土地利用类型对土壤微生物量和有机质的影响

对陕北黄土丘陵区农地、园地、人工草地、荒地、灌木林地、经济林地和乔木林地等7种不同土地利用类型土壤剖面4个土壤层次的土壤微生物量碳(MBC)、微生物量氮(MBN)、土壤呼吸(RS)和土壤有机质含量(SOM)进行了测定.分析了MBC,MBN,RS,SOM和全氮(TN)之间的相关性;并对土壤微生物对土壤健康的生物指示功能和土地利用类型对土壤有机质的影响进行了研究.结果表明,各土地利用类型表层土壤MBC和MBN分别在84.14～512.78和4.29～41.83 mg/kg之间,RS在108.69～235.71 mg/kg之间.荒地和乔木林地的土壤微生物量含量和RS值较高,农地较低;SOM在0.510%～1.547%之间,在乔木林地和经济林地较高,在农地,园地和人工草地较低,且在不同土地利用类型之间的差异显著.土壤微生物量和RS与SOC,TN显著相关,说明土壤微生物学特征可以用来表示土壤健康水平.农地转变为其它土地利用类型后会明显提高土壤微生物量和有机质含量,尤以表层土壤增幅最为明显.

Effects of Land- use Types on Soil Microbial Biomass and Organic Matter

Soil micro bial biomass carbon (MBC) , microbial biomass nitrogen (MBN) , soil respiration (RS) ,and soil organic matter (SOM) under various landuses including farmland, garden plot, artificial pasture, waste land, shrub land, economic w oodland, and arbor land in the loess hilly-g ully region w ere measured. The relationships among soil microbial biomass, soil respiration, soil organic matter (SOM) , and total nitrogen (TN) w ere studied and the function of soil microbial pro perties as bio-indicators of soil health w as illustrated. In addition, the effects of landuse on soil organic matter w ere evaluated. Results indicate that the content of MBC in topsoil ranges from 84. 14~ 512. 78 mg/ kg; the content of M BN, from 4. 29 to 41. 83 mg/ kg; and the content of RS, from 108. 69 to 235. 71 mg/ kg. The contents of microbial biomass and RS in to psoil are higher in w aste land and arbor land and low er in the farmland. T he content of SOM in topsoil is 0. 510%~ 1. 547% and it is higher in the economic w oodland and arbor land and low er in the farmland, garden plot, and artificial pasture. Its differences are significant in various landuses. Soil microbial biomass and RS are markedly correlated w ith organic matter and total nitrogen and soil micro bial properties can be used to indicate the health of soils. T he conversion of farmland into other landuses results in a remarkable increase in the amo unts of microbial biomass and soil organic matter, especially in topsoil.