通过树脂芯原位培养试验,分析水分因素对塔里木绿洲荒漠过渡带3种不同植被覆盖度(LCD:0~0.2;MCD:0.2~0.4;HCD:0.4~0.6)土壤矿质氮含量影响及氮矿化速率变化。结果表明,水分对土壤氮矿化作用有明显影响,土壤净氮矿化速率与土壤水分有明显相关性,3种植被覆盖度类型的剖面水分变化和净氮矿化速率呈正相关,相关系数LCD是0.866 9(P〈0.01),MCD是0.647 9(P〈0.05),HCD是0.594 0(P〈0.05);测定周期内绿洲荒漠过渡带土壤平均净氮矿化速率,LCD为0.334kg/(hm2·d),MCD为1.010kg/(hm2·d),HCD为0.998kg/(hm2·d);该区域土壤水分变化是影响氮矿化的主要因素之一,说明在极端干旱条件下,水分控制氮矿化作用,但随植被覆盖度递增土壤含水量增加,水分因素对土壤氮矿化作用逐渐递减。
The effects of moisture factor on soil mineral nitrogen content and nitrogen mineralization rate under 3different vegetation coverage(LCD:0~0.2;MCD:0.2~0.4;HCD:0.4~0.6)in oasis-desert ecotone in Tarim Basin were studied in an incubation experiment by using resin-core technique.The major results showed that soil moisture had the obvious effect on soil nitrogen mineralization,and there was significant correlation between soil moisture and soil net nitrogen mineralization rate.Moisture variation of soil profiles under 3different vegetation coverage had positive correlation with soil net nitrogen mineralization rate,and the correlation coefficient was 0.866 9in LCD treatment(P〈0.01),0.647 9in MCD treatment(P〈0.05)and0.594 0in HCD treatment(P〈0.05).Soil average net nitrogen mineralization rate in a cycle in oasis-desert ecotone was determined,which was 0.334kg/(hm2·d),1.010kg/(hm2·d)and 0.998kg/(hm2·d)in treatments of LCD,MCD and HCD,respectively.Therefore,soil moisture change in this region is one of important factors influencing nitrogen mineralization.Under extreme drought condition,soil moisture controls the nitrogen mineralization,but with the gradual increase of vegetation coverage and the increase of soil moisture content,the effects of moisture factors on soil nitrogen mineralization decreases gradually.