Get reliable rangeland science

Alfalfa (Medicago sativa L.) is the most important forage crop grown globally. Alfalfa is often called "Queen of Forages" because of its high productivity, great animal performance, and superior nutritive value. However, producers/ranchers face several challenges such as high and inefficient use of water, alfalfa weevil infestation, and bloat problems in grazing livestock. A field study was conducted in 2020-2021 and 2021-2022 growing seasons to compare forage productivity, nutritive value, alfalfa weevil abundance, and economic returns of monocrop alfalfa and different seeding ratios of alfalfa-grass mixtures planted at different planting configurations under full and deficit irrigation. Treatments included monocrop alfalfa, 75-25% mixture, 50-50% mixed row planting, and 50-50% alternate row planting of alfalfa with each of three perennial cool-season grasses (orchardgrass, tall fescue, and meadow bromegrass) under full and deficit irrigation. Full irrigation plots received 100% ETc (crop evapotranspiration) for the whole season while deficit irrigation plots received 100% ETc for the first harvest and 60% ETc for subsequent harvests. The study design was split plot with irrigation as whole plot factor and cropping system (monoculture and mixtures) as subplot factor. Results show th at intercropping alfalfa with grasses irrespective of planting configurations produces similar forage yield to monocrop alfalfa. Deficit irrigation reduced forage yield. Forage nutritive value was generally higher in monocrop alfalfa, however some mixtures produced similar nutritive value as monocrop alfalfa. Intercropping alfalfa with grasses reduced alfalfa weevil numbers. The 75-25% mixture of alfalfa and tall fescue under full irrigation produced the highest net present value. Deficit irrigation reduced costs but did not result in high net present value compared to full irrigation. Alternate row planting with orchardgrass under deficit irrigation produced similar net present value to full irrigation. Increasing unpredictability of the weather due to climate variability can make deficit irrigation a more viable and sustainable option.