Spatial and temporal variability of soil CO2 flux in sugarcane green harvest systems

The sugarcane green harvest system, characterized by mechanized harvesting and the absence of crop burning, affects soil quality by increasing crop residue on the soil surface after harvest; thus, it contributes to improving the physical, chemical, and microbiological properties and influences the soil carbon content and CO2 flux (FCO2). This study aimed to evaluate the spatial and temporal variability of soil FCO2 in sugarcane green harvest systems. The experiment was conducted in two areas of sugarcane in São Paulo, Brazil: the first had a 5-year history of sugarcane green harvest (SG-5) and the second had a longer history of 10 years (SG-10). The temporal FCO2 were evaluated in the dry and rainy periods, and spatial variability in the dry period, and related to soil chemical and physical properties, including organic C porosity, bulk density, soil penetration resistance, mean weight diameter of soil aggregates, clay, P, S, Ca, Mg and Fe. The temporal variability indicated no differences between the dry and rainy periods in SG-10, while in SG-5 soil moisture was increased by 33 % in the rainy period. The spatial variability indicated a different pattern from the temporal one, where FCO2 in SG-10 was correlated with soil temperature, air-filled pore space, total porosity, soil moisture, and the Ca and Mg contents; in the SG-5 area, FCO2 was correlated with soil mean weight diameter of soil aggregates and the sulfur content.4

Soil management of sugarcane fields affecting CO2 fluxes

The harvesting system of green sugarcane, characterized by mechanized harvesting and no crop burning, affects soil quality by increasing the remaining straw left on the soil surface after harvesting, thus, contributing to the improvement of physical, chemical, and microbiological soil attributes, influencing CO2 fluxes. This study aimed to evaluate CO2 fluxes and their relation to soil properties in sugarcane crops under different harvesting managements: burned (B), Green harvesting for 5 years (G-5) and Green harvesting for ten years (G-10). For this, a 1 ha sampling grid with 30 points was installed in each area, all located in the Northeast of São Paulo State, Brazil. In each point, CO2 fluxes were measured and the soil was sampled to analyze the microbial biomass, physical (soil moisture and temperature, mean weight diameter, bulk density, clay, macroporosity and microporosity) and chemical characterization (pH, organic C, base saturation and P). The CO2 fluxes were divided into four quantitative criteria: high, moderate, low and very low from the Statistical Division (mean, first quartile, median and third quartile) and the other data were classified according this criterion. The Principal Component Analysis (PCA) was used to identify the main soil attributes that influence CO2 fluxes. The results showed that G-10 CO2 fluxes were 28 and 41 % higher than those in the G-5 and B treatments, respectively. The PCA analysis showed that macroporosity was the main soil attribute that influenced the high CO2 fluxes

Spatial variability of soil physical properties and grain yield depending on geoforma landscape and irrigation center pivot

