Implications of cover crop planting and termination timing on rainfed maize production in semi-arid cropping systems

• Published in: Field crops research 2021-09, Vol.271, p.108251, Article 108251
• Main Authors: Rosa, Alexandre T., Creech, Cody F., Elmore, Roger W., Rudnick, Daran R., Lindquist, John L., Fudolig, Miguel, Butts, Liberty, Werle, Rodrigo
• Format: Article
• Language: English
• Subjects: biomass; corn; Cover crops; crop residues; fallow; grain yield; Haney test; Maize; Multivariate analysis; nitrates; nitrogen; planting; Semi-arid; soil depth; soil organic matter; Soil water; soil water content; spring; summer; total nitrogen; weed control; weeds; winter wheat
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/j.fcr.2021.108251

•Introducing cover crops in a rainfed wheat-maize-fallow rotation of semi-arid regions.•Cover crops induced nitrogen immobilization when terminated late in the spring.•Late terminated cover crops suppressed weeds early in the maize growing season.•Late terminated cover crops did not affect soil carbon and respiration.•Cover crops reduced maize grain yield regardless of the termination timing. Despite the potential to increase soil organic matter, cycle soil nutrients, and suppress weeds, there is a concern that cover crops (CCs) soil water use negatively impacts subsequent crops in water-limited environments. Cover crop management practices such as planting and termination timing may mitigate the detrimental impacts of CCs in semi-arid cropping systems. To determine the effects of CCs under water-limited environments, we evaluated the total CC biomass produced in the fall and spring, soil water content during the subsequent maize growing season, weed density and biomass, crop residue, and soil nutrients at the maize V6 development stage, and maize productivity. The experiment was conducted under a wheat-maize-fallow rotation at two sites (Grant and North Platte, NE) during 2016−2017 and 2017−2018. Treatments consisted of three planting timings after winter wheat harvest and three CC termination timings and fallow (no CCs) before maize establishment. Planting CCs shortly after winter wheat harvest increased CC biomass in the fall and early spring compared to late planting. Cover crops terminated early in the spring reduced weed biomass (−70 %), while CCs terminated late in the spring reduced both weed density (−56 %) and biomass (−82 %) compared to fallow. Due to above-normal precipitation during the experiment, soil water measured at 0−20 cm soil depth was impacted by CCs only at Grant 2016−2017. Cover crops terminated late in the spring increased crop residue biomass but decreased total nitrogen at 0−10 cm soil depth by 17 %, and decreased soil nitrate at the 10−20 cm soil depth up to 26 % compared to fallow. Cover crops planted late in the summer (August) and terminated late in the spring (May) had the most detrimental impact on maize grain yield. Late termination of CCs in the spring reduced corn grain yield by up to 20 % compared to fallow. Despite enhanced weed suppression and crop residue, CCs decreased soil nitrogen and maize grain yield, especially when terminated late in the spring. Producers in semi-arid regions of the Great Plains willing to inc