生物炭对豫西丘陵区农田土壤团聚体稳定性及碳、氮分布的影响

为研究生物炭对豫西丘陵地区农田土壤团聚体分布、稳定性及其碳、氮在团聚体中分布的影响,进一步探明生物炭对丘陵区农田土壤结构和养分的长期作用效果。采用田间长期定位试验,生物炭用量为0(C0),20(C20),40(C40)t/hm~2 3个处理,研究生物炭施用5年后对土壤团聚体组成及稳定性的影响,探究土壤团聚体中有机碳和全氮分布特性。结果表明:施加20,40 t/hm~2生物炭可提高0—20,20—40 cm土层的机械性0.5 mm以上粒级和水稳性0.053 mm以上粒级团聚体含量。在0—20 cm土层中,C20和C40处理下0.25 mm的机械性团聚体(DR_(0.25))分别较对照增加3.78%和6.83%,0.25 mm水稳性团聚体(WR_(0.25))分别较对照增加31.0%和49.45%,土壤不稳定团粒指数(E_(LT))分别较对照降低4.30%和6.85%,土壤团聚体破坏率(PAD)分别较对照降低9.71%和14.77%,土壤团聚体平均质量直径(MWD)分别较对照增加28.44%和45.34%,几何平均直径(GMD)分别较对照增加32.04%和54.92%。各粒级的有机碳和全氮含量随生物炭施用量的增加而增加,有机碳和全氮含量都以0.25～0.053 mm粒级最高,且0—20 cm土层的有机碳和全氮含量高于20—40 cm土层的有机碳和全氮含量;随着生物炭施用量的增加,2,2～0.25,0.25～0.053 mm粒级团聚体有机碳和全氮贡献率随之增加,而0.053 mm粒级微团聚体有机碳和全氮贡献率随之降低。总体来说,生物炭能够改善豫西丘陵地区农田土壤的团聚体结构,增加土壤大团聚体的含量,增强团聚体的稳定性,提高土壤团聚体中碳、氮含量,有利于豫西地区农田土壤肥力的保持和持续健康发展。

Effects of Biochar Application on Soil Aggregates Stability and Organic Carbon and Total Nitrogen Distribution in the Hilly Area of Western Henan Province, China

In order to investigate the effects of biochar application on soil aggregates stability, organic carbon, and total nitrogen distribution, further elucidate the long-term effective mechanism of biochar addition on farmland in the hilly area of western Henan Province, China, a 5-years field experiment was conducted to explore the effects of biochar application(0 (C0), 20 (C20), 40 (C40) t/hm²) on soil aggregates composition and stability, and illustrated the distribution characteristics of organic carbon and total nitrogen in soil aggregates. The results showed that biochar application with 20 and 40 t/hm² increased the contents of > 0.5 mm mechanical and > 0.053 mm water stable aggregates. In the 0-20 cm soil layer, compared with the control, C20 and C40 treatments increased the >0.25 mm mechanical aggregate (DR_0.25) by 3.78% and 6.83%, increased >0.25 mm aggregate water stability (WR_0.25) by 31.0% and 49.45%, decreased unstable soil aggregate index (E_LT) by 4.30% and 6.85%, decreased proportion of soil aggregate destruction (PAD) by 9.71% and 14.77%, increased the mean weight diameter (MWD) of soil aggregates by 28.44% and 45.34%, and increased the geometric mean diameter (GMD) significantly by 32.04% and 54.92%. The content of organic carbon and total nitrogen increased with the increase of biochar application rates in each size fraction, was the highest in 0.25~0.053 mm aggregate. The contents of organic carbon and total nitrogen in 0-20 cm soil layer was higher than that in the 20-40 cm soil layer. With the increase of biochar application amounts, the contribution rates of organic carbon and total nitrogen increased at >2, 2~0.25 and 0.25~0.053 mm aggregates, and the contribution rates of organic carbon and total nitrogen decreased at <0.053 mm aggregate. In general, biochar improved the soil aggregate structure, increased the content and stability of soil macro-aggregate, and increased the contents of organic carbon and total nitrogen in each size fraction, which was beneficial to maintain the soil fertility and the long-term healthy development of farmland in the hilly area of western Henan Province.