抑制剂及其组合对尿素^(15)N在小麦土壤系统中的行为和归宿的影响

应用加有脲酶抑制剂 (HQ)、硝化抑制剂 (DCD)及其组合的标记尿素进行春小麦盆栽试验 .结果表明 ,在生长季节结束时 ,小麦回收 ,土壤残留和损失的肥料N各占施入N量的 1 7.65～ 2 3.69%、43.72～ 56.32 %和 1 9.99～ 36.77% .其中 ,与单施尿素相比 ,两种抑制剂配合使用处理的肥料N总回收率高 1 6.78% ,小麦回收高 5.96% .施用氮肥对籽粒贡献最大 ,占吸收肥料N量 43.3～ 62 .0 % .

不同种类氮肥对土壤释放N_2O的影响

用培养试验模拟研究了在正常水分 ( 2 2 % )、干旱 ( 1 2 % )和高含水量 ( 32 % )条件下 ,普通碳酸氢铵 (普碳 )、尿素及新型肥料长效碳酸氢铵 (长碳 )对土壤释放N2 O的影响 ;同时考察了土壤NO-3 的形成时间和形成量 .结果表明 ,农田中施加的无机氮肥是大气中N2 O的重要来源 ,而长碳与普碳和尿素相比 ,不但可以明显延后N2 O释放高峰期出现时间 ,而且大多数情况下可以显著减少其释放量 (P <0 .0 1 ) .在 5个月的监测期内 ,与普碳和尿素相比其减少N2 O释放的比例分别为 80 .2 3和 88.41 % ( 1 2 %含水量 ) ,40 .0 0和2 7.59% ( 2 2 %含水量 ) ,无减少作用和 45.88% ( 32 %含水量 ) .本研究结果提示长碳具有作为农田生态系统N2 O减排措施的巨大潜力 ,同时暗示在农业中用长碳代替目前普遍应用的普碳 ,可以减少地下水中NO-3 引起的污染 .

Comparison of Urea-Derived N_2O Emission from Soil and Soil-Plant System

A pot experiment with a sandy loam soil and spring wheat as test crop was conducted to compare the N2O emission from soil system with plant cut off and from soil-plant system with plant kept. The results showed that after urea fertilizer applied, the N2O emission from soil and soil-wheat system decreased exponentially with time, and its total amount was 0.34%~0.63% and 0.33%~0.58% of applied urea-N respectively, no significant difference being found between these two systems. The N2O emission had a very significant negative relationship (P = 0.01) with the biomass of wheat plant. A combined application of urease inhibitor hydroquinone and nitrification inhibitor dicyandiamide could reduce the N2O emission by 50%~83% and 46%~74%, respectivelyl from soil and soil-wheat system. The N2O was mainly produced and emitted from soil, and the soil biochemical regulation, i.e., applying related inhibitors into soil could effectively diminish the urea derived N2O emission.

土壤空气中几种碳氢化合物氧化作用的理论研究

由氧气、硝酸根、铁离子、硫酸根氧化甲烷、乙烷、丙烷和乙烯的16种自发反应,是通过不同状态活度(和或者参加反应的中间产物)来估算的。估算表明,即使在估氧活度(10^(-27)Pa)很低的情况下,这些碳氢化合物气体也都是不稳定的。PH7时,这几种碳氢化合物在NO_3^-和Fe^(+3)存在下,是不稳定的。即使这些物质活度很低(10^(-10)M)。在所有指定的条件下,可以证实CO_2比烃类更具稳定性。PH7时,SO_4^(-2)度为10^(-8)—10^(-10)M时,能够产生甲烷、乙烷、和丙烷,但不能产生乙烯。