearly reduced with increasing NBPT concentrations until 1000 mg kg−1. Any further increase in the NBPT concentration did not result in a substantial reduction of NH3 volatilization. Increasing the NBPT concentration in urea is an effective approach to optimize the adoption of urea-based fertilizers in tropical GCTB systems.

Sugarcane straw, consisting of green tops and dry leaves, can be maintained on fields to improve soil quality, or harvested for bioenergy production. The optimum option between these two uses is still uncertain and requires further study. This study, conducted across three crop cycles, provides an assessment of the moisture, nutrients, ash, extractives, cellulose, hemicelluloses, and lignin contents of four sugarcane varieties across seven regions of south-central Brazil. Suitability of the straw fractions for nutrient recycling, bioelectricity, and second-generation ethanol production were also evaluated. Results showed that the sugarcane straw yield (dry mass) was 14.0 Mg ha−1, and the ratio of dry straw/fresh stalk was 12%. The composition of green tops and dry leaves differed consistently across varieties, sites, and crop cycles. Dry leaves represented 60% of the straw, but green tops contained about 70% of the total N, P, and K content. Therefore, green tops recycled up to four times more nutrients than dry leaves. Green tops also had six times higher moisture and greater chlorine content which decreased the mill process efficiency. In turn, dry leaves had higher lignin, cellulose, and hemicelluloses content, greater heating value (higher: 17.3 MJ kg−1; lower: 15.6 MJ kg−1) and tended to be a better second-generation ethanol production feedstock. Overall, the results show that it is preferable to use dry leaves for bioenergy production while leaving green tops on the field for nutrient recycling. This study pointed out that more efficient methods for separating these fractions in the field need to be developed. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

Large-scale bioenergy demand has triggered new approaches to straw management in Brazilian sugarcane fields. With the progressive shift from a burned to a nonburned harvest system, most of the straw presently retained on the soil surface has become economically viable feedstock for bioenergy production. The trade-offs between the need to preserve soil quality and produce more bioenergy have been the subject of intense discussion. This study presents a synthesis of available information on the magnitude of the main impacts of straw removal from sugarcane fields for bioenergy production and therefore represents an easily available resource to guide management decisions on the recommended amount of straw to be maintained on the field to take advantage of the agronomic, environmental, and industrial benefits. Crop residues remaining on sugarcane fields provide numerous ecosystem services including nutrient recycling, soil biodiversity, water storage, carbon accumulation, control of soil erosion, and weed infestation. Furthermore, several studies reported higher sugarcane production under straw retention on the field, while few suggest that straw may jeopardize biomass production in cold regions and under some specific soil conditions. Pest control is among the parameters favored by straw removal, while N2O emissions are increased only if straw is associated with the application of N fertilizer and vinasse. An appropriate recommendation, which is clearly site specific, should be based on a minimum mass of straw on the field to provide those benefits. Overall, this review indicates that most of the agronomic and environmental benefits are achieved when at least 7 Mg ha−1 of dry straw is maintained on the soil surface. However, modeling efforts are of paramount importance to assess the magnitude and rates of straw removal considering the several indicators involved in this complex equation, so that an accurate straw recovery rate could be provided to producers and industry toward greater sustainability.

