土壤水分对包膜尿素氮素溶出特性影响的研究

Effect of Soil Mosisture on Nitrogen Release Characteristics of Coated Urea

研究土壤水分对自行研制的包膜尿素(BG、BF)氮素溶出特性的影响。采用室内恒温土壤培养方式,探讨土壤水分为田间持水量的10%、40%、80%和100%条件下包膜尿素氮素溶出特性。结果表明:土壤水分为田间持水量的40%以下时,BG和BF在各培养时期内的氮素溶出率都比较低,在培养第42天氮素溶出率仅为66.3%和68.4%,土壤水分在田间持水量的80%以上时,溶出率均达到了80%以上;土壤水分在田间持水量40%、80%和100%条件下,氮素溶出50%所需要的天数,BG型包膜尿素比BF型延长了4.6d、0.2d和0.9d;氮素溶出特性可以用一级反应动力学方程N1=N0[1-exp(-kt)]描述,k为氮素溶出速率常数,包膜尿素BG的k值小于BF。土壤水分对包膜尿素氮素溶出率影响较大,随着土壤含水量的增加,氮素溶出率增大;硅藻土作为包膜材料对养分的缓释效果要好于沸石粉。

The characteristics of nitrogen release from inorganic mineral coated urea （BG and BF） under ditterent soil moisturewas studied. The nitrogen releasing characteristics was determined at 10%, 40%, 80% and 100% of soil water holding capacity at constant temperature by soil culture experiment. Results showed that the release of nitrogen was low when soil moisture was below 40% of soil water holding capacity, which was 66.3% and 68.4% in the BG and BF urea, respectively. The release of nitrogen was more than 80% when soil moisture was higher than 80% of soil water holding capacity. The days tor releasing 50% of nitrogen from coated urea was 4.6 d, 0.2d and 0.9 d behind in the BG than in the BF urea at the 40%, 80% and 100% water hohting eapaeity treatments, respectively. The characteristics of nitrogen releasing eould be deseribed well by the first-order reaction kinetic equation N1=Nο[l-exp（-kt）]. In the equation, k was the constant of nitrogen releasing rate was smaller for the BF urea treatment. Our results showed that the release of nitrogen increased with increase of soil moisture. BG is better than BF as coated materials in eontrolling nutrient release.