Soil Nutrients Change And Yield Response To N、P And K Fertilization On Jingdong Chestnuts

Jingdong chestnuts are mainly produced in Yanshan Mountain characterized with soils from Archaeozoic, Proterozoic and Cenozoic. In general, Chinese chestnuts are planted in hills or terrace dominated by brown soils, and the parent materials of soils are the residual sediments of granite and gneiss. In recent years, the area of Chinese chestnut is being gradually increased. However, with the gradual replacement of old varieties by new varieties, the un-scientific fertilization become an issue, which has resulted in many problems such as excessive tree growth, high empty rate of Chestnut shuck, reduced yield and quality. Therefore, balanced fertilization for chestnut production is highly needed. In this study, the current soil nutrients and their changes during the last 30 years(since second soil census) under different topography conditions were systematically evaluated; meanwhile, in situ experiment on the yield responses of Jingdong chestnut to nitrogen, phosphorus and potassium fertilizers were carried out according to the main influencing factors such as physiognomy, soil parent material, geologic time, cultivation and fertilization behavior in the research area. This will play an important role in improving the production of Jingdong chestnut in Yanshan Mountain. The main results are in below:1. During the last 30 years, the greatest increase of soil nutrients was found in Basin and followed by platform and then low hill.2. Analysis on the current status of nutrients in Jingdong chestnuts area shows that: soil organic matter(SOM), total nitrogen(TN), Olsen-P and available K was 10.66-19.45 g/kg, 0.76-0.93g/kg, 8.38-22.10mg/kg, 73.09-128.36mg/kg. From 1982 to 2012, the SOM, TN, Olsen-P and available K were increased with 0.66-2.25g/kg, 0.14-0.25g/kg, 11.95-21.59mg/kg, 6.05~60.34 mg/kg, respectively. It also indicated that soils used for chestnut production over one hundred years usually have lower nutrient contents than those of newly established chestnut areas.3. Application of NPK fertilizers significantly increased chestnut yields, where N fertilization increased the yield mainly through increasing Chestnut shuck number per plant and number of grain per Chestnut shuck, and for P fertilization mainly through reducing empty chestnut shuck rate, and for K mainly by increasing the number of chestnut shuck and fresh weight per Chestnut. Relative contrition to yields of N, P and K fertilizations is in an order of N, K> P. No significant impact of organic and chemical fertilizers on chestnut yields was observed when they have same amounts of N, P2O5 and K2 O. Results also indicated that the topdressing of a certain amount of K2 O can clearly increase Chestnut shuck number, fresh weight per Chestnut and reduce empty chestnut shuck rate.4. N,P and K nutrients of the aboveground organizations being distributed: If the N, P and K uptakes of chestnut tree was 100%,the N, P and K uptakes of chestnut trunk accounted for 47.6%, 59.2%, 55.8% of their total uptakes in 6-year-old chestnut trees; the N, P, and K uptakes of chestnut leaf accounted for 22.6%, 26.7%, 14.4%; the N, P, and K uptakes of chestnut shuck accounted for18.3%, 4.7%, 12.7%;the N, P, and K uptakes of chestnut fruit(chestnut seed and chestnut shell) accounted for 11.5%, 9.4%, 17.1% and chestnut seed accounted for 10.3%, 9.0%, 16.4% of their totals, respectively.5. The requirements of one hundred kilograms economic chestnut yield for nitrogen, phosphorus, potassium are estimated to be 3.85 kg, 0.58 kg, 1.11 kg respectively, where about 58.9%, 31.5%, 31.8% of these nutrients are within the chestnut shuck, 41.1%, 68.5%, 68.2% of these nutrients are within the chestnut(chestnut seed and chestnut shell) and 38.0%, 65.6%, 66.8% of these nutrients are within the chestnut seed. The total nitrogen, phosphorus and potassium comtent of chestnut shuck was1.05%, 0.042%, 0.14%; chestnut seed was1.73%, 0.24%, 0.52% and chestnut shesll was 0.73%, 0.034%, 0.081%.6. When the application rates of N, P and K were all 54 kg/hm2,with these nutrients surplus were observed for these nutrients, it is thus recommended that slightly less application rate in comparison with above values should be adopted in Yanshan Mountain.