Soil dissolved organic carbon responses to sugarcane straw removal

Global demand for bioenergy increases interest in biomass-derived fuels, as ethanol from sugarcane straw. However, straw is the main carbon source to soil and its removal reduces C input, affecting active fractions (dissolved organic carbon, DOC) and C storage. To quantify the effects of straw removal on DOC and C stocks, we built lysimeter system using soil (Rhodic Kandiudox) from sugarcane field. We evaluated four soil depths (1, 20, 50 and 100 cm) and four straw removal rates: no removal NR, medium MR, high HR and total TR, leaving 12, 6, 3 and 0 Mg/ha on the soil surface, respectively. After rainfall, drainage water was collected and analysed for DOC content. Soil C stocks were determined after the 17-month. Total DOC released at 1-cm depth amounted to 606, 500, 441 and 157 kg/ha in NR, MR, HR and TR, respectively. Net-DOC suggests straw as the main source of DOC. Most of DOC in NR (50%) was retained within the 1-20 cm layer, resulting in higher C stock (10 Mg/ha) in the topsoil. In HR and MR, DOC retention was higher within 20-50 cm, suggesting differences in DOC composition. DOC in TR was 40% higher at 20 cm than at 1 cm, indicating C losses from topsoil. Low concentrations of DOC were found at 100-cm depth, but representing 30% in TR. Straw removal for bioenergy production is sustainable, but we should leave at least 3 Mg/ha of straw to ensure DOC production and soil C storage, taking account the DOC contribution to key soil functions

Sampling grid size for characterization of the spatial variability of phosphorus and potassium in an Oxisol

O objetivo deste trabalho foi avaliar a acurácia na caracterização da variabilidade espacial de fósforo e potássio disponíveis no solo, pelo uso de diferentes dimensões de malhas amostrais, bem como a similaridade dos mapas temáticos gerados. O estudo foi conduzido em área de Latossolo Vermelho de 41,96 ha, em Boa Vista das Missões, RS. A amostragem de solo foi realizada na camada de 0,00–0,10 m, tendo-se utilizado sete dimensões de malha amostral: 50x50, 75x75, 100x100, 125x125, 150x150, 175x175 e 200x200 m. Os dados de P e K foram submetidos às análises de estatística descritiva e de geoestatística, e a similaridade dos mapas temáticos gerados foi analisada pelo coeficiente de desvio relativo e pela matriz de correlação de Pearson. A redução da dimensão da malha amostral aumenta a acurácia na caracterização da variabilidade espacial de P e K e, consequentemente, a qualidade das informações geradas por meio dos mapas temáticos. Malhas amostrais ≤100x100 m são recomendadas para planos de amostragem de solo adotados nas áreas de agricultura de precisão no Estado do Rio Grande do Sul.The objective of this work was to evaluate the accuracy in the characterization of the spatial variability of soil phosphorus and potassium, using different sampling grid sizes, as well as the similarity of the thematic maps generated. The study was carried out in a 41.96 ha Oxisol area in the municipality of Boa Vista das Missões, in the state of Rio Grande do Sul, Brazil. Soil sampling was done at the 0.00–0.10 m layer, using seven sampling grid sizes: 50x50, 75x75, 100x100, 125x125, 150x150, 175x175, and 200x200 m. P and K data were subjected to descriptive statistics and geostatistical analyses, and the similarity of the thematic maps generated was analyzed by the coefficient of relative deviation and Pearson’s correlation matrix. The reduction in the size of the sampling grid increases the accuracy in the characterization of the spatial variability of P and K and, consequently, the information generated by the thematic maps. Sampling grid sizes ≤100x100 m are recommended for soil sampling plans adopted in precision agriculture areas in the state of Rio Grande do Sul, Brazil

Hojas de información: buenas prácticas para una agricultura climáticamente inteligente

