Soybean yield contests have been generating useful information regarding the cultivation of this important crop commodity. The aim of this study was to analyze environmental, management, and economic variables associa...Soybean yield contests have been generating useful information regarding the cultivation of this important crop commodity. The aim of this study was to analyze environmental, management, and economic variables associated with soybean yield contest winners in Brazil. Data from eleven summer soybean harvests included grain yield, rainfall, climatic and agronomic efficiency, soil chemical and physical attributes, management strategies, and economic indicators. Two grain yield classes were evaluated: 1) high yield(4967–6839 kg ha^(-1)) and 2) very high yield(6859–8945 kg ha^(-1)). Enhanced soybean yield was due to adequate rainfall that led to high climatic efficiency(77%) and high agronomic efficiency;average values ranged between 78%(high yield class) and 86%(very high yield class). Correction and maintenance of soil chemical and physical quality(surface and subsurface), alternative fertilization and microbial co-inoculation were notable. Winners in the very high yield class reported higher soil K^(+), Ca^(2+), and Mg^(2+) levels, more frequent use of dolomitic limestone, greater soil structural quality, greater use of biostimulants(via foliar spray), and higher net revenue. While high climatic efficiency was fundamental for success, intensive integration of technologies with conservation practices for better soil and crop management are necessary to maximize soybean yield and economic gains.展开更多
Soil carbon mapping is extremely useful in assessing the effect of land management practices on soil carbon storage.Applications of neutron-gamma analysis in scanning mode for mapping of soil carbon are discussed.A Gl...Soil carbon mapping is extremely useful in assessing the effect of land management practices on soil carbon storage.Applications of neutron-gamma analysis in scanning mode for mapping of soil carbon are discussed.A Global Positioning System(GPS)device and softwares required to simultaneously acquire gamma signals and geographical positions during scanning operations were added to an existing measurement system.The reliability of soil carbon measurements in scanning mode was demonstrated to be in agreement with results acquired from static mode.The error analysis indicated that scanning measurements can be conducted with the same accuracy as static measurements in approximately one fourth the time.To obtain results suitable for mapping analogous to traditional chemical analyses(i.e.,±0.5 in weight percent or±0.5 w%),scanning time over a given site should be ca.15 min using the current measurement system configuration.Based on this measurement time,a reasonable towing speed of 3–5 km h^-1,the necessity for complete site coverage during scanning,the number of sites(within the surveyed field),and the required total measurement time can be estimated.Soil carbon measurements for 28 field sites(total area ca.2.5 ha)were conducted in ca.8 h.Based on acquired data,a soil carbon distribution map was constructed utilizing various softwares.The surveyed field area included an asphalt road that had carbon readings higher than the surrounding land.The clarity with which these carbon-rich zones were delineated on the constructed map represents evidence supporting the veracity of this method.Neutron-gamma analysis technology can greatly facilitate timely construction of soil carbon maps.展开更多
文摘Soybean yield contests have been generating useful information regarding the cultivation of this important crop commodity. The aim of this study was to analyze environmental, management, and economic variables associated with soybean yield contest winners in Brazil. Data from eleven summer soybean harvests included grain yield, rainfall, climatic and agronomic efficiency, soil chemical and physical attributes, management strategies, and economic indicators. Two grain yield classes were evaluated: 1) high yield(4967–6839 kg ha^(-1)) and 2) very high yield(6859–8945 kg ha^(-1)). Enhanced soybean yield was due to adequate rainfall that led to high climatic efficiency(77%) and high agronomic efficiency;average values ranged between 78%(high yield class) and 86%(very high yield class). Correction and maintenance of soil chemical and physical quality(surface and subsurface), alternative fertilization and microbial co-inoculation were notable. Winners in the very high yield class reported higher soil K^(+), Ca^(2+), and Mg^(2+) levels, more frequent use of dolomitic limestone, greater soil structural quality, greater use of biostimulants(via foliar spray), and higher net revenue. While high climatic efficiency was fundamental for success, intensive integration of technologies with conservation practices for better soil and crop management are necessary to maximize soybean yield and economic gains.
基金supported by the National Institute of Food and Agriculture(NIFA)Research Grant(No.ALA2016-67021-24417)“Precision geospatial mapping of soil carbon content for agricultural productivity and lifecycle management”
文摘Soil carbon mapping is extremely useful in assessing the effect of land management practices on soil carbon storage.Applications of neutron-gamma analysis in scanning mode for mapping of soil carbon are discussed.A Global Positioning System(GPS)device and softwares required to simultaneously acquire gamma signals and geographical positions during scanning operations were added to an existing measurement system.The reliability of soil carbon measurements in scanning mode was demonstrated to be in agreement with results acquired from static mode.The error analysis indicated that scanning measurements can be conducted with the same accuracy as static measurements in approximately one fourth the time.To obtain results suitable for mapping analogous to traditional chemical analyses(i.e.,±0.5 in weight percent or±0.5 w%),scanning time over a given site should be ca.15 min using the current measurement system configuration.Based on this measurement time,a reasonable towing speed of 3–5 km h^-1,the necessity for complete site coverage during scanning,the number of sites(within the surveyed field),and the required total measurement time can be estimated.Soil carbon measurements for 28 field sites(total area ca.2.5 ha)were conducted in ca.8 h.Based on acquired data,a soil carbon distribution map was constructed utilizing various softwares.The surveyed field area included an asphalt road that had carbon readings higher than the surrounding land.The clarity with which these carbon-rich zones were delineated on the constructed map represents evidence supporting the veracity of this method.Neutron-gamma analysis technology can greatly facilitate timely construction of soil carbon maps.
