稻壳深施改良苏打碱土理化性质长期效应

盐渍土是中国重要耕地土壤,由于土壤中盐基离子含量高,影响植物生育,为此改良盐渍土意义重大。该研究以黑龙江省苏打碱土为供试土壤,采用土层置换犁将稻壳埋于20~30cm土层中,以单独的机械耕作不埋稻壳为对照,田间作业8 a后再次调查土壤理化性质,研究结果:土壤有机碳、速效氮、磷、钾含量与对照比有增加趋势,各层土壤pH值降低0.37~0.41,Na~+降低40.68~212.35 mg/kg;土壤固相率约40%,与对照比下降了3.68%~8.86%,土壤总孔隙度增加到57.38%~60.58%之间,有效孔隙比例大,占总孔隙的22.7%~26.8%,对照有效孔隙占总孔隙的19.0%~23.7%;土壤通气、透水性分别是对照的10~121 5倍和118~173 5倍,0~30 cm土层水库容量高于对照18.58 mm;速效水库容高于对照10.71 mm;稻壳深施持续后效长,改善苏打碱土比单一机械耕作有效,是适合盐渍土改良的一项技术,而且可以通过机械手段得以实现。

Long-term effect of deep application of rice husk improving physical and chemical properties of soda alkaline soil

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 - 1215 times and 118 - 1735 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.