Double-Cropping Systems Based on Maize, Sorghum, and Alfalfa: Impact of Annual Combination on Biomass and Nutritional Yield

Forage crops can be grown in mixed species cultivation to provide productivity and nutritional benefits. In a three-round field test, two double-cropping systems (DCSs) based on maize and sorghum as the summer forage crop and alfalfa as the preceding winter forage crop were compared. There were comparisons of harvesting and growing time, nutritive value, as well as biomass and nutritional yields. The superiority of the M–A (alfalfa following a preceding crop of maize) was identified as compared with the S–A (alfalfa following a preceding crop of sorghum). Within the M–A, the maize Dongdan 60 (M1)–alfalfa WL525 (A) combination under the late sowing condition (D3) achieved the highest annual biomass production (fresh weight and dry weight). The maize/alfalfa combination achieved significantly higher nutritional yields compared to those of the sorghum/alfalfa combination. The highest yield of crude protein was obtained in the late sowing (D3) condition for the maize Dongdan 60 (M1)–alfalfa WL525 (A) combination. The highest yield of starch was obtained in the earliest sowing date (D1) in the maize Dongdan 60 (M1)–alfalfa WL525 (A) combination. The highest yield of crude fat was obtained in the latest sowing date (D3) in the maize Dongdan 1331 (M2)–alfalfa WL525 (A) combination. The study indicated that the winter alfalfa and maize DCS could be a promising strategy to achieve high biomass and nutritional productivity.