Document available in English, Portuguese and Spanish.Este documento posee información sobre las buenas prácticas para una agricultura climáticamente inteligente, abarcando la agricultura de conservación para la la no alteración del suelo mediante la labranza, la cobertura permanente del suelo y la rotación de cultivos. Seguido de la restauración de los bosques naturales para la transformación de los Ecosistemas degradados. Al igual que la recuperación de los pastos por medio de la reducción de las emisiones de gases de efecto invernadero. Finalmente, se menciona la producción sostenible del café, para el sostenimiento de los medios de vida de millones de familias en todo el mundo.This document contains information about the good practices for climate-smart agriculture, encompassing conservation agriculture for non-alteration of the soil through tillage, permanent soil cover and crop rotation. Followed by the restoration of natural forests for the transformation of degraded ecosystems. Like the recovery of pastures by reducing greenhouse gas emissions. Finally, the sustainable production of coffee is mentioned, to sustain the livelihoods of millions of families around the world.Este documento contém informações sobre boas práticas para uma agricultura inteligente para o clima, abrangendo a agricultura de conservação para não alterar o solo por meio de preparo do solo, cobertura permanente do solo e rotação de culturas. Seguido pela restauração de florestas naturais para a transformação de ecossistemas degradados. Como a recuperação de pastagens, reduzindo as emissões de gases de efeito estufa. Por fim, menciona-se a produção sustentável de café, para sustentar a vida de milhões de famílias em todo o mundo

Changes in soil temperature and moisture due to sugarcane straw removal in central-southern Brazil

Crop residues left in the field cover and protect the soil surface, and regulate key processes and functions, such as gas and water exchanges. However, the Brazilian sugarcane (Saccharum officinarum L.) sector has begun to use straw as feedstock to produce bioenergy. We conducted a field study to evaluate the effects of sugarcane straw removal in soil temperature and moisture changes at three sites (with different soil textures: Site 1 - clayey Oxisol, Site 2 - medium texture Oxisol, and Site 3 - sandy Ultisol) in the state of Sao Paulo, Brazil. The experimental design was randomized blocks with four rates of straw removal: i) no removal (NR); ii) moderate removal (MR); iii) substantial removal (SR), and iv) total removal (TR). Soil temperature was measured by sensors in the 0- to 5- and 5- to 10-cm soil layers. Undisturbed soil samples were collected from the 0- to 20- and 20- to 40-cm layers to determine soil moisture. Intensive straw removal (HR and TR) increased the soil temperature between 2 and 3 degrees C and the thermal amplitude between 5 and 9 degrees C in the 0- to 5-cm layer, compared to MR and NR. Soil moisture decreased between 0.03 and 0.07 g g(-1) in the 0- to 20-cm layer with intensive straw removal. The sandy soil was more susceptible to straw removal. Therefore, straw maintenance on the soil surface plays an essential role in temperature regulation and preservation of higher soil moisture, especially in regions with severe water deficits and long periods of water stress

Infiltração e Escoamento Superficial Sob Diferentes Usos e Ocupação em uma Bacia Hidrográfica

Com o aumento da área dos grandes centros urbanos e a diminuição da cobertura vegetal sobre a superfície do solo, ocorre um aumento das áreas impermeáveis, fazendo com que a água escoe carreando sedimentos até os cursos de água e reservatórios. Dessa maneira o presente estudo tem por objetivo analisar o escoamento e a infiltração de água no solo sob diferentes usos e ocupação em bacia hidrográfica. Para a realização dos testes foi utilizado o método "Cornell Sprinkle Infiltrometer", já para a determinação da compactação utilizou-se o um penetrômetro digital PLG 1020 PenetroLOG®. Foram observadas áreas onde não ocorreram escoamento superficial (áreas de mata nativa e área urbana) e áreas de arroz onde apresentaram as menores taxas. Em relação à resistência a penetração, a área de mata nativa apresentou os maiores valores, já os menores estiveram presentes sob o uso de pastagem e cultivo de arroz. Os pontos que apresentaram maior infiltração de água encontram-se sob o uso de campo nativo, pastagem e soja, respectivamente, já as menores taxas de infiltração foram obtidas nos pontos sobre o uso de arroz. As variáveis de tempo para início do escoamento superficial, taxa média de escoamento superficial e taxa média de infiltração instantânea a análise da variância na revelou efeito significativo dos usos e manejos do solo, pelo teste F (5%)

