Closing Yield Gaps in Corn and Soybean: Impact of Different Management Practices.

Yield gap between potential and actual on-farm yields are primarily defined by crop management practices and their interactions with the environment. Two fully irrigated research trials, one corn and one soybean, were conducted at Scandia, KS, during the 2014 and 2015 growing seasons. The objective was to study the contribution of different farming systems in developing efficient and high-yielding production systems. The experiment was layout as a randomized complete block design with five treatments: farmer practices (FP), common practices for the region (e.g., lower than optimal seeding rate, without P-K fertilization); comprehensive fertilization (CF), or balancing fertilizer nutrient application; production intensity (PI), optimal seeding rate and narrow row spacing; ecological intensification (CF+PI), balancing production and nutrient practices, and advanced plus (AD), high intensity input. Physiological traits, nutrient concentration, and yield components were determined in all site-years. Seasonal biomass and nutrient content patterns were synthesized from nine sampling times throughout crop growing season. For corn, in the year #1, treatment combinations did not differ significantly, ranging from 14.1 to 14.4 Mg ha-1. For soybean, FP and CF presented comparable yield levels, 3.2 Mg ha^-1, differing in 2.4 Mg ha^-1 when compared with PI, EI, and AD combinations (averaging 5.6 Mg ha-1). Larger yield gaps were detected on the soybean phase. Balancing nutrients under narrow row spacing and optimal seeding rates portrayed the largest yield improvement, in parallel to superior nitrogen (N) uptake. Further analysis of consequent growing seasons would permit better understand long-term effects not only with a productive but also with a sustainability focus on the corn-soybean cropping systems.