Soil Nutrition Characters Of Apple Orchard In Different Eclogical Regions On Loess Plateau

Loess Plateau, with high quantity and quality of apple orchard, is the largest and the most productive apple production base in China. However, farmers have overused fertilization, or even excessively in the persuit of high yield, not only did which lead to some economic losses but deceased the quality of apples as well. In this study, based on the the data from field investigation at the different age apple orchards located in different places (Fengxiang, Baishui, Changwu, Yanan, Jingning, Xifeng) and labortary experiment quantative study has been conducted by applying methods such as typical mutistatistical analysis, Soil Nutrition Index(SNI) method, information entropy method etc to clarify the soil nutrition variance among the different orchards for providing usful scintific basis for rational fertilization and efficient managment in apple orchard of Loess plateau. The main results are in the following:The soil nutrition content of different apple orchard in loess plateau vary significantly from one another.The orders of average nutrition content which each sampling site has posses are as follow:total Nitrogen (TN) content, Baishui> ChangWu> Xifeng>Fengxiang> Jingning> Yan’an; available phosphorus content, Baishui> Fengxiang> ChangWu> Xifeng> Jingning> Yan’an; total phosphorus(TP) content, Changwu> Jingning> Xifeng> Yan’an> Fengxiang> Baishui; total potassium(Tk) content, Fengxiang>Changwu> Xifeng> Jingning>Yan’an> Baishui; available phosphorous content, ChangWu> Xifeng> Baishui> Jingning> Fengxiang> Yan’an; organic matter (OM) content, Jingning> Yan’an> Baishui> Xifeng> ChangWu> Fengxiang. There are significant differences between different age orchard soil nutrient content of each investigation site. While the maximum or optimum fertility levels often occur in the flourishing orchard (mature orchard), the nutritions the young or the aging one has are relatively low. There are some similarity and also differences among the correlation between the various soil nutrition indicators of different apple orchard. While there is significant positive correlation betwwen some nutrients indicators, some others has significantly negative correlated. Besides, some relationships between indicators did not reach the significant level, relatively independent. Thus interaction between the various nutrition elements shouled be considered to improve the soil fertility and to increase production.The amount of soil nutrient contents within0-300cm soil profile in different age groups of the apple orchard is very uneven, volatility is more obvious, especially potassium, total potassium, available phosphorus. There is essentially no significant accumulation of TK in the whole soil profile probably due to potassium rich loess parent materials. TN, available potassium is decreasing with the increase of the soil depth, table clustering effect is obvious. OM content most of which accumulated at the bottom distribution over the entire profile layer is relatively even, the gap is not big. The variation magnitude which is decreasing and being more stablized after80-120cm layer of each nutrient in the0-120cm layer is relatively significant. There is no obvious relationships between the various of nutrient elements with increasing soil depth and changes in ages of apple trees. Different apple orchard soil nutrients have great volatility in the vertical distribution but with a certain similarity. Soil TN and available potassium significan amount of which are accumulated in the surface layer of the soil is volatily decreases as deepening of soil depth. While the gaps of OM and available phosphorus between the sampling sites are a bit obvious, basically there is no significant accumulation of TK and TP distribution of which is relatively even in the soil profile. Although all the nutrition elements changes drastically in0-80cm profile, variation curves starts be smooth from80cm, and gradually tends to be tabilized.The varioation of SNI in the soil vertical profile can roughly be divided into two stages, namely soil fertility level decreased rapidly from the surface layer to80-120cm profile and then starts to increase with volatility. While the overal soil fertility, which is accumulated at the top of the soil may due to using fertilizer of local passents, of Fengxiang, Changwu, Xifeng and Jingning fluctuated dramatically as deppening of soil. There are certain differences between overal soil fertility level of all the sampling sites, orders are in the following:Baishui> Changwu> Yan’an> Fengxiang> Xifeng> Jingning. Changwu and Baishui have the moset fertilized soil with higher SNI of>0.5, Fengxiang, Xifeng, Yan’an and Jingning, however, low fertilized soil SNI of which were less than0.45. There is a certain relationship betwwen ages of apple trees and the soil fertility level of apple orchard in that aging or young orchard has less fertilized soil than that of the orchard healthy mature trees.