Made available in DSpace on 2019-10-04T12:37:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Although Brazilian sugarcane crops use lower nitrogen rates when compared to other producing countries, the biological nitrogen fixation (BFN) could be performed aiming to reduce costs, since almost all nitrogen fertilization used in Brazil is imported. BFN can occur in sugarcane; however, its role in non-leguminous plants is controversial. Therefore, this study aimed to assess the nitrogen source contribution (using N isotope N-15 technique) along a growing period in sugarcane plants under different management (diazotrophic bacteria inoculation and N fertigation rates). The natural abundance of nitrogen isotope (N-15) abundance in +1 leaves of fourth ratoon cultivar SP 80-3280 was used to indicate the comparative importance of N sources, including BFN for sugarcane nutrition. The treatments were irrigated with two levels of nitrogen fertilizer 50 and 100kgha(-1) (urea source), including a control without fertilizer, with (I) and without (NI) inoculation of nitrogen-fixing bacterias. The bacteria cocktail used consisted of five strains: Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, H. rubrisubalbicans, Burkholderia tropica and Azospirillum amazonense. Although the nitrogen content in +1 leaves, the above ground dry matter, cane yield and stalk sugar content expanded by increasing nitrogen fertilizer rates, no significant interactions between nitrogen-fixing bacteria inoculation and nitrogen fertilizer rates were observed. In the treatment without N fertilizer application, no differences in N-15 parts per thousand (per thousand) values between sugarcane-inoculated and sugarcane-non-inoculated sugarcane leaves was found. The temporal variation of N-15 parts per thousand in sugarcane +1 leaves indicated that nitrogen content and N-15 parts per thousand values decreased during the phenological development stages and that the main sources of nitrogen for sugarcane were from synthetic fertilizer and mineralization of nitrogen from soil organic matter. Agencia Paulista Tecnol Agronegocios, Unidade Pesquisa & Desenvolvimento Helio de Morae, Rodovia SP 304, BR-17201970 Jau, SP, Brazil Univ Estadual Paulista, Programa Posgrad Irrigacao & Drenagem, Rua Jose Barbosa de Barros 1780, BR-18610307 Botucatu, SP, Brazil Univ Sao Paulo, CENA, Av Centenario 303, BR-13416000 Piracicaba, SP, Brazil Univ Estadual Campinas UNICAMP, FEM, BR-13083860 Campinas, SP, Brazil IAC, Av Barao de Itapura 1481, BR-13020902 Campinas, SP, Brazil Univ Sao Paulo, ESALQ, Piracicaba, SP, Brazil Univ Estadual Paulista, Programa Posgrad Irrigacao & Drenagem, Rua Jose Barbosa de Barros 1780, BR-18610307 Botucatu, SP, Brazil FAPESP: 2008/56147-1

Nitrification inhibitors (NIs), DCD (dicyandiamide), and DMPP (3,4‐dimethylpyrazole phosphate), in combination with urea (UR) and ammonium sulfate nitrate (ASN) fertilizers were studied under contrasting soil textures (sand, loam, and clay) from cultivated soils collected in Brazil and Germany. Soil samples were incubated over 50 days and the content of ammonium (N-NH4+), nitrate (N-NO3-), and soil pH were measured periodically. Applied NIs delayed the nitrification process across all soil textures. Correlation analysis indicated that combining ASN with NIs resulted in higher NH4+ content and efficiency in delaying the nitrification process with high N‐conversion rate (r = –0.82). The combination of ASN+ DMPP increased the efficiency of the N‐conversion rate (r = –0.86) due to H⁺ release in soil, while UR+DCD (r = –0.50) had an efficiency of the N‐conversion rate similar to UR (r = –0.42). All the NIs had a better performance in reducing N-NO3- formation in sandy soils as compared to the loam and clay textured soils. Use of DMPP with an N fertilizer results in a soil pH decrease and can be an option to increase the efficiency of the N‐conversion rate, reducing N losses in soil. Overall, our results suggest that NIs have a better performance in reducing N-NO3- formation in sandy soils as compared to that of the loam and clay textured soils. Use of DMPP with ASN results in a soil pH decrease and can be an option to reduce N losses in soil.

1203 The widespread use of high-analysis, granular S-free NP fertilizers such as urea, MAP, DAP, and TSP, together with more intensifi ed cropping with higher yields, has resulted in increasing occurrences of soil S-defi ciency in many countries (Chien et al., 2009). Furthermore, a reduction in SO2 emissions to the atmosphere from industry, as required by environmental laws, has a signifi cant local eff ect on S deposition from the atmosphere to soils. For example, Sawyer et al. (2011a, 2011b) reported signifi cant maize (Zea mays L.) and alfalfa (Medicago sativa L.) yield increases in response to S applications at fi eld sites in northeastern Iowa. Grant (2013) reported signifi cant canola (Brassica napus L.) response to S fertilizers in Canada. Because pure ES is 100% S, incorporation of ES into highanalysis granular NP fertilizers will not signifi cantly reduce N and P contents of the NP fertilizers and minimize increase in transportation costs as compared with the inclusion of AS. However, AS is considered readily plant available, whereas ES is not, unless it is oxidized to SO4–S by soil microbes. Th e oxidation rate of soil incorporated ES particles increases with decreasing particle size of ES (Boswell and Friesen, 1993). For this reason, some fertilizer companies have been developing processes in which the very fi ne micronized ES particles (

