Abstract:

In order to improve soil structure and enhance soil fertility in the black soil area， the long-term positioning experiment in the black soil area was used as the research platform to study the effects of the combination of biochar and nitrogen fertilizer on soil aggregate and organic carbon content， and to explore the maximum influencing factors. 3 biochar levels of 10 （C1）， 20 （C2） and 50 g·kg^-1 （C3） were set， and 3 nitrogen fertilizer levels of 0 （N0）， 300 （N1） and 600 kg·hm^-2 （N2） were set. The results showed， compared with CK， the soil bulk density decreased by 2.73%~8.20%， and the soil water content increased by 1.04%~31.24%， with no significant difference among all treatments. The combination application of biochar and nitrogen promoted the transformation of <0.053 mm aggregate to ≥2 mm aggregate. The aggregate stability was significantly improved， and the aggregate mass ratio （R_0.25）， mean weight diameter （MWD） and geometric mean diameter （GMD） of soil ≥0.25 mm increased by 25.06%， 21.71% and 12.50%， respectively. The organic carbon content of all grain grades of aggregates increased， and the organic carbon content of aggregates ≥2 mm and <0.053 mm increased significantly， with the increases of 13.19%~54.42% and 13.78%~41.34%， respectively. Principal component analysis （PCA） showed that R_0.25 was the key factor affecting soil organic carbon content， and C2N1 treatment was the best application measure to improve the structure of black soil. Above research results provided a theoretical basis for curbing the degradation of black soil in northeast China and improving soil fertility.

Key words: biochar, nitrogen fertilizer, black soil, aggregate, organic carbon content

摘要：

为改善黑土区土壤结构、提高土壤肥力，以黑土区长期定位试验为研究平台，以不施生物炭和氮肥为对照（CK），设置10（C1）、20（C2）和50 g·kg^-1（C3）3个生物炭水平和0（N0）、300（N1）和600 kg·hm^-2（N2）3个氮肥水平，研究生物炭-氮肥配施对土壤团聚体和有机碳含量的影响，并探讨其最大影响因子。结果表明，与CK相比，生物炭-氮肥配施使土壤容重降低2.73%~8.20%，土壤含水量增加1.04%~31.24%，各处理间差异不显著。生物炭-氮肥配施促进了<0.053 mm团聚体向≥2 mm团聚体的转化；团聚体稳定性显著提高，≥0.25 mm土壤团聚体质量比（R_0.25）、平均重量直径（mean weigh diameter，MWD）和几何平均直径（geometric mean diameter，GMD）的增幅分别为25.06%、21.71%和12.50%；各粒级团聚体的有机碳含量均增加，其中≥2 mm团聚体和<0.053 mm团聚体的有机碳含量显著增加，增幅分别为13.19%~54.42%和13.78%~41.34%。主成分分析表明，R_0.25是影响土壤有机碳含量的关键因子，C2N1处理是改良黑土结构的最佳配施处理。以上研究结果为遏制东北地区黑土退化、提升地力提供了理论依据。

关键词: 生物炭, 氮肥, 黑土, 团聚体, 有机碳含量