Cover crop systems impact on biomass production, carbon-to-nitrogen ratio, forage quality, and soil health in a semi-arid environment

Akwasi Opoku; Anuoluwapo M Ogunleye; Juan K Q Solomon; William A Payne

doi:10.1016/j.heliyon.2024.e39600

Cover crop systems impact on biomass production, carbon-to-nitrogen ratio, forage quality, and soil health in a semi-arid environment

Heliyon. 2024 Oct 18;10(20):e39600. doi: 10.1016/j.heliyon.2024.e39600. eCollection 2024 Oct 30.

Authors

Akwasi Opoku^{1

2}, Anuoluwapo M Ogunleye^{1

2

3}, Juan K Q Solomon¹, William A Payne⁴

Affiliations

¹ Department of Agriculture, Veterinary & Rangeland Sciences, University of Nevada, Reno, NV, 89557, USA.
² Environmental Sciences & Health Graduate Program, University of Nevada, Reno, NV, 89557, USA.
³ Department of Agriculture, Food Science and Kinesiology, Eastern New Mexico University, Portales, NM, 88130, USA.
⁴ College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV, 89557, USA.

Abstract

Cover cropping is a soil restorative strategy that can save degraded soils and offer additional benefits relative to the traditional fallow-based practice in semi-arid cropping systems. This study aimed to (i) quantify the above (shoot)- and belowground (root) biomass production, nutritive value, and tissue carbon and nitrogen concentrations from different annual cool-season cover crop systems, and (ii) determine their effects on soil organic carbon, total nitrogen, soil respiration, and soil microbial population biomass in a semi-arid environment. Treatments used were monocultures of annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), faba bean (Vicia faba L.), yellow sweetclover [Melilotus officinalis (L.) Lam], winter pea (Pisum sativum L.), two three-species mixtures (Mix 1: annual ryegrass + faba bean + yellow sweetclover and Mix 2: Oat + faba bean + winter pea), and a fallow laid out in a randomized complete block design with three replications. Averaged across years, Mix 2 produced greater shoot biomass (9714 kg DM ha^-1; SE = 699) than all other cover crop systems except, the monoculture of oat (7970 kg DM ha^-1; SE = 699). The plant tissue C/N ratio of the mixtures and monoculture legumes was mostly similar (range = 19.4-29.1). Overall, legumes produced superior relative feed value (RFV; 112-161) compared to grass monocultures and mixtures (RFV; 80-95). Soil gram-negative bacteria biomass was greatest under the yellow sweetclover monoculture. Based on the results of this study, the mixed cover crop systems (Mix 1 and Mix 2) offered a better chance of fulfilling the dual role of soil health improvement and feed quality for livestock in this semi-arid environment.

Keywords: And soil total nitrogen; Biomass; Carbon-to-nitrogen ratio; Cover crop; Forage quality; Microbial biomass; Soil organic carbon; Soil respiration.