ABSTRACT
We explored the effects of vegetation restoration on the soil nutrients and microbial pro-perties of soil aggregates with different particle size by comparing soils in a natural grassland which had been restored for nearly 30 years and in cropland in the loess hilly regions of Ningxia. We analyzed the soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil basal respiration (CO2-C) and respiratory quotient (qCO2) of different particle size soil aggregates collected from cropland and natural grassland. The results showed that soil aggregates of natural grassland had more micro-aggregates (particle size <0.25 mm), higher nutrient concentrations (SOC, TN and available K) and C/N than that of cropland. The highest concentrations of SOC and TN in 1-2 mm aggregates and higher C/N in natural grassland and cropland suggested that vegetation restoration could improve the capacity of soil aggregates to reduce nutrient loss and accumulate organic matter, with the highest nutrient accumulation in 1-2 mm aggregates. Microbial biomass (MBC, MBN) and CO2-C in natural grassland were higher than in cropland, but the qCO2 was significantly lower, suggesting that vegetation restoration could effectively improve soil microbial biomass and activity, and make soil habitats more stable. The magnitude of responses of the microbial characteristics of different particle aggregates to vegetation restoration varied due to the differences in nutrient characteristics. The MBC of 1-2 mm aggregates, the MBN of <0.25 mm, 0.25-1 mm and 1-2 mm aggregates, the microbial activity of 1-2 mm and >5 mm aggregates were more sensitive than the rest of the particle aggregates of vegetation restoration. In conclusion, vegetation restoration could effectively improve the fertility and structural characteristics of soil aggregates, and the most prominent improvement was in 1-2 mm particle size aggregates.
Subject(s)
Environmental Restoration and Remediation , Nitrogen/analysis , Phosphorus/analysis , Soil/chemistry , Carbon , China , Environmental Monitoring , Particle Size , Plants , Soil MicrobiologyABSTRACT
Taking the rhizosphere and non-rhizosphere soils of five typical plants Agropyron cristatum, Artemisia frigida, Pseudoraphis bungeana, Thymus mongolicus, and Artemisia sacrorum in a mountainous area of southern Ningxia as test objects, this paper studied their C and N forms contents. The C and N forms contents in the rhizosphere and non-rhizosphere soils differed with plant species. In the rhizosphere soil of A. sacrorum, the C content was the highest, with the total soil organic C (TOC), light fraction organic C (LFOC), and heavy fraction organic C contents being 22.94, 1.95, and 20. 88 g kg-1, respectively. In the rhizosphere soil of P. bungeana, the N content was the highest, with the total N (TN), mineralizable N (MN), and available N contents being 2.05 g kg-1 , 23.73 mg kg-1, and 11.99 mg kg-1 , respectively. In the rhizosphere soil of A. frigida, the LFOC/TOC and MN/TN ratios were the highest, which benefited the C and N transformed into more active forms. Light fraction organic C and mineralizable N could be used as the sensitive indicators of plant habitat change. For the five plant species, the contents of different C and N forms in the rhizosphere soil were generally higher than those in the non-rhizosphere soil.