Nitrogen management in crops is a key activity for agricultural production. Methods that can determine the levels of this element in plants in a quick and non-invasive way are extremely important for improving production systems. Within several fronts of study on this subject, proximal and remote sensing methods are promising techniques. In this regard, this research sought to demonstrate the relationships between variations in leaf nitrogen content (LNC) and sugarcane spectral behaviour. The work was carried out in three experimental areas in São Paulo State, Brazil, with different soils, varieties and nitrogen rates during the 2012/13 and 2013/14 seasons. A significant correlation was observed between the LNC and variations in the sugarcane spectra. The green and red-edge spectral bands were the most consistent and stable predictors of LNC among the evaluated harvests. Stepwise multiple linear regression analysis (MSLR) generated better models for LNC estimation when calibrated with experimental area, independent of the variety. The present research demonstrates that specific wavelengths are associated with the variation in LNC in sugarcane, and these are reported in the green region (near 550 nm) and in the red-edge wavelengths (680 to 720 nm). These results may help in future research on the direct in situ application of nitrogen fertilizers. Nitrogen management in crops is a key activity for agricultural production. Methods that can determine the levels of this element in plants in a quick and non-invasive way are extremely important for improving production systems. Within several fronts of study on this subject, proximal and remote sensing methods are promising techniques. In this regard, this research sought to demonstrate the relationships between variations in leaf nitrogen content (LNC) and sugarcane spectral behaviour. The work was carried out in three experimental areas in São Paulo State, Brazil, with different soils, varieties and nitrogen rates during the 2012/13 and 2013/14 seasons. A significant correlation was observed between the LNC and variations in the sugarcane spectra. The green and red-edge spectral bands were the most consistent and stable predictors of LNC among the evaluated harvests. Stepwise multiple linear regression analysis (MSLR) generated better models for LNC estimation when calibrated with experimental area, independent of the variety. The present research demonstrates that specific wavelengths are associated with the variation in LNC in sugarcane, and these are reported in the green region (near 550 nm) and in the red-edge wavelengths (680 to 720 nm). These results may help in future research on the direct in situ application of nitrogen fertilizers.

Organic vinasse, a residue produced during bioethanol production, increases nitrous oxide (N2O) emissions when applied with inorganic nitrogen (N) fertilizer in soil. The present study investigated the role of the ammonia-oxidizing bacteria (AOB) community on the N2O emissions in soils amended with organic vinasse (CV: concentrated and V: non-concentrated) plus inorganic N fertilizer. Soil samples and N2O emissions were evaluated at 11, 19, and 45 days after fertilizer application, and the bacterial and archaea gene (amoA) encoding the ammonia monooxygenase enzyme, bacterial denitrifier (nirK, nirS, and nosZ) genes and total bacteria were quantified by real time PCR. We also employed a deep amoA amplicon sequencing approach to evaluate the effect of treatment on the community structure and diversity of the soil AOB community. Both vinasse types applied with inorganic N application increased the total N2O emissions and the abundance of AOB. Nitrosospira sp. was the dominant AOB in the soil and was correlated with N2O emissions. However, the diversity and the community structure of AOB did not change with vinasse and inorganic N fertilizer amendment. The results highlight the importance of residues and fertilizer management in sustainable agriculture and can be used as a reference and an input tool to determine good management practices for organic fertilization.

Graphical abstract Schematic diagram of urea dissolution, diffusion and hydrolysis in the soil. (a) Without an inhibitor, hydrolysis is fast (dark blue color) causing NH3/NH4+ accumulation and increasing the pH close to the soil surface around the fertilizer granule, driving NH3 volatilization. As the ammonia species are less mobile in soil, diffusion is limited. (b) The inhibitor maintains urea unhydrolyzed for some time. Urea has no electrical charges and diffuses easily into the soil solution. When the effect of the inhibitor phases down and urea starts to hydrolyze, both the pH and the NH3/NH4+ concentrations are lower (light blue color) as a result of dilution. Part of the urea is incorporated into the soil before hydrolysis; the NH3 produced inside the soil is retained by the negative charges of colloidal material and losses are reduced even if no rain or irrigation incorporates urea into the soil., Urea is the most widely used nitrogen (N) fertilizer, with a projected increase in annual demand of 1.5% in the coming years. After its application to soil, urea undergoes hydrolysis via the urease enzyme, causing increases in the soil pH in the surrounding area of the granules and resulting in NH3 losses that average 16% of N applied worldwide and can reach 40% or more in hot and humid conditions. The use of urease inhibitors is an effective way to reduce NH3 losses. Several compounds act as urease inhibitors, but only N-(n-butyl) thiophosphoric triamide (NBPT) has been used worldwide, being the most successful in a market that has grown 16% per year in the past 10 years. Only in the past three years other compounds are being commercially launched. In comparison to urea, NBPT-treated urea reduces NH3 loss by around 53%. Yield gain by NBPT usage is of the order of 6.0% and varies from −0.8 to 10.2% depending on crop species. Nitrification inhibitors usually increase NH3 volatilization and mixing them with urease inhibitors partially offsets the benefits of the latter in reducing NH3 loss. The efficacy of NBPT to reduce NH3 loss is well documented, but there is a need for further improvement to increase the period of inhibition and the shelf life of NBPT-treated urea.

