施肥对板栗林土壤水溶性有机氮的影响

土壤水溶性有机氮(WSON)是指通过0.45 μm滤孔,且能溶解于水的,具有不同结构及分子质量大小的有机氮化合物.它是陆地生态系统中最活跃的氮素组分之一,一方面,WSON可以被植物和微生物直接吸收,从而对提高土壤生物学活性,改善土壤肥力具有重要意义(Nsholm et al.,1998;Barak et al.,1990);另一方面,它可以随水流失,会造成环境污染(Perakis et al.,2002).

Effect of fertilization on water-soluble organic N in the soils under chestnut stands

In order to investigate effect of fertilization on water-soluble organic N (WSON) in the soils under chestnut stands,a fertilization experiment was carried out in Lin-an county in Zhejiang province. The results of this study showed that fertilization increased WSON in the soils under chestnut stands. Excessive chemical fertilizer addition or combined application of chemical fertilizers and organic manure had most strong effects by increasing the concentrations of WSON in the soils respectively by 5.68 and 1.94 times,compared with the unfertilized control,There was no difference in WSON concentrations in the soils among the treatments with routine chemical fertilizer rate,organic manure alone and unfertilized control. Excessive fertilizer application induced the highest ratio of WSON/total N (5.76%),which was markedly greater than that done by other three treatments. The ratio of WSON/hydrolyzed N ranged from 9.34% to 37.04% with average value of 26.78%. The highest ratio of hydrolyzed N/total N (37.04%) was found from the treatments of excessive fertilizer application and the ratio was markedly greater than that of other three treatments. The correlation analysis showed that there were significant correlations between WSON and soil total N,hydrolyzed N,water soluble total N,water soluble NH4 -N or water soluble NO3-N. The corresponding correlation coefficients were 0.565 1,0.918 6,0.998 6,0.9939 and 0.5401,respectively.