Cool-season cover crop effects on forage productivity and short-term soil health in a semi-arid environment

Abstract

Abstract There have been no systematic experiments conducted in Nevada's water-limited environment that examined the simultaneous benefits of soil health and feed value derived from cool-season cover cropping systems. The objective of this study was to determine the influence of different annual cool-season cover crop systems on above and belowground biomass production, plant tissue carbon and nitrogen, forage nutritive value (crude protein, acid, and neutral detergent fiber), relative feed value (RFV), and short-term soil health indicators under irrigation in a semi-arid environment. Treatments (cover crop systems) were a fallow (no cover crop), five monocultures of rye (Secale cereale L.), winter lentil (Lens culinaris Medik.), arrowleaf clover (Trifolium vesiculosum Savi), white sweetclover (Melilotus alba), forage kale (Brassica oleracea L.), and two three-species mixtures in 50-25-25 seeding ratios (CCM 1: rye, winter lentil, arrowleaf clover; CCM 2: rye, white sweetclover, forage kale). Cover crop systems were arranged in an RCBD with three replications. Plots were fall seeded in Reno, NV early October of each year (2020 and 2021) and terminated at the end of July of 2021 and 2022, respectively. Averaged across years, aboveground biomass production was lowest for the monoculture of winter lentil (4104 kg DM ha−1; SE = 1551) compared to all other cover crop systems (average = 7593 kg DM ha−1; SE = 1551). Biomass carbon produced was lowest for winter lentil (1717 kg ha−1; SE = 675) relative to all other cover crop systems (average = 3227 kg ha−1; SE = 675). The CCM 1 system had a greater C/N ratio (36.3) than CCM 2 and the monocultures of winter lentil, arrowleaf clover, and white sweetclover (average = 24.9). Belowground biomass did not differ among cover crop systems (average = 3161 kg DM ha−1; SE = 962). Crude protein concentration was similar among cover crop systems but the RFV was greatest for forage kale (RFV = 165; SE = 4.0) among all cover crop systems. Soil total N and organic carbon concentration did not differ among cover crop systems but soil K concentration was greatest under fallow (428 mg kg−1 soil; SE = 26) relative to all other systems (average = 345.6 mg kg−1 soil; SE = 26). Soil microbial community biomass was not altered by cover crop system or its interaction with year. While the short-term impact of the cover crop systems on soil health indicators was minimal relative to the fallow system, the overall results suggested that there is potential to integrate cover crops in Nevada's semi-arid environment under irrigation.