Variations of soil organic matter in typical orchard regions

Eleven sampling regions were selected in the Loess Plateau, Jiaodong Peninsular and Beijing suburbs, and based on orchard age, the orchards in each sampling region were devided into three groups of 5~10, 10~15 and >15 years. 99 soil samples in the 0~20 cm layer in orchards and 33 samples in the 0~20 cm layer in nearby croplands were collected. Quantitative attributes of topsoil organic matter in orchard fields, differences in soil organic matter property between the orchard and cropland, and variations in soil organic matter among different orchard age groups were statistically analyzed. The results show higher soil organic matter content in Xixia, Jiaodong Peninsular, and Beijing suburb; and lower in Baota in the Losse Plateau. Compared with croplands, over 60% orchards exhibit statistically insignificant variation in soil organic matter. In less than 30% orchard fields, soil organic matter significant increase, averagely by 0.62%; and significant decrease in less than 10% orchards, averagely by 0.20%. Significant changes in topsoil organic matter content with the orchard age are observed only in two sampling regions. In high yield and high quilty fruit-producing areas, soil organic matter is enhanced by organic fertilizer application, growing grass in orchard, returning grass or stalk into orchard soil. On the whole, soil organic matter in orchard field is not high and varies greatly. Sustainable development capacity of the fruit production is also weak.