民勤青土湖区不同年限退耕地土壤水分和养分变化

(1.甘肃省治沙研究所, 甘肃省荒漠化与风沙灾害防治重点实验室, 甘肃 武威 733000; 2.甘肃省武威市石羊河林业总场, 甘肃 民勤 733399)

青土湖区; 退耕地; 土壤水分; 土壤养分

Soil Moisture and Nutrient Changes in Different Years of Abandoned Farmlands in Qingtu District
CHAI Chengwu1, WANG Lide1, WEI Qiushi1, WANG Fanglin1, WU Hao1, GUO Chunxiu1, CHEN Sihang1, XU Baoyi1, HE Fanglan1, MENG Cunhong2

(1.State Key Laboratory of Desertification Combating Prevention and Sandstorm Disaster of Gansu Province, Gansu Desert Control Research Institute, Wuwei, Gansu 733000, China; 2.Shiyanghe Forestry Headquarters in Wuwei of Gansu Province, Minqin, Gansu 733399, China)

Qingtu lake district; abandoned land area; soil moisture; soil nutrients

备注

以石羊河下游—民勤青土湖区不同年限退耕地为研究对象,利用时空替代法分析了该区不同恢复年限退耕地土壤水分与养分时间变异规律。结果 表明:(1)在退耕当年(CK),植被分布以一年生浅根性草本植物为主,但种类较为单一,此时土壤贮水量较高; 随着施肥活动的停止,退耕1~8 a,一年生及二年生草本植物逐渐恢复,对土壤水分的消耗量逐渐增大,此时土壤贮水量大幅度下降,以0—20 cm土层表现较为明显; 退耕13~20 a演替为以多年生小灌木黑果枸杞为优势种的单一植物群落,此时土壤水分含量逐渐回升; 退耕30~40 a时,多年生小灌木种类增加,对土壤水分的消耗量增大,土壤贮水量下降。(2)3种土壤养分的总体变化均表现为随退耕年限增加而减小并最终趋于稳定的趋势,在同一年限内均表现为0—20 cm土层中的含量大于20—40 cm,且同年内两层间的含量差异均虽退耕年限增加而逐渐减小,以土壤有机质和速效磷表现较明显; 整个退耕时间内土壤全氮含量变化幅度较小; 土壤速效磷含量在退耕当年(CK)的土壤表层0—20 cm含量最大,之后随退耕年限增加呈波动式下降趋势,并最终趋于稳定; 土壤有机质含量在CK至退耕8 a间变化幅度较大,且在第4年时有一个剧烈上升的拐点,13~40 a间变化较小。总之,青土湖区不同年限退耕地土壤水分和养分的变化基本一致,均表现为随退耕年限的增加而呈波动式降低的趋势。

Taking a typical area in Qingtuhu district of minqin in the lower reaches of Shiyanghe River as the research site, we analyzed the characteristics of soil particle composition and nutrient changes in the returned farmland of different restoration periods in this area by the spatiotemporal substitution method. The results show that:(1)in the first year of farmland conversion(CK), the vegetation distribution is dominated by annual shallow-root herbaceous plants, but the species is relatively single, and the soil water storage is relatively high; with the cessation of fertilization activities, farmland was returned after 1~8 years, and annual and biennial herbs gradually recover, and the consumption of soil water gradually increase; at this time, the soil water storage significantly decrease, which is more obvious in the 0—20 cm soil layer; The succession of 13~20 years is a single plant community dominated by the small perennial shrub black fruit lycium barbarum; after abandonment of 30~40 years, the species of small perennial shrubs increase, the soil water consumption increases, and the soil water storage decreases;(2)the overall changes of three kinds of soil nutrients decrease with the increase of a number of years of the farmland, and ultimately present the stable trend, in the same period, the contents of nutrients in 0—20 cm soil layer are greater than those in the 20—40 cm soil layer, and the content differences between the two layers in the same year, though a decreased gradually over years of the farmland abandonment, the changes in soil organic matter and available phosphorus are more obvious; the variation of total nitrogen content in soil during the abandonment is small; the content of available phosphorus in the soil surface(0—20 cm)of CK reaches the maximum value in the first year of abandonment, and then shows a fluctuating decreasing trend with the increase of the abandonment years, and stabilizes finally; the soil organic matter content varies greatly between CK and 8 years of abandonment, and there is a sharp increase abrupt point in fourth year of abandonment, and the change is small between 13~40 years of abandonment. The changes of soil moisture and nutrients in different years of farmland abandonment in Qingtuhu district are basically the same, showing a tendency of undulating decrease with the increase of years of farmland abandonment.