不同规格可降解沙障铺设5年后土壤粒度及有机质特征

为了探究可降解沙障铺设5 a后土壤粒度及有机质含量特征,采集库布齐沙漠东南缘铺设5 a后不同规格(0.5 m×0.5 m,1 m×1 m和2 m×2 m)、不同坡位(坡底、坡中、坡顶)的PLA沙障内近地表层(0—3 cm)土壤样品,通过激光粒度仪测试并分析了土壤粒度、有机质含量的变化情况及二者的相关性。结果表明:(1)PLA沙障内主要以细砂和粗砂为主,随着铺设规格的增加细砂含量逐渐增加,2 m×2 m(80.66%)>1 m×1 m(75.8%)>0.5 m×0.5 m(45.15%),每种规格坡顶处细砂含量最高分别为23.39%,31.73%,41.17%,坡中粗砂含量最高分别为44.91%,36.42%,42.88%。(2)障格内分选性均变差,峰态偏离正态分布,沉积物颗粒频率分布曲线部分波段变窄,表层颗粒逐渐细粒化。(3)土壤有机质含量表现出1 m×1 m>0.5 m×0.5 m>CK>2 m×2 m的规律; 3种规格有机质含量均表现为坡底>坡中>坡顶; 且极细砂与有机质含量呈现显著正相关,与中砂呈现显著负相关。上述结果说明,对于本研究区内,铺设5 a后1m×1m规格PLA沙障防护效益更优,且1 m×1 m规格和坡底处有利于有机质的积累,极细砂和中砂是有机质积累的关键粒级。

Characteristics of Soil Particle Size and Organic Matter After Five Years of Laying Different Specifications of Degradable Sand Barriers

In order to investigate the characteristics of soil grain size and organic matter content after the biodegradable sand barrier was laid for 5 years,soil samples of 0—3 cm in the PLA sand barrier with different sizes(0.5 m×0.5 m,1 m×1 m and 2 m×2 m)and different slope positions(bottom,middle and top)were collected in the southeastern edge of the Kubuqi Desert.The change of soil particle size determined by laser particle size analyzer and organic matter content and their correlation were analyzed.The results are as follows:(1)the soil in PLA sand barrier is mainly composed of fine sand and coarse sand.With the increase of laying specifications,the content of fine sand increases gradually,and the content decreases in the order:2 m×2 m(80.66%)>1 m×1 m(75.8%)>0.5 m×0.5 m(45.15%);the highest contents of fine sand at the slope tops of 3 specification sand barries are 23.39%,31.73%and 41.17%,respectively;the highest contents of coarse sand in middles slope are 44.91%,36.42%and 42.88%,respectively;(2)the uniformity of sorting in the barrier becomes worse,and the peakness deviates from the normal distribution;some bands of frequency distribution curve of sediment particles become narrower,and the surface particles become coarse-grained gradually;(3)the soil organic matter contents decreases in the order:1 m×1 m>0.5 m×0.5 m>CK>2 m×2 m;the organic matter contents in the slopes of the three specifications showed the order of bottom>middle>top;there is a significant positive correlation between the content of organic matter and very fine sand,and a significant negative correlation between the content of organic matter and medium sand.The above results indicate that 1 m×1 m PLA sand barrier has better protection efficiency in this study area,1 m×1 m PLA sand barrier and slope bottom are conducive to organic matter accumulation,and very fine sand and medium sand are the key grain sizes for organic matter accumulation.