味精废浆与化肥配施对杨树幼苗土壤活性有机碳与微生物活性的影响

为探讨味精废浆有机肥对林木土壤的生物学效应及确定味精废浆与化肥适宜的搭配比例,通过盆栽试验,研究了CK(对照,不施肥)、N100(尿素提供100%的氮)、M10N90(味精废浆和尿素分别提供10%与90%的氮)、M30N70(味精废浆和尿素分别提供30%与70%的氮)与M50N50(味精废浆和尿素各提供50%的氮)等处理对杨树幼苗土壤活性有机碳、碳库管理指数(CPMI)与微生物呼吸、代谢熵及生长的影响。结果表明:与N100处理相比,配施味精废浆处理的土壤活性、中活性和高活性有机碳含量均明显升高。M30N70处理的活性有机碳含量与CPMI显著高于其他处理,分别较N100处理高出34.78%和42.96;其微生物量碳、氮含量也明显高于其他处理。同时,M30N70处理还能显著增强土壤微生物呼吸作用,但降低了代谢熵,其中土壤微生物呼吸分别较CK、N100、M10N90和M50N50处理提高81.13%,35.21%,17.07%和5.49%,而代谢熵分别下降9.16%,10.37%,6.98%和5.80%。此外,M30N70处理的地径、苗高亦达最高值,并与其他处理差异达显著水平。同M30N70处理相比,M10N90与M50N50处理对杨树幼苗土壤及生长的影响效果较小。相关性分析表明,地径、苗高生长与土壤不同程度的活性有机碳、碳库管理指数及微生物活性有显著或极显著的相关性,各指标之间具有紧密的内在关联。综合分析认为,味精废浆与化肥以3∶7比例配施能显著提高杨树幼苗土壤的活性有机碳含量,明显增强土壤微生物活性,并促进其生长。

Effects of Monosodium Glutamate Wastewater Co-applied with Inorganic Fertilizer on Active Organic Carbon and Microbial Activity in Poplar Seedlings Soil

In order to explore the biological effect of monosodium glutamate wastewater on forest soil and determine the appropriate application level of monosodium glutamate wastewater and inorganic fertilizer for improving poplar growth, a pot experiment including five treatments, i.e. CK (neither urea nor monosodium glutamate wastewater was applied), N100 (100% of nitrogen was provided by urea), M10N90 (10% and 90% of nitrogen were provided by monosodium glutamate wastewater and urea, respectively), M30N70 (30% and 70% of nitrogen were provided by monosodium glutamate wastewater and urea, respectively) and M50N50 (50% and 50% of nitrogen were provided by monosodium glutamate wastewater and urea, respectively) was performed. The present study was conducted to determine the effects of different treatments on active organic carbon, carbon pool management index (CPMI), microbial respiration and metabolic quotient in soil, as well as growth of poplar seedlings. Results showed that in comparison with N100 treatment, monosodium glutamate wastewater application significantly increased the contents of active organic carbon, mid-active organic carbon and highly active organic carbon. The active organic carbon content and CPMI in M30N70 treatment were obviously higher than other treatments, increasing 34.78% and 42.96 compared with N100 treatment, respectively. The M30N70 treatment also significantly increased the contents of microbial biomass carbon and microbial biomass nitrogen. In the meantime, the microbial respiration was evidently enhanced by the use of M30N70 treatment, while the metabolic quotient was decreased, increasing 81.13%, 35.21%, 17.07% and 5.49% in microbial respiration over the treatments of CK, N100, M10N90 and M50N50, respectively. And the metabolic quotient was reduced by 9.16%, 10.37%, 6.98% and 5.80%, respectively. Additionally, the ground diameter and plant height in M30N70 treatment also reached the maximum and had significant differences with other treatments. However, in M10N90 and M50N50 treatments, less effect on micro-domain environment characteristics and growth was observed than that in M30N70 treatment. Correlation analysis revealed that ground diameter and plant height were significantly or extremely significantly correlated with different degree of soil active organic carbon, carbon pool management index (CPMI) and microbial activity, indicating close inner link among every indicator. These results suggested that monosodium glutamate wastewater combined with inorganic fertilizer, especially M30N70 treatment, was beneficial to increase the active organic carbon content, enhance the microbial activity in soil and promote growth of poplar seedlings.