Intercropping Sorghum into Alfalfa and Reed Canarygrass to Increase Biomass Yield

Abstract

Forage production requires high yields with minimal soil erosion to lessen production cost per unit forage and to protect the soil. Some annual crops have higher yield potential than perennial forage crops but allow more erosion on sloping soils. This study was conducted to learn if intercropping sorghum [Sorghum bicolor (L.) Moench] into alfalfa (Medicago sativa L.) or reed canarygrass (Phalaris arundinacea L.) could increase biomass yields over alfalfa or reed canarygrass grown alone and still protect soil from erosion. The study was conducted near Ames and Chariton, IA. Sorghum establishment in alfalfa or reed canarygrass was aided by using a power slot tiller to prepare the seedbed and by using band applications of paraquat to control growth of alfalfa or reed canarygrass. Interseeding 'M-81E' sweet sorghum or 'FFR 201' forage sorghum into 'Arrow' alfalfa increased dry-matter yields by an average of 38% (1.8 tons/acre) at Ames and 28% (1.2 tons/acre) at Chariton. Interseeding sorghum into reed canarygrass ('Venture'; Ames only) increased average yields by 35% (∼1 ton/acre). Sorghum intercropped into reed canarygrass appeared chlorotic and lacked the vigor of sorghum intercropped into alfalfa. Estimated annual soil erosion on the sloping soil at Chariton was less than I ton/acre for alfalfa and alfalfa intercropped with sorghum, whereas that for sole sorghum was more than 14 tons/acre. The forage produced was of moderate quality for livestock with neutral detergent fiber (NDF) concentrations ranging from about 50% for alfalfa to about 64% for reed canarygrass. So, we conclude that sorghum can be successfully interseeded into alfalfa and reed canarygrass to improve biomass yield if proper precautions are used to control plant competition during establishment and soil water is adequate.