Background Vinasse, a by-product of sugarcane ethanol production, is recycled by sugarcane plantations as a fertilizer due to its rich nutrient content. However, the impacts of the chemical and microbial composition of vinasse on soil microbiome dynamics are unknown. Here, we evaluate the recovery of the native soil microbiome after multiple disturbances caused by the application of organic vinasse residue, inorganic nitrogen, or a combination of both during the sugarcane crop-growing season (389 days). Additionally, we evaluated the resistance of the resident soil microbial community to the vinasse microbiome. Results Vinasse applied alone or 30 days prior to N resulted in similar changes in the soil microbial community. Furthermore, the impact of the application of vinasse together with N fertilizer on the soil microbial community differed from that of N fertilizer alone. Organic vinasse is a source of microbes, nutrients, and organic matter, and the combination of these factors drove the changes in the resident soil microbial community. However, these changes were restricted to a short period of time due to the capacity of the soil community to recover. The invasive bacteria present in the vinasse microbiome were unable to survive in the soil conditions and disappeared after 31 days, with the exception of the Acetobacteraceae (native in the soil) and Lactobacillaceae families. Conclusion Our analysis showed that the resident soil microbial community was not resistant to vinasse and inorganic N application but was highly resilient. Electronic supplementary material The online version of this article (10.1186/s40168-018-0525-1) contains supplementary material, which is available to authorized users.

Crop residues returned to the soil are important for the preservation of soil quality, health, and biodiversity, and they increase agriculture sustainability by recycling nutrients. Sugarcane is a bioenergy crop that produces huge amounts of straw (also known as trash) every year. In addition to straw, the ethanol industry also generates large volumes of vinasse, a liquid residue of ethanol production, which is recycled in sugarcane fields as fertilizer. However, both straw and vinasse have an impact on N2O fluxes from the soil. Nitrous oxide is a greenhouse gas that is a primary concern in biofuel sustainability. Because bacteria and archaea are the main drivers of N redox processes in soil, in this study we propose the identification of taxa related with N2O fluxes by combining functional responses (N2O release) and the abundance of these microorganisms in soil. Using a large-scale in situ experiment with ten treatments, an intensive gas monitoring approach, high-throughput sequencing of soil microbial 16S rRNA gene and powerful statistical methods, we identified microbes related to N2O fluxes in soil with sugarcane crops. In addition to the classical denitrifiers, we identified taxa within the phylum Firmicutes and mostly uncharacterized taxa recently described as important drivers of N2O consumption. Treatments with straw and vinasse also allowed the identification of taxa with potential biotechnological properties that might improve the sustainability of bioethanol by increasing C yields and improving N efficiency in sugarcane fields.

