The effects of integrated food and bioenergy cropping systems on crop yields, soil health, and biomass quality: The EU and Brazilian experience

Integrated food and bioenergy production is a promising way to ensure regional/national food and energy security, efficient use of soil resources, and enhanced biodiversity, while contributing to the abatement of CO2 emissions. The objective of this study was to assess alternative crop rotation schemes as the basis for integrating and enhancing the sustainable biomass production within the food-energy agricultural context. Sunn hemp (Crotalaria spp.) in rotation with wheat (Triticum spp.) in the EU and with sugarcane (Saccharum spp.) in Brazil were evaluated. Sunn hemp did not negatively affect crop's productivity and soil fertility; wheat grain yields were maintained around the mean regional production levels (6, 7, 3 and Mg ha(-1) in Greece, Italy, and Spain, respectively), and the cumulative biomass in the extended rotation (wheat straw+sunn hemp) was between 1.5 and 2.0 times higher than in the conventional rotation. In Brazil, sugarcane stalks yield in clay soils increased by around 15 Mg ha(-1) year(-1) under sunn hemp rotation in comparison with bare fallow. Moreover, sunn hemp in the EU rotations did not have negative effects on soil available macronutrients, organic matter, pH, and cation exchange capacity, neither on C and N stocks in Brazil. The qualitative characteristics (mineral, ash, and hemicelluloses contents) of the cumulated biomass were somehow higher (in average +26%, +35%, and +3.4%, respectively) than in the conventional system. In summary, in temperate and tropical climates the integration of dedicated biomass legume crops within conventional systems could lead to enhanced biomass availability, crop diversification, and efficient use (in space and time) of the land resources

Optimal plant density and nitrogen rates for improving off-season corn yields in Brazil

Integrating plant density and nitrogen (N) management is a strategy for improving corn yields, especially for off-season corn production in the tropics. This study tested the hypothesis that increasing plant densities and N rates promotes yield gains for off-season corn production in high-yielding environments. The aim of the study was to investigate the yield performances of two hybrid versions (DKB PRO and DKB PRO3) submitted to three plant densities (55,000; 65,000 and 75,000 plants ha−1) and four N rates (control, 60, 120 and 180 kg ha−1 N). Field trials were undertaken at Uberlândia-MG (site1 and 2) and Pedro Afonso-TO (site 3), Brazil from which data on corn yield parameters were collected and analyzed. Multivariate analysis separated the three trial areas into two groups, presenting high (sites 1 and 2) and low yields (site 3), which were related to weather conditions. There was no influence of a hybrid version or plant densities on crop yields at site 1 or 2. In contrast, there was a positive response to increasing plant densities and the use of DKB PRO3 at site 3. A significant response to N was observed at sites 2 and 3, following a plateau model. Our results suggest that N application rates and plant densities do have the potential to increase off-season corn yields in low yielding environments

Availability of nitrogen in soil and productivity of sugarcane in function of crop rotation

