Studies On N Absorption,Allocation And Green Manures Decomposition Regularity In Green Manure-apple Intercropping System

From2012to2013, the experiments were conducted on four frequently used orchard green manure (Perennial ryegrass, Alfalfa, Tall fescue, Chicory) and potted two-year-old apple variety Gala in the National Research Center for Apple Engineering and Technology and Horticulture Research Station of Shandong Agricultural University. The15N absorption, utilization and distribution were preliminarily characterized in two-year potted apple tree intercropped with different green manure crops, and the dynamics of four green manures decaying and nutrition releasing in orchard soil were also exploratoryly expounded in virtue of the nylon mesh bag method. The main results were as follows:1. It was showed that N absorption capacity of green manure was significantly higher than that of apple tree at the early stage of the growth. The Ndff value of the underground part of four green manures and apple tree was around3%, but the absorption of the aboveground of four green manures was significantly higher than that of apple tree. Along with the growth of green manure, the ratio of absorption of green manure to15N was significantly increased. So the Ndff value of apple tree was significantly higher than that of green manure after August10. In terms of green manure itself, the Ndff value of the aboveground was higher than that of the underground. The absorption ability of Perennial ryegrass and Chicory was higher than that of Alfalfa and Tall fescue.2. It was shown that total nitrogen utilization was rated as T1>T2>T4>T3>CK. The15N utilization of apple tree was significantly different between different intercropping groups. It was on July10showed that the15N utilization of apple tree was scaled as CK>T1>T2>T4>T3, and the differences were significant between different treatments groups. The15N utilization of green manures was denoted as T2>T1>T4>T3, and the differences were significant between different treatment groups. As the growth proceeded, the15N utilization ratio of green manure and apple tree were increasing among different treatments, and the growth rates was different between treatment groups.15N utilization rate was the fastest under Chicory intercropping. Overall utilization was increased from5.57%on July10to22.06%on August10. It was suggested that the utilization ratio of15N of potted apple trees intercropped with green manure were decreased, while overall15N utilization was increased. 3. It was showed that15N allocation rate of green manure was gradually increased with the growth proceeding. On August10the allocation rate of green manures was up to50%except Tall fescue.4. It was shown that in the four kinds of green manure turned over in summer was decayed faster in the early but slower in the later. Green manures after turning over were decayed faster. By five days after turning over,58%of Chicory and49%of alfalfa had decayed with the rates of474mg/d and1126mg/d, respectively. Tall fescue was decayed slower and there was a decaying peak on20d after turning over. Decaying rates of four green manures were essentially unchanged within35d after turning over. The decaying quantities of Chicory, Alfalfa, Tall fescue and Perennial ryegrass were more than80%,70%,70%and63%, respectively.Green manures turned over in winter were decayed slower than in summer. The decomposition rate of4green manures was about20%within45d after turning over. The decomposing peak was appeared at90～110d after turning over. The decomposition rate was declined on120d, and since was unchanged. Decomposition rate of Chicory and Alfalfa were more than70%, but decomposition rate of Perennial ryegrass and Tall fescue were less than60%within110d after turning over. The decomposing rates of4green manures were about70%within180d after turning over.5. It was shown that the release of nitrogen was the fastest in the early and slower in the later when green manures were turned over in summer, and nitrogen was fastest released within15d after turning over. The release rates of Chicory and Alfalfa were higher than those of Perennial ryegrass and Tall fescue. The release rate became slower after15d, more than80%Chicory and Alfalfa released, and about70%Perennial ryegrass and Tall fescue were released. Nitrogen was slowly released within45d after turning over in winter, and showed no significant differences. Decomposition rate was accelerated on120d, then was released slower after180d and showed no significant differences.The release of P was similar to that of N. Decomposition rate of Chicory, Alfalfa and Perennial ryegrass was about50%, and Tall fescue was about24%in summer after turning over. Then the P releases of Chicory and Alfalfa were still the fastest, and decomposition rate was up to80%. Tall fescue and Perennial ryegrass had a period of slower release, and then faster release, decomposition rate was about80%on30d. The difference of decomposition rates of4green manures was no significant, reaching about70%on100d.It was shown that the release of K was faster in the early and slower in the later. Tall fescue had a steady phase within10～20d. The Ks in others were released faster and K had been completely released by10d. K was faster released within120d after turning over in winter, from then on it became stable. K was released more completely regardless of in summer or in winter. Decomposition rate of4green manures was up to95%.