Made available in DSpace on 2018-11-26T15:30:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-08-01 CNEN (National Nuclear Energy Commission) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The aim of this study was to evaluate the response of sugarcane to nitrogen (N) application with drip irrigation and the relation with carbon isotope discrimination (Delta C-13), aboveground dry matter cane yield and the N balance in consecutive ratoon crops of sugarcane. An experiment was set up in Jau, SP, Brazil, in which the second and third ratoon crop cycles (2008/2009 and 2009/2010) were evaluated. The experiment included an unfertilized N control in both years (T1), and the following three nitrogen (N) fertilizer rates (in kg ha(-1)) applied in 2008 and 2009, respectively: 70 and 50 (T2), 140 and 100 (T3), and 210 and 150 (T4). Fertilization with N caused a marked gain in stalk yields by 98 Mg ha(-1) in 2 years. The N export with harvest was higher than N application in the control treatment T1 and at the lower rate (T2); this, in addition to the observed linear response to N, indicate the need to increase N fertilization in irrigated sugarcane. The values of Delta C-13 decreased with the increase of N supply showing a significant negative correlation (p < 0.05) with stalk as well as whole plant aboveground dry matter yields. The values of Delta C-13 in top leaves may be used as a tool to characterize the N status of sugarcane plants and its relation to aboveground dry matter and yield. Lab Nacl Ciencia & Tecnol Bioetanol CTBE, Rua Giuseppe Maximo Scolfaro 10-000, BR-13083970 Campinas, SP, Brazil Agencia Paulista Tecnol Agronegocios, Jau, SP, Brazil Inst Agron Campinas, Campinas, SP, Brazil Univ Sagrado Coracao, Bauru, SP, Brazil Univ Estadual Paulista, Botucatu, SP, Brazil Univ Sao Paulo, CENA, Piracicaba, SP, Brazil Univ Estadual Paulista, Botucatu, SP, Brazil FAPESP: 2008/56.147-1

Nitrogen fertilizer broadcast application over maize (Zea mays L.) is becoming more common as narrow row spacing is adopted and larger fields are cultivated. The contact of N fertilizers with plant leaves can partially damage leaf tissues and consequently affect crop yield. This study was conducted to evaluate the effect of source, method, and time of application of N fertilizer on maize leaf area and grain yield. A field trial was conducted in Brazil during two growing seasons. Urea (UR) and ammonium nitrate (AN) were applied at V5 and V10 maize growth stages broadcasted over the canopy or banded on the soil at a rate of 200 kg N ha–¹. Solid fertilizers were broadcasted over dry and wet leaves whereas for applications to the soil solid fertilizers or solutions were used. In the first season, broadcasting AN reduced the leaf area at silking by 15.7% compared to soil application regardless of leaf moisture. In the following year, broadcasting AN reduced by 7.5% the leaf area at silking compared with UR. In the first growing season, the grain yield with UR was 10.1% greater than that with AN when both fertilizers were broadcasted. In the second season for the same application method, the grain yield from crops fertilized with UR was 32% higher than those where AN was used. In addition, the yield was 18% greater when fertilizers were applied to the soil than when they were broadcasted. Broadcasting N fertilizers causes leaf phytotoxicity and may decrease grain yield, especially when AN is used.

The environmental benefits of producing biofuels from sugarcane have been questioned due to greenhouse gas emissions during the biomass production stage, especially nitrous oxide (NO) associated with nitrogen (N) fertilization. The objective of this work was to evaluate the use of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4 dimethylpyrazole phosphate (DMPP) and a controlled-release fertilizer (CRF) to reduce NO emissions from urea, applied at a rate of 120 kg ha of N. Two field experiments in ratoon cycle sugarcane were performed in Brazil. The treatments were (i) no N (control), (ii) urea, (iii) urea+DCD, (iv) urea+DMPP, and (v) CRF. Measurements of NO fluxes were performed using static chambers with four replications. The measurements were conducted three times per week during the first 3 mo and biweekly afterward for a total of 217 and 382 d in the first and second seasons, respectively. The cumulative NO-N emissions in the first ratoon cycle were 1098 g ha in the control treatment and 1924 g ha with urea (0.7% of the total N applied). Addition of NIs to urea reduced NO emissions by more than 90%, which did not differ from those of the plots without N. The CRF treatment showed NO emissions no different from those of urea. The results were similar in the second ratoon: the treatment with urea showed NO emissions of 0.75% of N applied N. Application of NIs resulted in a strong reduction in NO emissions, but CRF increased emissions compared with urea. We therefore conclude that both NIs can be options for mitigation of greenhouse gas emission in sugarcane used for bioenergy.

