| Weibei Loess Plateau is recognized as the world’s best suitable area of apple. In this area, apple production has become one of the leading industries in Shaanxi Province. To achieve high yield and quality of apple and increasing the income of agriculture, rural areas and farmers, this study was systematic analysis fertilization condition of red Fuji apple orchard, soil nutrient status, leaf nutrient status, leaf nutrition diagnosis and balanced fertilization techniques in the Weibei Loess Plateau, through field investigation, laboratory test and fertilization experiment.The major achievement as follows:1. This study made an investigation on fertilization situation on Fuji apple in Weibei Loess Plateau, and found out the main problems in Fuji apple fertilization management. The Fuji apple orchards with N, P2O5, K2 O average fertilization amount were 774 kg/hm2, 542 kg/hm2, 366 kg/hm2. The average of N: P2O5: K2 O was 2.58:1.81: 1.22 and it did not conform to the recommended ratio of fertilization. The fertilization status of Fuji apple orchards in Weibei Loess Plateau was that the application N fertilizer was excess and P2O5, K2 O were insufficient. The main types of fertilization were chemical fertilizer. The use of organic fertilizer was ignored.2. The research raveled the status of soil nutrient content of Fuji apple orchard, and made an soil nutrient standards of Fuji apple orchard in Weibei Loess Platea. The soil mechanical composition of Fuji apple orchard was showed that the content of silt was largest and clay was least, except cultivated loessial soil. Using DRIS the orders of nutrient requirement of soil of Fuji apple orchard were made as follows:Skeletol soil SOM>Mn>K>Fe>Cu>Zn>P>N;Cinnamon soil Cu>Fe>SOM>Zn>K>Mn>P>N;Red soil K>SOM=Zn>N>Cu>P>Mn>Fe;Lou soil P>Cu>SOM>Fe>K>Mn>Zn>N;Dark loessial soil Fe>Cu>SOM=N>P>K>Mn>Zn;Huangshan soil N>SOM>K>P>Cu>Zn>Mn>Fe;Cultivated loessial soil K>P>SOM>Zn>Cu>Mn>Fe>N.A soil nutrient standard of Fuji apple orchard in Weibei Loess Platea was also made by DRIS. The Optimum ranges were SOM 9.55-17.67 g/kg, alkali-hydrolyzale N 70.05-110.51 mg/kg, available P 16.63-37.71 mg/kg, available K 208.83-434.63 mg/kg, available Fe 3.27-6.62 mg/kg, available Mn 4.64-13.52 mg/kg, available Cu 1.13-1.97 mg/kg, available Zn 1.07-2.38 mg/kg, respectively.3. The leaf nutrient status of Fuji apple was evaluated by DRIS, M-DRIS, DOP and CND, and the advantages and disadvantages were comparing of these methods. The research raveled the status of leaf nutrient content of Fuji apple, and made a leaf nutrient standard of Fuji apple in Weibei Loess Platea. The relationship between the mineral elements in apple leaves showed that the elements were very significant positive correlated: P-K, P-Ca, K-Ca, Mn-Zn, elements were significantly negative related were: K-Fe. DRIS, M-DRIS, DOP, CND for evaluating the nutrient status of apple leaf showed that the results of DRIS and M-DRIS were similar. The results of DOP and CND were little different from DRIS and M-DRIS. It was suggested that two methods should be chosen for diagnosis in order to get the accurate results. A leaf nutrient standard of Fuji apple in Weibei Loess Platea was also made by DRIS. The Optimum ranges were N 25.12-30.04 g/kg, P 1.9-2.86 g/kg, K 6.38-14.48 g/kg, Ca 9.33-19.78 g/kg, Mg 2.68-5.45 g/kg, Cu 5.23-20.00 mg/kg, Fe 134.26-319.5 mg/kg, Mn 60.3-124.26 mg/kg, Zn 14.87-43.26 mg/kg, respectively.4. The correlations between nutrients content of soil nutrients content and leaf nutrients content, soil nutrients content and fruit yield, leaf nutrients content and fruit yield, fertilization and fruit yield were researched. According to the research, there were quadratic regression relationships between apple yield and soil nutrients content, leaf nutrients content, fertilization. But relationship was significant between yield and leaf nutrients content more than yield and soil nutrients content. There were quadratic regression relationships between soil alkali-hydrolyzale N, available P, available Fe, available Cu, available Zn and leaf N, P, Cu, Fe, Zn. The regression relationships between soil available K, available Mn and leaf K, Mn were not significant.5. The ternary quadratic fertilizer effect function model about N, P, K fertilizer and apple yield was established by fertilization experiment. The best proportion of balanced fertilization of Fuji apple orchard was obtained. Single factor analysis showed that the apple yield were first increased and then decreased steadily with the increase of the N, P, and K application. The two factor interaction analysis indicated that there existed an Ⅱ area which was formed by the two ridges and axes. In this area, increasing fertilizer can promote the apple yield. The economic benefit analysis of model showed that fertilization can significantly increase the net income, the ratio of output to input and incremental investment of apple orchard. The best economic optimum ratio line of NP, NK, PK were obtained. R value was also obtained by the model, so the cost of different fertilization could be obtained, and thus farmer could choose less investment and high profit fertilization program. The optimal fertilization amounts calculated by the model were N 35.46-36.45 kg/667m2, P2O5 26.39-27.58 kg/667m2, K2 O 24.88-25.48 kg/667m2, and the best fertilizer ratio was N: P: K = 1.43: 1.06-1.08: 1, respectively. |
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