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Effects of land use on the level, variation and spatial structure of soil enzyme activities and bacterial communities 总被引:1,自引:0,他引:1
K. Wallenius H. Rita K. Lappi H. Hartikainen R.M. Niemi 《Soil biology & biochemistry》2011,43(7):1464-351
The aim of this study was to evaluate the long-term influence of contrasting rural land use types on the level, plot-scale variation and horizontal spatial structure of decomposition activities and the bacterial community in soil. Experimental data were collected in the southern boreal zone from topsoil layers of adjacent spruce forest, unmanaged meadow (former field) and organically cultivated field that all shared the same soil origin. The forest soil was sampled separately for the organic and mineral layers. A geostatistical design comprising 50 sampling points per plot area of 10 × 10 m2 was used. The measured microbiological characteristics included eight different hydrolytic soil enzyme activities involved in C, P and S cycles, bacterial 16S rDNA length heterogeneity profiles (LH-PCR) and total DNA yield as a relative estimate of microbial biomass.Effects of land use were pronounced on both the bacterial community structure and soil enzyme activities. Soil organic matter (SOM) content predicted well the major differences in soil enzyme activities and microbial biomass. Highest enzyme activities were generally found in the forest organic soil whereas the underlying mineral soil showed significantly lower activities with a pattern similar to those of the other mineral soils, especially the cultivated field. Bacterial LH-PCR fingerprints were distinct but at the same time remarkably similar between field and meadow soils whereas the forest organic layer differed clearly from the mineral soils. Within-plot variation of soil microbiological characteristics was best explained by the variation of SOM. Relative standard deviations of soil microbiological characteristics typically decreased in the order: forest organic layer ≈ forest mineral layer > meadow > field. However, bacterial fingerprints showed lowest variation within the meadow. Most of the microbiological variables studied showed no or only weak spatial structure at the scale sampled. 相似文献
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长期施磷稻田土壤磷素累积及其潜在环境风险 总被引:8,自引:1,他引:7
应用常规化学分析法和数学统计方法,基于太湖地区13年的长期定位试验,研究长期不同施磷水平下[0(不施磷)、30 kg.hm 2.a 1(低磷)、60 kg.hm 2.a 1(适磷)、90 kg.hm 2.a 1(高磷)]稻麦轮作系统稻田土壤磷素累积规律及磷素流失引发的环境风险。在本试验区土壤环境条件下,可能发生稻田磷素淋溶及径流的土壤耕层(0~15 cm)Olsen-P临界值分别为26.0 mg.kg 1和24.8 mg.kg 1。连续13年适磷、高磷施肥,土壤耕层Olsen-P含量分别达到26.9 mg.kg 1和33.2 mg.kg 1,均高于临界值浓度,且已导致稻田田面水与30 cm渗漏水中总磷浓度显著升高,大大提高了稻田磷素淋溶及径流的风险。低磷施肥土壤Olsen-P长期稳定在(10.1±2.0)mg.kg 1水平,并且每年的稻麦产量与高磷、适磷处理相比并无显著差异,而长期低磷施肥土壤磷的流失风险也较小。因此,在太湖地区稻麦轮作体系下,磷肥不宜以常规适磷水平长期施用,建议以低磷水平(30 kg.hm 2.a 1)长期施用或以适磷水平(60 kg.hm 2.a 1)间歇式施用。 相似文献
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《Pedobiologia》2014,57(3):161-169
C mineralization and aggregate stability directly depend upon organic matter and clay content, and both processes are influenced by the activity of microorganisms and soil fauna. However, quantitative data are scarce. To achieve a gradient in C and clay content, a topsoil was mixed with a subsoil. Single soils and the soil mixture were amended with 1.0 mg maize litter C g soil−1 with and without endogeic earthworms (Aporrectodea caliginosa). The differently treated soils were incubated for 49 days at 15 °C and 40% water holding capacity. Cumulative C mineralization, microbial biomass, ergosterol content and aggregate fractions were investigated and litter derived C in bulk soil and aggregates were determined using isotope analyses. Results from the soil mixture were compared with the calculated mean values of the two single soils. Mixing of soil horizons differing in carbon and clay content stimulated C mineralization of added maize residues as well as of soil organic matter. Mixing also increased contents of macro-aggregate C and decreased contents of micro-aggregate C. Although A. caliginosa had a stimulating effect on C mineralization in all soils, decomposition of added litter by A. caliginosa was higher in the subsoil, whereas A. caliginosa decreased litter decomposition in the soil mixture and the topsoil. Litter derived C in macro-aggregates was higher with A. caliginosa than with litter only. In the C poor subsoil amended with litter, A. caliginosa stimulated the microbial community as indicated by the increase in microbial biomass. Furthermore, the decrease of ergosterol in the earthworm treated soils showed the influence of A. caliginosa on the microbial community, by reducing saprotrophic fungi. Overall, our data suggest both a decrease of saprotrophic fungi by selective grazing, burrowing and casting activity as well as a stimulation of the microbial community by A. caliginosa. 相似文献
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Rings of wire placed on the soil surface of two pastures containing populations of Lumbricidae were recovered after 52 months. They had been buried at the rate of 9–10 mm per year. At a forest site where only Megascolecidae were present there was no burial. At the pasture sites, populations of Lumbricidae in tubes of soil sterilized with methyl bromide 52 months earlier were indistinguishable from those in untreated soils. 相似文献
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不同水氮耦合管理下耕层土壤的氮动态 总被引:1,自引:1,他引:0
以中国科学院封丘农业生态试验站水氮耦合长期试验地为研究平台,采集了不同水氮耦合管理下耕层0~10 cm、10 ~ 20 cm和0~20 cm土壤,测定了六种形态的氮(无机氮、有机氮、酸解有机氮、酸解铵态氮、溶解性有机氮和微生物生物量氮)和三种与氮周转密切相关的生物性指标(脲酶活性、蛋白酶活性和硝化势).三因素方差分析结果表明,施氮和耕层深度对六种形态氮均有显著作用,而灌水对这六种形态氮无显著作用.单因素方差分析结果显示施氮明显提高了耕层0 ~ 20 cm土壤无机氮、有机氮、脲酶活性及硝化势,而对土壤酸解有机氮和酸解铵态氮无显著影响;六种形态的氮、蛋白酶活性及硝化势均不受灌水量的影响.不同水氮耦合管理下耕层0 ~ 10 cm土壤六种形态氮、脲酶活性、蛋白酶活性及硝化势几乎均明显地高于10~20 cm土壤.通过对不同水氮耦合管理下耕层土壤氮动态的研究,本研究得出最佳的水氮耦合管理模式是灌水至20 cm土层的田间持水量和每季施氮190 kg hm-2. 相似文献