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

Soil Organic Matter Responses to Anthropogenic Forest Disturbance and Land Use Change in the Eastern Brazilian Amazon

Anthropogenic forest disturbance and land use change (LUC) in the Amazon region is the main source of greenhouse gas emissions to the atmosphere in Brazil, due to the carbon (C) and nitrogen (N) emitted from vegetation clearance. Land use conversion associated with management practices plays a key role in the distribution and origin of C in different soil organic matter (SOM) fractions. Here, we show how changing land use systems have influenced soil C and N stocks, SOM physical fractions, and the origin of SOM in the Santarem region of the eastern Brazilian Amazon. Soil C and N stocks were calculated for the surface layer of 0-30 cm. Anthropogenic disturbances to the standing forest, such as selective logging and wildfires, led to significant declines in soil C and N stocks. However, in the long-term, the conversion of the Amazon forest to pasture did not have a noticeable effect on soil C and N stocks, presumably because of additional inputs from pasture grasses. However, the conversion to cropland did lead to reductions in soil C and N content. According to the physical fractionation of SOM, LUC altered SOM quality, but silt and clay remained the combined fraction that contributed the most to soil C storage. Our results emphasize the importance of implementing more sustainable forest management systems, whilst also calling further attention to the need for fire monitoring systems, helping to ensure the resilience of C and N stocks and sequestration in forest soils; thereby contributing towards urgently needed ongoing efforts to mitigate climate change

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

Sequestro de carbono do solo através da adoção de práticas de manejo sustentável: potencial e oportunidades para os países das Américas.

Provides the first data tools for the LiSAm initiative in the American hemisphere, with the main methodologies used to measure soil C stocks and GHG emissions in the field, current land use, and soil C stocks , and potential soil C reserves. Sequestration of C through the adoption of sustainable management practices. Various approaches to assess soil C sequestration and GHG emissions were presented and discussed. Finally, it identifies some promising sustainable management practices that could be adopted in the Americas. Finally, it is concluded that the sustainable management practices suggested by the LiSAm initiative can guide new protocols to stop land degradation, promote soil health and soil C sequestration in the Americas.Proporciona las primeras herramientas de datos para la iniciativa LiSAm en el hemisferio americano, con las principales metodologías utilizadas para medir las reservas de C del suelo y las emisiones de GEI en el campo, el uso actual de la tierra y las reservas de C del suelo, y las reservas potenciales de C del suelo. Secuestro de C mediante la adopción de prácticas de gestión sostenible. Se presentaron y discutieron varios enfoques para evaluar el secuestro de C del suelo y las emisiones de GEI. Por último, identifica algunas prácticas de manejo sostenible prometedoras que podrían adoptarse en las Américas. Finalmente se concluye que las prácticas de manejo sostenible sugeridas por la iniciativa LiSAm pueden guiar nuevos protocolos para frenar la degradación de la tierra, promover la salud del suelo y el secuestro de C en el suelo en las Américas.Fornece as primeiras ferramentas de dados para a iniciativa LiSAm no hemisfério americano, com as principais metodologias utilizadas para medir os estoques de C do solo e emissões de GEE no campo, uso atual da terra e estoques de C do solo e reservas potenciais de C do solo. Sequestro de C por meio da adoção de práticas de manejo sustentável. Várias abordagens para avaliar o sequestro de C do solo e as emissões de GEE foram apresentadas e discutidas. Finalmente, identifica algumas práticas promissoras de gestão sustentável que poderiam ser adotadas nas Américas. Por fim, conclui-se que as práticas de manejo sustentável sugeridas pela iniciativa LiSAm podem orientar novos protocolos para deter a degradação da terra, promover a saúde do solo e o sequestro de C do solo nas Américas