Nutrients In Orchard And Response Of Kiwifruit To Fertilizer On The Northern Slope Of Qinling

Kiwifruit is one of the main fruit crops grown on the northern piedmont of QinlingMountain in Shaanxi, where is the suitable area for kiwifruit in China. Kiwifruit has graduallybecome one of pillar agricultural industry in the region. But in practice, excessive applicationof fertilizers in the kiwifruit orchards is very common; and it results in a series of problems,which affects the quality and yields of kiwifruit. It also increases the cost of production. Theaccumulated nitrogen（N）in the orchard soil is high. At the same time, rainfall in this regionis sufficient. It increases the risk of leaching loss. Therefore, how to control and reduce theproblem caused by unreasonable fertilization is an important scientific topic. It is helpful todecrease the agricultural no-point source pollution caused by nutrients loss.Therefore, in this research, we had chosen the Yujia River catchment, Zhouzhi county,located at the foot of the northern piedmont of Qinling Mountain as research region, to surveythe fertilization status through field investigation in2012and2013, and to analyze nutrientsin leaf and soil at the same time. A field fertilizer trail was carried out to study the effects ofdifferent fertilizer treatments on soil nutrient, yield and quality in kiwifruit orchard. The mainconclusion are as following:（1）An investigation in271kiwifruit orchards was conducted in2012and2013toevaluate the status of fertilization. We found that only two-thirds of orchards in the regionused manure fertilizer. The average application rates of nitrogen （N）, phosphorus （P2O5）,and potassium（K2O）fertilizer was893kg hm-2,388kg hm-2and556kg hm-2, respectively. Itindicates that excessive application of fertilizers in kiwifruit orchards was very common.（2）The soil samples at the depths of0-20cm and20-40cm soil layer from88kiwifruitorchards were collected and determined. The results indicated that the average soil pH at the0-20and20-40cm soil layer was7.63, and7.78, respectively；and it belongs to weakalkaline. The average soil organic matter content in0-20and20-40cm soil layer was17.23gkg-1,12.05g kg-1, respectively; it fell in the lower level. So was the average soil total nitrogen,it was1.19g kg-1,1.81g kg-1. The average soil mineral nitrogen was also very low. However,the average content of soil available phosphorus was86mg kg-1,51mg kg-1in the two soillayers; and for the soil available potassium, it was360mg kg-1,239mg kg-1, respectively; they were both extremely high. We suggest local farmers to continue to use different organicfertilizers, and to reduce application rates of phosphate and potassium fertilizers in theirorchards.（3）The different nutrients in leaves of144kiwifruit orchards in2012and2013wereanalysized. We found that the main cultivar in this research region was "Qinmei", and thesecond was "Yate". Yield was significantly negative correlation with leaf area and freshweight. There was not significant correlation between yield and leaf nutrients of kiwifruit. Itindicates that there are more factors that limits the fruit yields of kiwifruit tree. Based on ourresults, we formulated kiwifruit leaf nutrient diagnosis standard on the northern piedmont ofQinling Mountain. We divided the nutrients in leaves into5ranks: i.e., deficiency, low,suitable, high and excessive. We found that leaf nutrients of N, P and K in most of theorchards were suitable; and more than10%of orchards have excessive N and P nutrients inleaf.（4）The field experiment of fertilizer showed that when the application rate of Nfertilizer was reduced by25%of the local conventional N fertilizer application rate, it has notsignificantly effect on yield and the quality of kiwifruit. However, compared with the localconventional application of N fertilizer treatment, the reduced N fertilizer treatment reduced182kg hm-2mineral nitrogen accumulation in0-2m soil profile. The treatment of controlledreleased N fertilizer reduced mineral nitrogen accumulation in0-2m soil by485kg hm-2.Compares with the ordinary N fertilizer, the controlled releases N fertilizer reduced nitrogenaccumulation in0-2m soil by303kg hm-2. It indicates that reducing N fertilizer applicationrate and using controlled releases N fertilizer has a positive role in reducing the undergroundwater pollution caused by nitrogen leaching.