Combined Straw and Plastic Film Mulching Enhances Cauliflower Yield, Quality, and Irrigation Water Use Efficiency in Arid and Semi-Arid Regions

Although plastic film mulching enhances crop yield, it impedes water infiltration, potentially restricting agricultural productivity. To address this issue, we evaluated the effects of different mulching methods on cauliflower growth, yield performance, quality traits, soil properties, and irrigation water use efficiency. We implemented three mulching treatments and two control groups: combined straw and plastic film mulching (T1), partial straw mulching (T2), full straw mulching (T3), no mulching (CK1), and plastic film mulching alone (CK2). These treatments were applied to two consecutive crops of cauliflower over a two-year period (2019–2020) in the arid and semi-arid regions of Gansu Province, China. Our findings revealed that T1 significantly enhanced plant height, stem diameter, and both above- and belowground fresh biomass compared to CK2. Moreover, T1, T2, and T3 promoted the accumulation of nitrogen, phosphorus, and potassium in the roots, stems, and leaves, as well as the concentrations of macro- (N and K), meso- (Ca and Mg), and micro-elements (Fe, Mn, Cu, and Zn) in the cauliflower heads. Compared to CK2, the soluble sugar and vitamin C contents increased by 17.43% and 8.68% in T1, and the soluble protein contents increased by 13.10% and 9.50% in T2 and T3 compared to CK2. Conversely, the nitrate content decreased by 28.28%, 42.06%, and 31.54% in T1, T2, and T3, respectively. Additionally, T1 increased economic yield and irrigation water use efficiency by 16.36–23.80% and 23.94–36.88% in the two years, along with notable improvements in the soil’s total nitrogen, total phosphorus, available phosphorus, and organic matter content. Multivariate classification modeling using principal component analysis (PCA) and hierarchical cluster analysis (HCA) further indicated that T1 enhanced cauliflower quality, yield, and irrigation water use efficiency and boosted soil fertility. These findings provide valuable insights for sustainable agricultural practices in arid and semi-arid regions.