微型蒸发器测量精度的影响因素试验

为优化微型蒸发器（MLS）的使用方式及提高测量精度，在15 d不更换筒内土体的情况下，采用田间试验的方法对影响其测量精度的多种因素进行了研究。结果表明：各处理精度均较高，最高达97.40%；内筒打孔与否对测量精度无显著影响；套筒打孔的处理比不打孔的处理精度更高，且孔洞适宜均匀分布，但数目不可过多，直径为3 mm时不宜超过36个；套筒封底会降低测量精度，内筒封底材料越薄、透气性能越好精度越高；内筒与套筒的间隔较小时精度更高。对露水进行的考察显示，夜间的露水会明显降低测量精度，当其凝结量大于土壤蒸发量时，无法利用MLS精确测出土壤蒸发量。测量精度随时间变化而相应改变，MLS刚装入土体后的前3 d土壤水分较大，精度比其后各日都低。在有适量水分补充的情况下，15 d不更换MLS筒内土体可行。

Field experiment of measurement accuracy influencing factors of micro-lysimeters

In order to optimize the micro-lysimeters (MLS) and improve its measurement accuracy, influential elements of accuracy was studied by the field testing without changing soil in 15 days. Result showed that the accuracy of all test treatments was high. The highest point was up to 97.40%. Whether the inner cylinder was drilled or not did not affect obviously the measurement accuracy. The accuracy of the drilled outside cylinder was higher than the undrilled ones, and the drilled holes were better to be equally distributed. Further more, the holes number was less than 36 when the diameter was 3 mm. The sealed outside cylinder could lower the measurement accuracy. The thinner material of sealed inside cylinder was and the more ventilative function was, the higher accuracy could be achieved. Moreover, when the space between inside and outside cylinder was smaller, the measurement accuracy also became higher. Dew studying results indicated that dew at night could markedly lower measurement accuracy of MLS. When the condensed quantum was above soil evaporation, MLS could not accurately measure out soil evaporation. Meanwhile, the measurement accuracy varied from time to time. The soil water content in the first 3 days was more, but the accuracy of MLS was lower than the later days. If there was available water supply, it was practicable without changing the MLS soil in 15 days.