Soil Fertility Evaluation And Its Application In Xuyi County

Cultivated land is the basic resources for the agricultural production, plays an irreplaceable role in it, and is the base for the sustainable development of our society and national economy as well. To provide a scientific basis to guide agricultural production, it is very desirable to develop the work on evaluation of fertility and suitability of cultivated land. Additionally, it is the high request to protect the agricultural eco-environment, ensure quality and safety of agricultural products, improve the efficiency of resource utilizing, and carry on the restructuring of agriculture to realize the sustainable development of agriculture. The quality of cultivated land would directly affect the agricultural efficiency and rural incomes, and it relates to the agriculture, rural and the entire national economy sustainable development.In this paper, the Xuyi County, Jiangsu Province was selected as the study area. Supporting with the GIS, the weighted value of quality factor is obtained though combined with the contribution of each land quantitative evaluation to the fertility of farmland. At first, we selected12evaluation indicators in our county from the evaluation index system of this province (for example, soil organic matter, available phosphorus, available potassium, geomorphological type, slope, drainage modulus, Irrigation modulus, pH, texture, configuration of soil profile, topsoil thickness, and soil parent materials). Then, arable production performance index was calculated by Analytic Hierarchy Process. Based on these method established, the grading scheme of integrated fertility index are determined. Meanwhile, it was assessed with weight and membership degree. Based on composite index obtained by cumulative method, the fertility level of each assessment unit was determined. According to evaluation data of fertility level, we analyzed the trends of soil organic matter, total nitrogen, available phosphorus, available potassium, and pH. Thereafter, the evaluation results of soil fertility were applied to formula fertilization, agricultural structure adjustment, and soil improvement.1. Report for soil fertility evaluation. The total land area of the county is1.1×106mu. Based on evaluation index system and method of land fertility at county levels, the lands were divided four grades:High-yield field (215275mu,19.57%), Medium field (531486mu,48.32%), Lower field (291068mu,26.46%) and Low-yielding field (62212mu,5.66%). According to evaluation index system at ministry level, however, there are only two divisions of land fertility. Of these, the High-yielding field are802400mu (72.95%), while Low-yielding field are297600mu (27.05%). Meanwhile, according to the evaluation results of soil fertility as well as analysis of major features and distribution in each arable land, the utilization and management recommendations were proposed.2. Temporal and Spatial Changing Characteristics and evaluation of Soil Nutrients. In our county, we carried out the project of formula fertilization by soil testing in2006. Soil nutrients in our county were experienced20years of evolution as compared to the general survey of soil since1990s. Accordingly, the cultivated soil properties had also changed. At the same time, each index of soil nutrient had great change. Also, it had a bit of difference in various soil type and soil nutrient in each village. Overall, soil nutrients were generally higher in plain area of the east part of Xuyi County than areas along the Huaihe River and Lake District of west part, and the lowest nutrients were existed in Southern mountain area.3. Soil fertility evaluation and soil improvement and its rational utilization. According to the evaluation results of soil fertility, the area of Lower and Low-yielding field in our county is about35.33×104mu, accounting for the total area of arable land of32.12%. As a result, soil fertility improvement needs to be enhanced. In the last several years, under the leadership of the government, we invested much effort and money in construction of cultivated lands and soil improvement, such as soil erosion control, agricultural infrastructure and ecological environment construction, and improvements in low-yielding fields. However, due to financial, technical and other reasons, there are still many problems. For example, investment is insufficient on land, fertilizer structure is irrational, and fertilizer use efficiency is low, and so on. With consideration of soil improvement, this paper mainly from comprehensive control of soil erosion, supporting infrastructure, combined with both manure and chemical fertilizers, strengthen the long-term monitoring of arable land soil conditions and so on to put forward some suggestions.4. Soil fertility evaluation and formula fertilization by soil testing. All kinds of data can be constantly updated and improved by soil testing, farmers’investigation and experiments and demonstrations, etc. Meanwhile, the data and documents of land management information system keep improving. Consequently, the use of this system can design a formulation, produce a fertilizer zoning map for each township and make a fertilizer recommendation tables for the whole County unit of each village.With the county’s soil fertility GIS-based evaluation, the dynamics of soil nutrient was analyzed, the assessing system on soil fertility level were rationally defined and applied in agricultural practices. It is also important with this evaluation to hold the concrete conditions of soil fertility in this county, ensure the development of agriculture, and realize the agricultural modernization and sustainable development.