水氮条件对南亚热带玉米产量及农田土壤有机碳氮组分的影响

Effects of Water and Nitrogen Conditions on Subtropical Maize Yield and Soil Organic Carbon and Nitrogen Components in Sub-Tropical Soils

为探究水氮条件对玉米产量及农田土壤碳氮的影响,试验于2018年在广西一年两季玉米种植区春玉米和秋玉米生长季进行。玉米品种为万川1306,种植密度为59524株/hm^(2),行株距为60 cm×28 cm,小区面积为16.8 m^(2)。试验采用裂区试验设计,主处理水分条件分别为雨养和灌溉,副处理施氮量分别为0 kg/hm^(2)(N_(0))、150 kg/hm^(2)(N_(1))、200 kg/hm^(2)(N_(2))、250 kg/hm^(2)(N_(3))和300 kg/hm^(2)(N_(4))。在玉米成熟期采集土壤耕层(0~20 cm)样品,测定土壤有机碳、土壤微生物量碳、土壤有机氮组分。试验结果表明:同一处理条件下,土壤有机氮各组分含量表现为酸解铵态氮≈氨基酸态氮>酸解未知氮>氨基糖态氮。春玉米,灌溉结合N_(3)的产量达到最大,为7806 kg/hm^(2),秋玉米,灌溉与雨养产量基本持平。施氮量与作物产量呈极显著正相关(P<0.01),但当施氮量超过250 kg/hm^(2)时,产量不再显著增加。酸解总氮与作物产量呈极显著正相关(P<0.01)。广西春玉米在阶段性干旱条件下,适时合理补水结合250 kg/hm^(2)施氮量,具有较好的土壤供碳氮潜力,并获得较高产量。

In order to investigate the effects of water and nitrogen conditions on maize yield and soil carbon and ni-trogen,the experiment was carried out in 2018 in maize and autumn maize growing season in the maize growing re-gion of Guangxi.The variety is Wanchuan 1306,the planting density is 52,500 plants/ha,row spacing was 60 cm,and the plot area is 16.8 m^(2).Split plot design was used in the experiment.The main treatment water conditionswere rain-fed and irrigation,and the nitrogen application rates were 0 kg/ha(N_(0)),150 kg/ha(N_(1)),200 kg/ha(N_(2)),250 kg/ha(N_(3)),300 kg/ha(N_(4)).Soil organic carbon,soil microbial biomass carbon and soil organic nitrogen compo-nents were measured in soil surface layer(0-20 cm)at maize maturity stage.The result showed that the order of soilorganic nitrogen was amino acid nitrogen≈ammonia nitrogen>acid hydrolysis unknown nitrogen>amino sugar ni-trogen.In spring maize,the yield of irrigation combined with N_(3) reached the highest value,which was 7,806 kg/ha,and in autumn maize,the yield of irrigation and rain-fed was basically the same.There was a significant positive cor-relation between nitrogen application rate and crop yield(P<0.01),but excessive nitrogen application could not sig-nificantly increase crop yield.Soil microbial biomass carbon was positively correlated with crop yield(P<0.01).Un-der the condition of periodic drought,spring maize in Guangxi had better soil potential of carbon and nitrogen sup-ply and higher yield with proper water supply and nitrogen application rate of 250 kg/ha.