Semiarid Land Sustainable Agricultural Practices: The Evaluation of Annual Cover Cropping Systems Influence on Forage Productivity and Short-Term Soil Health Impact

Abstract

The objective of this studies was to determine the influence of different annual cool-season and warm-season cover crop systems on above and belowground biomass production, tissue carbon and nitrogen, forage nutritive value, nutrient cycling, and short-term soil health indicators under irrigation in a semiarid environment. The first study was carried out at the Valley Road Field Laboratory study site, Reno, NV, USA. 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 a randomized complete block design (RCBD) with three replications. Plots were fall seeded in early October of each year (2020 and 2021) and terminated at the end of July of 2021 and 2022 respectively. Responses were considered different P < 0.05. Averaged across years, aboveground biomass production was least 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). For the second study, treatments from the previous winter cover crop study were incubated to evaluate biomass loss, residual carbon and nitrogen, and carbon-to-nitrogen ratios. These were evaluated over six incubation periods; (30, 60, 90, 200, 230, and 278) days. Each treatment was replicated three times per incubation period to make a total of 126 treatments. At the end of the study (278 days), forage kale significantly reduced in mass compared to other cover crop systems. The 30-d incubation period significantly differed in percentage mass loss from the other incubation periods evaluated in the experiment. The third study was carried out in Fallon, Nevada. Treatments comprised ten treatments, including four monocultures of sorghum [Sorghum bicolor (L.) Moench] ‘Silo Pro-BMR’, foxtail millet [Setaria italica (L.) Beauv.] ‘Golden German’, cowpea [Vigna unguiculata (L.) Walp.] ‘Red ripper’, and soybean [Glycine max (L.) Merr.] ‘Large lad’. The four binary mixtures consisted of sorghum + cowpeas, sorghum + soybean, millet + cowpeas, and millet + soybean, and the tenth treatment was fallow. All systems were seeded on a pure live seed basis and arranged in an RCBD with four replications. Interaction effects between SCC system × year were observed for biomass carbon, biomass nitrogen, and forage nutritive parameters of ADF, NDF, DDM, and DMI. The main effect of SCC was observed in C and N concentrations, and no effects were observed in CP and the C/N ratio.