不同分子量壳聚糖对土壤碳、氮及呼吸的影响

The effect of molecular weight of chitosan on soil's carbon, nitrogen and soil respiration

考察了不同分子量壳聚糖对土壤微生物量C、N、土壤呼吸及矿质N的影响。研究发现:不同分子量的壳聚糖施入土壤后,土壤的微生物量C、N、呼吸及矿质N均明显提高。微生物量C、N及土壤呼吸有相似的变化趋势:随壳聚糖用量的增加而增大。低分子量壳聚糖施入土壤后,微生物量C、N及土壤呼吸均先快速增加,然后下降;中等及高分子量壳聚糖施入土壤后则是开始时变化较小,第14天开始快速增加,34d后下降。研究还发现,NO-3N与NH+4N变化趋势不完全相同,NO-3N开始时变化较小,第14天开始快速增加,34d后快速下降;低分子量壳聚糖处理时,NH+4N开始时快速增加,之后缓慢下降;中等分子量壳聚糖处理时,因加入量不同而不同;高分子量壳聚糖处理时则是从第24天开始变化显著。

The molecular weight （MW） of chitosan added to the soil ecosystem has an apparent influence on the microbial biomass carbon and nitrogen （MBCN） from soil, soil respiration rate （SRR） and the mineral nitrogen e.g. NO3-N and NH4-N in soil, all of which increase with the amount of chitosan used. In the case of chitosan with lower MW, the MBCN, SRR and the NH4-N increase rapidly first, and then gradually decrease. When chitosan with either medium or high MW was applied, no apparent change was observed on the MBCN and SRR at the initial period, starting from the 14^th day they increase rapidly, followed by the decrease after 34 days. The changes of NO3-N follow the same trend as that the MBCN and SRR exhibited. This is in contrast to the NH4-N. The latter increases significantly at the beginning of the addition of chitosan with lower molecular weight to the soil, and then slows down. When chitoson with medium MW was applied, the changes of NH4-N were directly associated with the concentration of chitoson. After chitoson with high MW was added to the soil, one cannot observe the considerable changes of NH4-N until the 24^th day.