Effects of dual mulching with wheat straw and plastic film under three irrigation regimes on soil nutrients and growth of edible sunflower
Jinxia Zhang, Liangliang Du, Zisheng Xing, Rui Zhang, Fuqiang Li, Tao Zhong, Fangfang Ren, Meng Yin, Lin Ding, Xingrong Liu
Abstract
Mulching is an important practice to reduce soil water loss and improve productivity in agriculture. To investigate the influence of dual mulching with crushed wheat straw padding and plastic film combined with different irrigation amounts on soil nutrients and the growth of edible sunflower, a field experiment was conducted in Minqin Experimental Station of Gansu Institute of Hydraulic Sciences from 2016 to 2018. The experiment adopted a two-factor design with four mulching methods: no mulching (N), straw mulching (S) at 4500 kg ha−1, plastic film mulching (F), crushed wheat straw padding and plastic film mulching (SF) at 4500 kg ha−1, and three irrigation levels: high (H=900 m3 ha−1), medium (M=750 m3 ha−1) and low (L=600 m3 ha−1). The results showed that the soil nutrients under the dual mulching of crushed wheat straw padding and plastic film were improved. The soil available phosphorus (AP) content was highest under SFH treatment, varying significantly with treatments (P < 0.05). Soil available potassium (AK) and alkali-hydrolyzed nitrogen (AHN) contents were also significantly higher under SFM treatment than other treatments. The contents of soil AP, AK and AHN decreased with soil depth, with a greater rate of decrease in the 0–40 cm soil layer than the 40–120 cm layer. Overall, the soil nutrient status was improved by mulching in comparison with no mulching, and the dual mulching of crushed wheat straw padding and plastic film gave the best results than other mulching methods. The medium irrigation level led to better soil nutrient improvement than other irrigation levels. Dry matter yield of sunflower varied with treatments, the higher yields were obtained in treatments SFM, SFL, SFH and FH. However, plant height, stem diameter, leaf area, stem dry weight, head dry weight, leaf dry weight and seed yield were the highest under the SFM treatment. The comprehensive score ranking of the principal component analysis indicated that the SFM treatment had the highest score and was the best planting practice. Therefore, in the Minqin oasis area with drought and little rain, it was determined that edible sunflower should be grown under the dual mulching method of crushed wheat straw padding and plastic film as an optimal conservation tillage method determined through this study.