DOI: 10.13930/jki.cjea.210002
孙瀚, 屈杰, 王晓雯, 郑文魁, 李成亮, 刘艳丽. 黄河三角洲盐渍土有机氮组成及氮有效性对土壤含盐量的响应[J]. 中国生态农业学报(中英文), 2021, 29(8): 1397 1404
SUN H, QU J, WANG X Wicod, ZHENG W K, LI C L, LIU Y L. The respon of soil organic nitrogen fractions and nitrogen availability to salinity in saline soils of the Yellow River Delta[J]. Chine Journal of Eco-Agriculture, 2021, 29(8): 1397 1404
黄河三角洲盐渍土有机氮组成及氮有效性
对土壤含盐量的响应*versace是什么意思
孙 瀚, 屈 杰, 王晓雯, 郑文魁, 李成亮, 刘艳丽**
(土肥资源高效利用国家工程实验室/山东农业大学资源与环境学院 泰安 271018)
摘 要: 土壤盐分胁迫下有机氮组成及氮有效性对黄河三角洲盐渍土壤肥力的形成和生产力的提高具有重要作用。本研究采集黄河三角洲盐渍土壤区小麦-玉米轮作的3种盐渍土壤, 分别为
轻度盐渍土(含盐量2.28 g∙kg–1, S1)、中度盐渍土(含盐量3.73 g∙kg–1, S2)和重度盐渍土(含盐量6.69 g∙kg–1, S3), 分析不同盐分含量土壤的作物产量和土壤有机氮组分含量、无机氮含量、微生物生物量氮含量及相关酶活性等指标的变异特征, 明确盐分含量对土壤有机氮组成及氮有效性的影响。结果表明: 3种土壤中有机氮的酸解总氮含量是有机氮的主要组分, S1、S2和S3处理下分别占土壤总有机氮68.79%、61.60%和52.30%; 不同处理下各形态含量酸解总氮为酸解铵态氮>酸解未知氮>酸解氨基酸氮>酸解氨基糖氮, 且各形态含量均以S1处理显著高于S2和S3处理(P<0.05)。非酸解氮含量在3种处理间差异不显著, 且均低于酸解总氮含量, 其占全氮比例随土壤含盐量增加而提高。S1处理土壤硝态氮含量(22.08 mg∙kg–1)和微生物生物量氮含量(20.71 mgajk∙kg–1)最高, 显著高于其他两种处理的土壤(love story 安室奈美惠P英语卡通电影<0.05); 铵态氮含量在各处理下差异不显著。S1处理的小麦、玉米总产量分别是S2和S3的1.74倍和5.85倍。回归分析发现土壤可溶性全盐含量分别与土壤无机氮、微生物生物量氮含量呈显著的负指数关系, 与小麦、玉米总产量、氨基酸态氮含量之间存在显著的负线性关系。土壤无机氮含量与土壤酸解总氮含量之间呈显著的正指数关系。土壤中较高含量的可溶性全盐抑制土壤酸解有机氮的形成及氮素有效性的提高。
关键词: 盐渍土壤; 小麦-玉米轮作; 土壤无机氮; 土壤有机氮; 土壤微生物生物量氮; 土壤可溶性全盐
中图分类号: S153.6 小学培训班
The respon of soil organic nitrogen fractions and nitrogen availability to salinity in saline soils of the Yellow River Delta*
SUN Han, QU Jie, WANG Xiaowen, ZHENG Wenkui, LI Chengliang, LIU Yanli**
(National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources / College of Resources and Environment, Shandong Agricultural University, Tai’an 271018, China)
Abstract: The soil organic nitrogen composition and nitrogen availability play important roles in the soil fertility and agricultural production of saline soils. This study investigated the effects of soil salinity on soil organic nitrogen fractionation and nitrogen availability in
saline soils of the Yellow River Delta (YRD). Soil samples were taken from three wheat-maize rotation fields with low (2.28 g∙kg–1, S1), moderate (3.73 g∙kg–1, S2), and high (6.69 g∙kg–1, S3) salinities on the Huibang Bohai Farm in the YRD. The crop yields were recorded, and the soil organic nitrogen fractions, including ammonia nitrogen (AN), amino acid nitrogen (AAN), amino sugar nitrogen (ASN), hydrolyzable unknown nitrogen (HUN), non-hydrolyzable nitrogen (NHN), soil inorganic nitrogen, and microbial biomass nitrogen were quantified. The activities of the nitrogen transformation-related enzymes (i.e., urea, protea, and nitrate reducta) were determined, and the relationships between the soil organic nitrogen fractions, inorganic nitrogen, crop yield, and soil salinity were analyzed. The results showed that total acid hydrolyzable nitrogen (TAHN), which is the sum of AN, AAN, ASN, and HUN, was the main fractions of soil organic nitrogen, taking up 68.79%, 61.60%, and 52.30% of the total organic nitrogen in S1, S2, and S3 soils, respectively. The contents of the four TAHN fractions (AN, AAN, ASN, and HUN) were all significantly higher in S1 than in S2 and S3 (P<0.05), and the contents of AN, AAN, and HUN were all significantly higher in S2 than in S3 (P<0.05). The contents of the fraction
s were AN > HUN > AAN > ASN in S1, and AN > AAN > HUN > ASN in S2 and S3. Converly, the NHN content was in the order of S1 > S2 > S3, but the differences were not significant (P>0.05). For the same soil, the NHN content was lower than the TAHN content. The highest soil nitrate nitrogen content (22.08 mg∙kg–1) and microbial biomass nitrogen (20.71 mg∙kg–1) were found in S1, which was significantly higher than tho in S2 and S3 (P<0.05). The ammonium nitrogen content did not differ among the three soils. The activities of urea and nitrate reducta were in the order of S1 > S2 > S3, and the differences were significant (event是什么意思P<0.05). Protea activity was significantly higher in S1 than in S2 and S3 (P<0.05). The total yield of wheat and maize in S1 was 1.74 times of that in S2 and 5.85 times of that in S3. Correlation analys showed that the inorganic nitrogen, microbial biomass nitrogen, AN, and HUN contents had negative exponential relationships with the soil total soluble salt content, whereas the total yield of wheat and maize and the AAN content had significant negative linear relationships with the soil total soluble salt content. The soil inorganic nitrogen content was significantly and positively correlated with the soil TAHN content. The high total soluble salt content in the soils inhibi
ted the formation of acid hydrolyzable organic nitrogen and improved the soil nitrogen availability. The results provide theoretical support for the regulation of soil nitrogen availability in saline soils in the YRD.
