Long- and short-term cover crop management effects on soil health in no-till dryland cropping systems in the semi-arid central Great Plains


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Integrating cover crops (CCs) into dryland cropping systems in the semi-arid central Great Plains could improve soil health and provide forage for livestock. Two experiments were conducted in western Kansas to examine the effects of CC management in place of fallow on soil properties in a no-till (NT) winter wheat (Triticum aestivum L.)-grain sorghum (Sorghum bicolor Moench)-fallow (WSF) cropping system. A long-term study was initiated in 2007 near Garden City, KS to investigate CCs in a wheat-fallow (WF) rotation and was transitioned to WSF in 2012. Treatments included peas (Pisum sativum L.) for grain as well as one-, three-, and six-species CC mixtures compared to fallow. Half of each CC treatment was hayed to a height of 15 cm. A second study was initiated in 2015 near Brownell, KS, and treatments were oat (Avena sativa L.)/triticale (×Triticosecale Wittm.) CCs in place of fallow that were either hayed to a height of 15 cm, grazed by yearling heifers, or left standing. Forage accumulation and nutritive value were also determined in the experiment at Brownell. At Garden City, soil organic carbon (SOC) stocks were greater with CCs compared to fallow in 2012 after three cycles of the WF rotation. In 2018, after two cycles of the WSF rotation, SOC was similar among treatments, likely because CC residue was less following a succession of drought years. However, SOC had increased in all treatments since 2012 mostly due to the residue contribution of grain sorghum (r² = 0.35; P = 0.0025). Soil aggregation was greater with CCs compared to peas or fallow and was unaffected by CC diversity. Mean weight diameter (MWD) of water stable aggregates (WSA) was greater with standing CCs (1.11 mm) compared to peas (0.77 mm), and standing and hayed CCs (3.59 mm) had greater MWD of dry aggregates compared to fallow (2.75 mm). Water infiltration were greater with CCs compared to peas. Findings suggest simple CC mixtures and CCs managed for forage provide similar soil health benefits as diverse CC mixtures and CCs left standing. At Brownell, results showed forage accumulation averaged 3546 kg ha⁻¹ for standing CCs. Hayed and grazed CCs removed 73 and 26% of the available forage. Greater nutritive value with grazed CCs was observed because of differences in maturity at harvest. In 2019, SOC stocks with standing and hayed CCs (27.54 Mg ha⁻¹) were greater than fallow (24.79 Mg ha⁻¹) which was similar to grazed CCs (26.87 Mg ha⁻¹). However, in 2020, SOC with hayed CCs (21.80 Mg ha⁻¹) was less compared to grazed or standing CCs (24.27 Mg ha⁻¹) which were similar to fallow (23.22 Mg ha⁻¹). The MWD of WSA was greater with standing and grazed CCs (2.89 mm) compared to fallow (1.67 mm) in both years, and hayed CCs were greater than fallow in only one year. Findings suggest that CCs can replace fallow to produce forage while improving soil health. However, residue management is critical such that grazing is more desirable than haying to maintain soil properties when CC productivity is low.



Dryland cropping systems, Central Great Plains, Cover crops, Soil health, Soil organic carbon, Water stable aggregates

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Master of Science


Department of Agronomy

Major Professor

Johnathon D. Holman; Kraig L. Roozeboom