Research On Techniques And Their Extension For Soil Testing And Formulated Fertilization Of Soil In Nanjing

China is a large agricultural country with limited cultivated land resources. Thus, the increase of agricultural production in China relies largely on the increase in yield per unit area. In fact, the application of the chemical fertilizer is playing an important role to improve crop yield. However, the excessive use of the fertilizer in China is very common and results in many negative problems such as increased agricultural production costs and degraded farmland quality and agricultural environment. Application of techniques on soil testing and formulated fertilization of soil is essential to avoid abuse of chemical fertilizers. However, it is necessary to assess the performance of this practice. The projects concerning the building of the cropland soil quality monitoring and the soil testing and formula fertilization systems and so on were conducted in the past several years in Nanjing city. The results showed that the nutrients in the cropland soil were increased comparing with those in the Second National General Soil Survey. Hereinto, the increase of available phosphorus was the highest increase of nutrient contents, up to 120%. while other nutrient contents increased less than 15%. The contests were enhanced 7.6% for organic matter.13.9% for total nitrogen,13.8% for available potassium, respectivley. The results also showed that the contents of soil organic matter, total nitrogen and available kalium were not enough for the crop growth. The soil was acidic in some context. Thus, a new strategy "limitation of nitrogen fertilizer amount, reduction of phosphorus fertilizer amount and supplement of kalium fertilizer amount" was suggested. In this study, the fraction standard of cropland soil fertility in Nanjing City has been proposed, and the corresponding assessment results have been obtained. Based on the results of "3414" experiment that the main crops have been investigated in different soil types of different fertilities, the fertility index assessment system for some main crops in Nanjing city has been established, and 24 patterns of the soil testing and formula fertilizer and 34 fertilizer confections for the main soil types and crops in Nanjing city have been conducted. In addition, for extension of the techniques on soil testing and formulated fertilization to farmers'practice, several extension molds were proposed such as service supplied by planters who plants large acreage, service on agricultural techniques and means of production ensured by local government, and service with combination of "five aspects". i.e., soil testing, fertilizer formulation, crop cultivation, fertilizer supply and fertilizer application. These molds were proven to be effective in solving the "last mile" problem in agro-technical extension.