【作者】 刘健；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育， 2010， 硕士

【摘要】 氮肥是林业生产中必需的肥料之一,由于不合理的管理措施,虽有大量的氮肥施入土壤,但植物对氮素的利用率却很低,氮素损失严重。其中,淋溶作用是氮素损失的重要途径之一,氮素在土壤中的运移主要由施肥量,降水量,土壤性质等因素决定。研究不同施肥量条件下土壤氮素的淋溶规律可以为合理施肥提供理论依据,一方面可以减少施肥后由于土壤的淋溶作用带来的损失,节约成本：另一方面也可以防止淋溶到深层的养分元素进入地下水,避免环境污染。本试验以室内土柱模拟淋溶的方式,分别取砂上、壤土和粘土3种质地的土壤按照土壤密度回填形成土柱,以北京年平均降雨量为标准分12次模拟降水对土柱进行淋洗,分别收集淋溶液对其中不同形态的氮素进行测定,结果如下：1.硝态氮是氮素淋溶的主要形式,在本试验条件下,经过12次淋洗后,3种质地的土壤中均有超过60%的氮素以硝态氮的形态发生淋溶,而铵态氮淋溶量占全氮淋溶总量的比例不足15%；2.施肥量是影响土壤氮素淋溶的重要因素之一,本试验中,当施肥量在0、200、400和800kg·hm-2时,3种质地土壤氮素的淋溶量均随施肥量的增加而增大,各深度氮素淋溶量与施肥量之间的关系可用直线方程进行拟合。3种质地土壤60cm处全氮淋溶量(y,kg·hm-2)和施肥量(x,kg·hm-2)之间的回归方程分别为：砂土：y=0.4261x+127.83(R2=0.9606)壤土：y=0.2508x+220.67(R2=0.9297)粘土：y=0.5994x+58.937(R2=0.9299)：3.降水量是影响土壤氮素淋溶的又一重要因素,当土壤没有种植植物或外界施肥量超过植物的吸收量时,降水极易造成氮素淋溶。本试验在模拟降水的条件下得出不同质地土壤各深度在不同施肥处理情况下全氮淋溶量和降水量之间的回归方程,其中以以下4种方程的拟合度最高(R2>0.90)：y=ax+b,y=1nx+b，1ny=ax+b和1ny=1nx+b。4.本研究结果显示,对于砂土,当施肥量在100 kg·hm-2以下时,施肥不会造成20cm深度氮素的淋溶,当施肥量达到200 kg·hm-2时,由于施肥带来的氮素淋溶深度不会超过造成60cm；对于壤土,施肥量在200 kg·hm-2以下时,施肥不会造成20cm深度氮素的淋溶；对于粘土,当施肥量小于100 kg·hm-2时,由于施肥造成的氮素淋溶深度不会超过40cm。当植物的根系在上述相应的深度范围内时,若施肥量不超过对应的施肥量,则不必考虑由于施肥造成的氮素淋溶。更多还原

【Abstract】 Nitrogen fertilizer is one of the most important fertilizers used in forest management. Due to unreasonable management, the ratio that plant takes the fertilizer is low although a large amount of fertilizer is applied, the loss of nitrogen is still very high, and leaching is one of the most important ways of nitrogen losing. Transportation of nitrogen in the soil is effected mainly by the amount of fertilizer, precipitation, soil texture, study the leaching regulations of soil under different amount of fertilizer applied can provide envidence for reasonable fertilizing, on one hand, it can reduce the loss caused by soil leaching after fertilizing, on the other hand, it can avoid pollution by preventing nitrogen from leaching down to underground water.This study used a column method and sitimulated rainfall to determine the nitrogen leaching of different textures of soil, and the results were as follows:1. Nitrate is the main nitrogen leaching form, in this study over 60% of nitrogen leached as nitrate in 3 types of soil, while the proportion of ammonium was under 15%.2. The amount of fertilizer applied to the soil was one important factors influnced the nitrogen leaching, the amount of leaching increased while the fertilizer increased, and the equation of total nitrogen leaching amount and fertilizer amount can be described as follows: sandy soil:y=0.4261x+127.83 (R2=0.9606) loam soil:y=0.2508x+220.67 (R2=0.9297) clay soil:y=0.5994x+58.937 (R2=0.9299).3. Precipitation was another factor influced the nitrogen leaching. It would cause leaching easily under the condition that there were no plants or the fertilizer was much sufficient to the plant. This study showed the equation between total nitrogen leaching amount and precipitation amount.4. The results showed that, in sandy soil, fertilizing would not cause leaching at 20cm while the amount of fertilizer is under 100 kg·hm-2, when it reaches to 200 kg·hm-2, fertilizing would not cause leaching at 60cm; in loam soil, fertilizing would not cause leaching at 20cm while the amount of fertilizer is under 200 kg·hm-2; while in clay soil, fertilizing would not cause leaching at 40cm while the amount of fertilizer is under 100 kg·hm-2. When roots are within certain depth and the amount of fertilizer is under certain amount, nitrogen leaching caused by fertilizing would be neglected.更多还原