不同渗漏计对稻田氮素渗漏量的测定差异

采用直管型和弯管型渗漏计，对不同施氮水平下水稻生育期间渗漏水中的铵态氮、硝态氮和全氮浓度进行测定分析.结果表明：2007年直管与弯管渗漏计中渗漏水的铵态氮浓度变化范围均在0～8 mg·L^-1，高于2006年0～4 mg·L^-1的铵态氮浓度变化范围;2007年直管渗漏计中渗漏水的硝态氮浓度主要集中在0～4 mg·L^-1，与2006年基本一致，而弯管渗漏计中渗漏水的硝态氮浓度变化较大，其变动范围主要集中在0～20 mg·L^-1，高于2006年的硝态氮浓度;2007年渗漏水中的全氮浓度变化范围为0～60 mg·L^-1，远高于2006年0～16 mg·L^-1的全氮浓度变化范围.稻田渗漏水中的氮素以硝态氮为主.2007年直管型渗漏计中总氮(TN)渗漏流失负荷为15.81 kg·hm^-2，NO₃^--N为9.33 kg·hm^-2，弯管型渗漏计中TN渗漏流失负荷为7.21 kg·hm^-2，NO₃^--N为4.25 kg·hm^-2.稻田渗漏水中铵态氮和硝态氮的渗漏流失途径不同，应当采用不同的计算方法估算直管型及弯管型渗漏计中的氮素渗漏量，采用直管型渗漏计对氮素渗漏量的估算较接近于用测坑试验测定的氮素渗漏负荷.

Measurement difference in paddy field nitrogen leakage by using different type lysimeters.

Vertical and ‘T’ types of lysimeter were used to measure the concentrations of ammonia N, nitrate N, and total nitrogen (TN) in the leakage of paddy field in rice growth season under different N application levels. For ammonia N, its concentration measured with these two types of lysimeter all ranged in 0〖KG-*2〗-〖KG-*7〗8 mg·L-1 in 2007 and 0〖KG-*2〗-〖KG-*7〗4 mg·L-1 in 2006; for nitrate N, its concentration measured with vertical lysimeter was 0〖KG-*2〗-〖KG-*7〗4 mg·L-1 in 2007 and basically the same in 2006, while that measured with ‘T’ type lysimeter was 0〖KG-*2〗-〖KG-*7〗20 mg·L-1 in 2007 but lower in 2006. The TN concentration in the leakage was 0〖KG-*2〗-〖KG-*7〗60 mg·L-1 in 2007, much higher than that (0〖KG-*2〗-〖KG-*7〗16 mg·L-1) in 2006. In the leakage, nitrate N was the dominant N form. The total leakage loss of N in whole rice growth season in 2007 was 1581 kg·hm-2 of TN and 933 kg·hm-2 of nitrate N when measured with vertical lysimeter, and 721 kg·hm-2 of TN and 425 kg·hm-2 of nitrate N when measured with ‘T’ type lysimeter. Due to the difference in the pathways of ammonia-N and nitrate-N leakage, different methods for calculating N leakage should be employed when using the two types of lysimeter in measurement. The N leakage measured by vertical lysimeter was more close to that estimated by paddy plot-leaching measurement method.