Ridge Film Mulching Combined Straw Mulching Technology For Arid Apple Orchad Of The Loess Plateau

The Loess Plateau is the largest apple production base, where apple yield and area are more than 1/3 of the whole country. Due to less rainfall, strong evaporation and high water consumption of apple tree, soil water deficit and soil desiccation happened quite frequently in deep soil. Therefore, drought and wter scarcity is the most urgent problem to be resolved. Field trials for ridge film mulching combined straw mulching technology were carried out at Luochuan and Ansai to study the effect of the technology on soil water-holding capacity, soil physical and chemical properties, growth and fruit quality of apple orchard. Main research results are as follows:(1) The ridge film mulching combined straw mulching technology could improve the physical and chemical properties of soil. Under the condition of ridge film mulching cobined straw mulching, the soil temperature increased 1 ℃ than control. The soil bullk density decreased and the soil porosity increased. The organic matter content increased 1.4%~1.6%; the nitrate nitrogen content increased 38.4%~41.8%; the content of available P increased 49.2%~ 65.5% and the content of available K increased 8.2%~11.5%. The pH decreased a little than control.(2)The ridge film mulching combined straw mulching technology could increase the content of soil moisture markedly, improve soil water environment, advance the rainwater infiltration and decrease the evaporation. Under the condition of ridge film mulching combined straw mulching, the soil water content in the root-layer(0~60 cm soil layer) increased 10.5%~66.6%; in the rhizosphere layer(60~200 cm soil layer), the soil water content increased 9.2%~144.0%; at the new shoot growth period, the content of soil moisture in 0~60 cm soil layer increased 16.1% than control; at the flower bud differentiation period and fruit expanding period, the content of soil moisture in 0~200 cm soil layer was significantly higher than that in control; in deep soil(200~500 cm soil layer), the soil water content under the condition of rainwater harvesting ditch increased 6.6%~90.0%. The infiltration depth under condition of rainwater harvesting ditch was greater than control and the infiltration content under condition of rainwater harvesting ditch increased 5.9%~250.8%. The soil evaporation content decreased 12.1%~64.5% than control in the growth season. From June to August, the diurnal soil evaporation content decreased 1.1%~ 76.4% than control.(3)The ridge film mulching combined straw mulching technology could increase the water content of leaf, improve the efficiency of photosynthesis and promote the growth of the tree branches, leaves and fruit. The water content of leaf increased 7.9% than control and the net photosynthetic rates significantly higher than that in control. Under condition of ridge film mulching combined straw mulching, the proportion of med-branches(10-30 cm) increased 3.2 percentage points; the proportion of short branches(<10 cm) increased 18.0 percentage points; the length of one-year-old twig increased 50.0%; the area per leaf increased 5.9 cm2; the fresh weight per 100 leaves increased 14.74 g. During fruit expanding period(Jul~Sep), the fruit diameter under condition of ridge film mulching combined straw mulching increased 13.6%~178.1%. The yield increased 11.5%~18.4%; the average weight of single fruit increased 2.8%~40.5%; the rate of excellent fruit increased 29.9~39.5 percentage points,the water use efficiency increased 11.8%~48.2% than control.Above all, assembling and integrating the ridge film mulching and straw mulching will be of significance for improving water management level of arid apple orchards, improving the soil water condition of apple orchards, promoting the quality upgrading, production increasing and sustainable development of apple industry. It is suggested to be extended widely in apple growing area of the Loess Plateau.