Footprints of corn nitrogen management on the following soybean crop

Abstract

Corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] is among the most typical crop rotations in the U.S. Corn Belt, and N is the most limiting nutrient for both crops.This study aims to assess the effects of N management for corn on the following soybean crop. Two corn-soybean rotation N fertilizer rate studies-a long-term study (1983 and a two-season study (2019-2020, Case Study II)were conducted in Kansas (United States). Case Study I focused on soybean seed yield as the response variable, whereas Case Study II included a detailed seasonal characterization of soil N, symbiotic N fixation (SNF), and plant N uptake for soybean considering N fertilizer rates on the previous corn crop. Apparent N budgets from corn (N fertilizer minus grain N removal) ranged from approximately −100 to approximately +50 kg N ha −1 , and soybean yields were slightly or not affected by corn N management. Case Study I showed that long-term N budgets in corn crops did not affect the following soybean crop yields. In Case Study II, the previous corn N management produced negative or small N surplus that influenced neither soil residual N nor SNF, without compromising soybean productivity. Farmers applying close to economic optimum N rates on corn will likely not generate scenarios of N surplus to compromise SNF or soybean yields. Forthcoming research should further address how long-term and large soil N mining or surplus in corn may enhance or inhibit N fixation for the next soybean crop. INTRODUCTIONAlternating soybean [Glycine max (L.) Merr.] with corn (Zea mays L.) has been demonstrated to promote higher yields than monocrop scenarios (

WITHDRAWN: Biological nitrogen fixation in field pea and vetch: contribution from above and belowground structures to the partial N balance.

“…Total N concentration (%N) and 15 N natural abundance analysis (δ 15 N‰) were determined in a mass spectrometer. Nitrogen uptake was calculated as the product of %N in each structure and the respective biomass.…”

“…Biological N xation (%Ndfa) was determined using the natural 15 N abundance method (Shearer and Kohl 1986) :…”

“…Biological N xation (%Ndfa) was determined using the natural 15 N abundance method (Shearer and Kohl 1986) : (1) Where B value is 15 N considering the whole plant (including belowground structures) of eld pea or vetch fully dependent upon N 2 xation growing in the greenhouse and were − 0.63 and − 0.33 for Facon CL and cv. Viper SL , respectively, and − 0.39 for vetch (Enrico et al 2020); 15 N ref is the natural abundance of 15 N in a non-xing crop that only depends on soil N growing under the same conditions and 15 N Legume is the 15 N natural abundance of eld pea or vetch.…”

“…An aggregate 15 N for all structures (i.e. sum of stems, leaves, podwalls, belowground, and seed depending on the phenological stage) (Unkovich et al 2008) was used to calculate %Ndfa.…”