Ning Yu-Fei, Wei Liang, Wei Xiao-Meng, Zhu Zhen-Ke, Yuan Hong-Zhao, Ge Ti-da, Wu Jin-Shui
Key Laboratory of Subtropical Agriculture Ecology, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2020 Jun 8;41(6):2852-2860. doi: 10.13227/j.hjkx.201909140.
The availability of carbon (C), nitrogen (N), and other substrates in soil determines the growth and metabolism of microorganisms and affects the activity of extracellular enzymes. To study the activities of -1,4-glucosidase (BG) and -1,4--acetylglucosaminidase (NAG) in response to C and N availability, samples that underwent four treatments-non-fertilization (CK), chemical fertilizer (NPK), combination of organic manure and chemical fertilizer (OM), and mixture of straw and chemical fertilizer (ST)-were collected from long-term fertilization paddy soil and incubated for 0, 4, 8, and 12 months to obtain soil with different C and N availability gradients. The results showed that the dissolved organic carbon(DOC) content of OM and ST treatment samples was 2-3 times higher than that of CK and NPK treatment samples. With the increase of DOC and ammonium (NH-N) contents, the activities of BG and NAG and the contents of microbial biomass C (MBC) and N (MBN) showed no increase during incubation within each treatment. Fertilization treatments, incubation time, and their interaction are crucial factors varying the contents of DOC, NH-N, MBC, and MBN among different fertilization treatments (<0.01). There was a positive correlation between MBC/MBN and DOC/NH-N of OM treatment (<0.05) and a negative relationship between ln(BG)/ln(NAG) and DOC/NH-N of ST treatment (<0.01), indicating that the availability of substrates played a key role in the potential activity of extracellular enzymes in paddy soil, and the carbon-nitrogen ratio of microbial biomass was controlled by the C/N stoichiometry of substrates in soil. The results have a certain guiding significance for further study on the variation of extracellular enzyme activity in paddy soil, regulating the balance of carbon and nitrogen, and improving the fertility of paddy soil.
土壤中碳（C）、氮（N）及其他底物的有效性决定了微生物的生长和代谢，并影响细胞外酶的活性。为研究β-1,4-葡萄糖苷酶（BG）和β-1,4-N-乙酰氨基葡萄糖苷酶（NAG）的活性对碳和氮有效性的响应，从长期施肥的稻田土壤中采集了经过四种处理的样品——不施肥（CK）、化肥（NPK）、有机肥与化肥组合（OM）以及秸秆与化肥混合（ST），并分别培养0、4、8和12个月，以获得具有不同碳和氮有效性梯度的土壤。结果表明，OM和ST处理样品的溶解有机碳（DOC）含量比CK和NPK处理样品高2 - 3倍。随着DOC和铵态氮（NH₄⁺-N）含量的增加，各处理培养期间BG和NAG的活性以及微生物生物量碳（MBC）和氮（MBN）的含量均未增加。施肥处理、培养时间及其相互作用是导致不同施肥处理间DOC、NH₄⁺-N、MBC和MBN含量变化的关键因素（P<0.01）。OM处理的MBC/MBN与DOC/NH₄⁺-N之间存在正相关（P<0.05），ST处理的ln（BG）/ln（NAG）与DOC/NH₄⁺-N之间存在负相关（P<0.01），表明底物有效性对稻田土壤细胞外酶的潜在活性起关键作用，微生物生物量的碳氮比受土壤中底物的碳氮化学计量比控制。研究结果对进一步研究稻田土壤细胞外酶活性变化、调控碳氮平衡及提高稻田土壤肥力具有一定指导意义。
