稻草与生石灰添加介导的温室内土壤团聚体稳定性及碳分布特性

土壤中稳定的团聚体为碳的固定提供良好的物理保护,同时土壤中的碳又会促进团粒结构的形成,二者相辅相成,但在长期稻草和生石灰添加介导的设施内土壤中二者如何变化,却少见报导。以长期施肥定位试验为依托,采用湿筛法研究了施用鸡粪(M)的基础上,配施稻草(R)和生石灰(Ca)对设施土壤团聚体组成、稳定性及碳分布的影响,以不施肥(CK)为对照。结果表明:(1)在鸡粪基础上加入稻草(MR)或生石灰(MCa),与单施鸡粪(M)相比,0.25mm团聚体含量分别增加了123%和37%;稻草和生石灰同时添加可显著增加5~2mm大团聚体含量,较MR、MCa、M分别提高12%,59%,141%。(2)在鸡粪基础上施入稻草或生石灰均可增加MWD、GMD、R_(0.25),提高团聚体的稳定性,其中MR处理最高,MRCa处理次之,二者均显著高于MCa、M、CK处理。(3)在鸡粪基础上加入稻草或生石灰,均可提高土壤全碳含量,其中MRCa处理最高,较MR、MCa、M分别增加20%,40%,55%;稻草和生石灰同时施入可显著增加5~2mm大团聚体中碳含量;加入生石灰可增加0.5~0.25mm团聚体中碳含量;施入稻草或生石灰均可显著增加0.25mm团聚体中的碳对土壤全碳的贡献。(4)土壤全碳含量与5~2,2~1,1~0.5mm团聚体含量呈显著正相关,与0.25mm微团聚体含量呈显著负相关;MWD、GMD、R_(0.25)均与0.25mm团聚体含量呈显著正相关,与0.25mm微团聚体含量呈显著负相关。设施土壤在施入鸡粪的基础上同时加入稻草和生石灰,可改善土壤结构,提高土壤碳水平,有利于缓解设施生产中因长期连作所导致的土壤结构劣变问题。

Soil Aggregation and Total Carbon Distribution in Soil Amended with Straw and Lime of Greenhouse

The stability of soil aggregates provide physical protection for soil carbon, while soil carbon promotes the formation of soil aggregates. To evaluate the effects of long-term straw and quicklime application on soil aggregates stability and total carbon (TC) accumulation at aggregate, soils from plots amended with M (chicken manure), MR (chicken manure + straw), MCa (chicken manure + quicklime), MRCa (chicken manure + straw + quicklime) were collected compared with CK (no-fertilizer). Soil was separated into five size fractions (5~2, 2~1, 1~0.5, 0.5~0.25, < 0.25 mm) by wet-sieving. The results showed as follows:(1) Straw return or liming increased the distribution of > 0.25 mm size fractions, MR and MCa caused 123% and 37% increase relative to the M, respectively; while application of straw and quicklime together had a significant effect on the distribution of 5~2 mm size fraction, compared with MR, MCa and M, the MRCa caused 12%, 59% and 141% increase, respectively. (2) Application of straw and quicklime could increase the MWD, GMD and R_0.25. MR treatment had the highest MWD, GMD and R_0.25, followed by the MRCa treatment, MR and MRCa were significantly higher than those of MCa, M and CK. (3) Addition of straw and quicklime could increase the TC content, compared with MR, MCa and M, MRCa caused 20%, 40% and 55% increase, respectively; straw return and liming significantly increased the TC content of 5~2 mm size fraction; liming could increase the TC content of 0.5~0.25 mm size fraction; both straw and lime could significantly increase the contribution of TC in the >0.25 mm size fractions to the bulk soil TC. (4) TC content was positively correlated with the distribution of 5~2, 2~1, 1~0.5 mm size fractions, and negatively correlated with the distribution of < 0.25 mm size fraction. MWD, GMD and R_0.25 were positively correlated with the distribution of > 0.25 mm size fractions, and negatively correlated with the distribution of < 0.25 mm size fraction. Therefore, straw return and liming could improve the soil structure and carbon level. These findings were beneficial to alleviate the problem of soil structural fission caused by long-term continuous cropping in the agricultural production of greenhouse.