Orientadores: Zigomar Menezes de Souza, Reginaldo Barbosa da SilvaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia AgrícolaResumo: O emprego de irrigação tem promovido alterações na função do tipo de íons e sua valência presentes na solução do solo, forma variável de pH do solo no grau de floculação crítica de partículas. O desequilíbrio e interação destes fatores podem causar alteração na dispersão da fração argila, alterando a estrutura do solo. O objetivo deste trabalho foi verificar o Delta pH do solo e sua relação com o grau de floculação e dispersão de argila no solo e então avaliar o efeito da migração de argila no adensamento do solo, bem como o aumento da compactação do solo no desenvolvimento de raízes no solo e a produtividade alcançada do feijoeiro. O experimento foi realizado na região de Cristalina-GO, em área irrigada sob pivô central, com coordenadas geográficas de 16°53'35,59" de latitude sul e 47°32'16,75" de longitude oeste, 1.021 m de altitude, o solo foi classificado como Argissolo Vermelho-Amarelo. Os atributos físicos do solo foram coletados nos pontos de cruzamento de uma malha com intervalos regulares de 10 m entre pontos em três posições ao longo do declive da área com 1,8 ha nas profundidades de 0,00-0,10, 0,10-0,20 e 0,20-0,30 m, sob um pivô central, em cada posição da encosta, ou seja, terço superior, médio e inferior foram coletados 60 pontos perfazendo o total de 180 pontos. Os dados foram submetidos à estatística descritiva, bem como a geoestatística considerando os modelos esféricos, o exponencial, o linear e o gaussiano, posteriormente, tais modelos foram usados no desenvolvimento de mapas de isolinhas (krigagem). Os resultados confirmam a predominância de carga líquida negativa pelos valores de delta pH alcançados, que provocou o elevado grau de floculação e dispersão do solo causando a movimentação de argila na vertente, contribuindo para o aumento da densidade do solo e a resistência do solo à penetração, a compactação do solo limitou o alcance do sistema radicular do feijoeiro as camadas mais profundas implicando em perdas significativas de produtividade do feijoeiroAbstract: The use of irrigation has promoted changes in the type of ions and their valence present in the soil solution, so variable soil pH in critical flocculation of particles. The imbalance and interaction factors can cause this change in dispersion of clay, changing the soil structure. The objective of this work was to verify the Delta soil pH and its relationship to the degree of flocculation and dispersion of clay in the soil and then assess the effect of the migration of clay in soil compaction and increased soil compaction in the development of roots in the soil and the productivity achieved bean. The experiment was carried out in the region of Crystalline-GO in irrigated area under central pivot, with geographic coordinates of 16 ° 53'35, 59 "south latitude and 47 ° 32'16, 75" W, 1021 m altitude the soil was classified as Ultisol. The physical attributes of soil were collected at the intersections of a grid with intervals of 10 m between points in three positions along the slope area with 1.8 ha at depths of 0.00-0.10, 0.10 -0.20 and 0.20-0.30 m, under a center pivot at each position of the slope, ie the upper, middle and bottom were collected 60 points totaling 180 points. Data were subjected to descriptive statistics and geostatistics models considering spherical, exponential, linear, and Gaussian, then such models were used in the development of maps (kriging). The results confirm the predominance of net negative charge by the values of delta pH achieved, which caused the high degree of flocculation and dispersion of the soil causing the movement of clay in part, contributing to the increase of soil density and soil resistance to penetration soil compaction limited the scope of the root bean deeper layers resulting in significant losses in grain yieldMestradoAgua e SoloMestre em Engenharia Agrícol

Soil management of sugarcane fields affecting CO2 fluxes

ABSTRACT The harvesting system of green sugarcane, characterized by mechanized harvesting and no crop burning, affects soil quality by increasing the remaining straw left on the soil surface after harvesting, thus, contributing to the improvement of physical, chemical, and microbiological soil attributes, influencing CO2 fluxes. This study aimed to evaluate CO2 fluxes and their relation to soil properties in sugarcane crops under different harvesting managements: burned (B), Green harvesting for 5 years (G-5) and Green harvesting for ten years (G-10). For this, a 1 ha sampling grid with 30 points was installed in each area, all located in the Northeast of São Paulo State, Brazil. In each point, CO2 fluxes were measured and the soil was sampled to analyze the microbial biomass, physical (soil moisture and temperature, mean weight diameter, bulk density, clay, macroporosity and microporosity) and chemical characterization (pH, organic C, base saturation and P). The CO2 fluxes were divided into four quantitative criteria: high, moderate, low and very low from the Statistical Division (mean, first quartile, median and third quartile) and the other data were classified according this criterion. The Principal Component Analysis (PCA) was used to identify the main soil attributes that influence CO2 fluxes. The results showed that G-10 CO2 fluxes were 28 and 41 % higher than those in the G-5 and B treatments, respectively. The PCA analysis showed that macroporosity was the main soil attribute that influenced the high CO2 fluxes

Spatial and Temporal Variability of Soil CO 2 Flux in Sugarcane Green Harvest Systems

ABSTRACT: The sugarcane green harvest system, characterized by mechanized harvesting and the absence of crop burning, affects soil quality by increasing crop residue on the soil surface after harvest; thus, it contributes to improving the physical, chemical, and microbiological properties and influences the soil carbon content and CO 2 flux (FCO 2 ). This study aimed to evaluate the spatial and temporal variability of soil FCO 2 in sugarcane green harvest systems. The experiment was conducted in two areas of sugarcane in São Paulo, Brazil: the first had a 5-year history of sugarcane green harvest (SG-5) and the second had a longer history of 10 years (SG-10). The temporal FCO 2 were evaluated in the dry and rainy periods, and spatial variability in the dry period, and related to soil chemical and physical properties, including organic C porosity, bulk density, soil penetration resistance, mean weight diameter of soil aggregates, clay, P, S, Ca, Mg and Fe. The temporal variability indicated no differences between the dry and rainy periods in SG-10, while in SG-5 soil moisture was increased by 33 % in the rainy period. The spatial variability indicated a different pattern from the temporal one, where FCO 2 in SG-10 was correlated with soil temperature, air-filled pore space, total porosity, soil moisture, and the Ca and Mg contents; in the SG-5 area, FCO 2 was correlated with soil mean weight diameter of soil aggregates and the sulfur content

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

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