施氮对不同紫花苜蓿品种氮积累及土壤氮动态变化的影响

在甘肃省秦王川灌区种植"甘农3号"和"陇东苜蓿"的紫花苜蓿(Medicago sativa)试验田,采用完全随机区组设计,设置3个施氮水平0,51.75和103.50 kg(N)·hm^-2(记为N0,N51.75,N103.50),研究施氮对不同紫花苜蓿品种氮积累及土壤氮动态变化的影响。结果表明:施氮可以提高西北荒漠灌区紫花苜蓿物质积累,紫花苜蓿植株干物质积累和氮积累随施氮量的增加而增加,在N103.50水平下最高,经回归分析得出施氮量与干物质积累和氮素积累之间符合一元二次方程;施氮可以显著提高西北荒漠灌区刈割苜蓿田土壤碱解氮含量,对全氮含量没有太大影响。因此,西北灌区紫花苜蓿适宜施氮量为103.50 kg(N)·hm^-2,为了使紫花苜蓿达到更高产量,应在每次刈割后补施氮肥。

Effect of Nitrogen Fertilizer on Nitrogen Accumulation in Alfalfa and the Content of Nitrogen in Soil

Gannong No.3' and 'Longdong alfalfa' were used as test materials in Qinwangchuan. Based on the method of randomized block design,3 levels of N treatments that were 0,51.75 and 103.50 kg·hm^-2(N0,N51.75,N103.50) were applied, and the effect of nitrogen fertilizer on dry matter and nitrogen accumulation in alfalfa and available N and total N in soil were studied. The results were summarized as follows:Nitrogen improved the northwest desert alfalfa matter accumulation in the irrigation area.Dry matter accumulation and nitrogen accumulation in alfalfa increased with the increase of N application. By regression analysis, N level and dry matter accumulation or nitrogen accumulation data fit to a quadratic equation with one variable. Dry matter accumulation and nitrogen accumulation reached the highest on the 103.50 kg·hm^-2 level; Nitrogen significantly improved alkaline hydrolysis nitrogen content of alfalfa field in irrigation area of the northwest desert.The study suggested that the optimum N level in alfalfa in Gansu Province was 103.50 kg·hm^-2. To achieve higher yield of alfalfa, we suggest applying nitrogen after each harvest(or cutting).