A adoção da rotação de culturas com leguminosas em áreas de implantação e reforma de canaviais é uma estratégia promissora para recuperação e manutenção da fertilidade do solo, e tem potencial no aproveitamento do N para as soqueiras. A análise mais detalhada do comportamento do N no solo durante o ano agrícola e dos parâmetros de produção em locais que possuem solo e clima contrastantes, permitem aprimorar o manejo da adubação nitrogenada da cana-de-açúcar. As hipóteses deste trabalho são (1) a rotação de culturas irá aumentar a disponibilidade de N no solo, a qual suprirá parte da demanda do N das soqueiras subsequentes e (2) a rotação de culturas promoverá redução da resposta das soqueiras à adubação nitrogenada. Objetivou-se avaliar o efeito da rotação de culturas nas transformações do N no solo (N mineral, N-ISNT e N e C da biomassa microbiana) e na produtividade da primeira soqueira. Os experimentos foram instalados em quatro regiões representativas de cultivo de cana-de-açúcar na região Centro Sul do Brasil: Quatá/SP (Local A); Iracemápolis/SP (Local B); Chapadão do Céu/GO (Local C) e Quirinópolis/GO (Local D). Em cada local, foi instalado um experimento em esquema de parcelas subdivididas no delineamento blocos ao acaso com quatro repetições, em áreas submetidas (com rotação) ou não (sem rotação) ao plantio de leguminosa do gênero crotalária. Após a colheita da cana planta, foram implantados os seguintes tratamentos: 60, 120 e 180 kg ha-1 de N e um controle (sem N), aplicados superficialmente sobre a palhada. Foram realizadas três amostragens para determinação do conteúdo de N mineral, N-ISNT e C e N da biomassa microbiana. Entre 150 a 180 dias após a colheita da cana-planta, foram realizadas avaliações de perfilhamento e índice SPAD. Na colheita, avaliou-se matéria seca da parte aérea, produtividade e atributos tecnológicos. Os resultados demonstraram que a mineralização dos resíduos da crotalária influenciaram a dinâmica do C e N e os reservatórios de N no perfil do solo ao longo do ciclo da primeira soqueira, com destaque para o solo de textura média (Local A). Apesar da rotação de culturas ter modificado o conteúdo de N mineral, N-ISNT, e aumentado o perfilhamento e índice SPAD no local A, somente nos solos argilosos (Locais C e D), a rotação aumentou a produtividade da soqueira. A hipótese de que a rotação de culturas reduz a demanda de fertilizantes nitrogenados não foi aceita; houve resposta à adubação nitrogenada nos quatro locais, independentemente da rotação de culturas. Porém, a rotação demonstrou potencial em aumentar a produção de biomassa com manutenção da dose de N. Esta pesquisa demonstrou a viabilidade de rotação de culturas em solos argilosos com elevado conteúdo de C e N total, com potencial de aumentar a produtividade do canavial, porém sem reduzir a demanda de adubação nitrogenada.The adoption of crop rotation with sugarcane is a promising strategy for the recovery and maintenance of soil fertility, and it shows potential in the use of N to the sugarcane ratoon. A more detailed analysis of the transformations N in soil during the agricultural year and production parameters in sites that have contrasting soil texture and climate, allows to improve management of N fertilization for sugarcane. The hypothesis of this work are (1) crop rotation will increase soil N availability, which will satisfy part of N requirements of sugarcane ratoon and (2) crop rotation will reduce the sugarcane ratoon response to N fertilization. The objective was to evaluate the effects of sunn hemp rotation in the transformations of N in soil (mineral N content, ISNT-N and microbial biomass C and N) and sugarcane ratoon yield. The field trials were installed in four representative regions of cultivation of sugarcane in Brazil: Quatá/SP (Site A); Iracemápolis/SP (Site B); Chapadão do Céu/GO (Site C) e Quirinópolis/GO (Site D). At each site, a field trial was installed in split plot in a randomized block experimental design with four replications, in areas sowed (rotation) and not sowed (no rotation) with sunn hemp. After the harvest of cane-plant, the following treatments were applied: 60, 120 and 180 kg ha-1 of N and a control (without N) over the straw. Three sampling were performed to determine the soil inorganic N content, ISNT-N, C and N of microbial biomass. Between 150 to 180 days after the harvest of the cane-plant, tillering was counted and SPAD index was measured. At harvest of the sugarcane ratoon, biometric parameters, yield and quality parameters were evaluated. The results showed that mineralization of residues of sunn hemp influenced the dynamics of C and N and N content in the soil profile throughout the cycle of the sugarcane ratoon, with emphasis on medium-textured soil (Site A). Despite crop rotation has modified mineral N stocks, ISNT-N, and increased tillering and SPAD index in site A, crop rotation only increased the sugarcane ratoon yield on clay soils (Sites C and D). The hypothesis that crop rotation reduces N-fertilizer requirement was not accepted; there was response to N fertilization in four sites, regardless of crop rotation. However, the rotation showed potential in increase biomass production with maintenance of N rate. This research demonstrated the viability of crop rotation in clay soils with high total C and N content, with potential to increase sugarcane yield, but without reducing N-fertilizer requirement

Can reduced tillage sustain sugarcane yield and soil carbon if straw is removed?

Straw removal for bioelectricity, cellulosic ethanol, or other bio-products has become a common practice in Brazilian sugarcane areas, but long-term effects on soil organic carbon (SOC) and yield are unknown. Our objective was to quantify tillage intensity and removal levels on SOC stocks and sugarcane yield on contrasting edaphoclimatic conditions in Brazil. Conventional tillage-CT and reduced tillage-RT coupled with three straw removal levels (none-NR; moderate-MR; total-TR) were combined to create six treatment combinations: CTNR, CTMR, CTTR, RTNR, RTMR, and RTTR, respectively. Sugarcane yield was measured annually and soil samples to a depth of 40 cm were collected and analyzed before and after 5 years of treatments. Neither tillage practices nor straw removal significantly affected sugarcane yield on sandy loam soil, but CTMR, CTTR, and RTTR showed substantial yield reductions on clayey soil. SOC stocks for RTNR increased by as much as 1.64 Mg ha(-1) year(-1) on clayey soil, while CTMR and CTTR favored depletion of SOC stocks on both soils. Overall, each Mg of straw returned to the soil increased SOC stock by 95 kg ha(-1) for clayey soil under both tillage practices and 55 kg ha(-1) for sandy loam under the CT system. Furthermore, straw removal decreased microbial biomass C and b-glucosidase activity. These findings suggest that the adoption of RT attenuates the adverse impacts of straw removal on SOC stocks while ensuring sugarcane yields for a more sustainable bioenergy production in Brazil12476477

