不同耕作年限对耕地土壤质地和有机碳垂直分布的影响

研究不同耕作年限新疆玛纳斯县耕地的土壤颗粒组成、不同土壤颗粒有机碳含量变化特征以及二者的相关关系。选取4种不同耕作年限耕地为研究对象,采集土层0—300cm的土壤样品,采用激光法获取土壤颗粒组成,探讨长期耕作对土壤颗粒组成以及不同土壤颗粒有机碳含量的影响。结果表明:研究区域土壤剖面颗粒组成主要以砂粒(约占21.0%~35.4%)和粉粒(约占46.0%~50.0%)为主,砂粒含量下部明显高于上部,而粉粒含量中部明显低于上部和下部;随着耕作年限增加,剖面上部(0—60cm)土壤质地由粉砂质粘壤土转变为壤土,60—100cm土层土壤质地由粉砂壤土转化为壤土,中部和下部(100—300cm)土壤质地变化较小;土壤有机碳含量随着开垦年限的增加呈现先增加后降低的趋势,增幅达到71.8%,耕作年限越长有机碳增加值趋于平缓;土壤粉粒、砂粒与有机碳含量相关性不高,而粘粒与有机碳含量呈现显著正相关关系,未耕作(Y0)、耕作20a(Y20)、耕作30a(Y30)和耕作50a(Y50)的土壤粘粒与有机碳含量的相关系数(r)范围在0.67*~0.75*,均达到显著性差异(P0.05)。耕作对土壤颗粒组成以及有机碳含量产生一定影响,科学合理的耕作能够提高土壤的固碳能力,对土壤碳循环系统起到良好的保护作用。

Effect of Cultivation Years on Vertical Distribution of Soil Texture and Organic carbon

Effects of characteristics of soil particle composition, organic carbon content in different soil particles and the correlation between them were studied in Manasi county, Xinjiang province. Selected four years of reclamation of cultivated land as the research object, and soil samples collected from 0~300 cm soil layer, obtained the composition of soil particles by laser method, to investigate the long-term effects of tillage on soil particle composition and organic carbon content of different soil particles. Results showed that the research of regional soil particle composition in sand (about 21.0%~35.4%) and powder (about 46.0%~50.0%), lower significantly higher than the upper content, sand content and silt content was significantly lower than the upper and lower in the middle. With the increase of cultivated fixed number of year, the silty clay loam upper top layer (0~60 cm) was transformed into loam, the silt loam in 60~100 cm was transformed into loam, the soil texture in middle and lower (100~300 cm) had less change. The soil organic carbon content increased first and then decreased with the increasing of the year of cultivation, growth rate reached 71.8%, and the increasing of the length of the organic carbon increased the value of tillage. At the same time, the correlation between silt, sand and soil organic carbon content was not high, and the clay and organic carbon content showed significant positive correlation. The range of correlation coefficient (r) between soil clay and organic carbon content under unused (Y0), 20 years cultivation (Y20), 40 years cultivation (Y40) and 60 years cultivation (Y60) was (0.67*)~(0.75*), achieved significant difference (P<0.05). Human farming methods on the composition of soil particles and organic carbon content had an impact, so scientific and reasonable farming could increase soil carbon sequestration ability, had good protection effect on soil carbon cycle system.