麦秸分解及其对土壤氮素有效转化的影响动态

模拟密山地区白浆土麦秸伏季还田后经三个月的变温培养分解,CO_2总释放量占麦秸有机碳量的25—34％,氮和磷肥能显著促进其分解。三个月中,麦秸固定土壤无机氮可达8.41—12.91mg/100g土,为施入麦秸原重量的0.56—0.86％;与此同时,伴随着土壤6NHCl水解氮的增加(13.3—29.1mg/100g土)。在三个月中,虽然未观察到固定氮的净矿化现象,但固定总量将逐渐下降,故土壤无机氮含量逐渐回升,如果在最适分解条件下经三个月分解的玉米秸,所释放的无机氮可达36—41mg/100g土,占施入氮量的70.6—82.0％。

The Wheat Stem Calabolism and its Effects on the Effective Transform if Nitrogen in Soil

The decomposed process of wheat stem which was cultured under changed temperatures during three monthes after returned to the field in Mish-an area was simulated. The total release size of CO was about 25%-34% of organic carbon contained in wheat stem. The N and P fertilizer could promote the resolving of the stem. Within three monthes, the fixed soil inorganic N by the decomposing of wheat stem was about 8.41-12.9lmg/100g soil that was 0.56-0.86% of the original wheat stem weight. Meanwhile, the 6N CHI hydrolytic N was increased (13.3-29.1 mg/100g soil) .Although the net mineralization of fixed N was not found within three monthes, the total amount fixed was descended gradually and so the inorganic N amount in soil was increased by degrees. Comparatively, the amount of inorganic N released by corn stem which was decomposed under most suitable condition for three monthes would be 36-41mg/100g soil that was 70.6%-82.0% of total fertilized to the soil.