Contrasting effects of ammonium and nitrate additions on the biomass of soil microbial communities and enzyme activities in subtropical China
Contrasting effects of ammonium and nitrate additions on the biomass of soil microbial communities and enzyme activities in subtropical China
复制标题
铵盐和硝酸盐添加对中国亚热带土壤微生物群落生物量和酶活性的影响对比
DOI：
10.5194/bg-14-4815-2017
复制
发表时间：
2017-10-27
期刊：
影响因子：
4.9
通讯作者：
Sun, Xiao-Min
中科院分区：
文献类型：
--
作者：
Zhang, Chuang;Zhang, Xin-Yu;Sun, Xiao-Min
近年来，潮湿大气沉积物中氮（N）化合物中硝酸盐与铵的比例有所增加，这引起了一些关注，因为硝酸盐和铵沉积对不同土壤微生物群落生物量和酶活性的影响仍然很难确定。我们建立了一个田间试验，并施加铵（NH4Cl）和硝酸盐（NaNO3）在4年的时间内，每月的间隔。在春、夏、秋3个季节，分别采集铵态氮和硝态氮处理和对照样地的土壤样品，研究不同土壤微生物群落生物量和酶活性对铵态氮（NH4Cl）和硝态氮（NaNO3）施用的响应。结果表明，铵态氮和硝态氮处理使磷脂脂肪酸总量分别下降了24%和11%。铵对革兰氏阳性菌（G（+））和细菌，真菌，放线菌和丛枝菌根真菌（AMF）PLFA含量的抑制作用在三个季节范围从14%到40%。铵态氮和硝态氮对C、N、P水解酶和氧化酶的绝对活性均有抑制作用，但硝态氮对酸性磷酸酶（AP）活性的抑制作用强于铵态氮。在铵态氮和硝态氮处理下，氮素吸收特异性酶活性（酶活性按PLFA总量归一化）分别比对照低21%和43%。而磷吸收特异性酶活性在铵态氮处理中比对照高19%左右。冗余分析（RDA）结果表明，土壤C、N、P水解和多酚氧化酶（PPO）活性与土壤pH和铵态氮含量呈正相关，与硝酸盐含量呈负相关。PLFA生物标志物含量与土壤pH、土壤有机碳（SOC）和全氮含量呈正相关，与铵态氮含量呈负相关。土壤酶活性季节性变化明显，3月最高，10月最低。微生物PLFA生物标志物含量在10月高于3月和6月。由于酸化，铵可能比硝酸盐更强烈地抑制PLFA生物标志物的含量。本研究为铵态氮和硝态氮对土壤微生物群落和酶活性的影响提供了有用的信息。
The nitrate to ammonium ratios in nitrogen (N) compounds in wet atmospheric deposits have increased over the recent past, which is a cause for some concern as the individual effects of nitrate and ammonium deposition on the biomass of different soil microbial communities and enzyme activities are still poorly defined. We established a field experiment and applied ammonium (NH4Cl) and nitrate (NaNO3) at monthly intervals over a period of 4 years. We collected soil samples from the ammonium and nitrate treatments and control plots in three different seasons, namely spring, summer, and fall, to evaluate the how the biomass of different soil microbial communities and enzyme activities responded to the ammonium (NH4Cl) and nitrate (NaNO3) applications. Our results showed that the total contents of phospholipid fatty acids (PLFAs) decreased by 24 and 11% in the ammonium and nitrate treatments, respectively. The inhibitory effects of ammonium on Gram-positive bacteria (G(+)) and bacteria, fungi, actinomycetes, and arbuscular mycorrhizal fungi (AMF) PLFA contents ranged from 14 to 40% across the three seasons. We also observed that the absolute activities of C, N, and P hydrolyses and oxidases were inhibited by ammonium and nitrate, but that nitrate had stronger inhibitory effects on the activities of acid phosphatase (AP) than ammonium. The activities of N-acquisition specific enzymes (enzyme activities normalized by total PLFA contents) were about 21 and 43% lower in the ammonium and nitrate treatments than in the control, respectively. However, the activities of P-acquisition specific enzymes were about 19% higher in the ammonium treatment than in the control. Using redundancy analysis (RDA), we found that the measured C, N, and P hydrolysis and polyphenol oxidase (PPO) activities were positively correlated with the soil pH and ammonium contents, but were negatively correlated with the nitrate contents. The PLFA biomarker contents were positively correlated with soil pH, soil organic carbon (SOC), and total N contents, but were negatively correlated with the ammonium contents. The soil enzyme activities varied seasonally, and were highest in March and lowest in October. In contrast, the contents of the microbial PLFA biomarkers were higher in October than in March and June. Ammonium may inhibit the contents of PLFA biomarkers more strongly than nitrate because of acidification. This study has provided useful information about the effects of ammonium and nitrate on soil microbial communities and enzyme activities.