Abstract:

【Objective】 To provide a theoretical basis for soil testing and fertilizing recommendation for rapeseed production in the region of Yangtze River valley. 【Method】 Field experiments were conducted in 10 main rapeseed production provinces in the valley during 2004-2006. A series of soil samples were taken before rapeseed transplanting and analyzed by ASI (Agro Services International) method. The abundance and deficiency indices were determined based on the relationship between crop relative yield and available soil nutrient values. Compared to the complete treatment, the relative yields of 60%, 75%, 90% and 95% obtained from the －P, －K and －B treatments were selected to establish the abundance and deficiency indices of soil available P, K and B for winter rapeseed. 【Result】 The extreme deficiency, deficiency, slight deficiency, optimum and abundance indices for soil available P were ＜5.5, 5.5-12.5, 12.5-28.5, 28.5-38.0 and ＞38.0 mg P?L-1, respectively. The extreme deficiency critical values for soil available K and B were not appeared in this research. The deficiency, slight deficiency, optimum and abundance critical values for soil available K and B were ＜30, 30-75, 75-100 and ＞100 mg K?L-1; and ＜0.25, 0.25-0.95, 0.95-1.50 and ＞1.50 mg B?L-1, respectively. 【Conclusion】 The relative yields of the －P, －K and －B treatments were significantly correlated with soil available P, K and B contents. The soil available P, K and B critical indices established using the ASI systematic approach and field experiments can be used as guidance for soil testing and fertilizing recommendation for winter rapeseed production in the valleys.

Key words: rapeseed (Brassica napus L.), ASI method, soil available phosphorus, soil available potassium, soil available boron, abundance and deficiency indices