Effects Of Organic Manure And Inorganic Fertilizer Combination On Increasing Fertility Of Black Soil

A practical cropping system is needed to be established to keep the soil fertility of black soil at a relatively constant or higher level. This is called the elevation of soil fertility of black soil. The experiment was carried out on a typical black soil (mollisol in soil taxonomy) in Dongxing Village, located at Shuangcheng city belong to Ha'erbin city in Heilongjiang Province of China. Dairy manure, the commonly used manure in the region, was taken as the experimental organic fertilizer. Soil characteristics such as bulk density, porosity, water-stable aggregates, field water capacity, labile nutrients, available Nitrogen, phosphorus, potassium, cation exchange capacity, organic matter, soil pH, microbial biomass carbon, total carbon, active organic carbon, soil carbon pool management index (CPMI), soil enzyme activities were determined, crop yield was measured too to evaluate the variation of farmers'agricultural income from cultivation. An optimal model of elevating fertility of black soil was established by means of studying soil physicochemical characteristics, enzymes'activities, CPMI index and the increase in yields.The results showed that the organic manure - inorganic fertilizer combination treatment can significantly improve soil physicochemical properties compared to unique application of chemical fertilizer, of which the middle and high rate of organic manure and chemical fertilizer combination N1M5, N2M4, N3M3 treatments elevated the active organic carbon and microbial carbon, and significantly promote the growth of crop. The CPMI was 0.2-3.6 times higher, of which the treatment N3M3 was the best, reaching 3.6 times of the CK. At the same time, combination of organic manure and chemical fertilizer significantly lowered the bulk density of soil at 0.17-1.62% and significantly increased the water content of soil compared with the unique fertilizer application treatment.From the variation of water stable aggregate content of five groups, > 5mm, 5 - 2mm, 0.5 - 0.25mm, 1 - 0.5 mm and > 0.25mm, the general trend, a slow increase of water stable aggregate content with the rate of organic manure, was found. In addition, the combination of organic manure and chemical fertilizer could increase soil cation exchange capacity, and enhance the release of soil available nitrogen, phosphorus and potassium. By analyzing the correlation between the relevant indicators, it was found that available nitrogen, phosphorus and potassium and CEC had a nice positive correlation, but an inverse correlation with bulk density, salinity, pH of soil. Middle rate of organic manure and inorganic fertilizer combination treatment N3M3 could significantly increase the microbial carbon and active carbon, and elevate the urease activity of soil.Take all factors into consideration, in the context of elevating soil fertility, treatments N2M4 and N3M3 , i.e., middle rate of organic manure combined with inorganic fertilizer had the best improvement results, of which N2M4 was slightly better than treatment N3M3 on physical property amelioration, but the treatment N3M3 was better according to the chemical, microbial properties and CPMI.Taking into account elevating soil fertility and the income from crop, middle rate of organic manure and inorganic fertilizer treatment N3M3 was the optimal model of fertilization which exerted the most remarkable influence on CPMI. In the future, it is recommended to make more use of rainy season (7-8 months) of high temperature, by using local materials such as livestock and poultry manure to compost to produce more organic manure in order to lower the chemical fertilizer rates, a best model with the feature of low cost, easy to operate. This research was not only a bit innovative on elevating the fertility of black soil by using the organic manure and chemical fertilizer combination, but also under the local condition of limited organic manure resources, by adjusting the ratio of different organic manure and chemical fertilizer, exploring without stop, and ultimately found a model of elevating fertility of black soil and ensuring the crop production income at the same time.