Abstract:
Abstract: Saline soil is an important soil resource in China. The area of saline soil in China is 9.91×106 hm2. The total area of saline soil in Heilongjiang province is 2.43×106 hm2, and the area cultivated for cultivated land is 1.6×106 hm2. The saline soil in Heilongjiang province is mainly distributed in Anda, Zhaodong, Zhaoyuan, Daqing in the Songnen Plain, and the Sanjiang plain also has a small amount of distribution. Because of the high content of exchange base in saline soil, it is harmful to the growth of crops. Therefore, governments at all levels and scientific research departments have spent great amount of resources to the improvement of saline soil, and have developed various techniques and methods for improving saline soil, such as subsoiling, gypsum, soil conditioner, salt pipe disposal and so on. However, there are some problems with these methods. Rice husk deep application technology is the technology for improving saline soil developed by our research group for many years. Rice husk has many advantages, such as ample source of material, low cost and resistance to decay. In this study, soda alkaline soil of Heilongjiang province was used as test soil, and rice husk was embedded in 20 - 30 cm soil layer by a special machine, and the single mechanical tillage without rice husk was used as the control. The results of two years’ investigation showed that rice husk deep application had significant effects on improving soil physical and chemical properties and forage yield. Based on that, field with rice husk amendment conducted eight years ago was investigated for soil physical and chemical properties. The results showed that after eight years of deep application of rice husks, the effects on the physical and chemical properties of the modified soda alkaline soil were still obvious. The soil organic carbon, available nitrogen, phosphorus and potassium content of rice hull deep application showed an increasing trend compared with treatments without rice husk applications. The total amount of exchange base decreased in 0 - 30 cm soil layer, and the pH value of each layer decreased by 0.37-0.41, and the content of Na+ decreased by 40.68 - 212.35 mg/kg soil. After eight years of deep application of rice husk, the soil solid phase rate was still in a downward trend, the solid phase of soil was about 40% and decreased 3.68% - 8.86% than control soil. The total soil porosity increased between 57.38% - 60.58%. The proportion of effective pores is large, accounting for 22.7%-26.8% of the total porosity. The soil aeration and water permeability were obviously higher than those of control, and were 10-1 215 times and 118-1 735 times as much as those of the control. The reservoir capacity of 0-30 cm soil layer was increased, 18.58 mm higher than that of the control. The available reservoir capacity was 33.19 mm, 10.71 mm higher than that of the control. Rice hull deep application has long lasting effect, and the improved effect of soda alkaline soil is obvious. The effectiveness of rice husk application with single mechanical tillage is a technique suitable for the improvement of saline soil and can be achieved by mechanical means.