Effect of Co-application of Ridge-Furrow Rainwater Harvesting and Mulching on Fodder Yield, Quality, and Soil Desiccation in Alfalfa (Medicago sativa) Production

Alfalfa (Medicago sativa) is a major crop grown in northwestern China, but severe water shortages due to low rainfall and soil erosion hinder the growth of the crop. An increase in water availability is essential for continuous alfalfa cultivation; however, only a few studies have assessed ridge-furrow rainwater harvesting effects on alfalfa yield and water use efficiency. To expand on these studies, we evaluated the effect of plastic film mulched ridge-furrow rainwater harvesting on fodder yield and quality. This study had ten treatments with three ridge-mulching materials and three ridge widths and flat planting (FP) as a control laid out in a randomized complete block design (RCBD) with three replications for 5 years. Compared to flat planting, ridges mulched with plastic film increased yield (33%) and water use efficiency (19.79%) by decreasing crop water consumption (2.35%) over the cultivation seasons of alfalfa. Ridge mulched with plastic film (PF60) had the highest crude protein of 202 g kg−1, while ridge mulched with bio-degradable film (BF) had the lowest mean acid detergent fiber content of 348 g kg−1. Flat planting had the highest neutral detergent fiber of 505 g kg−1, while BF treatment had the lowest mean neutral detergent fiber of 471 g kg−1. Thus, severe soil desiccation was observed during alfalfa cultivation seasons. Nevertheless, PF60 had the lowest degree of soil water deficit. Our results indicate that co-application of ridge-furrow rainwater harvesting and mulching in alfalfa production over the 5 years increased fodder yield and quality by markedly reducing soil desiccation with a higher cost–benefit ratio. We, therefore, recommend co-application of ridge-furrow rainwater harvesting and mulching with 60-cm ridge width under semiarid conditions for improving yield and decreasing soil desiccation.