间作对土壤团聚体有机碳储量的影响及其氮调控效应

基于5年的田间小区定位试验,采用干筛法对不同施氮水平下的玉米单作、马铃薯单作和玉米马铃薯间作土壤进行团聚体分级并测定各粒级团聚体有机碳含量,研究间作对土壤团聚体有机碳储量的影响及其氮调控效应。结果表明:92%以上的土壤有机碳储藏在土壤大颗粒团聚体(2 mm)和小颗粒团聚体(2～0.25 mm)中。间作提高了土壤大颗粒团聚体(2 mm)和小颗粒团聚体(2～0.25 mm)的比例,但对不同粒级团聚体有机碳含量的影响与施氮量相关。对比2种单作,间作在低氮(N1)和常规施氮(N2)下增加了土壤总有机碳储量,在不施氮(N0)和高氮(N3)下无显著影响或降低有机碳储量。其中,间作通过增加土壤大颗粒团聚体(2 mm)的比例及其有机碳含量,在低氮(N1)时产生最强的间作固碳优势,土壤总有机碳储量分别较玉米单作和马铃薯单作提高24.8%和5.7%。因此,适量施用氮肥可以充分发挥间作效应,有效提高土壤有机碳储量。

Effects of Intercropping on Soil Aggregate-associated Organic Carbon Storage and Nitrogen Regulation

Aimed to study the effect of intercropping on soil organic carbon storage and its nitrogen regulation effect, soil samples were collected from a 5-year field plot located experiment with maize monoculture, potato monoculture and maize and potato intercropping under different nitrogen application levels. Soil aggregates were graded by dry sieve method, and organic carbon content of aggregate in each size fraction was determined. The results showed that more than 92% of soil organic carbon was reserved in soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm). Intercropping increased the mass proportion of soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm), but the effect of intercropping on organic carbon contents of soil aggregates was related to nitrogen application. Compared with the two monocultures, intercropping under low nitrogen (N1) and conventional nitrogen (N2) application increased total organic carbon reserves of soil, but did not significantly affect or reduce the organic carbon reserves under no nitrogen (N0) and high nitrogen (N3) application. Among them, intercropping produced the strongest intercropping carbon sequestration advantage at low nitrogen (N1) by increasing the mass proportion of soil macro-aggregates (>2 mm) and their organic carbon contents, where the total organic carbon reserves of soil were 24.8% and 5.7% higher than those of maize monoculture and potato monoculture respectively. Therefore, proper application rates of nitrogen fertilizer could give full play to intercropping effect and effectively increase soil organic carbon reserves.