Tillage and cover crops effects on crop yield in wheat double-cropping systems

The United States is experiencing longer crop growing season in most states, which could afford producers the opportunity to diversify into double-cropping (DC) and cover crop systems rather than the predominant summer and winter fallow systems. Thus, this study evaluated DC and cover crops effects on wheat (Triticum aestivum L.), cotton (Gossypium hirsutum L.), and soybean (Glycine max) yield under conventional tillage (CT) and no-tillage (NT). Summer cover crops (SCCs) were sunn hemp (Crotolaria juncea L.) and sorghum sudangrass (Sorghum bicolor), while winter cover crops (WCCs) were Austrian winter pea (Pisum sativum) and wheat. Cropping systems were wheat-fallow (W-F), wheat-cotton (W-C), wheat-soybean (W-S), W-SCC, WCC-C, F-C, WCC-S, and F-S. Tillage effect on crop yields varied across years. In 2021, wheat yield in CT of W-C, W-F, and W-SCC (2831, 2689, and 2646 kg ha⁻¹) significantly differed from NT of W-S (1720 kg ha⁻¹). No significant tillage effect was observed on cotton lint yield between W-C and WCC-C. For soybean, in 2020, the CT of W-S and WCC-S significantly outyielded the NT of W-S and WCC-S. Cropping system effect on wheat yield between W-S and W-SCC (1419 and 1987 kg ha⁻¹) was significant in 2020 due to low stand counts in W-SCC arising from the thick SCC biomass. Cotton lint yield in WCC-C outyielded W-C in all 3 years but was not significant. Soybean grain yield in W-S was consistently higher than in WCC-S, though not significant. Cotton lint and soybean grain yield in the fallow systems were the least. Overall, in a short term, crop yield in DC and cover crop systems were similar.