We propose an approach for assessing the efficiency of coating materials on controlling nitrogen (N) availability to plants. It is based on the use of coated and soluble urea (UR) applied to corn over 3 growing cycles, as follows: coated UR with longevity of 2 (UR-2m) or 4 months (UR-4m) with application of 900 mg N∙pot−1 at the beginning of the experiment, soluble UR with a split application of 900 mg N∙pot−1 (300 mg N∙pot−1 per growing cycle, UR-3x), soluble UR with a sole application of 900 mg N∙pot−1 at the beginning of the experiment (UR-1x), and a control treatment. At the end of each growing cycle, shoots were harvested to estimate N provision by the UR by quantifying dry matter (DM) and N uptake. In the first cycle, UR-2m and UR-4m promoted lower plant growth and N accumulation in shoots than UR-1x. However, in the third cycle, higher shoot N uptake and DM production was recorded in UR-4m than in UR-1x. Furthermore, fertilizer contribution for shoot N uptake in UR-4m plants was higher than those in UR-1x and UR-2m at the end of the experiment. Accordingly, consecutive growing cycles combined with forms of soluble UR application were able to characterize the pattern of N release from coated fertilizers, being, thus, a suitable method to evaluate the efficiency of such products. We argue that our practical approach could be used by the industry in fertilizer quality programs and to register fertilizer coating materials by regulatory agencies.

Nitrogen recommendation systems for sugarcane (Saccharum spp.) generally does not consider the N supply from soil. Identifying a reliable soil test for estimating N availability is crucial to avoid yield losses or environmental pollution. Therefore, the objective of this study was to correlate and calibrate N availability indices with field–based measures of soil N supply. Between 2006 and 2013, 15 trials for rate–response to N fertilizer by sugarcane ratoons were performed in Sao Paulo, the main sugarcane–producing state in Brazil. The following indices were tested: KMnO4 oxidizable C, hot KCl extractable N, phosphate–borate buffer distillable N, NaOH distillable N, Illinois Soil N Test, organic C, total N, mineral N, anaerobic incubation, soil respiration, substrate–induced respiration, microbial biomass C, metabolic quotient, microbial quotient, and gross N mineralization. The indices were then correlated with sugarcane yield (Y0N) and N content of the crop (N0N) in N–unfertilized plots, relative yield (RY), and the N rate predicted to achieve 90% of the RY (NR 90%RY). Although weak correlations were found between Y0N with anaerobic incubation, total N, and soil respiration, as well as between N0N and anaerobic incubation, no index correlated with RY or NR 90%RY. Grouping sites based on soil texture or byproduct management did not improve prediction of RY. Therefore, we concluded that none of the fifteen laboratory indices is a reliable predictor of soil N supply, and hence could not be used to adjust N fertilization rate for sugarcane.

Sugarcane-derived ethanol from Brazil has a high output to input energy ratio and high greenhouse gas savings compared to fossil fuels. Current ethanol production is based on first generation (1G) technology, which ferments the sugars extracted from sugarcane stalks. Cellulosic ethanol (2G) can be produced from what is currently considered agricultural and agro-industrial residues (straw and bagasse), and also from dedicated high biomass-producing crops. 2G ethanol provides an opportunity to intensify production, obtaining more energy per unit of area cropped and potentially reducing the environmental footprint. Straw removal from the field has more negative than positive consequences for the environment and the production system, but the effects need to be evaluated at the site and regional levels. The use of bagasse as feedstock should be evaluated using life cycle assessment methods to account for its alternative uses as raw material and in cogeneration. Energy cane, a vigorous and rustic crop selected for total biomass production rather than for sucrose, is a promising feedstock for 2G ethanol. The presence of rhizomes, a deep root system, and intensive tillering contribute to erosion control, crop longevity, and soil carbon sequestration. There is a need for more long-term experiments focusing on soil quality, nutrient cycling, greenhouse gas emissions, and crop production using innovative techniques such as stable isotope labeling and intensive soil flux measurements with automatic chambers to understand the impact of removing crop residues for bioenergy production and of using high-biomass dedicated crops. Process-based models are useful in sustainability assessments of 2G sugarcane ethanol production since they take into account site and regional variability in soil biogeochemistry, climate parameters, management practices, plant genetic traits, and the interactions of these factors. The integration of models and geographic information systems allows for regional assessments of the potential impacts of bioenergy production, contributing to the identification and promotion of sustainable pathways for cellulosic ethanol production.

