Managements Practices to Close Yield Gaps in Soybeans.

Intensifying productivity via utilization of improved fertilizer and crop management practices (i.e., narrower row spacing, higher seeding rate, and balanced nutrition) can impact plant biomass, nitrogen (N) uptake, and the partitioning efficiency measured by seed harvest index (HI) and NHI components. Soybean experiments evaluating the combination of management practices were conducted during 2014-15-2016 growing seasons at Scandia (KS, US), under irrigated and rainfed conditions (both phases in each season). Each experiment consisted of 5 treatments with five replications in a completely randomized block design: 1) common practices (CP), (272,000 seeds ha^-1 + no-inoculation + no-nutrient application + 76-cm row spacing); 2) comprehensive fertilization (CF), (272,000 seeds ha^-1 + inoculation + nutrient application + 76-cm row spacing); 3) production intensity (PI), increasing productivity via narrowing rows and increasing seeding rate (430,000 seeds ha^-1 + inoculation + no-nutrient application + 38-cm row spacing); 4) ecological intensification (CF + PI; 430,000 seeds ha^-1 + inoculation + nutrient application + 38-cm row spacing); and 5) advanced plus (AD), or increasing input applications (430,000 seeds ha^-1 + inoculation + nutrient application + 38-cm row spacing). Under irrigation, EI and AD yielded 5.7 Mg ha^-1 averaging three seasons, followed by PI, CF, and CP with 5.1, 4.1 and 3.7 Mg ha^-1 all with statistical differences among them. In the rainfed scenario, PI, EI and AD yielded 4 Mg ha^-1 with no differences between treatments, and CP and CF yielded 3 Mg ha^-1 on average. Corn yield (2015, 2016) after soybean (2014, 2015) was penalized in non-fertilized treatments. Partial factor productivity of the fertilizer increased 22% (irrigated) and 28% (rainfed) comparing CF and EI. Sustainable intensification of soybean production systems requires an integrated approach, combining optimal fertilizer and crop management practices that result in an overall improved efficiency of the farming system.