Research on the characteristics of soil nutrients in a‘Korla fragrant pear'orchard with different ages for the trees

【Objective】Some features,such as low content of organic matter, coarse soil texture, and lowcontent of effective nutrients, are found to exist in the soil of the‘Korla fragrant pear'growing areas. Cou-pled with severe sandstorm disasters, soil depletion is common; the development of the‘Korla fragrantpear'growing industry is seriously affected by the fragile ecological environment and harsh natural condi-tions. Currently, some scientific and technical problems exist, which include: unknown factors in orchardsoil fertility, constraint factors in fertilization, outdated technology for fertilization and lack of a fertiliza-tion technique theoretical support system, in the production process of the‘Korla fragrant pear.'In orderto solve the low productivity of the‘Korla fragrant pear'orchards, maximize the use of land resources;and to increase the income of the orchard farmers, we must analyze and discuss the characteristics of soilnutrients in the‘Korla fragrant pear'orchards. Studies have been conducted on the evolution of soil fertil-ity and how to improve soil fertility, but researchers have concentrated more on the orchard soil nutrientstatus and the soil nutrients comparison with different varieties of orchards, while studies on the soil nutri-ent changes over time in a single fruit tree species orchard over different ages are rare. So we selected the‘Korla fragrant pear'as our research subject to determine the soil nutrients of the‘Korla fragrant pear'orchards over different ages, with the purpose of mastering the distribution characteristics of soil nutrientsin the‘Korla fragrant pear'orchard over different ages, and to understand the soil nutrient abundance sta-tus or lack of status as well as soil fertility obstacles.【Methods】We selected 100‘Korla fragrant pear'or-chards approximately equidistant in the‘Korla fragrant pear'planting areas of Ku'erle City. The ages ofthe trees for the‘Korla fragrant pear'orchards were different, ranging from 8 to 25 years. There were 13‘Korla fragrant pear'orchards with the ages of the trees ranging from 8 to 10 years, 29‘Korla fragrantpear'orchards with the ages of the trees ranging from 12 to 15 years, 45‘Korla fragrant pear'orchardswith the ages of the trees ranging from 16 to 20 years, and 13‘Korla fragrant pear'orchards with the agesof the trees ranging from 22 to 25 years. In early September 2012, by using GPS technology, we collected0-30 cm soil samples in the selected 100‘Korla fragrant pear'orchards, determined the contents of theorganic soil matter, available nutrients and micronutrients, and used the data processing system of Origin-Pro8 to analyze the data of the soil nutrients.【Results】The changes in the orchard soil nutrients are along and complicated process, and as important ecological factors, the soil nutrients are always co-devel-oped with the plants, and they always exhibit different characteristics in the different growing regions andunder various growing conditions. There are some differences between the soil nutrients of the‘Korla fra-grant pear'orchards with different ages of the trees. The variation coefficient of the organic soil mattercontent is between 26.48%-44.68% in the‘Korla fragrant pear'orchard with different ages of the treesegments, which represents a moderate variation. The variation coefficient of the alkaline hydrolysis Ncontent is between 13.50%-17.29%, which represents a weak variation. The variation coefficient of thesoil available P content is between 26.03%-37.43%, which represents a moderate variation. The varia-tion coefficient of the soil available K content is between 11.70%-34.13%, which represents a moderatevariation. The variation coefficient of the soil available Fe content is between 31.51%-86.22%, whichrepresents a strong variation. The variation coefficient of the soil available Mn content is between51.79%-62.43%, which represents a strong variation. The variation coefficient of the soil available Cucontent is between 41.55%-88.38%, which represents a strong variation. The variation coefficient of thesoil available Zn content is between 24.18%-42.21%, which represents a moderate variation. The con-tent of each soil nutrient index has shown an increasing trend in the‘Korla fragrant pear'orchards withthe increasing years of planting for the‘Korla fragrant pear', soil nutrients and yield of the‘Korla fra-grant pear'which are all significantly correlated with age of the trees for the‘Korla fragrant pear.'Thecontents of the organic soil matter, alkaline hydrolysis N, available Fe and Mn gradually increased with in-creasing the age of the trees for the‘Korla fragrant pear,'but the differences of organic soil matter con-tents and alkaline hydrolysis N contents gradually reduced among the different ages of the tree segments,and the differences of the available Fe and Mn contents were not significant. With increasing the ages ofthe trees for the‘Korla fragrant pear,'the contents of the available soil P and Zn first decreased, and thenincreased, but the differences of the available soil P and Zn contents were not significant among the differ-ent ages of the tree segments. With increasing the age sof the trees for the‘Korla fragrant pear,'the con-tents of available soil of K and Cu first increased, and then decreased, but the difference of the availablesoil for the K content was significant among the different ages of the tree segments, the difference of theavailable soil for the Cu content was not significant. The yield of the‘Korla fragrant pear'has shown anincrease- decrease- increasing trend with the increasing years of planting for the‘Korla fragrant pear,'the yield of the‘Korla fragrant pear'is the largest in the 22-25 ages of the tree segments, which is consis-tent with the high contents of the organic soil matter and alkaline hydrolysis N in the orchards with 22-25 ages of the trees.【Conclusion】The soil fertility of the‘Korla fragrant pear'orchard with different ages ofthe trees are generally at a low level, the contents of the organic soil matter, alkaline hydrolysis N, avail-able P and Cu are at average levels, the contents of the available K and Zn are at abundant levels, whilethe contents of the available Fe and Mn are at lacking levels. The contents of the organic matter and alka-line hydrolysis N are relatively deficient, and the contents of the available Fe and Mn are rather scarce,which are the main obstacles for soils in the‘Korla fragrant pear'orchards. Therefore, increasing theamount of organic fertilizer in the‘Korla fragrant pear'orchards, and implementing a formula fertilizationapproach, as well as applying the nitrogen, phosphorus, potassium and trace fertilizers reasonably, couldcontinuously cultivate the soil fertility of the‘Korla fragrant pear'orchards, improve the overall soil pro-ductivity, and achieve efficient use of the soil nutrient resources in the‘Korla fragrant pear'orchards andlead to sustainable production.