Nitrogen (N) fertilization is important for sugarcane crops, for both agronomic and environmental reasons. Better use of N from fertilizer is required for crop management, and in order to achieve it, adequate N nutrition monitoring is necessary. Sap extract analysis is a sensitive technique that has been adopted in other crops to tackle this objective, and can be used for sugarcane. The aim of this study was to evaluate the behavior of N and the response of sugarcane after N fertilization, using sap and leaf tissue analysis. The study was undertaken in two experimental areas in 2012/2013 season, using ratoon cane, following application of 0, 50, 100, and 150 kg&middotha-1 of N. The youngest visible leaves were sampled from sugarcane at five time points between 0 and 150 days after fertilization, to evaluate the nitrate, ammonium, and total N content of sap extract, and total N content of leaf tissue. At the first sampling point (30 days after N fertilizer application), mineral N in sap increased as a result of N fertilization in medium-textured soil, and remained high until 120 days after fertilization in clayey soil. The total N content of sap followed a similar behavior. Stalk yield was only observed to increase in sugarcane grown in the clayey soil. Sap analysis proved to be an efficient method for monitoring N status in sugarcane grown in different soil types.

In no-tillage systems (NTS), biological activity and nitrification process in thesoil are higher due to higher organic matter and moisture contents, resulting in higher levelsof nitrate compared with areas under conventional tillage systems. However, nitrogen in theform of nitrate is more easily leached, helping to reduce nitrogen use efficiency (NUE) byplants, besides contaminating water resources. Therefore, the use of alternatives that promotethe persistence of ammonium in the soil contribute to increased nitrogen use efficiency inagricultural systems, as well as to their sustainability. The purpose of this review was todiscuss the process of nitrification inhibition. We observed that it is possible to increase thecontent of ammonium in the soil, contributing to the reduction of N loss through leachingand increasing the efficiency of nitrogen use by crops, thus providing sustainability toagricultural systems. To this end, the use of cover crops, such as Brachiaria species, andsynthetic nitrification inhibitors incorporated to nitrogen fertilizers are among the alternatives.Nevertheless, studies should be developed in order to clarify the conditions under whichthese cover crops can be introduced in agricultural systems for this purpose and also whichfactors interfere on the efficiency of synthetic nitrification inhibitors.

Made available in DSpace on 2014-12-03T13:11:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-11-01Bitstream added on 2014-12-03T13:22:35Z : No. of bitstreams: 1 S0100-06832013000600023.pdf: 137304 bytes, checksum: 9092c82320c58bf1ba7d5aba0eb6de41 (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The grain yield of upland rice under no-tillage has been unsatisfactory and one reason could be the nitrate/ammonium balance in the soil. Cover crops and nitrogen fertilization can be used to change the nitrate/ammonium relation in the soil and improve conditions for the development of upland rice in the no-tillage (NT) system. The aim was to study the effect of cover crops and nitrogen sources on grain yield of upland rice under no tillage. The study was carried out on the Fazenda Experimental Lageado, in Botucatu, State of Sao Paulo, Brazil, in an Oxisol area under no-tillage for six years. The experiment was arranged in a randomized block split-plot design with four replications. The plots consisted of six cover crop species (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and the split-plots of seven forms of N fertilizer management. Millet is the best cover crop to precede upland rice under NT. The best form of N application, as nitrate, is in split rates or total rate at topdressing or an ammonium source with or without a nitrification inhibitor, in split doses. When the cover crops C. spectabilis, B. brizantha, B. decumbens, B. humidicola, and B. ruziziensis preceded rice, they induced the highest grain yield when rice was fertilized with N as ammonium sulfate source + nitrification inhibitor in split rates or total dose at topdressing. Univ Western Sao Paulo UNOESTE, BR-19067175 Presidente Prudente, SP, Brazil Sao Paulo State Univ UNESP, Dept Crop Sci Agr, Coll Agr Sci, BR-18603970 Botucatu, SP, Brazil Agron Inst Campinas, Ctr Soil & Environm Resources, BR-13012970 Campinas, SP, Brazil Embrapa Rice & Beans, BR-75375000 Santo Antonio De Goias, Go, Brazil Sao Paulo State Univ UNESP, Dept Crop Sci Agr, Coll Agr Sci, BR-18603970 Botucatu, SP, Brazil

Sugarcane crop residues from green cane harvests may affect the greenhouse gas fluxes from the soils. Therefore, it is important to understand how changes in soil moisture covered with cane trash alter the N2O and CO2 emission. The aim of this study was to evaluate N2O and CO2 emission from repacked soil columns incubated with (16 Mg ha−1) or without crop residues and N fertilizer (0 or 2.1 g N m−2), and as a function of four soil moisture levels (25, 50, 75 and 100 % of water holding capacity). For gas samplings, the columns were closed with a lid and four gas samples were taken in 20 min. The N2O fluxes increased linearly (p

