施肥方式对稻麦轮作土壤团聚体分布的影响

土壤是人类赖以生存的重要资源,团聚体作为土壤结构的基础单元,不仅提高土壤肥力、调节养分的生物有效性,而且增强土壤抗侵蚀能力。通过6年试验,研究了不施肥(CK)、常规施肥(CF)、秸秆+缓释肥(SRF)和有机无机混施(OCF)4种施肥方式对土壤养分含量及各粒级团聚体分布的影响,为揭示施肥措施对土壤地力形成演变的影响机制提供理论基础。结果表明:SRF和OCF处理0—20,20—40 cm土层土壤的SOC含量较CF显著增加10.06%,19.23%和9.84%,16.79%;3种施肥处理0—20,20—40 cm土层的TN差异不显著,但均高于CK处理;OCF处理中0—20 cm土层的C/N比较CF增加16.44%(p0.05)。SRF处理较CK显著提高了0—20 cm土层R_(0.25)(10.93%);20—40 cm土层,OCF处理中R_(0.25)显著高于其他3个处理,分别高出32.62%(CK),19.75%(CF),19.44%(SRF)(p0.05)。相比CF处理,SRF和OCF提高了0—20,20—40 cm土层的平均质量直径MWD(1.54%～16.92%,2.17%～28.26%)和平均几何直径GMD(5.88%～14.71%,13.04%～39.13%),降低了分形维数D(1.11%～2.09%,4.99%～5.44%),且OCF处理更为显著(p0.05)。可见,秸秆+缓释肥和有机无机混施处理均有利于土壤肥力提升,且后者效果更为显著。MWD和GMD与土壤SOC和TN的相关性较高,均适合用于揭示团聚体与土壤总有机碳、总氮含量之间的关系;但分形维数D与之无显著相关性关系。

Effects of Fertilization Patterns on Soil Aggregates Distribution in Rice-wheat Rotation Systems

Soil is an important resource for human survival. Soil aggregate, as the basic unit of soil structure, can not only improve soil fertility, regulate the bioavailability of nutrients, nut also, but nutrients also enhance soil anti-erosion ability. In this research, four fertilization patterns were applied in a rice-wheat rotation system at Shanghai Zhuanghang long-term positioning test station for six years, which were non-fertilization (CK), conventional inorganic fertilization (CF), straw returning to field with slow release fertilizer (SRF), and mixed organic fertilizer with chemical fertilizer treatment (OCF). It provides a theoretical basis for revealing the influence mechanism of fertilization methods on the formation and evolution of soil fertility. SRF and OCF increased the SOC contents in 0-20 cm and 20-40 cm soil by 10.06%, 19.23% and 9.84%, 16.79%, respectively. OCF also increased the level of C/N in 0-20 cm (16.44%). There was no significant difference in TN contents in both 0-20 cm and 20-40 cm soil layers under CF, SRF, and OCF. But they were all higher than that of CK. Compared with CK, SRF significantly improved R_0.25 in 0-20 cm soil layer by 10.93%. OCF increased the R_0.25 in 20-40 cm, compared with the other three treatments (32.62% CK, 19.75% CF, 19.44% SRF) (p<0.05). Compared with CF, SRF and OCF increased MWD (1.54%~16.92%, 2.17%~28.26%) and GMD (5.88%~14.71%, 13.04%~39.13%), decreased D (1.11%~2.09%,4.99%~5.44%) in the 0-20 cm and 20-40 cm soil layers, with the more prominent effect for OCF (p<0.05). In conclusion, both SRF and OCF were beneficial to soil fertility improvement, and effect of OCF was more significant. The correlations between MWD and GMD and soil SOC and TN were significant, which, therefore, were suitable for revealing the relationships between aggregation and the soil nutrient contents. However, there was no significant correlation between soil nutrients and D.