Investigation On Situation Of Fertilizer Application And Monitoring Of Soil Fertility In Farmland In Shaanxi Province

Although fertilization investigation has its disadvantages such as limitation to some extent and unaccuracy, it can supply enough information from macroscope, and the information is generally much more than that from the level of a given field. Carrying out fertilization investigation of crops and monitoring fluctuations of soil nutrients in farmland, can supplies very useful materirals for macro-management of nutrient resources in Shaanxi province, and it also can give some information for policy-making of fertilizer and macro-agriculture, therefore, this work is very important. In this study, the literature combining actual investigation for fertilization and measurement of soil nutrients, studying issues fron micro and macro aspects, and evaluating the situation of nutrient resources use and change of soil nutrients in farmland in Shaanxi province, and the results obtained is as follows:(1) The data investigated on soil and fertilization based on household's levels during 1986 to 2000 in Shaanxi province was analyzed and calculated, and the use of organic manures and chemical fertilizers as well as nutrient balance situation in farmland was evaluated, and according to optimized fertilization program, the fertilization situation of the major crops was evaluated and analyzed. The results showed that, in general, the input of nitrogen fertilizer has already excessive, and the input of phosphorus and potassium fertilizers are generally rational, but there existed big difference among in different ecological regions, and in the future the input of organic manure should be paid much attention.(2) In the meantime, the above data was used to analyze the distributions of fertilizers in the whole province in six ecological regions (Great Wall Wind-sand Region, North Shaan Hilly-Gully Region, Weibei Rain-fed Upland Region, Guangzhong Irrigation Region, Qinba Mountain Region and South Shaanxi Plain Region) and among different crops. The results indicated that, the economic value, practical experiences and habits, and economic development level were important factors that influence input of organic manures. Therefore, the distribution of organic manure has obvious regional characteristics;there existed big difference for distribution of fertilizers among the crops, and organic manure and fertilizers had the same principles for the distribution between crops, the fertilizers were mainly used in planting of wheat and maize, secondly they were also largely used in apples trees;the farmers in Shaanxi province has had very good habit in using organic manure, and organic manure had been very important source of field nutrients. And potassium fertilizer was mainly used incash crops such as apples, and the amount used in other crops was very little, and in the future the potassium balance in farmland should be taken into account and measures should be taken to maintain the balance of potassium in the farmland.(3) The investigation study on the fertilization situation of cucumber and tomato crops grown in nine cities such as Weinan city, Xianyang city etc was conducted. The results showed that, the farmers investigated commonly pay much attention the use organic manure, the phenomena of excessive or poor use of nitrogen and phosphorus fertilizers existed, and little use or no application of potassium fertilizer was serious. Among them, the excessive application of N and P fertilizers occupied by 17.0% and 23.3%, and the percentages of poor fertilization occupied by 31.5% and 33.6%, little and no application of K fertilizer was 52.2%;and the medium and micronutrients fertilizer were largely neglected, the households that no medium and micro-nutrients fertilizers occupied by 67%. Through analyzing the fertilization rates and combination situation of every households, it was found that the proportions of households whose fertilization was rational and less than 15%, that is to say, more than 80% households fertilized inadequately.(4) The soil organic matter content (SOM) in agricultural soils showed very clear regional characteristics, the content of SOM is very low in Great Wall Wind-sand Region and North Shaan Hilly-Gully Region, and it lies in middle level in Weibei Rain-fed Upland Region and Guangzhong Irrigation Region, and the content of SOM is relatively high in Qinba Mountain Region and South Shaanxi Plain Region. And the content of SOM maintains basically stable during 1994 to 2002. The total nitrogen and available nitrogen also indicates clearly regional distribution principles, namely, the content increases from north Shaanxi to south;in North Shaanxi area soil available phosphorus content increased sharply in recent years, in Guanzhong Plain Region and South Shaanxi Area the soil available phosphorus maintains high level during a long time, soil available potassium content showed the increase tendency year by year, it is highest in Weibei Dryland Plateau and Guanzhong Plain Area, and its content in Qinba Mountainous Area and South Shaanxi Valley Region lies in the middle area. It is worth mentioning that, in the whole province range, soil available potassium content did not decrease obviously, however, it is still necessary that to strengthen monitoring of the balance of excess or deficit in farmland soil.