土壤有机碳与土壤质量和全球气候变化关系极为密切,为探明河西绿洲灌漠土农田土壤有机碳库的变化规律,以1982年设置在西北干旱区的长期定位试验为基础,研究了长期施肥对土壤有机碳库及水稳性团聚体的影响。研究结果表明,与1982年起始值相比,无论是化肥单施或配合施用,耕作层土壤(0 ~ 20 cm)有机碳储量都年均降低160 kg hm~(-2)。施用有机肥,年均投入有机碳2342 kg hm~(-2),不但可完全抵消土壤有机碳降低的趋势,而且以年均260 kg hm~(-2)的速度递增。27年连续施用有机肥可增加土壤有机碳和全氮储量7015 kg hm~(-2)和1298 kg hm~(-2),相当于有机肥中有机碳和全氮输入量的31%和25%。因此维持或提高河西绿洲灌漠土有机碳储量,年最少有机碳投入量为516 kg hm~(-2)。长期施用有机肥显著增加了土壤大水稳性团聚体(> 0.25 mm)的数量和有机碳在大水稳性团聚体中分配比例,进而增强了有机肥中有机碳的土壤固存率。
英文摘要:
Soil organic carbon is closely related to soil quality and global climate change. In order to clarify the change regulation of irrigated desert soil organic carbon stock in Hexi oasis, an investigation was carried out to study the influence of fertilization on soil organic carbon stock and soil aggregate through the long-term fertilization experiment that was established on irrigated desert soil at arid region of Northwest China in 1982. The results showed that compared with the initial value of soil organic carbon stock in 1982, no matter chemical fertilizers applied either alone or combined, soil organic carbon stock annually decreased by 160 kg hm~ (-2) in tillage layer (0 ~ 20 cm) . However, organic manure addition at the amount of 2342 kg hm~ (-2) every year could offset the downward trend, and soil organic carbon stock annually increased at the rate of 260 kg hm~ (-2) . Compared with the initial value in 1982, soil organic carbon and total nitrogen stocks increased by 7015 kg hm~ (-2) and 1298 kg hm~ (-2) respectively after 27 years continuous application of organic manure, which were equal to 31% organic carbon and 25% total nitrogen in organic manure carried into soil. Therefore, to maintain or promote irrigated desert soil organic carbon stock in Hexi oasis, the least input amount of the organic carbon was 516 kg hm~ (-2) every year. Long-term application of organic manure significantly increased the quantities of soil macro water-stable aggregates (> 0.25 mm) and the proportion of soil organic carbon distributed in macro water-stable aggregates, and then promoted the soil organic carbon sequestration ratio.