改良剂对复垦土壤团聚体组成及有机碳含量的影响

Effects of Amendment on Aggregates Composition and Organic Carbon Content in Reclaimed Soil

为探究改良剂对复垦土壤团聚体组成及有机碳含量的影响,采用田间微区的方法按表层0—20 cm土壤重量占比1%,3%,5%的比例添加泥炭、腐殖酸和蛭石,研究3种改良剂对复垦土壤团聚体组成、总有机碳、各粒级团聚体有机碳含量、土壤红外光谱特征的影响。结果表明:施用3种改良剂后各处理土壤机械稳定性团聚体均以>5 mm的最多,施用泥炭和腐殖酸后>5 mm团聚体含量随着改良剂施用比例的升高而增大,且MWD(平均质量直径)值均高于CK。其中,5%腐殖酸对调控>5 mm团聚体含量效果最佳,在6个月时>5 mm机械稳定性团聚体占比达到60.03%。而施用蛭石后>5 mm机械稳定性团聚体的占比与CK相比有所下降。施用3种改良剂后土壤水稳性团聚体以<0.053 mm团聚体含量最高,但其含量均随改良剂施用比例的升高而降低。泥炭和腐殖酸能够提高复垦土壤总有机碳的含量,增强抗侵蚀能力和团聚体的稳定性,而施用蛭石后有机碳含量减少。泥碳、腐殖酸和蛭石各处理下各粒级机械稳定性团聚体有机碳含量均以>5 mm最高,0.053~0.25 mm次之,<0.053 mm最少,有机碳含量贡献率也以>5 mm团聚体的最大,泥炭和腐殖酸处理下>5 mm团聚体有机碳含量贡献率均高于50%,<0.053 mm团聚体有机碳贡献率仅有0.63%~2.82%。从土壤的红外光谱特征峰可以看出,施用腐殖酸能够增加土壤中的多糖类物质,而多糖类物质有大量的—OH,能与黏粒矿物晶面上的氧原子形成氢键而把土粒团聚起来。

In this study,a series of field microfield experiments were set to explore the effect of amendments on aggregates composition and organic carbon distribution in reclaimed soil.Peat,humic acid and vermiculite as amendments were added to the soil(0-20 cm)at the weight ratios of 1%,3%and 5%.Soil aggregates composition,total organic carbon,organic carbon distribution in each fraction aggregates,soil infrared spectrum characteristics were analyzed.The results showed that soil mainly composed by>5 mm mechanical stabilized aggregates,and the content of>5 mm aggregates increased with the increase of the proportion of peat and humic acid application in all treatment,and the MWD in all treatments were higher than CK.The effect of 5%humic acid application was the best for improving the content of>5 mm mechanical stabilized aggregates,and the proportion of>5 mm mechanical stabilized aggregates reached to 60.03%in the sixth month.However,compared with CK,the proportion of>5 mm mechanical stabilized aggregates decreased after vermiculite was used.After the application of amendments,soil mainly composed by<0.053 mm water stabilized aggregates,but its content all decreased with the increasing amounts of amendments.Peat and humic acid could increase the content of total organic carbon and the resistance to erosion and the stability of aggregates for reclaimed soil.However,the organic carbon content decreased after vermiculite was used.For all peat,humic acid and vermiculite treatments,the content of organic carbon in>5 mm aggregates were the highest,followed by 0.053~0.25 mm aggregates,and the content of organic carbon in<0.053 mm aggregates were the lowest.The organic carbon contribution in>5 mm aggregates were the highest.The organic carbon contribution rate of>5 mm aggregates were higher than 50%.The organic carbon contribution rate of<0.053 mm aggregates were the lowest,and accounted for 0.63%~2.82%in all of peat and humic acid treatments.The soil infrared spectroscopy characteristic showed that humic acid increased the content of polysaccharides in soil.There were many hydroxyl in polysaccharides and they could form hydrogen bonds with the oxygen atoms on the crystal surface of clay minerals,which can agglomerate the soil particles.