The area under mechanized sugarcane (Saccharum spp.) harvesting is expanding in Brazil, increasing the return of trash to the soil. The main questions regarding this management are: (i) after adopting unburned mechanical harvesting, how long will it take to observe decreases in fertilizer requirements, (ii) what will be the magnitude of this decrease and, (iii) the impact in the short run of removing trash for energy purposes in the nutrient cycling? This study aimed to build an N prediction model for long term assessment of the contribution of sugarcane crop residues to sugarcane nutrition and to evaluate the cycling of other nutrients derived from crop residues. Keeping crop residues over the soil will increase soil N stock and N recovery by sugarcane, reaching equilibrium after 40 years with recovery of approximately 40 kg ha-1 year-1 of N. Removing trash for energy production will decrease the potential reduction in N fertilizer requirement. Of the total nutrients in the trash, 75 % of the K2O (81 kg ha-1 year-1) and 50 % of the N (31 kg ha-1 year-1) are in the tops, indicating the importance of maintaining tops in the soil to sustain soil fertility. Because the input data employed in the simulations are representative of the conditions in Southeast Brazil, these results might not be definitive for situations not represented in the experiments used in the study, but the model produced is useful to forecast changes that occur in the soil under different trash management.

Because low-phosphorus (P) availability limits citrus growth, rootstocks with a relatively high capacity for P uptake are desirable. An experiment was conducted with trees on Cleopatra mandarin (CM) and Rangpur lime (RL). Treatments consisted of P rates (20, 40, and 80 mg kg−1 of soil) applied in soil layers of 0–0.30 m and/or 0.31–0.60 m, besides an unfertilized control. The P fertilization increased root and shoot growth, and P nutrition was improved as indicated by greater leaf P concentration, P uptake, and P root uptake efficiency (PUE). The P applied in both soil layers improved shoot growth, P uptake, and PUE. Trees on RL took up 23–126% more P and had root systems with greater growth and PUE compared to those on CM. Thus, P uptake by citrus trees in low-P soils can be improved by augmenting the depth of fertilizer application and the use of more adapted rootstocks.

After harvest, sugarcane residues left on the soil surface can alter nitrogen (N) dynamics in the plant-soil system. In Oxisols, the nitrogen fertilizer applied had its effects on the levels of ammonium and nitrate in the soil, N concentration in the plant leaves, and on the growth and productivity of second ratoon plants. The N rates tested were of 0, 60, 120, 180, and 240 kg ha−1. Each treatment was replicated four times. Four months after the experiment was started, ammonium and nitrate concentration in the soil, N levels in plant leaves, and plant growth were evaluated. Productivity was evaluated 11 months after the experiment was set. By increasing the content of mineral N in soil, plant growth variables reflected differences in the production of stems; however, it did not affect foliar N. The use of leaf analysis was not important to assess the nutritional status of nitrogen in the ratoon sugarcane. Nitrogen concentration in soil was affected by nitrogen fertilization, but not the N content in leave...

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.

Fluorine (F-) stands out for its phytotoxic potential, because it accumulates in plants, changes enzymes activity, reduces chlorophyll content and, consequently, affects growth and yield of crop plants. An experiment was conducted to evaluate the effects of F- on leaf gas exchange in coffee and sweet orange plants, compared to sensitive (gladiolus) and tolerant (ryegrass) reference species. Plants grown in pots were exposed to F- in a semi-open mist chamber. The experimental design was completely randomized with treatments defined by the combination of plant species and two intensities of exposure to atmospheric F, with nebulization of HF solutions (low = 0.065 mmol·m-3 and high = 0.260 mmol·m-3) in a mist chamber, as well as with non-exposed control samples. CO2 assimilation (A), transpiration (E), stomatal conductance (gs) and chlorophyll fluorescence rates were measured after 27 days of treatment application. The leaf gas exchange variables in ryegrass and orange plants did not vary in response to the increase in atmospheric F, while an increase in gs and E values was observed in gladiolus and coffee plants. A decrease in A and potential quantum efficiency of photosystem II (Fv/Fm) was found for gladiolus plants. On the contrary, an increase of A for coffee plants was associated with the apparent effect previously reported about the loss of leaf stomatal regulation related to the short assessment period of plants in this experiment. Damages caused to the photosynthetic system were reflected in the susceptibility of the evaluated species to the contamination by the element.