Profitability and soil health impacts of cover crops and annual forages with integration of livestock into wheat-based systems

Abstract

Integrating annual forages and livestock into dryland cropping systems can increase profitability and improve soil health. A study was conducted from 2021-2025 at the Kansas State University Agricultural Research Center in Hays, KS, to investigate the soil health, production, and profitability effects of integrating ruminant livestock and forage sorghum (FS) (Sorghum bicolor Moench) into a no-till (NT) dryland winter wheat (Triticum aestivum)-grain sorghum-fallow (W-GS-F) rotation. Treatments included W-GS-F (control), W-GS-F with GS residues grazed (W-GSG-F), W/FS-FS-F with FS grazed (W/FSG-FSG-F), and W/FS-FS-F with FS hayed (W/FSH-FSH-F). The study was a randomized complete block design with four replications, with all phases of rotations present each year. Double-crop FS averaged 2,894 to 2,951 kg/ha, and was not harvested in 2 out of the 5 years due to limited moisture post-wheat and extreme drought conditions. Full-season FS forage dry matter averaged 6,933 to 7,338 kg/ha, and provided adequate production each year of the study, despite extreme drought conditions in 2022 and 2023. In 3 years of double-crop FS grazing, ~60% of forage biomass was retained as residue post-graze, while haying retained ~40% of forage biomass as residue. Grazing full-season FS retained ~50% of biomass as residue compared to ~30% when hayed. Wheat yields were collected in 2023-2025 after all rotations had made a complete cycle, and experienced extreme spring droughts in each growing season, resulting in low yields. Because of poor yields, no significant effect was observed across rotation. Grain sorghum yields were collected in 2024 and 2025, again, after all rotations had made a complete cycle. Similar to wheat yields, no significant rotation effect was observed in grain sorghum yield between W-GS-F and W-GSG-F. Averaged across the 0-15 cm sampling depth, no differences in bulk density, bulk SOC or particulate organic matter were observed among treatments. However, dry aggregate associated SOC was greater in W-GSG-F and W/FSG-FSG-F than W-GS-F and W/FSH-FSH-F in nearly all aggregate sizes. No differences in mean weight diameter (MWD) of water stable aggregates were observed among treatments. Dry-aggregate MWD was similar for W-GS-F, W-GSG-F, and W/FSG-FSG-F treatments, but significantly less for W/FSH-FSH-F. Percent wind erodible fraction was consistently higher for W/FSH-FSH-F. Cropping system net returns varied by year but were consistently significantly higher for W-GSG-F. The second study was established on-farm in fall 2022 on a 20-hectare producer field in Russell County, KS to investigate the effects of cover crop (CC) biomass removal with cattle grazing on soil health parameters and grain crop yields in a no-till dryland cropping system. The study design was a randomized complete block with three treatments and four replications. The treatments included ungrazed CCs (UGR), “take-half-leave-half” (T-H-L-H, 50% biomass removal), and “graze-out” (G-O, 90% biomass removal). Averaged across 2023-2024, the T-H-L-H and G-O significantly reduced CC residue amount, height, and residue cover when compared to UGR. In 2023, T-H-L-H had 224 kg/ha more residue remaining and 15 cm taller residue than the G-O treatment. Though, in 2024, CC biomass parameters were not significantly different between T-H-L-H and G-O, because biomass removed from each grazing treatment was essentially the same. Cover crop management had no significant effect on concentrations of SOC and particulate organic matter. However, averaged across the 0-15 cm soil depth, phosphorus (P) concentration was reduced by T-H-L-H and G-O compared to UGR, likely due to purposefully avoiding sampling near manure pats on the grazed plots that may be high in P. Grazing CCs increased soil bulk density compared to UGR at the 0-5 cm soil depth. Take-half-leave-half also increased soil penetration resistance in one of two years. Percent wind-erodible fraction, MWD, time-to-runoff, and subsequent grain sorghum yield were unaffected by CC management. Nearly every measured soil property declined from initial sampling to 2024 in all treatments including the UGR control, possibly because the study site was converted to crop production from Conservation Reserve Program grass prior to study implementation in 2021. In 2023, we were relatively close to our target T-H-L-H and G-O removal goals, but in 2024 there was no biomass removal difference between T-H-L-H and G-O due to limited biomass production. Grazing intensity effects on soil properties differed in the two-years of investigation, but overall soil health was maintained with grazing in both studies and even increased aggregate associated SOC concentrations within the Hays study, while haying annual forage diminished soil properties. Our findings from both studies showed no significant impact on subsequent grain production from addition of forage for haying and grazing while providing extra revenue, but the less intensive grazed system W-GSG-F was the most profitable in the Hays study.