Improvement Of Soil Nutrient Management By Using Information Technology

Soil nutrient management with information technology is an important part of information agriculture. Compared with developed countries, China is far behind in terms of information technology use in soil nutrient management. Development of different approaches to meet the needs of site-specific nutrient management for the small scale operation under family responsibility system in China, is a great challenge in China. Rapid development of information technology provides an opportunity to improve soil nutrient management by using the advanced information technology. In this study, two villages (Ershilipu of Xinzhou city (northern experimental site) and Nanma of Linfen city (southern experimental site)) were selected as two experimental sites to represent the two major cropping systems and two major soil types in Shanxi province. The research objective are 1) to establish a spatial database to document and analyze soil nutrient status and its distribution; 2) to develop a management system for site-specific soil nutrient management in the selected sites under the family responsibility system; 3)to validate the applicability and effectiveness of the developed soil nutrient management system. Main results and new progress were summarized as following:1, Basic information and result of farmers fertilizer use surveyThere are significant differences between the two experimental sites in cropping system, cropping pattern, the rate of fertilizer applied as well as farmer's decision-making. Nitrogen and phosphate fertilizers were commonly applied in two experimental sites, potassium and micro-nutrient fertilizer was not commonly used, and the ratio of nitrogen and phosphate fertilizers applied was irrational. There is no scientific basis for farmer's fertilizer decision-making. As far as average rate of applied fertilizer was concerned, the difference of nitrogen fertilizer applied was not obvious between the two experimental sites. Average N application rate at the northern site (199.8kg N/ha) was slightly higher than that at southern site (182.0kg N/ha), but the variation of N application rates at southern site (49.6% ) was slightly greater than that at the northern site (43.1%); The rate of phosphate fertilizer applied at southern site (143.7kg P₂O₅/ha) was higher than that at the northern site (120.6kg P₂O₅/ha), but the variation in P₂O₅ application rates at the southern site (43.2%) was less than that at the northern site (69.7%). The ratio of N and P₂O₅ applied at the southern site slightly higher than that at the northern site.The average farmer's cultivated area and plot numbers managed were different in two experimental villages. The statistic results of farmer's land showed that average plot area of southern site was relative bigger than that at the northern site. The average plot area of southern site was 0.244±0.212 ha, and 0.107±0.050 ha at the northern site. But crop structure was relative complex at the southern site, some crops such as grain, vegetable, oil and cash crops were planted. Crop structure was relativelysimple for northern site, maize was main crop, but management unit was relative small. The results showed that there exist great difficulties in soil nutrient management at these villages with small scale operation. It would be helpful to understand profoundly farmer's fertilization status and soil nutrient status through mapping farmer's plot managed with information technology.2. Evaluation of soil nutrient statusAvailable nutrient contents of surface soil samples from two experimental villages were determined using the systematic approaches for soil nutrient evaluation. The results showed that soil properties of two experimental villages varied greatly and did not always belong to normal distribution, and some soil properties belonged to log-normal distribution. Soil organic matter, soil available K, Cu and Zn belonged to log-normal distribution at the southern experimental site, and OM, P, Cu, Mn, Zn at the northern experimental village. The results also indicated that the average content of soil organic matter and soil available N (NH4+-N), P, K, Mg, Cu, Mn, and Zn in the southern experimental village were higher than those in northern experimental village. But available Ca, S, B and Fe, were higher in the northern experimental village than those in the southern experimental village. These results were related to cropping system, soil type, soil texture, as well as fertilization practice. Based on soil nutrient status evaluation and higher yield limited factor analysis, nutrient factors managed were determined in two experimental villages. Soil available N, P, K and Zn were main nutrient management factors for southern site, and N, P, K, Zn and Mn for northern experimental village.3. Soil nutrient spatial variabilityThere existed spatial variability of soil properties in the two experimental villages. Nitrogen, P and OM had a greater variability, which were mainly affected by agricultural fertilization measures. On the contrary, Ca, Mg, K, Cu, Fe and Mn had a smaller spatial variability due to little input as fertilizer. Soil properties all had semi-variance structure, and model best fit included spherical, linear and exponential. Semi-variance model was not always consistent for one nutrient. Some soil properties had same semi-variance model at the two experimental sites, for example, Mg, P, S, and Cu belonged to linear model; K, Fe belonged to exponential model. Though some nutrients had same model, there still existed a difference in the limit distance of spatial correlation as well as the extent of soil spatial variability. In two experimental villages, there existed stronger spatial correlation for Ca, N and Mn, medium spatial correlation for K, P, and S. The semi-variance structure of other properties was not consistent. These indicated that there existed some difference in cropping system, soil type, soil texture and fertilization.4. Soil nutrient spatial distributionSoil nutrient contour map was made using Kriging interpolation technique for soil properties in the two experimental villages. The contour map of soil properties may directly reflect the spatial distribution characteristic of diversified soil nutrient element; also help to understand the nutrient status to provide the foundation to rational fertilization. The integrated map was conducted with overlaying the nutrient contour map and farmer's plot map to understand soil nutrient status of each farmer's plot. With that site-specific nutrient management based on farmer's plot or fanners' plot specific nutrient management, can be realized with advanced information technology.5 Study on fertilization parameters of main cropsRational parameters for fertilizer recommendation were important for site-specific nutrient management. A series of fertilizer experiments were conducted to fulfill this purpose based on understanding soil nutrient status, soil nutrient spatial variability and soil nutrient spatial distribution of two experimental villages. The rational and economic rates of fertilizer applied were obtained for main crops of the two experimental villages, including winter wheat, summer maize, soybean, sunflower, spring maize and so on. At same time, the fertilizer contribution to grain yield of crops and fertilizer use efficiency was studied. Main results were summarized as following: 1) Applying only of N and P fertilizer on winter wheat would lead to the depletion of soil potassium, and soil potassium was depleted by 99.7kg K/ha annually. Applying K fertilizer (150kg K2O/ha) and straw return to soil would help to increase wheat yield by 19.8%. At the same time, soil potassium fertility was maintained. 2) Applying all kinds of fertilizer required, especially potassium on diversified crops helped increasing yield by 17.1%²5.7%, and increasing net return by 3974-9904 yuan/ha in southern experimental site. At same time, the uptake for N, P and K were increased to help to improve nutrient use efficiency due to balanced fertilization. 3) The relation between spring maize yield or net return and different rates of N, P, and K fertilizer applied were best fit quadratic equation in northern experimental village. For maximum yield, the rates of N, P and K fertilizer applied was 206²25kg N/ha, 150kg P2O5/ha and 200kg K2O/ha, respectively. 4) The contribution of N, P and K fertilizer applied to crop yield affected by soil fertility level. The contribution ratio of N, P and K fertilizer were relative higher under middle and low yield condition than that under high yield level. 5) The contribution of soil N, P and K nutrient to crop yield decreased year after year, and N, P, K fertilizer use efficiency had an increasing tendency under the condition of continuously treatment of no N, P and K application.These results above provided reliable parameters for fertilization model based on GIS, provided technical guarantee to fulfill site-specific nutrient management, and further provided important foundation for balanced fertilization, which based on management unit of farmer's field.6 Establishing soil nutrient management system based on integrating fertilization model and GISSoil nutrient management information system was established and exploited based on GIS with the first...