【摘要】 在陕西永寿和河南洛阳进行2年大田试验,研究铵态和硝态氮肥在小麦不同播期施用和播前15~20天施用的效果。试验设不施氮、施铵态氮和硝态氮各100kg/hm2 3个处理;试验期间分别测定根际与非根际土壤铵、硝态氮和pH变化,以及不同时期植物体内铵态氮、硝态氮和酰胺态氮的含量。试验表明,在硝态氮含量低的土壤上,硝态氮肥效果一般优于铵态氮肥,但效果大小和播期早晚、施氮早晚有关。早期播种硝态氮对籽粒增产量比铵态氮高出0.68倍,晚期播种增产1.75倍;播前15天施氮,硝态氮和铵态氮的增产率分别为10.7%和8.8%,无显著差异,而晚期施氮,分别为10.5%和6.2%,差异显著。施用硝态氮,小麦根际土壤pH有上升而施用铵态氮有下降现象,升降幅度为0.1左右pH单位。非根际土壤向根际土壤的养分传输低于作物吸收速率,根际内土壤的硝态氮有耗竭现象,非根际土壤硝态氮平均浓度为11.7mg/kg,而根际土壤仅为4.4mg/kg,后者仅为前者的38%。硝态氮肥不但能使小麦吸收较多的硝态氮,而且能将吸收的硝态氮较快地转化为铵态氮和酰胺态氮,及时转送到茎叶生长部位,对保证作物氮素营养有更好效果。更多还原

【Abstract】 Field experiments were conducted for two years in Yongshou,Shaanxi Province,and Luoyang,Henan Province,to study the effects of application of nitrate and ammonium nitrogen(N)at different wheatsown time and at 15~20 days before wheat sowing on wheat yield.Trials included three treatments,control(without N fertilization),and application of nitrate N and ammonium N at a rate of 100 kg N/hm2 as basal fertilizer.During the plant growing period,soil pH,concentrations of ammonium N and nitrate N were determined in rhizosphere and non-rhizosphere soil,and those of nitrate N,ammonium N and amide N in plants were measured at three wheat growing stages.Results showed that in soils deficient in nitrate N,effect of nitrate N fertilizer was generally superior to ammonium N.However,the effect magnitudes of the two N forms were determined by wheat-sown time and N applied date.When wheat was sown earlier than usual,nitrate N increased seed yield by 0.68 times while when sown later,it increased by 1.75 times compared to ammonium N.Similarly,application of N fertilizer 15 days earlier before wheat sowing,nitrate N and ammonium N increased seed yield by 10.7% and 8.8%,respectively,and there was no significant difference between the two N forms.In contrast,when applied time was delayed,their increases were 10.5% and 6.2%,respectively,being significant at 0.05 level.Soil pH in rhizosphere increased with application nitrate N while decreased with ammonium N addition,the increase or decrease being varied around 0.1pH unit.The transfer of nitrate N from non-rhizosphere to rhizosphere soil was so slow that depletion of nitrate N occurred in rhizosphere soil:The concentration of nitrate N was 11.7 in non-rhizosphere soil while 4.4mg/kg in rhizosphere,the latter being 38% of the former.Compared to ammonium N,application of nitrate N not only increased nitrate N concentrations in wheat plants,but ammonium N and amide N concentrations as well.Due to the rapid transformation of the mineral N taken up in plants and timely transferred to shoots,fertilization of nitrate N ensured a beneficial N nutrition environment for wheat growth.更多还原