新疆昌吉州耕地土壤有机质空间变异动态研究

土壤有机质在提高土壤肥力和作物生产力方面发挥重要作用,研究其空间变异性可为精准施肥以及可持续的土地利用和管理提供科学依据。本文以新疆昌吉州为研究区,基于多重分形方法,使用第二次土壤普查（1980年前后）、2010年和2018年共3期土壤有机质数据,计算多重分形参数来探究土壤有机质空间变异的动态。结果表明：① 第二次土壤普查—2018年期间,昌吉州土壤有机质含量呈增加趋势。② 第二次土壤普查—2018年期间,昌吉州土壤有机质的空间分布总体上具有非均匀的多重分形特征,土壤有机质值域范围逐渐变窄,空间分布变异性降低,趋于均一化。其中阜康市、吉木萨尔县和木垒哈萨克自治县的有机质变异程度在2010—2018年略有上升。③ 2018年,昌吉州土壤有机质在空间上自西向东值域分布范围逐渐变宽,变异程度增加,内部差异变大,趋向于非均匀化。④ 三个时期昌吉州土壤有机质数值中均是低值数据分布概率较大,其变异程度高于高值数据,仅阜康市和木垒哈萨克自治县在2018年由高值数据占主导地位。长时间的耕作经营使得土壤有机质含量有所提高,空间分布逐渐趋向均一化,但仍存在部分区域有机质较高,部分区域较低的情况。分区管理措施可以有效提高区域的整体肥力水平,应在阜康市、吉木萨尔县和木垒哈萨克自治县等有机质变异程度较高的区域继续推进精准施肥,改进灌溉和耕作措施以降低土壤有机质空间变异性。

Dynamic research on spatial variability of cultivated soil organic matter in Changji Prefecture,Xinjiang

Soil organic matter(SOM)plays an important role in improving soil fertility and crop productivity,and studying its spatial variability can provide a scientific basis for targeted fertilization and sustainable land use and management.This paper selected Changji Prefecture of Xinjiang as the study area,and used three-stage SOM data(the second soil survey,2010 and 2018)to calculate the generalized dimension spectrum D(q),multifractal singularity indexɑ(q)and the multifractal spectrum function f(ɑ(q))based on the multifractal method to explore the dynamic changes of SOM spatial variability.The results showed that:(1)The average SOM contents in the three periods were 10.46,16.69 and 18.16 g/kg,respectively,showing an upward trend.However,the SOM contents of all counties were lower than the national average level(24.30 g/kg)in 2018.(2)The spatial distribution of SOM in Changji Prefecture had non-uniform multifractal characteristics from the second soil survey to 2018.The distribution range of SOM value gradually became narrowed,and the spatial distribution variability decreased,tending to be uniform.The degree of SOM spatial variability in Fukang city,Jimusaer county,and Mulei Kazakh autonomous county increased slightly from 2010 to 2018.(3)In 2018,the spatial distribution range of SOM widened from west to east,with an increasing variation degree,and internal differences became larger,tending to be non-uniform.(4)In the three periods,all the low-value data had a greater variability,with the variation degree being higher than that of the high-value data.Fukang and Mulei were dominated by the high-value data in 2018.Long-term farming had increased the SOM content,and the spatial distribution gradually tended to be uniform.However,there was obvious spatial heterogeneity of SOM.It is necessary to adopt targeted approaches to improve overall soil fertility in different parts of the study area.It is recommended to promote targeted fertilization and to improve irrigation and farming measures in the places with high spatial variability of organic matter,such as Fukang,Jimusaer and Mulei.