Improved soil biological health increases corn grain yield in N fertilized systems across the Corn Belt

Jordon Wade,Jaimie R West,Antonio P Mallarino,John H Grove,Hanna Poffenbarger,Matthew Ruark,Jessica A R Logan,Steve W Culman,Joshua M Mcgrath,M Scott Demyan

doi:10.1038/s41598-020-60987-3

Abstract

Nitrogenous fertilizers have nearly doubled global grain yields, but have also increased losses of reactive N to the environment. Current public investments to improve soil health seek to balance productivity and environmental considerations. However, data integrating soil biological health and crop N response to date is insufficient to reliably drive conservation policy and inform management. Here we used multilevel structural equation modeling and N fertilizer rate trials to show that biologically healthier soils produce greater corn yields per unit of fertilizer. We found the effect of soil biological health on corn yield was 18% the magnitude of N fertilization, Moreover, we found this effect was consistent for edaphic and climatic conditions representative of 52% of the rainfed acreage in the Corn Belt (as determined using technological extrapolation domains). While N fertilization also plays a role in building or maintaining soil biological health, soil biological health metrics offer limited a priori information on a site’s responsiveness to N fertilizer applications. Thus, increases in soil biological health can increase corn yields for a given unit of N fertilizer, but cannot completely replace mineral N fertilization in these systems. Our results illustrate the potential for gains in productivity through investment in soil biological health, independent of increases in mineral N fertilizer use.

Highlights

Since the Green Revolution, nitrogenous mineral fertilizers have helped to nearly double global grain crop yields[1]
Incorporating the positive direct effect of soil health on inorganic N content (β = 0.44, p < 0.0001) shows that soil biological health indirectly influences responsiveness to N (β = 0.12, p = 0.012)
It is unexpected that soil biological health did not have a stronger, direct effect on relative yield

Summary

Introduction

Since the Green Revolution, nitrogenous mineral fertilizers have helped to nearly double global grain crop yields[1]. Recently have studies sought to integrate these metrics into nitrogen management strategies[33,34] These studies used a single measurement of soil health and fertility and were conducted under a limited range of climatic and edaphic conditions. Trials included in this study represented a variety of soil health-building managements across a range of edaphic and climatic conditions, allowing for inference across a breadth of contexts. To answer these questions, we constructed two multilevel structural equation models (Fig. 1)—referred to as the N responsiveness model and the N fertilizer rate model, respectively—to quantitatively define soil health and elucidate its relationships with crop-soil N dynamics (see Methods). We quantified overall crop productivity using relative yield—the ratio between the yield in a given experimental plot and the calculated agronomic optimum yield—where increasing relative yield indicates decreasing N responsiveness

Methods

Results

Conclusion