Effect of previous soil management on sugarcane response to nitrogen fertilization

ABSTRACT: N Fertilizer recommendations must be improved to optimize N use efficiency (NUE) for bioenergy crops. A study was conducted to test the hypothesis that sites varying in historical usage of by-product differ in soil N-supplying power and sugarcane (Saccharum spp.) responsiveness to N fertilization. Our aim was to quantify soil N availability and N fertilizer rates, sources, and application timings for their effects on sugarcane yield and NUE. Three N response trials, each involving 0 to 200 kg N ha−1, were conducted in the state of São Paulo, Brazil, at sites varying historically in the usage of vinasse. Before fertilizer application and at harvest, soil inorganic N content was quantified and potential N mineralization estimated by the Illinois Soil Nitrogen Test (ISNT); stalk yield and sugar content were measured at harvest and used to estimate NUE. Sugarcane showed significant response to N fertilization only at the sites with no history of vinasse usage. Reducing the N rate from 120 to 80 kg N ha−1 showed limited potential for lowering yield (~ 1 %), while increasing the NUE by 54 %, which was far better than the 14 % increase achieved by modifying the N source or application timing. Monitoring inorganic N and ISNT levels over time to estimate soil N-supplying power has potential for predicting the responsiveness of sugarcane to N fertilization; however, ISNT interpretations must consider factors that impede mineralization or crop N utilization, such as soil acidity or a limitation on the availability of Ca or P. Soil N testing can help optimize NUE for sustainable bioenergy production

Soil physical quality associated with tillage practices during sugarcane planting in south-central Brazil

Soil tillage operations had been carried out during the sugarcane planting to improve soil's physical quality, thus providing proper conditions for sugarcane growth. Long-term field experiments were designed to assess the implications of tillage operations during sugarcane planting on soil physical quality and the associated effects on sugarcane yields under two soil types in south-central Brazil. In 2013, two treatments were arranged in a randomized block design with four repetitions: (i) conventional tillage (CT) and ii) no-tillage (NT). Undisturbed soil samples were collected representing the row and inter-row positions to a 0.40-m depth (0-0.10, 0.10-0.20 and 0.20-0.40 m) over four crop cycles (from 2014 to 2017). In the laboratory, bulk density (BD), soil resistance to penetration (SRP), snacroporosity (MaP) and microporosity (MiP) were evaluated. Additionally, sugarcane yields were measured annually using an instrumented truck equipped with load cells. CT management alleviated soil compaction only in the plant cane cycle, indicating that the intensive machinery traffic performed in sugarcane harvesting nullify the effects of tillage practices. The opening of planting furrow in both tillage systems reduced soil physical limitations, thus favoring the crop development in the row position. The changes in soil physical attributes were observed mostly in the inter-row position. In clayey soil, BD increased by 24 and 16%, and the SRP by 63 and 55% in the 0-0.10 m layer from plant cane to 3rd ratoon for CT and NT, respectively. Similarly, in sandy loam soil, the SRP increased over time in the 0-0.10 m layer for CT and NT, reaching values higher than 2 MPa. Likewise, MaP decreased for values lower than 0.10 m(3) m(-3) after four years for both soils and tillage systems. Regardless of soil type, tillage management did not show differences in sugarcane yields over the assessed period. Our findings suggest that NT could be a feasible strategy to reduce soil mobilization and its negative implications on several ecosystem services without compromise sugarcane yield195CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP406922/2013-688882.143419/2017-012017/23978-7; 2018/09845-7This research was supported by National Council for Scientific and Technological Development-CNPq (grant 406922/2013-6) and the Brazilian Federal Agency for Support and Evaluation of Graduate Education - (CAPES/CNPEM program) (contract grant number 88882.143419/2017-01) for providing PhD scholarship to Leandro C. Barbosa. We are grateful to Agrisus Foundation (grant 2563/18) and São Paulo Research Foundation-FAPESP (grants 2017/23978-7; 2018/09845-7). We would like to thank LNBR technicians’ group for all the support in the field and laboratory activities, and Quatá and Boa Vista Mills for providing the experimental sites and the logistical support during the fieldwor

