摘要
将经过风干、过筛后的 2种旱地红壤加水培养 ,并和新鲜土培养条件相比较 ,研究干土效应对土壤生物组成及矿化与硝化作用的影响。试验共 4个处理 :(1)农田旱地风干土加水培养 (RU) ;(2 )农田旱地新鲜土培养 (FU) ;(3)苗圃旱地风干土加水培养 (RN) ;(4 )苗圃旱地新鲜土培养 (FN)。结果表明 :红壤风干土加水预培养 5d后 ,细菌、放线菌、真菌数量比新鲜土显著增加 (p <0 0 1) ,细菌数量增加最为明显 ,农田旱地和苗圃旱地风干土处理分别是新鲜土的 6 2 6倍和 6 84倍 ,红壤风干土加水培养处理的微生物量碳、氮也随之增加。培养 2 8d后土壤中微生物数量趋于稳定 ,与预培养 5d时的数量相当或稍有下降 ,但风干后加水培养处理的微生物数量仍保持大于新鲜土的趋势 (农田旱地的放线菌除外 ) ,微生物量碳、氮也存在同样的趋势。风干土加水培养后微生物数量的迅速增加 ,使得氮素矿化速度加快 ,由此导致NH+ 4 N量显著增加(p <0 0 1) ,培养 2 8d后 ,NH+ 4 N量较预培养 5d时有所增加 ,且明显高于新鲜土培养处理 ;NO-3 N含量也增加 ,但新鲜土处理显著高于风干土处理。土壤风干处理对土壤自由生活线虫的影响比较大 ,农田旱地和苗圃旱地风干土加水培养 2 8d后 ,其自由生活线虫数量仅为新鲜土的 16 0 %和 30 1% ,显?
Effects of rewetting of air-dried red soil on soil biota composition, nitrogen mineralization and nitrification were studied in the laboratory. Four treatments were designed: (1) rewetting of air-dried upland red soil (RU); (2) fresh upland red soil (FU); (3) rewetting of air-dried nursery red soil (RN); (4) fresh nursery red soil (FN). The results indicate: the populations of soil microorganisms including bacteria, fungi, actinomycetes in the rewetted red soil increased obviously after 5 days incubation when compared with those in the fresh red soil, especially the population of bacteria, which were 6.26 and 6.84 times as large as that in the fresh of upland and nursery soil, respectively. As a result of the increase in soil microbes, the soil microbial biomass C (SMBC) and soil microbial biomass N (SMBN) increased in the rewetted air-dried red soil treatments. The increasing population of soil microbes after 28 days' incubation leveled off and was still somewhat equal to or a bit smaller than that after 5 days's pre-incubation of all the treatments. However, the population of microbes in the rewetted air-dried red soil was still larger than that in the fresh red soil after 28 days' incubation. With the increase in microbe population and biomass, nitrogen mineralization was sped up, which led to increase in NH + 4-N concentration. After 28 days' incubation, the NH + 4-N concentrations in the rewetted air-dried soils increased in comparison with those after 5 days' pre-incubation and obviously higher than in the fresh soils. At the same time, NO - 3-N concentrations also increased, but they were significantly higher in the fresh soils than in the rewetted red soil. The experiment also shows that after 28 days' incubation, the population of free-living nematodes in the treatments of rewetting air-dried upland and nursery red soil of could hardly recover, being 16.0% and 30.1% of that in the fresh red soil, respectively. After 28 days' incubation of the rewetted air-dried red soil, the net mineralization and mineralization rate increased significantly (p<0.05), but the net nitrification and the net nitrification rate decreased significantly (p<0.05), when compared with that in the fresh red soil. The possible reason was that the populations of ammonium oxidizers and nitrite oxidizers, which play a key role in the process of nitrification, could hardly get recovered from the damage of air-drying.
出处
《土壤学报》
CAS
CSCD
北大核心
2004年第6期924-930,共7页
Acta Pedologica Sinica
基金
中国科学院红壤生态开放实验站基金 ( 2 0 0 1 K 0 3 )资助
