Effects of different mulching on soil water-heat and spring maize yield in newly reclaimed land

With rapid urbanization, the net cultivated land area continues to decrease, and it is important to utilize potential land resources for Chinese food security. To examine the effects of different tillage practices on soil water-heat characteristics and crop growth in newly reclaimed land, we conducted field experiments in 2018 and 2019 with four treatments: plastic film mulching (FM), buried straw layer (BS), buried straw layer with plastic film mulching (F+S), and traditional tillage (CK) as the control. We measured the soil moisture, soil temperature, and growth and yield of spring maize under each treatment. The 2018 results showed that under F+S, BS, and FM, the average soil moisture increased by 24.4%, 16.5%, and 12.6% at 0-20 cm depth, respectively, and by 9.1%, 3.2%, and 3.7% at 20-40 cm depth, respectively, compared with those under CK. Water storage of the soil profile (0-100 cm) under each treatment ranked as FM > F+S > CK > BS in 2018 in maize seedling stage indicating higher water storage under treatments with film mulch than that under no mulching. In 2019, it ranked as F+S > BS > FM > CK. The soil temperature increased under F+S, BS, and FM at each depth, especially at the 5 cm depth, compared with that under CK. The soil temperature (5-25 cm) ranking was F+S > FM > BS > CK. The temperature decreased with increasing soil depth during the growth period; the improved soil temperature effect of mulching and tillage was the strongest at the early growth stage and weakened later. The plant height dynamics were similar among treatments; it improved to a maximum at approximately 70 days after sowing but then reduced and remained stable. The plant height and leaf area index were higher in the treatments with film mulching than those under the no film mulching treatments (P < 0.05). The maize yield under the F+S, BS, and FM treatments were significantly higher than that under the CK treatment in 2018 (P < 0.05), and the yield increased by 17.0%, 13.5%, and 6.6% in 2018 and by 30.5%, 23.9%, and 3.8% in 2019, respectively. Stepwise regression analysis of the yield composition showed that ear length had the greatest effect on maize yield, and yield was positively correlated with the number of ear rows and hundred-grain weight. F+S treatment conferred a comprehensive advantage and effectively regulated the soil water and heat conditions, improved the soil environment, and promoted plant growth and development, resulting in a high yield. Therefore, F+S treatment represents an appropriate mulching and tillage management system for spring maize in a newly reclaimed land.