Effects of composted cattle manure and cover crops on winter wheat performance and soil fertility

Dryland winter wheat (Triticum aestivum L.) production in the semiarid Northern High Plains region of the United States is challenged by inadequate soil organic matter, plant nutrients, and frequent droughts. A single application of a high rate of composted cattle manure (compost) may help to address these issues. To conserve compost-associated benefits and to prevent compost-amended soils from weed infestation, spring planting of cover crops has been recommended. The objective of this study was to evaluate the legacies of a single application of compost (0, 15, 30, and 45 Mg ha⁻¹) and annual cover crop planting in the fallow phase on soil moisture, nitrogen (N), carbon (C), and plant-available phosphorus (AP) 3–7 years after application. Results suggest no synergy between compost and cover crops, but that compost alone can improve soil health. The highest rate of compost showed elevated levels of plant-available N, dissolved organic carbon, and AP in the 0–5 cm and 5–15 cm soil profiles throughout the duration of the study (2018–2022). Soil organic C and total N remained elevated at both soil profile depths when measured in 2019. However, wheat grain yield and protein were not affected by these improvements to soil health at this time. A single application of compost at a rate of 45 Mg ha⁻¹ was sufficient to increase soil health and plant-available nutrients over the 5-year study period but did not increase crop yield. Growing cover crops did not negatively affect crop yield.