Decomposition characteristics of rapeseed and wheat straw under different water regimes and straw incorporating models

摘要

In order to study the decomposition characteristics and nutrient release patterns of rapeseed and wheat straw, wheat (Triticum aestivum L.cv.) and rapeseed (Brassica napus) straws were all wrapped in net nylon bags and put on the soil surface or buried into the soil under different water regimes and straw mulching models in 2007 and 2008 growth seasons, respectively, to study the decomposition characteristics and nutrient release patterns of rapeseed and wheat straw. The results showed that the decomposition rate of straw was faster within the first 30 days and then slowed down until the end of the experiment. Under water-saving cultivation model, the decomposition rate of straw buried into soil was high up to 61.06% after 90 days. The cumulative decomposition rates of wheat and rapeseed straw were 48.88-59.95% and 50.88-61.06%, respectively. Under conventional cultivation model, the straws that were mulched decomposed faster than those incorporated into the soil did. For straw mulching, there wasno significant difference on decomposition rates between the two cultivation models. When buried into the soil, the straw under water-saving cultivation model decomposed faster than under the conventional cultivation model. The sequence of nutrient release rates was K>P>N~C. Release rates of wheat and rapeseed straw for C were up to 48.29-63.79% and 50.29-66.55%, for N 48.35-52.83% and 46.48-57.67%, for P 54.83-67.49% and56.44-75.64% and for K 91.98-95.99% and 92.31-96.24% after 90 days decomposition, respectively. The effect of cultivation model and incorporation method on N, P and C release patterns was similar and K release rate was more than 90% after 30 days decomposition. It indicated that on the basis of straw mulching, the water-saving cultivation model can increase straw decomposition and release of nutrients. At the same time, it also can preventthe loss of nutrients from the soil, prevent pollution and make the best use of water.