The Effect Of Plastic Film Mulching Cultivation With Ridge And Furrow System On Soil Water, Heat And Nitrate Transport And Maize Production On Drylands Of Loess Plateau

It’s important to ensure the agricultural sustainable development in drylands of China, because drylands have about 500 million hectares, accounting for about 50% of total arable land. Large amount of nitrogen fertilizers were continued input and caused nitrate accumulation in the semi-arid region of Northwest China; at the same time, it seriously lacks of water in this area, plastic film mulching cultivation was widely used for saving water, improving maize yields and water use efficacy. However, it’s not well understood how the soil water and heat under plastic to effect nitrate leaching and accumulation. Thus the scientific management of nitrogen and water were limited. In this study, we took different planting patterns and nitrogen levels as the research object by monitoring soil water, soil temperature and distribution of soil nitrate connected with the yield and biological characters of maize under this situation, and combing with economic and environmental benefits to study. Depict characterizations of the ridge and furrow Mulched with plastic film, groove and flat for three site conditions, differences in soil moisture and temperature and its dynamic characteristics, especially the difference of the response of the three to the water in the event of rain. It aimed to study that how nitrate accumulation and maize yields affected by mulching cultivation with ridge and furrow system. The results showed that:(1) mulching cultivation with Ridge and furrow system(RM), can significantly improve the 0-10 cm temperature of soil surface layer, the warming effect of which meets the needs of maize activity in seedling stage and development stage that is beneficial to the emergence of maize and its growth and development. In the whole growth period, the average temperature of the RM-ridge up to 10 cm high is 2.01℃ higher than trench and 1.75℃ than flat;(2) RM can make less than 10 mm invalid precipitation conversion exists for effective storage of water in soil through micro topographic changes and plastic film covering catchment, inhibition of evaporation which significantly improve 30-60 cm soil moisture(RM than flat plot without mulching is about 10%); at the same time, water in the furrow due to the ridge of the accumulation achieves value-added rainfall, through strengthening rainfall infiltration, water under conducive to preserving storage depth; during rainfall events, there showed significantly differences among the ridge in RM, furrow in RM and the flat cultivation on the amount and the time of water change(start time and water peak time), which proves that ridge and furrow for infiltration of rainfall in different ways. Ridge of water to increase mainly depends on the furrow water due to the gradient of water potential difference about 30 cm by the water side of the infiltration supplement on the ridge, the main trench to vertical permeability, which manifests the increase of the soil moisture of the ridge from 10 cm to 30 cm to be lagging behind in the same trench soil and ridge on the part of the moisture content of relatively low;(3) RM can keep nitrate well in the root zone by reducing rainfall erosion so as to reduce the occurrence of nitrate leaching which manifests the phenomenon of the accumulation of nitrate in the soil surface layer(0-40 cm) in the maize growing season;RM showed the differences among the the ridge in RM, furrow in RM and the flat cultivation on the amount of the water, which caused the migration of nitrate with different degree of water, finally lead to the accumulation of nitrate peak in the "RM-ridge, RM-furrow and flat" gradually down, which meaning the rainfall events under the ridge, the leaching rate of the three are different and nitrate can be effectively avoided to be caught in deeper soil under RM;In low-nitrogen cases(recommended fertilization: 180 kg N/hm2), leaching of nitrate migration is inhibited, while in the high-nitrogen cases(conventional fertilization:260 kg N/hm2), the maize growing season late in 160 cm soil layer within significant leaching of migration and a crop after skimming the surface on a large number of cumulative;(4) Plastic film mulching improved soil temperature and water content, promoted the absorption of nitrogen in maize, and can achieved continuously high yields of Maize. Meanwhile, it can reduce the nitrate leaching under recommended fertilization, which is a good cultivation to achieve the high production and high n use efficiency in drylands of loess plateau.