配施有机肥减氮对川中丘区土壤微生物量与酶活性的影响

通过田间减施氮肥试验,设置减氮20%+不施有机肥(N_1O_0),减氮20%+普通有机肥(N_1O_1),减氮20%+生物有机肥(N_1O_2),减氮40%+不施有机肥(N_2O_0),减氮40%+普通有机肥(N2O1),减氮40%+生物有机肥(N_2O_2)处理,以不施肥(CK0)和全氮100%(N_(100))为对照,研究配施有机肥减氮对川中丘区玉米土壤微生物量碳、土壤酶活性及玉米产量的影响,为玉米生产减氮增效提高玉米氮素利用率提供理论依据。结果表明:随施氮量减少土壤脲酶、蔗糖酶、过氧化氢酶活性及微生物量碳含量逐渐降低,较N_(100)相比,N_1O_0、N_2O_0分别吐丝期微生物量碳降低25.6,35.08mg/kg;大喇叭口期脲酶降低11.1%和14.1%;蔗糖酶降低30.4%,97.1%;产量降低921.98,1 719.62kg/hm~2。配施有机肥提高了土壤脲酶、蔗糖酶、过氧化氢酶活性及微生物量碳含量和玉米产量。与N_1O_0相比N_1O_1、N_1O_2,土壤微生物量碳增加38.57%和54.45%;脲酶活性提高9.73%和14.82%;蔗糖酶提高42.75%和64.26%;过氧化氢酶提高11.05%和11.93%;增产2%和6%,且N_1O_2较N_1O_1产量提高4.0%。配施生物有机肥减氮20%降低了玉米秃尖长、增加了穗长、穗粒数、百粒重,玉米产量为8 710.83kg/hm~2。土壤微生物量碳、酶活性与玉米产量呈显著或极显著相关。说明配施生物有机肥减氮20%,可以提高玉米生育期土壤微生物量碳、土壤酶活性,改善植株根系生长环境,促进玉米产量增加。

Effects of Reducing Nitrogen and Applying Organic Fertilizers on Soil Microbial Biomass Carbon and Enzyme Activity in the Hilly Area of Central Sichuan Basin

Two random block experiments were conducted to study the effects of reducing nitrogen and applying organic fertilizers on soil microbial biomass carbon and enzyme activity in the hilly area of central Sichuan basin.The treatments included different types of organic fertilizers and different application rates of nitrogen fertilizers (reducing 20 ％ of nitrogen + without organic fertilizer N1 O0,reducing 20 ％ of nitrogen-+-ordinary organic fertilizer N1O1,reducing 20％ of nitrogen + biological organic fertilizer N1O2,reducing 40％ of nitrogen + without organic fertilizer N2O0,reducing 40％ of nitrogen + ordinary organic fertilizer N2O1,reducing 40％ of nitrogen + biological organic fertilizer N1 O2).Two control treatments (CK0.:No fertilizer;N100:Nitrogen100％) was established in order to study the effects of reducing nitrogen on increasing benefits and raising the utilization efficiency of nitrogen.The results showed that with the decrease of nitrogen fertilizer application rate (N1O0,N2O0),the activities of soil urease,invertase and catalase,and the contents of microbial biomass carbon showed decreasing trends.Compared with N100,N1O0 and N2 N0 the content of microbial biomass carbon was decreased by 25.6 mg/kg and 35.08 mg/kg at the silking stage;the urease activity was decreased by 11.1％ and 14.1％,and the invertase activity was decreased by 30.4％ and 97.1％ at the big trumpet stage.The yield was decreased by 921.98 kg/hm2 and 1 719.62 kg/hm2,respectively.The experiment also showed that using organic fertilizers could increase the activities of soil urease,invertase and catalase,the contents of microbial biomass carbon content and grain yield.Compared with N1 O0,the contents of microbial biomass carbon was increased by 38.57％ and 54.45％,the activity of urease was increased by 9.73％ and 14.82％,the activity of invertase was increased by 42.75％ and 64.26％,and the activity of catalase was increased by 11.05％ and 11.93％,and the yield was increased 2％ and 6 ％ by N1O1 and N1O2,respectively,with N1O2 increasing the yield by 4％ more than N1O1.Reducing 20％ of nitrogen and using organic fertilizers reduced bare top length,increased spike length,ear rows,100 kernel weight and grain yield.The correlation between the content of soil microbial biomass carbon,the activities of soil enzyme and the yield was significant or extremely significant.Reducing 20％ of nitrogen fertilizer and applying biological organic fertilizer could not only improve maize yield,biomass carbon,soil enzyme activity significantly,but also improve the condition of plant root growth to promote maize yield in the upper dome area under poor siltstone soil conditions.