Double-Cropping Systems Based on Maize, Sorghum, and Alfalfa: Impact on Nutritive Value and Silage Fermentation Quality

The accelerating development of the forage industry and the land resources finiteness require the high-efficient forage cropping strategies. To investigate the nutritive quality of the mixed forage crop cultivation, a three-round field test of two double-cropping systems (DCSs) based on maize (Dongdan 60 and Dongdan 1331) and sorghum (1230 and cfsh30) as the summer forage crop and alfalfa as the preceding winter forage crop were compared. This study investigated the impact on nutritive value and silage fermentation quality. The M-A system (alfalfa following a preceding crop of maize) outperformed the S-A system (alfalfa following a preceding crop of sorghum) in silage fermentation quality (by 2.81 of M and 2.22 of A), crude ash (by 0.94% of M and 3.5% of A), phosphorus content (by 0.1% of M and 0.17% of A), and potassium content (by 0.47% of M and 0.41% of A). Within the M-A, the maize Dongdan 60 (M1)–alfalfa WL525 (A) combination under the suitable sowing condition (D1) achieved the best nutritive quality exhibiting, not only the highest Flieg score (88.17 of M1 and 92.5 of A) but also the highest crude ash content (6.71% of M1 and 11.82% of A), phosphorus content (0.38% of M1 and 0.48% of A), and potassium content (1.68% of M1 and 1.55% of A). Delayed sowing reduced nutrient accumulation and altered fermentation profiles, highlighting the importance of timely sowing. The study revealed that the double-cropping rotation of maize and alfalfa is a promising strategy to optimize nutritive quality.