秸秆腐解过程中土壤热值与有机养分动态

研究玉米秸秆在3种长期试验地(葡萄园、桃园、农田)腐解过程中土壤热值和养分动态变化情况,为秸秆资源的合理利用和土壤培肥提供科学依据。于2011年10月至2012年10月在陕西杨凌进行,采用尼龙网袋法进行玉米秸秆腐解试验,定期取样测定秸秆的腐解残留率,研究紧贴尼龙网袋土壤的热值及其养分变化。结果表明:随着腐解时间的增加,秸秆在0～270d腐解迅速,残留率基本为50%左右,在270～360d腐解速度减慢,最终玉米秸秆在农田、桃园、葡萄园的腐解残留率分别为41.73%、36.11%、46.14%。3个试验地对秸秆腐解过程中土壤热值的影响差异不显著。土壤温度与秸秆腐解的残留率变化呈极显著负相关,影响秸秆在土壤中的腐解速度。整个腐解期间,除了秸秆腐解过程中土壤有机碳的变化不大,农田土壤pH基本不变,果园土壤pH下降了2.06%～2.32%;农田和桃园土壤速效磷分别增加了14.2%和67.5%,而葡萄园土壤速效磷降低了26.9%;农田、桃园和葡萄园的土壤速效钾分别增加了49.9%,43.0%和89.2%。3个试验地土壤易氧化有机碳、稳定性有机碳和碱解氮质量分数之间差异不显著。秸秆腐解在前、中期降解较快,后期趋缓。土壤温度、易氧化有机碳、稳定性有机碳、速效钾影响玉米秸秆在土壤中的腐解速度。果园土壤的有机碳和速效钾质量分数极显著高于农田土壤,说明生草可以提高果园土壤的部分养分质量分数,提高秸秆还田效果,农田土壤在秸秆还田时可调控因素比果园土壤多。可见,植物秸秆在腐解过程中会不同程度影响土壤养分质量分数的变化,提高部分有效养分质量分数,对土壤肥力和质量的提升起到一定的作用。

Dynamics of Soil Thermal Analysis and Organic Nutrients during Straw Decomposition

Study on maize straws decomposition and the changes of soil nutrient and heat value in the fields of three long-term field experiments (vineyard,peach orchard,farmland) ,can provide a scientific basis for the rational use of straw resources and soil fertility improvement. The field experiment was initiated in October 2011 and ended in October 2012 at Yangling town in Shaanxi province. Nylon mesh bag method was used to test maize straw decomposition,and changes of nutrients and heat values of the soils surrounding with the nylon mesh bag. The results showed that with increasing time of decomposing,maize straw decomposed rapidly in 0-270 d,residue rate was around 50%.In 270-360 d decomposing slowed down,ultimately decomposing maize residual rate were 41.73%,36.11%, 46.14% in the farmland,peach orchard,vineyard respectively. There were no significant differences on soil heat values in 3 fields during the process of straw decomposition. There was a significantly negative correlation between straw residual rate and soil temperature. During decomposition,in addition to the little changes of soil organic carbon,soil pH in farmland almost did not change,while soil pH in orchard decreased 2.06%-2.32%; soil available phosphorus in farmland and peach orchard increased by 14.2% and 67.5%,while soil available phosphorus in the vineyard decreased 26.9%; soil readily available potassium in farmland,peach orchard and vineyards increased by 49.9%,43.0% and 89.2%. The differences of soil easily-oxidized organic carbon,stable organic carbon and alkalytic N were not significant. Straw degraded rapidly before the mid-term and slow down in the later. Soil temperature,easily-oxidized organic carbon,stable organic carbon,soil readily available K affected decomposition rate of maize straw in the soil. Organic carbon and soil readily available K in orchard soil was significantly higher than farmland soil,indicating that straw mulching could improve the nutrient content of orchard soil and straw mulching effect. There were more regulatory factors in farmland soil than in orchard soil when straw was returned to field. Decomposition of plant stalks in the process of change would affect different levels of soil nutrient content,which could improve partially effective nutrient content and play a role in increasing soil fertility and quality.