Soil fertility, leaf nutrients and their relationship in kiwifruit orchards of China’s central Shaanxi province

Understanding soil fertility and leaf nutrients provides the basis for optimizing fertilization for fruit crop production. However, for central Shaanxi province of China, the largest kiwifruit-producing region in the world, limited information is available on soil fertility and leaf nutrients of these orchards. Here, we assessed 17 soil fertility parameters and 12 leaf elements for 116 kiwifruit orchards in central Shaanxi. The investigated region included five locations: Zhouzhi, Mei, Yangling, Wugong and Qishan. The soils in this region had an average pH of 7.54 and exchangeable Ca of 5.68 g/kg, indicating that the soils were calcareous. Over a quarter of the orchards were deficient in soil organic matter. Although over 50% of the soils were excessive in NO3–-N and over 25% both deficient and excessive in P and K, more than 65.0% of the orchards were deficient in leaf N, P and K, implying the low NPK use efficiency in central Shaanxi. Moreover, Cl and Zn deficiencies as well as Cu and Ca excesses were found in both soil and leaf diagnosis. Analysis of variance showed that, among the study locations, Zhouzhi was characterized by low soil pH, low soil/leaf Ca and high soil/leaf N, whereas Wugong was featured by high soil/leaf Na. Correlation analysis indicated that soil pH positively correlated with soil Ca, and both parameters negatively correlated with soil N, P, Fe, Mn, Cu and Cl (P < 0.01). Additionally, soil N, Ca, Mn and Cl positively correlated with the corresponding leaf elements (P < 0.001). These results could be used to guide the sustainable nutrient management of kiwifruit production in central Shaanxi