Grazing cover crops increases soil microbial biomass in Texas semiarid ecoregion

Abstract

Integrated crop-livestock systems (ICLS) bring diversity to agricultural systems, enhancing soil ecosystem services, food production, and environmental sustainability. Resource utilization efficiency practices under semiarid ecoregions include dual systems that grow wheat (Triticum aestivum L.) for both grain and grazing (G) and recently complementary to wheat dual systems, cover crops (CC) for feeding both the soil and cattle during the fallow period. The latter continues to generate interest and there is a paucity of information on associated biochemical cycles. The objective was to evaluate the impact of CC and grazing thereof on soil microbiota structure, diversity, proliferation, and nutrient cycling. Introducing CC to no-till (NT [NTC]) and grazing CC (NTCG [ICLS]), increased total PLFA biomass (TPB) for ungrazed CC (NTC) by 12%, and grazed CC (NTCG [ICLS]) by 20%; total bacteria biomass (TBB) by 10% for NTC and 24% for NTCG; total fungal biomass (TFB) by 9% for NTC and 21% for NTCG. The CC significantly increased Gram (−) bacteria biomass by 17% and 34% for NTC and NTCG, respectively; the CC significantly increased Gram (+) bacteria biomass by 6% and 12% for NTC and NTCG, respectively; and the CC significantly increased arbuscular mycorrhizal fungi by 55% and 89% for NTC and NTCG respectively, compared to NT fallow practice. Significant correlations were observed for NO₃⁻–N, NH₄⁺–N, water-extractable organic nitrogen, total nitrogen, and water-extractable organic carbon with TPB, TBB, and TFB using Haney soil health methods. Based on the measured parameters, the soil health status decreased in the order NTCG > NTC > NT > CT, where NT is the no-till, C is the cover crop, G is the grazing, and CT is the conventional-till. Grazing CC enhanced soil bacterial biomass over CC in solitude.