Managing Soil Carbon and Nitrogen for Productivity and Environmental Quality
Abstract
In this study, we investigated the impact of cropping system management on C and N pools, crop yield, and N leaching in a long‐term agronomic experiment in Southwest Michigan. Four management types, conventional (CO), integrated fertilizer (IF), integrated compost (IC), and transitional organic (TO) were applied to two crop sequences, a corn ( Zea mays L.)–corn–soybean [ Glycine max (L.) Merr.]–wheat ( Triticum aestivum L.) rotation and continuous corn, which were grown with and without cover crops in the IF, IC, and TO managements. Using compost as a fertility source and reducing the use of herbicides and other chemicals resulted in long‐term changes in soil organic matter pools such TO ≥ IC > IF ≥ CO for total C and N and for the labile C and N measured through aerobic incubations at 70 and 150 d. Mineralizable N varied within the rotation, tending to increase after soybean and decrease after corn production in all systems. Corn yield was closely associated with 70‐d N mineralization potential, being greatest for first‐year corn with cover and least for continuous corn without cover under all management types. Although the TO and IC systems produced the lowest yield for second‐year or continuous corn, the combination of soybean and wheat plus red clover ( Trifolium pratense L.) always supported high yield for first‐year corn. Fall nitrate level and nitrate leaching were higher for commercially fertilized corn than for any other crop or for compost‐amended corn.