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以中亚热带地区的5年生杉木(Cunninghamia lanceolata)人工林为研究对象,探讨施肥对土壤酶活性和活性有机碳含量的影响,实验包括对照(CK)、施氮肥(200 kg N·hm~(-2)·a~(-1))、施磷肥(50 kg P·hm~(-2)·a~(-1))、施氮磷肥(200 kg N·hm~(-2)·a~(-1)和50 kg P·hm~(-2)·a~(-1))等4个处理。结果表明:在表层(0~10 cm)土壤中,施NP肥处理的土壤蔗糖酶和过氧化氢酶活性分别比CK降低了40.2%和36.5%,β-葡萄糖苷酶活性比施P肥处理降低了31.1%;亚表层(10~20 cm)土壤中,施N肥处理的脲酶活性显著低于CK;施N肥、P肥和NP肥处理的蔗糖酶活性分别比CK降低了46.9%、37.8%和42.4%;施NP肥处理的过氧化氢酶活性比施P肥处理降低了22.6%;在表层土壤中,施N肥、P肥处理的土壤水溶性有机碳含量分别比CK降低24.1%和29.4%;施NP肥处理的微生物生物量碳显著低于CK;土壤活性有机碳组分在不同土层之间差异显著,均表现为表层土壤活性有机碳含量高于亚表层土壤。相关性分析结果显示:蔗糖酶活性与硝态氮含量呈极显著负相关,表明施NP肥增加了硝态氮含量,一定程度上抑制了蔗糖酶的活性;水溶性有机碳与脲酶活性呈显著正相关,土壤微生物生物量碳与脲酶、过氧化氢酶和β-葡萄糖苷酶活性呈显著正相关。研究表明,水溶性有机碳、微生物生物量碳和土壤酶活性的降低可能会抑制土壤碳的释放,从而增加土壤碳的固定。
Taking Cunninghamia lanceolata plantation in subtropical region as research object, the effects of fertilization on soil enzyme activities and active organic carbon contents were studied. The experiment included CK and N fertilizer application (200 kg N · hm ~ (- 2) · a ~ (-1), P application rate (50 kg · hm -2 · a -1) and N / P (200 kg N · hm -2 · a ~ (-1) and 50 kg P · hm -2 (-2) · a -1, respectively. The results showed that the activities of sucrase and catalase in the soil treated with NP were decreased by 40.2% and 36.5%, respectively, compared with CK, and the activities of β-glucosidase were higher than those treated with P fertilizer in the surface layer (0-10 cm) (31.1%). In the subsurface (10-20 cm) soil, the activity of urease under N fertilizer application was significantly lower than that of CK. The invertase activity of N, P and NP fertilizers decreased by 46.9% 37.8% and 42.4%, respectively. The activities of catalase in treated NP decreased 22.6% compared with those in treated P. The content of water-soluble organic carbon in surface soil was decreased by 24.1 % And 29.4%, respectively. The microbial biomass carbon of NP treatments was significantly lower than that of CK. The contents of soil active organic carbon in different soil layers were significantly different, which showed that the content of soil active organic carbon in surface soil was higher than that in sub-surface soil. Correlation analysis showed that there was a significantly negative correlation between invertase activity and nitrate nitrogen content, indicating that applying NP fertilizer increased the content of nitrate nitrogen and inhibited the activity of invertase to a certain extent. The activities of water-soluble organic carbon and urease were significantly There was a positive correlation between soil microbial biomass carbon and urease, catalase and β-glucosidase activities. The results show that the decrease of water-soluble organic carbon, microbial biomass carbon and soil enzyme activity may inhibit the release of soil carbon, thus increasing soil carbon fixation.