Study On The Current Situation Of Organic Matter And Total Nitrogen In Cultivated Soil And Its Affecting Factors In Baojing County Of Western Hunan Province

Soil organic matter was an important index of soil fertility, was crop nutrient, especially the main source of nitrogen nutrient, and soil nitrogen exists mainly in soil organic matter. Therefore, there was a close relationship between soil organic matter and nitrogen. In addition, soil organic matter was also the principal factor affecting soil structure, tilth, function of water the fertilizer and so on. Accurately estimating soil organic matter and nitrogen current situation, affecting factors and controlling technics has key practial significance to soil fertility maintaining, ecological environment management as well as sustainable developments of agriculture. In this paper, the study on the current status of soil organic matter and nitrogen in Baojing Country of western Hunan Province and its influence factors were conducted, using the mathematical statistics and the principal component analysis method, based on reference from soil testing and fertilizer project national agricultural ministry in2006. The main results were as follows:1. The content of SOM in cultivated land of Baojing county was intermediate level and the content of nitrogen was high-level. The content of SOM and nitrogen of cultivated land in the northern and southern regions was higher level, howerver, it was low level in central-west regions.2. SOM and total N content of all subgroup paddy soil was low and that of gleyed paddy soil was highest-level, reaching26.99g/kg. The average Total N content of wterlogged paddy soil was highest-level, reaching1.71g/kg. Among thirteen sub-groups of lime soil, Content SOM and Total N in leaching limestone red soil was was lower than average values of other soil. The SOM and total N content of different type of sub-groups soil increasing with the altitude decreasing.3. Accounting for27.68%of the total area of cultivated land. In paddy field, only the content of SOM and total N in wterlogged paddy soil and typical yellow were higher than the average value of whole county and having a lower varying level. In dryland Soil, SOM content of five type of sub-groups soil such as dark-yellow-brown soil, yellow soil, rendzina and typical yellow soil and limestone red loam soil was higher than the county average value., the varying level was lower except the dark yellow brown soi. 4. The content of SOM and total N which belong the soil of the three sub-classes Were higher than the county average. Development of residual material formed by the acidic mudstone sub-categories of soil organic matter and total nitrogen content was lower. Among them, only the typical yellow soil organic matter, slightly higher than the county average5. Different soil texture of the cultivated land and total nitrogen content of soil organic matter also has certain change rule:Namely with soil particles thinner or become sticky soil texture and total nitrogen content heavy organic matter is gradually increasing potential.6. Soil0～15cm soil organic matter and total nitrogen content is slightly higher than that of15～30cm of bottom layer of soil organic matter and total nitrogen content. Each subclass soil0～15cm soil total nitrogen average values were higher than those ofl5-30cm soil layer soil nitrogen average value.7. The flooded sterile paddy soil sub-categories of barriers are irrigation of improved soil organic matter and total nitrogen content was low lever. Barren fertility of the soil in the four sub-class soil yellowish brown, typical yellow soil Yellowish brown and typical yellow earth soil organic matter content is high, respectively to reach33.08g/kg and33.31g/kg. The typical yellow soil total nitrogen content is also very high, reaching2.01g/kg. Sloping ladder modified barrier types in different types of soil organic matter and total nitrogen content was the highest dark yellow brown soil, reached34.41g/kg and3.19g/kg.8.Based on PC A, this thesis has extracted the main factors of soil organic matter and nitrogen contents. The argument, the index of profile configuration has closely influence to or soil ganic matter, Secondary influence factors for irrigation level. Factors such as the quality of a material of content of soil organic matter exists certain effect. The index ofOrganic matter content and profile has closely influence to soil organic matter, The secondary influencing factors of irrigation level and quality, again level factors influencing soil parent materials and soil thickness.9. Analysis shows that through the same point the level of the principal component score. Reasonable farming, improve the soil profile construct, improve farmland soil irrigation and drainage measures, rational fertilization measures to strengthen farmland fertilizer management. So that the the Baojing soil organic matter and total nitrogen content to a reasonable level, improve the quality of soil fertility, and promote farmers increase production.