紫花苜蓿对建筑复垦土壤的改良效果

Effect of Alfalfa on Improving Soil in Constructed Reclamation Land

在建筑复垦地上种植紫花苜蓿,连续5年进行土壤分层（0-10cm、10-20cm、20-30cm）取样,通过土壤理化性质的测定与分析,研究种植紫花苜蓿对建筑复垦土壤生物改土效果和土壤碳固存效应。结果表明：土壤全量养分在种植苜蓿后出现不同程度的增加,种植第二年表层土壤全氮含量达0.73g/kg,高于种植前43.1%,且表层0~10cm全氮含量最高,全磷含量0~10cm层在种植第三年显著增加（P〈0.05）,全钾在种植苜蓿期间差异不显著。速效养分中碱解氮含量随苜蓿种植年限的增加而增加,而速效钾和磷含量呈先增加后降低的趋势,且二者分别在第三年和第二年达到高峰期;土壤有机碳含量和碳密度均在种植苜蓿第四年显著增加（P〈0.05）,其中表层增幅最大,分别增加68.0%（有机碳）和59.3%（有机碳密度）;表层土壤大颗粒趋于细化,小于0.01mm的土壤颗粒没有明显变化,种植紫花苜蓿四到五年可以显著改善复垦地的土壤理化性质以及提高土壤碳库储量。

The experiment was conducted to study the soil physical and chemical properties and soil or-ganic carbon sequestration efficiency of different planting alfalfa years through sampling the soil in 0-10cm,10-20cm,20-30cm layers in August 2007-201 1 in order to know about the soil improvement effect and soil organic carbon sequestration efficiency of planting alfalfa on constructed reclamation land. The re-sults indicated that：The soil total nutrients were improved differently after alfalfa plantation,the total ni-trogen content was up to 0.73 g/kg which was more 43.1% than that before planting alfalfa,and it was the highest in the surface in 0-10cm soil layer. The total phosphorus content in 0-10cm layer was increased significantly in the third year of alfalfa plantation（P〈0.05）. The soil total potassium content was not sig-nificantly different during alfalfa plantation（P〉0.05）. The Alkali solution nitrogen content increased with the increase of planting alfalfa time,but the available phosphorus and potassium increased firstly and then decreased with the increase of planting alfalfa time,and they reached the peak in the third year and second year of alfalfa plantation separately. Soil organic carbon and carbon density were increased significantly in the fourth year of alfalfa plantation（P〈0.05 ）,the highest increase was in the surface layer which were separately increased by 68% （organic carbon）and 59.29% （carbon density）.The soil faction in surface tended to be fine and soil particles that was less than 0.01 mm had no changed after alfalfa plantation. Therefore,planting alfalfa for 3-4 years on reclamation land can improve the soil physical and chemical properties and improve the soil carbon sequestration efficiency to achieve the effect of soil improvement.