Effects Of Rainfed Agriculture Technique Models On Harvesting Rainfall And Conservation Soil Moisture In Ningxia

The middle arid zone and southern mountainous area of Ningxia is typical in arid areas of Northwest China.The development of dry land water saving farming in this area has great influence on dry land agricultural production in China.At present,mulching is the most important measure of water conservation and increase production in among all kinds of dry farming techniques.Conventional film-mulching cultivation methods(semi-membrane covered cultivation)have the problems of small area of mulching film,large amount of bare land(about 50%),poor soil moisture holding efficiency and poor infiltration of rainwater.In this study,we deeply understood and accurately grasped the theories about the periodical changes of soil moisture in dry land,in-situ infiltration of rainwater,suppression of evaporation in farmland and the superposition of precipitation enrichment.The innovative integration in the modern technology system of water conservation and rain collection with film mulching is focused on the predominant crops and leading industries in Ningxia arid area.The above technical system can extremely improve the retention rate,utilization ratio,production efficiency of the limited precipitation resources,radically break through drought,realize the shift from passive drought resistance to active disaster avoidance and construct the mechanism of drought resistance and disaster mitigation.The main results obtained are as follows:1.Through the analysis of a large number of experimental results,6 major technical models including water conservation with film mulching in autumn,early spring mulching,whole plastic-film mulching on double ridges,whole field soil-plastic mulching,ridge film and soil mulching,cover film using with stubble wintering were concluded.The key technical parameters of each technical mode had been established respectively.A comprehensive supporting technology for each mode had been put forward.Thus,the modern technology system of water conservation and collecting rainfall with film mulching was constructed.2.This study summarized the formation of the above technical system.First,four major changes had been achieved in the film mulching time,film mulching area,planting methods and soil tillage in traditional mulching cultivation methods.The above changes included changing the filming period from sowing date to the autumn of last year or the early spring of the year,changing the semi-film mulching to full film mulching,changing the bunch planting to ridge and furrow planting,changing uncovered tillage and soil preparation at the harvest period to wintering conservation tillage(no-till with stubble mulch).Second,the suitable technical models for mulching cultivation of main dryland crops in the region were put forward.These technical modes included the double ridge whole-mulching furrow sowing technology mode of corn,the whole field soil-plastic mulching technology mode of dense planting crops represented by wheat,the technical mode of potato ridge mulching and covering soil mulching.Third,the regional adaptability of dryland crops were enhanced,which creating good combination of water and temperature for growing corn,potatoes,small coarse cereals and other crops in some cold and high altitude areas and extremely arid areas.Fourth,the water using efficiency of dry land crops was raised to a new level.The production potential of limited precipitation was maximized.The application of water conservation and collecting rainfall with film mulching made precipitation utilization rate of maize up to 78%with an average of 70%and the highest water production efficiency reached3.32kg/mm·666.7m~2with an average of 2.25kg/mm·666.7m~2in the middle arid zone and southern mountainous area of Ningxia.The application of this technology also made potato precipitation utilization up to 88%with an average value of 75%and water production efficiency up to 2.11kg/mm·666.7m~2with an average of 1.54kg/mm·666.7m~2.3.The popularization and application of this technical system had fundamentally improved the soil moisture conditions and effectively enhanced the ability of crops to resist drought and resilience.It had realized the transition from confrontational planting to adaptive planting and promoted agricultural supply-side structural reform.The application of this technical system had enhanced planting production performance,boosted the increasing of the planting proportion of high-yield autumn grain such as corn,potato and small coarse cereals,which effectively supported the stable development of grain production.The promotion of this technology excavated the potential for increasing income within the dryland agriculture and expanded the external income space for agriculture in Ningxia and effectively boosted the farmers' income.