Impact of cover crop on corn–soybean productivity and soil water dynamics under different seasonal rainfall patterns

Abstract

The effect of cover crop (CC) on soil water balance and agricultural production isclosely related to rainfall amount and distribution in rainfed cropping systems. Thisstudy used the root zone water quality model, RZWQM2, calibrated and validatedwith 4-yr field measurements to predict the effect of planting a winter wheat (Triticumaestivum L.) CC in a no-till rainfed corn (Zea mays L.)–soybean (Glycine max L.)rotation on soil water balance, crop yield, and grain water-use efficiency (WUE) innortheast Mississippi. Seasonal rainfall for 80 consecutive years (1938–2017) wasclassified as ‘wet,’ ‘normal,’ and ‘dry’ years using frequency analysis, and the datasets matched chronologically to wheat, corn, and soybean growth periods were usedas an input parameter in RZWQM2 simulations. During autumn and spring (earlyOctober to early April), the CC reduced deep drainage by 69 (11%), 53 (15%), and51 mm (21%) in wet, normal, and dry years, respectively. Averaged across 40 yr,the CC decreased surface evaporation by 64 (32%) and 38 mm (24%) for corn andsoybean growth periods, respectively. Wheat CC also improved soil water storagein early crop growth period during April–June in any of the three rainfall patterns.Regardless of rainfall patterns, the increase in WUE can be attributed to a decreasein evapotranspiration during cash crop period without sacrificing cash crop yield inthe CC system. Introducing CC into cropping systems is beneficial to reduce annualdeep drainage and evaporation while maintaining higher crop yields under differentrainfall patterns.

Citation

Yang, Wei; Feng, Gary; Read, John J.; Ouyang, Ying; Han, Jianjun; Li, Pinfang. 2020. Impact of cover crop on corn–soybean productivity and soil water dynamics under different seasonal rainfall patterns. Agronomy Journal. 112(2): 1201-1215. https://doi.org/10.1002/agj2.20110.