The Characters Of Soil Moisture Of Rainwater Harvesting-Anti-seepage In Soil And Its Influence On Fruit Yield And Quality In Arid Hilly Orchard

Rainwater harvesting-soil anti-seepage technology is a new technology based on the ridge film mulching and furrow rainwater harvesting.The soil of the apple orchards in Yulin mountain in northern Shaanxi are mostly loessal soil with extremely loose soil,and the evapotranspiration and infiltration of rainwater rapid quickly.In order to explore the application effects of rainwater harvesting-soil anti-seepage technology,four different treatments designed as contrast(CK),loessal soil with compacted anti-seepage treatment(L1),red clay with anti-seepage treatment(R1)and red clay with compacted anti-seepage treatment(R2)were set respectively in a red “Fuji” hillside orchard in Mizhi Demonstration Station of northern Shaanxi Province.Soil bulk density,stable infiltration rate,characteristics of soil water infiltration,seasonal distribution,lateral distribution,vertical distribution and infiltration depth of soil water under different treatments,apple tree growth,fruit quality and yield,water use efficiency were measured for those four treatments.The main finding follows:(1)R2 had the best anti-seepage efficiency with the highest bulk density(1.61 g·cm-3),the minimum water holding capacity and the least stable infiltration rate(0.02 mm·min-1)among all the treatments.The empirical formula of Kostiakov equation was suitable for describing water infiltration characteristics of four treatments.(2)In dry season and rainy season,R2 treatment could increase the soil water content in a large range outside the ditch,the horizontal diffusion distance was significantly greater than that of other treatments.The soil water content of 0~60 cm soil layer increased by 20.4 % and12.2 % respectively compared with CK in the range of horizontal diffusion distance of R2 after two rainfall events,improve the soil moisture effectively.(3)Throughout the full growing season,soil moisture for 0~60 cm soil depth in the rainwater harvesting ditch could be improved by the different anti-seepage treatments,R2 had the highest soil water content all the time and could satisfy the suitable water content standard for growth and development of apple trees in the dry season.After the anti-seepage treatment,there was an obvious “low humid layer” with 20~30 cm of soil layer under 60 cm soil depth,but the variation tendency of soil water content from “low humid layer” to 200 cmsoil layer was stable and slightly higher than CK.(4)Rainwater harvesting-soil anti-seepage treatments could change the water transport law in the vertical direction of rainwater collection ditch,reduce the infiltration depth and the amount of soil water leakage effectively.When the regional sub-rainfall reaches 35.4 mm,the infiltration depth of each treatment was different,and the larger the sub-rainfall is,the more obvious the difference is," dislocation" phenomenon is more prominent.(5)Rainwater harvesting-soil anti-seepage treatments could promote the growth and development of fruit trees obviously,increase fruit yield and water use efficiency,and improve the quality of fruit.R2 treatment has the most obvious effect,the branch length and diameter was 38.6% and 27.1% higher than that in CK respectively,leaf area,fresh weight and thickness was 36.2%,15.1%,25.0% higher than that in CK respectively,fruit yield was19.2% higher than CK,good fruit rate increased by 26.5%,and water use efficiency increased by 24.5% compared with CK.The results show that,to integrate rainwater harvesting and soil anti-seepage assembly as a whole,raining to root zone of fruit tree and reduce evapotranspiration of soil moisture and reduce or block infiltration of deep soil moisture as much as possible,so that the limited rainwater resources are concentrated around the roots of fruit trees for a long time,improves soil water control capacity,it is of great significance to promote the sustainable and healthy development of the apple industry in northern Shaanxi,therefore rainwater harvesting-soil anti-seepage technology was recommended as the effective agricultural measure in the apple production in loess hilly areas of northern Shaanxi Province.