Intensifying a crop–fallow system: impacts on soil properties, crop yields, and economics

Abstract Intensifying crop–fallow systems could address increased weed control costs, increased land or rental costs, reduced crop diversity, and degraded soil properties in water-limited environments. One strategy to intensify such systems could be the insertion of a short-season crop during fallow. But, how this strategy affects soils, crop production, and farm economics needs further research. Thus, we studied the impacts of replacing fallow in a winter wheat ( Triticum aestivum L)–corn ( Zea mays L.)–fallow system with a short-season spring crop [field pea ( Pisum sativum L.)] on crop yields and economics from 2015 to 2019 and 5-yr cumulative effects on soil properties using an experiment in the west-central US Great Plains. After 5 yr, replacing fallow with field pea increased microbial biomass by 294 nmol g −1 and plant available water by 0.08 cm 3 cm −3 , and reduced bulk density by 0.1 g cm −3 and cone index by 0.73 MPa in the 0–5 cm depth. It had, however, no effect on other soil properties. Field pea yield averaged 2.24 Mg ha −1 . Field pea reduced subsequent crop yield by 15–25% in two of three crops compared with fallow. However, economic analysis showed replacing fallow with field pea may improve net income by $144–303 ha −1 , although income across the 5 yr differed by $65 ha −1 in favor of fallow. Replacing fallow in winter wheat–corn–fallow rotation with a short-season spring crop offers promise to improve some near-surface soil properties while increasing net economic return during fallow under the conditions of this study.