Effects Of Plastic Film Mulching On Maize Development And Soil Ecological Environment In The Semi-arid Loess Area

On the semi-arid Loess Plateau of China, the crop productivity is primarily restricted by low temperatures and water shortages. Plastic film mulching significantly increased the soil temperature and water content. It has been widely used in this areas to improve crop productivity. However, the mechanism accountable for this yield-increasing technology by counteracting the shortage of water and the low temperature is not clear. Especially, about the effect of plastic film mulching on soil microbial community functional diversity and the distribution of water and heat in growth period.Here we study used maize(Zea mays L.), one of the staple crops in this typical semi-arid region, as material. Field experiment was conducted in 2014 and 2015 to determine the effects of plastic film mulching on soil temperature and water, corn growth, soil nutrient, soil microbial community functional diversity and the distribution of water and heat. The experiment comprised two treatments, plastic film mulching(M) and non-mulched(CK).The results showed that:1. Plastic film mulching significantly accelerated maize growth and development, increased stem length and diameter, and promoted the dry matter accumulation.And the growing stage from seeding to maturity became earlier 8-21 d than CK.Mulching significantly shortened the vegetative period and prolonged the reproductive growth phase.Grain yield under M increased by 140% in 2014 and 179% in 2015, compared with CK.2. Plastic film mulching significantly increased the soil temperature. The soil temperature at 5-50 cm depth in M was higher than in CK by 2.84-3.37 °C during the early growth season, but the difference gradually decreased as the plant canopy grew.Soil temperature at 5-50 cm depth increased by 1.07-2.14 °C under plastic film mulching during the whole growth season.Plastic film mulching increased the soil water content significantly, and consistently raised soil water-holding capacity in maize growth period.Compared with the CK, the water-use efficiency significantly increased by 141% in 2014, and 131% in 2015 for the M treatment. Plastic film mulching also significantly improved the heat-use efficiency.3. Plastic film mulching significantly changed the heat distribution during maize growth period: the higher soil temperature in M treatment during sowing to 6th leaf stage significantly accelerated growing degree days of soil(GDDsoil), met the needs of the heat resources from sowing to seedling, compensated the shortage of the growing degree days of air(GDDair), and leaded to the growth stage of corn arrive early. It avoided the waste of GDDair, and resulted GDDair of maize under M treatment increased by 112.1、145.4°C·d during the reproductive growth.The increase of the heat can basically meet the demand for heat during maize yield formation, it induced greater assimilation and translocation for grain growth, made the grain fully grouted, and then enhanced harvest index and grain yield.4. The total nitrogen, total phosphorus and soil organic carbon content at 0-20 cm layer were not changing significantly during the maize growth period in two years.Plastic mulching significantly reduced the soil available phosphorus(AP) content, increasing the consumption of AP. It also significantly increased the content of nitrate nitrogen, increasing the mineralization of nitrogen.5. Plastic film mulching increased the average well color development(AWCD), Shannon-Wiener index and Mc Intosh index, and this effect is more significantly in seedling and harvest time. Carbohydrates, Am ino acids and Esters were the main carbon resources of microbe utilization.Principal component analysis(PCA) showed that there was variation among carbon source utilization mode and metabolic function of soil microbial communities under two treatments at different stage.Plastic film mulching caused significant differences in structure and functional diversity of soil microbial communities during maize growth season. In addition, there were differ in root exudates utilization patterns under two treatments at different stage.