关键词: 鸡传染性法氏囊病病毒超强毒株, 鸡传染性法氏囊病病毒超强毒株, 动物回归, 分离鉴定

Abstract:

In order to reveal characteristics of soil nutrients and guiding the fertility maintaining practices in the farmland in semiarid regions, the trend and mechanism of change in main soil fertilities (organic matter, total nitrogen, available P and available K) in farmlands of Xinfu County, Shanxi Province was analyzed by using soil survey data for 1963, 1980, 2006 and 2010, from which a sustainable strategy for agricultural nutrient resource management was put forward. The results indicated that, a significant change in soil fertility for 1963 through 2010. Since 1963, whole area mean soil nutrient contents in the overall decreased significantly, down to the minimum level in 1980. And then, the nutrients began to raise slowly, higher speed after 2006. Serious shortage of inputs and change of cropping patterns lead to fertility decline in the former stage, while a dosage augment of chemical fertilizer and improving irrigation promoted soil fertility after 1980, and returning straw to field speeded up the recovery of soil fertility after 2006. By 2010, organic matter, total nitrogen, available phosphorus and available potassium content reached 15.3, 0.79, 15.6, 149 mg/kg, respectively. To further enhanced the soil fertility, implementation of precision fertilization, combined the application of organic and inorganic fertilizers, increment of incorporated straw into the soil, and implement conservation tillage, improving irrigation and the expansion of irrigated area, should be the main regulation direction of agricultural management in the future in the area.