Keywords: Saline soil; Wheat-maize rotation; Soil inorganic nitrogen; Soil organic nitrogen; Soil microbial biomass nitrogen; Total soluble salt in soil
黄河三角洲土壤盐渍化现象较为普遍, 盐分胁迫下土壤有机氮的存在形态及氮素有效性对盐渍土壤肥力的保持与调控尤为重要[1-2]。有机氮是土壤氮素的主要组成, 是土壤无机氮的源与汇, 土壤无机氮是土壤氮素的有效形态[3-5]。土壤有机氮在微生物和酶的作用下转变为无机态氮而直接供作物吸收利用[6-7]。研究发现黄河三角洲不同开垦年限的小麦(Triticum aestivum)-玉米(Zea mays)轮作土壤, 随开垦年限增加, 土壤全盐含量降低, 表层土壤全氮和碱解氮含量呈增加趋势[8]。而盐化条件下砂壤土氮素添加的培养试验发现, 盐化并未直接影响土壤氮素的有效形态, 外源无机氮的添加通过促进土壤微生物的活性而改变土壤氮的有
效性, 外源硝态氮比铵态氮对土壤微生物生物量氮含量的增加具有更强的促进作用hlod[9]。以上研究说明土壤微生物活性影响土壤有机氮的分解作用[10-11]。黄河三角洲地区盐渍土壤氮转化的培养试验结果发现, 土壤盐分含量达2.9 g∙kg–1时显著地抑制土壤氮素有效化进程, 降低土壤有效氮含量, 使土壤肥力明显低于非盐渍土壤[12]自戕。但是盐化条件下土壤盐分含量对土壤氮素有效性的影响及与土壤不同形态氮含量之间的定量关系尚未明确。
盐分胁迫下土壤微生物及酶活性的变化影响土壤有机氮的分解作用。关于土壤盐分对土壤微生物活性影响的模拟试验和培养试验研究表明: 土壤微生物数量、生物量和土壤酶活性均与盐分的添加量呈负相关关系[13-14], 土壤盐分含量>5 g∙kg–1显著降低了土壤微生物活性及对外源碳的利用率[15]。不同盐碱化草地的研究发现随盐碱化程度的增大其微生物数量逐渐减少, 酶活性不断减弱, 土壤全氮与碱解氮含量也随之降低[16]all什么意思。对盐渍土壤有机氮组成中氨基糖氮含量变异特征的研究发现, 轻度盐渍土氨基糖氮含量显著高于中度盐渍土, 而不同种类氨基糖氮含量对盐渍土的响应因微生物种类不同而有所差异[17]。有关东北滨海盐渍水稻土开垦年限对土壤有机氮含量影响的研究发现, 与未开垦旱地土壤相比, 种植水稻(Oryza sativa) 5年和30年均使表层土壤酸解全氮含量明显下降, 但种植水稻5年使土壤酸解
氨基酸态氮和氨基糖态氮含量及其占全氮比率明显增加, 氨态氮和未知态氮的含量及其占全氮比率明显下降[18]。非盐渍土壤的研究发现, 不同土壤有机氮组成对土壤有机氮矿化的贡献存在差异[19]。由此说明不同开垦年限下土壤有机氮含量影响土壤氮素的有效性, 但是盐化条件下盐分含量对盐渍土壤有机氮组成及土壤氮素有效性影响的量化关系尚不明确。因此, 本研究选择黄河三角洲连续小麦-玉米轮作的3种盐分含量土壤, 以土壤无机氮含量表征土壤氮素的有效性, 分析土壤有机氮组成及含量、微生物生物量氮含量及与氮素转化相关的酶活性, 研究盐分含量变化与土壤不同形态氮含量之间的定量关系, 明确盐分含量对土壤氮素有效性的影响, 为黄河三角洲盐渍土壤氮素有效性的调控提供数据支持和理论依据。
