| 樊代佳,李成芳,曹凑贵.氮肥深施对免耕稻田土壤有机质化学特性和胞外酶活性的影响[J].农业环境科学学报,2021,40(3):621-630. |
| 氮肥深施对免耕稻田土壤有机质化学特性和胞外酶活性的影响 |
| Effects of nitrogen deep placement on chemical properties of soil organic matter and extracellular enzyme activity in no-tillage paddy fields |
| 投稿时间：2020-09-24 |
| DOI：10.11654/jaes.2020-1125 |
| 中文关键词: 氮肥深施 免耕稻田 腐殖质 胞外酶 热裂解气相色谱/质谱 |
| 英文关键词: nitrogen deep placement no-tillage paddy humus extracellular enzyme pyrolysis-gas chromatography/mass spectrometry |
| 基金项目:国家重点研究计划项目（2017YFD0301403）；国家自然科学基金项目（31671637）；湖北省自然科学基金项目（2018CFB608） |
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| 中文摘要: |
| 为了探究氮肥深施措施对免耕稻田土壤有机质化学特性及土壤酶活的影响机制，于2015—2016年在湖北省武穴市花桥镇试验点开展水稻-油菜免耕复种大田试验。本试验通过13C核磁共振和热裂解气相色谱/质谱联用法测定土壤有机质的化学特性，通过冗余分析揭示土壤有机质化学特性及土壤胞外酶活性之间的相互作用关系。结果表明，与传统表施相比，氮肥深施提高腐殖质中胡敏酸的有机碳含量（10.5%~30.7%）、轻组有机质的有机碳含量（31.7%~53.5%）、胡敏酸的疏水性（1.3%~11.6%）和轻组有机质中多糖与脂质的含量（9.0%~24.1%和43.4%~68.3%），降低土壤β-葡萄糖苷酶（BG）（22.2%~48.9%）和β-N-乙酰氨基葡糖苷酶（NAG）活性（32.7%~40.4%），提高L-亮氨酸氨基肽酶（LLA）（37.1%~38.5%）和酚氧化酶（PHO）活性（11.0%~16.0%）。冗余分析显示，土壤有机质的化学特性与LLA和PHO活性呈正相关，与BG和NAG活性呈负相关。本研究结果表明，与传统表施相比，氮肥深施尤其是深施10 cm主要通过促进作物和微生物群落生长提高土壤胡敏酸和轻组有机质的有机碳含量，且通过调控土壤BG、NAG和PHO活性改变胡敏酸和轻组有机质的化学组成与性质，从而改善土壤惰性有机质稳定性且提高活性有机质，最终提高土壤肥力和质量。因此氮肥深施尤其是深施10 cm值得在免耕稻田生产中得到进一步推广。 |
| 英文摘要: |
| This study investigated the impacts of N deep placement on the chemical properties of soil organic matter(SOM) and soil enzyme activity in no-tillage(NT) paddy soil. Multiple cropping of rice and rapeseed was carried out under NT in the experimental site located in Huaqiao County, Wuxue City, Hubei Province from 2015 to 2016. The growing seasons of rice and rapeseed were from June to October and from October to May of the next year, respectively. Five fertilizing treatments, including no N fertilizer(CK), N surface broadcasting(SB), and N deep placement at soil depths of 5 cm, 10 cm(10D), and 20 cm were applied with three replicates per treatment. The soil organic carbon(SOC) contents of different SOM fractions, the chemical compositions and properties of humic acid(HA) and light fraction organic matter(LFOM), and the activities of different soil enzymes were determined. Redundancy analysis was carried out to reveal the relationships between the chemical properties of SOM and enzyme activity. The results showed that compared with SB, N deep placement significantly increased the SOC contents in the HA and LFOM by approximately 10.5%~30.7% and 31.7%~53.5%, respectively. The hydrophobicity of HA under N deep placement was 1.3%~11.6% higher than that under SB. Moreover, N deep placement significantly improved the contents of polysaccharides and lipids in the LFOM by 9.0%~24.1% and 43.4%~68.3%, respectively. Compared with those under SB, N deep placement significantly inhibited the activities of β-glucosidase(BG) and β-N-acetylglucosaminidase(NAG) by 22.2%~48.9% and 32.7%~40.4%, respectively, whereas it significantly stimulated the activities of L-leucine aminopeptidase(LLA) and phenol oxidase(PHO) by 37.1%~38.5% and 11.0%~16.0%, respectively. In addition, the redundancy analysis showed that the contents and hydrophobicity of HA and the contents of polysaccharides and lipids in the LFOM were positively correlated with the LLA and PHO activities and negatively correlated with the BG and NAG activities. The results demonstrated that the chemical compositions and properties of humus and LFOM were regulated by the soil enzyme activity. Nitrogen deep placement decreased the humus aromaticity by stimulating the PHO activity and increased the polysaccharide contents in the LFOM by inhibiting the BG and NAG activities. Moreover, compared with those under SB, N deep placement, especially 10D, increased the SOC contents in the HA and LFOM mainly by activating the growth of crops and microbial communities, and altered their chemical properties and compositions mainly through regulating the activities of BG, NAG, and PHO, thereby promoting the soil fertility and quality. Therefore, it is worthwhile to further advocate for and improve the application of 10D placement in NT paddy fields. |
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