| Due to unreasonable cultivation and fertilization pattern, soil fertility reduction, land quality declination, and soil acidification have been important factors for threatening integrated potential productivity and food security of Heilongjiang Province. Aiming at black soil in Nenjiang County with original high soil fertility, two key agricultural techniques including subsoiling and balanced fertilization were studied. Through investigation and field experiment, optimal integration of above two techniques and integration effects were studied and fertile soil technical modes aiming at Nenjiang County were also provided, which was important for protecting black soil resource and improving comprehensive grain production capacity. Results were listed in the followings:1. There was balanced nutrient in the soil treated with formulated fertilization by soil testing, while there was reduced organic matter and acidification in the soil with unreasonable fertilization. In the farmland treated with straw-returning, the total amount, available value, and organic matter of soil nutrients were higher than those without straw-returning.2. Compared to the cultivation patterns of spring harrowing and original ridge tillage, the subs oiling pattern was beneficial to improve soil physical and chemical properties such as water permeability, soil aeration, and soil bulk density, accelerate soybean growth and increase soybean yield.3. Influences of ratios of N, P, and K on the growth and yield of soybean were different. There was significant regression relationship between the fertilizer rate of N, P, and K. and soybean yield. Based on the "3414" experiment, one soybean fertilizer model was established for guiding soybean fertilization measurement in Nenjiang County. The results of field experiment showed that balanced fertilization method accelerated soybean growth and improve soybean yield, with respective increasing yield rate of 17.2%,12.5%, and 11.7% in three demonstration areas.4. The plant height, root length, fresh plant weight, fresh root weight, nodule mass, and chlorophyll content were significantly increased in shallow ploughing-subsoiling+organic fertilizer treatment as compared with those in the control. The organic fertilizer model based on organic fertilizer application improved soil pH and part of available nutrients. In 2007, the soybean yield increased by 268.0kg/hm2, with increasing rate of 19.96%; in 2008, the soybean yield treated with organic fertilizer increased by 4.87%, as compared with that of the control.Generally, study on the techniques of soil tillage, fertilization, organic fertilizer in Nenjiang County, the fertile soil technical modes suitable for Nenjiang County was able to improve the physical and chemical characteristics of soil, promote soybean growth, and increase soybean yield. |
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