亚热带红壤硝化特性的干土效应响应

风干处理常对土壤中的硝化细菌数量和活性造成显著影响.为研究土壤硝化作用的干土效应,以分别发育于第四纪红土(quaternary red earth,Q)和红砂岩(tertiary red sandstone,S),利用方式为水稻(rice,R)与旱地(upland,U)的4个农田土壤的新鲜土与风干土为供试材料,进行35d的室内培养试验.结果表明,对于无外源铵输入的处理而言,旱地土壤QU的新鲜土和风干土的硝化率分别为48%和54%,SU则分别为76%和78%,硝化作用的干土效应均不显著(p0.05);但干土效应却显著影响了水稻土的硝化作用(QR的新鲜土和风干土的硝化率分别为40%和89%,SR分别为76%和94%,p0.01),且其风干土样的硝化作用表现出明显的微生物激活过程.外源铵的加入促进了土壤的硝化作用强度且使得旱地土壤的干土效应显著,所有供试土壤新鲜土的硝化率均显著高于风干土的硝化率.总之,土壤利用方式显著影响了硝化作用对干土效应的响应,而且利用方式和加铵对硝化作用的干土效应有着极显著的交互作用.

Response of Soil Nitrification Characteristics in Subtropical Area to Air-Drying

Populations and activities of nitrifier can be significantly influenced by air-drying. A 35-day incubation study was conducted to determine the effects of air-drying on nitrification potential of four acid subtropical soils after applying 0 and 150 m g·kg^-1 of ammonium bicarbonate. Four soils, designated QR, QU, SR and SU, derived from Quaternary red earth and Tertiary red sandstone, were collected from rice and upland field. The results indicated that, without ammonium input, the responses of nitrification in upland soils to air-drying were insignificant(p>0.05). The nitrification ratio in fresh and air-dried samples of soil QU were 48% and 54% respectively, and 76% and 78% for SU; however, air-drying did have a significant effect on the nitrification in paddy soils(p<0.01). Nitrification ratios were 40% and 89% for fresh and air-dried samples of QR, 76% and 94% for SR, and there was a lag-phase of the nitrification in air-dried paddy soils. Ammonium input would accelerate nitrification and make the nitrification ratios of fresh samples significantly higher than those of air-dried ones. In generally, land-use type presents a significant impact on the response of nitrification to air-drying effect, and there was a significant interaction of land-use type and fertilization.