Research Of Decomposition And Nurient Release Of White Choye(trifolium Repens) Litter In Apple Orchard

It was conducted to disclose the nutrient release dynamic during the decomposition ofthe main planted-grass white clove (Trifolium repens) in apple orchard of Guanzhong Area.We put the white clover leaves and stems in the nylon bags and respectively buried them inthe different depths of the orchard soil:0cm (left on the ground),7.5cm,15cm,22.5cm and30cm on May3,2011. The decomposition of0cm treatment was lowest but it was popular inpractice, and that of the treatment15cm was quicker. So, to compare the effect of thebeginning time of composition on the nutrient release, the nylon bags with the grass wereburied in the soil0cm and15cm deep on August3,2011. The contents of the organic matter,the total nitrogen(N), the total phosphorus(P), the total kalium(K), the soluble sugar, the crudefiber of the residuals were respectively analyzed on the30d,60d,90d,150d and210d afterthe bury. To learn the effect of the released nutrients on the soil fertility, we cut the whiteclover and put it with15cm thick in the ditch in the ridged apple orchard in August. And theorganic matter content, the soluble and total contents of the nitrogen(N), the phosphorus(P),the kalium(K) of the0～5cm soil were analyzed on the30d,60d and90d of thedecomposition. The0～5cm soil in the same ditch without the grass cover was taken as thecontrol. The results showed:1In the decomposition of white clover, there was a rapid decrease of the dry matter andthe nutrients in the30days. Then the decrease rate became slow. The dry matter, the organicmatter, the soluble sugar, the total nitrogen(N)，the total phosphorus(P), the total kalium(K)respectively decomposed40～55%,90%,70%,90%,40～57%,50～83%in the30days. Inthe next days, the fastest rates of30days were no more than25%, and even bellow1%forsome nutrient.2The decomposition rate of the dry matter and the nutrient release of0cm were slowerthan that of the buried white clover. Among the5treatments, the grass buried in the22.5cmsoil decomposed quickest, and that of15cm was followed. Interestingly, the treatment30cmdecomposed slowlier than22.5cm and similar to7.5cm.3The decomposition beginning time influenced the decomposition and the nutrientrelease of the white clover. The effect was related to the kind of the nutrients, thedecomposition days, and the input ways of white clover to the apple orchard: covering or bury. The total nitrogen (N) and the organic carbon of the grass decomposed from May3weredecreased faster than that from August3, but for the total kalium (K) and the soluble sugar, itconversed. For the grass covered on the ground, the dry matter of treatments in Maydecreased faster than that in August as the degradation days increased, but for the grass buriedin the soil15cm deep, there was an opposite trend. The total phosphorus (P) of the whiteclover covered on the ground in May released faster than that in August in the90early days,and that of the grass buried in the soil15cm deep in May decreased faster than in August inthe30early days, but it conversed in the following days, respectively.4The soil fertility especially the soluble nutrients increased after the decomposition ofwhite grass placed in the ditch in the ridged apple orchard. And as the degradation went on,the increase of the nutrients became slower. The trend was consistent with the decompositionand nutrient release dynamic of the white clover. In detail, in the90early days, the solublenitrogen (N)， the soluble phosphorus(P) and the soluble kalium(K) of the treatmentrespectively increased242.4%,272.7%and132.06%while the organic matter, the totalnitrogen (N), the total phosphorus(P), the total kalium(K) of that went up74.17%,34.88%,4.18%,51.43%than the control under the white grass0～5cm depth in the soil.