Mapping within­field variability of soybean evapotranspiration and crop coefficient using the Earth Engine Evaporation Flux (EEFlux) application.

Accurate information about the spatiotemporal variability of actual crop evapotranspiration (ETa), crop coefficient (Kc) and water productivity (WP) is crucial for water efficient management in the agriculture. The Earth Engine Evapotranspiration Flux (EEFlux) application has become a popular approach for providing spatiotemporal information on ETa and Kc worldwide. The aim of this study was to quantify the variability of water consumption (ETa) and the Kc for an irrigated commercial planting of soybeans based on the EEFlux application in the western region of the state of Bahia, Brazil. The water productivity (WP) for the fields was also obtained. Six cloud-free images from Landsat 7 and 8 satellites, acquired during the 2016/17 soybean growing season were used and processed on the EEFlux platform. The ETa from EEFlux was compared to that of the modified FAO (MFAO) approach using the following statistical metrics: Willmot's index of agreement (d-index), root mean square error (RMSE), mean absolute error (MAE) and mean bias error (MBE). The Kc from EEFlux was compared to the Kc used in the soybean field (Kc FAO-based) and to the Kc values obtained in different scientific studies using the d-index. A similar procedure was performed for WP. Our results reveal that EEFlux is able to provide accurate information about the variability of ETa and the Kc of soybean fields. The comparison between ETa EEFlux and ETa MFAO showed good agreement based on the d-index, with values of 0.85, 0.83 and 0.89 for central pivots 1, 2 and 3, respectively. However, EEFlux tends to slightly underestimate ETa. The Kc EEFlux showed good accordance with the Kc values considered in this study, except in phase II, where a larger difference was observed; the average WP of the three fields (1.14 kg m-3) was higher than that in the majority of the previous studies, which is a strong indicator of the efficient use of water in the studied soybean fields. The study showed that EEFlux, an innovative and free tool for access spatiotemporal variability of ETa and Kc at global scale is very efficient to estimate the ETa and Kc on different growth stages of soybean crop.

Yield of six grasses cultivated by grazing under effect of different nitrogen fertilization and annual seasons / Produção de seis capins manejados por pastejo sob efeito de diferentes doses nitrogenadas e estações anuais

Dry matter yield of six irrigated grasses cultivated by grazing under different nitrogen fertilization and annual seasons in Brazil. The experiment was conducted in a split plot design, tends a factorial design 4 x 6 (nitrogen and grasses) in the plots and season (autumn/winter and spring/summer) in the split-plots, in a completely randomized block, with four repetitions. The nitrogen doses were of 100; 300; 500 and 700kg/ha/ano and the grasses were: Xaraes, Mombaça, Tanzania, Pioneiro, Marandu and Estrela. The irrigation system was semi-fixed conventional sprinkling. The dry matter yield was obtained by means of the dry material in ventilated stoves at 60C, for 72h. The appraised grasses presented different dry matter yield. The factor temperature was the responsible for the differences among seasons. The increase of the nitrogen fertilizer did not affect the dry matter yield due to methodology for its determination and for the degradation of the physical quality of the soil. It was observed, in the general, that the Xaraes, Tanzania and Mombaça presented larger, and Pioneiro, smaller dry matter yield, respectively. The highest temperatures happened in the spring/summer season and provided larger dry matter yield. The nitrogen fertilization did not influence the dry matter yield of the appraised grasses.

Objetivou-se avaliar a produtividade de matéria seca de seis capins irrigados manejados por pastejo sob efeito de diferentes adubações nitrogenadas e estações anuais na região Leste do estado de Minas Gerais. O experimento foi conduzido em parcelas subdivididas, com um esquema fatorial 4 x 6 (doses de nitrogênio e capins), e nas subparcelas as estações do ano (outono/inverno e primavera/verão) foram avaliadas no delineamento em blocos casualizados, com quatro repetições. As doses nitrogenadas foram de 100; 300; 500 e 700kg/há/ano, e os capins foram Xaraés, Mombaça, Tanzânia, Pioneiro, Marandu e Estrela. O sistema de irrigação utilizado foi aspersão convencional semifixo. A produtividade foi obtida por meio do material seco em estufa ventilada a 60C, por 72h. Os capins avaliados apresentaram diferentes produtividades de matéria seca. O fator temperatura foi o responsável pelas diferenças encontradas entre estações. O aumento da dose nitrogenada não afetou a produtividade de matéria seca devido à metodologia para sua determinação e pela degradação da qualidade física do solo. Os capins Xaraés, Tanzânia e Mombaça apresentaram maiores, e o Pioneiro apresentou menor produtividade de matéria seca, respectivamente. As maiores temperaturas ocorridas na estação primavera/verão proporcionaram maior produtividade de matéria seca. A adubação nitrogenada não influenciou as produtividades d

Yield of six grasses cultivated by grazing under effect of different nitrogen fertilization and annual seasons / Produção de seis capins manejados por pastejo sob efeito de diferentes doses nitrogenadas e estações anuais

Dry matter yield of six irrigated grasses cultivated by grazing under different nitrogen fertilization and annual seasons in Brazil. The experiment was conducted in a split plot design, tends a factorial design 4 x 6 (nitrogen and grasses) in the plots and season (autumn/winter and spring/summer) in the split-plots, in a completely randomized block, with four repetitions. The nitrogen doses were of 100; 300; 500 and 700kg/ha/ano and the grasses were: Xaraes, Mombaça, Tanzania, Pioneiro, Marandu and Estrela. The irrigation system was semi-fixed conventional sprinkling. The dry matter yield was obtained by means of the dry material in ventilated stoves at 60C, for 72h. The appraised grasses presented different dry matter yield. The factor temperature was the responsible for the differences among seasons. The increase of the nitrogen fertilizer did not affect the dry matter yield due to methodology for its determination and for the degradation of the physical quality of the soil. It was observed, in the general, that the Xaraes, Tanzania and Mombaça presented larger, and Pioneiro, smaller dry matter yield, respectively. The highest temperatures happened in the spring/summer season and provided larger dry matter yield. The nitrogen fertilization did not influence the dry matter yield of the appraised grasses.

Objetivou-se avaliar a produtividade de matéria seca de seis capins irrigados manejados por pastejo sob efeito de diferentes adubações nitrogenadas e estações anuais na região Leste do estado de Minas Gerais. O experimento foi conduzido em parcelas subdivididas, com um esquema fatorial 4 x 6 (doses de nitrogênio e capins), e nas subparcelas as estações do ano (outono/inverno e primavera/verão) foram avaliadas no delineamento em blocos casualizados, com quatro repetições. As doses nitrogenadas foram de 100; 300; 500 e 700kg/há/ano, e os capins foram Xaraés, Mombaça, Tanzânia, Pioneiro, Marandu e Estrela. O sistema de irrigação utilizado foi aspersão convencional semifixo. A produtividade foi obtida por meio do material seco em estufa ventilada a 60C, por 72h. Os capins avaliados apresentaram diferentes produtividades de matéria seca. O fator temperatura foi o responsável pelas diferenças encontradas entre estações. O aumento da dose nitrogenada não afetou a produtividade de matéria seca devido à metodologia para sua determinação e pela degradação da qualidade física do solo. Os capins Xaraés, Tanzânia e Mombaça apresentaram maiores, e o Pioneiro apresentou menor produtividade de matéria seca, respectivamente. As maiores temperaturas ocorridas na estação primavera/verão proporcionaram maior produtividade de matéria seca. A adubação nitrogenada não influenciou as produtividades d