不同比例硫酸铵替代尿素对玉米根际土壤环境及微生物群落的影响

Effects of Different Proportions of Ammonium Sulfate Replacing Urea on Soil Nutrientsand Rhizosphere Microbial Communities

为了探究工业副产物硫酸铵以不同比例替代尿素做为氮肥施入土壤后对土壤养分以及微生物群落的影响,进行了盆栽玉米试验.试验采用完全随机设计方法,共设置5个处理:CK(不施肥)、U_(10)S_(0)(100%尿素)、U_(8)S_(2)(80%尿素+20%硫酸铵)、U_(6)S_(4)(60%尿素+40%硫酸铵)和U_(0)S_(10)(100%硫酸铵).应用常规方法进行土壤基本理化性质以及玉米植株干重的测定,通过Illumina Nova Seq平台进行微生物测序.结果表明:①在玉米的各个生育期,施肥处理土壤p H(7.85~8.15)与CK(8.1~8.21)相比都有所下降,并且随着硫酸铵比例的增加p H呈不断下降的趋势;②在玉米各生育期土壤碱解氮含量随着硫酸铵比例的增加呈逐渐增加的趋势,U_(0)S_(10)处理比CK和U_(10)S_(0)处理分别提高了30.56%~63.68%和13.22%~38.43%;有机碳含量变化趋势为:U_(8)S_(2)>U_(6)S_(4)>U_(0)S_(10),但除苗期以外其他生育期添加硫酸铵的处理都仍高于U_(10)S_(0)处理;③所有的施肥处理蛋白酶活性都高于对照,并且随着玉米的不断生长和硫酸铵比例的增加蛋白酶活性逐渐增强,U_(0)S_(10)处理在玉米各生育期都高于U_(10)S_(0)处理,提高了10.54%~100%;各施肥处理土壤蔗糖酶活性范围为0.04~0.24 mg·(g·24 h)^(-1),并在所有生育期U_(0)S_(10)处理都显著高于U_(10)S_(0)和CK处理,分别提高了20.32%~99.16%、24.31%~79.33%;④所有施肥处理的玉米根际细菌和真菌物种丰富度都低于CK处理,U_(10)S_(0)处理仅低于CK,硫酸铵替代尿素的3个处理细菌群落物种多样性趋势为:U_(8)S_(2)>U_(0)S_(10)>U_(6)S_(4),真菌为:U_(6)S_(4)>U_(8)S_(2)>U_(0)S_(10);⑤U_(0)S_(10)和U_(10)S_(0)处理玉米植株干重最大,分别比CK处理提高了39.47%和36.16%,U_(0)S_(10)处理高于U_(10)S_(0)处理但差异不显著;Pearson模型表明相关环境变量对土壤根际真菌和细菌物种丰富度和多样性有一定影响,其中p H值和土壤碱解氮含量是影响微生物物种多样性的最主要因素.综上,在石灰性褐土的玉米种植中,以一定比例硫酸铵替代尿素比单施尿素更能提高土壤养分,在一定程度上影响了玉米生长及根际微生物群落,并且有更大的产出.

In order to investigate the effects of ammonium sulfate,an industrial by-product,on soil nutrients and microbial community when applied in different proportions instead of using urea as nitrogen fertilizer,a pot corn experiment was conducted.A completely randomized block experimental design was used,with a total of five treatments:CK(no fertilization),U_(10)S_(0)(100%urea),U_(8)S_(2)(80%urea+20%ammonium sulfate),U6S(460%urea+40%ammonium sulfate),and U_(0)S_(10)(100%ammonium sulfate).The basic physical and chemical properties of soil and the dry weight of maize plants were determined by conventional methods,and microbial sequencing was performed using the Illumina NovaSeq platform.The experiment results showed that:①In each growth stage of maize,the pH of soil treated with fertilization(7.85-8.15)was decreased compared with that of CK(8.1-8.21),and the pH showed a decreasing trend with the increase in ammonium sulfate content.②The soil available nitrogen content increased gradually with the increase in the ammonium sulfate ratio at each growth stage of maize.Compared with that in the CK and U_(10)S_(0)treatments,the ratio in the U_(0)S_(10)treatment increased 30.56%to 63.68%and 13.22%to 38.43%,respectively.The variation trend of organic carbon content was opposite to that of available nitrogen(U_(8)S_(2)>U_(6)S_(4)>U_(0)S_(10)),and the addition of ammonium sulfate was still higher than that of U_(10)S_(0)at other growth stages except for the seedling stage.③The protease activity of all fertilization treatments was higher than that of the control,and the protease activity was gradually enhanced with the continuous growth of corn and the increase in the ammonium sulfate ratio.The protease activity of the U_(0)S_(10)treatment was higher than that of the U_(10)S_(0)treatment at each growth stage of corn,which increased by 10.54%-100%.Soil sucrase activity ranged from 0.04 to 0.24 mg∙(g∙24 h)^(-1),and those in the U_(0)S_(10)treatments were significantly higher than those in the U_(10)S_(0)and CK treatments at all growth stages,increasing by 20.32%to 99.16%and 24.31%to 79.33%,respectively.④The species abundance of bacteria and fungi in maize rhizosphere under all fertilization treatments were lower than those under the CK treatment,followed by those under the U_(10)S_(0)treatment.The species diversity trend of the bacterial community in the three treatments with ammonium sulfate replacing urea were U_(8)S_(2)>U_(0)S_(10)>U_(6)S_(4),and that of fungi were U_(6)S_(4)>U_(8)S_(2)>U_(0)S_(10).⑤The maize dry weight of the U_(10)S_(0)treatment and U_(0)S_(10)treatment was the highest,which was 39.47%and 36.16%higher than that of the CK treatment,respectively,but the difference was not significant.The Pearson model showed that the species abundance and diversity of soil rhizosphere fungi and bacteria were affected by relevant environmental variables,among which pH value and soil available nitrogen content were the most important factors affecting microbial diversity.In conclusion,when corn planting in calcareous brown soil,replacing urea with a certain proportion of ammonium sulfate can improve soil nutrients more than urea alone,which affects the growth and rhizosphere microbial community of corn to a certain extent and has a greater yield.