Legume nitrogen credits for sugarcane production: implications for soil N availability and ratoon yield

One of the steps needed to achieve sustainable bioenergy is to reduce our reliance on synthetic nitrogen (N). Despite the fact that legume cover crops have the potential to increase soil quality and sugarcane (Saccharum spp.) yield, much information is still needed to determine amount of N available from cover crops to sequential ratoon cycles. This study was designed to assess the impacts of sunn hemp (Crotalaria spectabilis) cover crop on soil N dynamics and sugarcane ratoon response to N fertilization during two harvest seasons across three contrasting soil and climatic conditions in southern Brazil. The treatments consisted of cover crop and fallow established prior to sugarcane replanting; in addition to three N-fertilizer rates 60, 120 and 180kgNha(-1) and a 0-N control applied during the first and second ratoons. Although there was increased sugarcane yield (8-13Mgha(-1) in first ratoon and 10-16Mgha(-1) in second ratoon) in plots planted with cover crop, it was not possible to detect significant increases in soil inorganic N, microbial biomass C and Illinois Soil N Test content under cover crop compared with fallow. Cover crop with sunn hemp increased the accumulated two-year yields by 14-25Mgha(-1) at all sites and NUE (Mg stalks kg(-1)N) across all N rates at two sites. Our findings support the conclusion that cover crop did not change the N requirement of succeeding ratoon crops but increases the yield, thereby improving NUE in sugarcane systems1133307322CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo308007/2016-62014/05591-

Multilocation straw removal effects on sugarcane yield in south-central Brazil

Sugarcane straw is a crop residue that has a dual purpose and can be maintained on the fields or used to produce bioenergy. The straw retention in the field provides multiple ecosystem services, and the complex interactions between straw and yield responses are hard to predict by local studies. The aim of this study was to investigate the straw removal effects on sugarcane yield in south-central Brazil. To achieve the objective, a set of 21 field studies was conducted in contrasting edaphoclimatic conditions. In addition, data of seven studies from the literature were included to build a more robust dataset. Since straw removal treatments were not homogeneous in all experiments, they were grouped as follows: NR, no removal (baseline treatment); LR, low removal; MR, moderate removal; and TR, total removal. To facilitate the data analysis, the experiments were gathered in four macroregions: southern Goias, western Sao Paulo, central-eastern Sao Paulo, and northeastern Sao Paulo. The site location was the most effective individual factor to explain the straw removal effects on sugarcane yields. Compared with NR treatment, the average yield losses induced by LR, MR, and TR were 2, 10, and 13 Mg ha(-1) in southern Goias and 2, 4, and 6 Mg ha(-1) in western Sao Paulo states, respectively. In other regions, no clear pattern was observed, and only site-specific effects were observed. Straw removal affected sugarcane yields in all soil types, but higher responses were observed under best conditions for sugarcane growth (i.e., clayey soils in southern Goias). Our findings indicated harvesting season has a relevant role on determining yield responses to straw removal and younger ratoons are more responsive to straw removal. Conclusions from this study suggest straw removal recommendations cannot be designed based on isolated factors but require holistic and integrated knowledge to ensure that the straw amount left on field is enough to sustain multiple soil ecosystem services and crop yields12481382

Optimal plant density and nitrogen rates for improving off-season corn yields in Brazil

ABSTRACT: Integrating plant density and nitrogen (N) management is a strategy for improving corn yields, especially for off-season corn production in the tropics. This study tested the hypothesis that increasing plant densities and N rates promotes yield gains for off-season corn production in high-yielding environments. The aim of the study was to investigate the yield performances of two hybrid versions (DKB PRO and DKB PRO3) submitted to three plant densities (55,000; 65,000 and 75,000 plants ha−1) and four N rates (control, 60, 120 and 180 kg ha−1 N). Field trials were undertaken at Uberlândia-MG (site1 and 2) and Pedro Afonso-TO (site 3), Brazil from which data on corn yield parameters were collected and analyzed. Multivariate analysis separated the three trial areas into two groups, presenting high (sites 1 and 2) and low yields (site 3), which were related to weather conditions. There was no influence of a hybrid version or plant densities on crop yields at site 1 or 2. In contrast, there was a positive response to increasing plant densities and the use of DKB PRO3 at site 3. A significant response to N was observed at sites 2 and 3, following a plateau model. Our results suggest that N application rates and plant densities do have the potential to increase off-season corn yields in low yielding environments