长期氮磷配施对褐土细菌多样性及土壤酶活性的影响

Effects of long-term combined application of nitrogen and phosphorus on bacterial diversity and soil enzyme activities in cinnamon soil

为探明不同氮磷化肥配施对土壤细菌群落结构和酶活性的影响,以山西寿阳褐土长期施肥定位试验为依托,选择5个施肥处理:CK(不施肥)、N_(1)P_(1)(N:60 kg·hm^(-2);P:37.5 kg·hm^(-2))、N_(2)P_(2)(N:120 kg·hm^(-2);P:75 kg·hm^(-2))、N_(3)P_(3)(N:180 kg·hm^(-2);P:112.5 kg·hm^(-2))和N_(4)P_(4)(N:240 kg·hm^(-2);P:150.0 kg·hm^(-2)),采集玉米收获后耕层(0~20 cm)土样,通过Illumina HiSeq高通量测序技术,对土壤细菌16S rRNA的V3-V4区进行测序;采用比色法测定土壤蔗糖酶、脲酶和碱性磷酸酶活性,分析细菌群落结构与土壤酶活性之间的相关性。结果表明,4个氮磷配施处理均提高了土壤养分及玉米产量。与CK相比,N1P1、N2P2、N3P3和N4P4处理中,碱解氮、有效磷、有机质及玉米产量的增加率分别为3.3%~60.9%,120.1%~862.6%,7.9%~18.4%和63.9%~86.1%。随着氮磷施用量的增加,细菌α-多样性在N1P1处理中达到最高,之后呈现下降趋势;β-多样性分析发现,不同氮磷配施显著影响细菌群落结构。RDA分析表明,土壤有效磷和全氮对细菌群落结构差异的贡献率最大。随着氮磷施用量的增加,脲酶活性逐渐升高,碱性磷酸酶和蔗糖酶的活性呈现降低趋势。因此,化肥施用过量,不利于土壤中细菌多样性及土壤酶活性的维持和提高。

To explore the effects of different combinations of nitrogen and phosphorus fertilizer application on soil bacterial community structure and enzyme activities,five fertilization treatments were set up based on the long-term fertilization experiment in cinnamon soil of Shouyang,Shanxi Province.The treatments included CK(no fertilizer),N_(1)P_(1)(N:60 kg·hm^(-2);P:37.5 kg·hm^(-2)),N_(2)P_(2)(N:120 kg·hm^(-2);P:75 kg·hm^(-2)),N_(3)P_(3)(N:180 kg·hm^(-2);P:112.5 kg·hm^(-2))and N_(4)P_(4)(N:240 kg·hm^(-2);P:150.0 kg·hm^(-2)).Soil samples from the tillage layer(0~20 cm)after maize harvest were collected,and the V3-V4 region of soil bacteria 16S rRNA was sequenced by Illumina HiSeq high-throughput sequencing technology.The activities of soil sucrase,urease and alkaline phosphatase were measured by colorimetric method,and the correlation between bacterial community structure and soil enzyme activities was analyzed.The results showed that the combined application of nitrogen and phosphorus increased soil nutrients and maize yield.Compared with CK,the yield of maize under N1P1,N2P2,N3P3 and N4P4 treatments increased by 3.3%~60.9%,120.1%~862.6%,7.9%~18.4%and 63.9%~86.1%,respectively.With the increase of nitrogen and phosphorus application rates,bacterialα-diversity reached the highest in N1P1 treatment,and then showed a downward trend.β-diversity analysis indicated that different nitrogen and phosphorus combinations significantly affected bacterial community structure.RDA analysis showed that soil available phosphorus and total nitrogen contributed the most to the difference of bacterial community structure.With the increase of nitrogen and phosphorus application amount,urease activity increased gradually,while alkaline phosphatase and sucrase activity displayed a trend of decrease.Therefore,excessive application of chemical fertilizer was not conducive to the maintenance and improvement of soil bacterial diversity and soil enzyme activity.