水氮用量组合对冻融期土壤相变区硝态氮迁移与累积的影响

Effect of irrigation and nitrogen treatments on nitrogen migration and accumulation in soil phase transition during freezing-thawing period

为了研究冻融期水氮用量对土壤硝态氮迁移及累积的影响,设置了两个灌水量(375、750 m^3·hm^(-2))、三个施肥水平(100、300 kg·hm^(-2)和500 kg·hm^(-2))组成6种水氮组合,进行田间冬灌试验。结果表明,水氮处理显著增加了相变区(0~60 cm)土壤硝态氮水平,各处理下硝态氮累积量差异显著。未冻期和冻结期0~60 cm土壤硝态氮累积量随水、氮量的增加而增加,消融期硝态氮累积量随肥量的增加而增加。冻结前、后期土壤剖面聚氮区(特指硝态氮)由0~30 cm逐渐下移至30~60 cm。硝态氮向相变区的迁移量随水氮量的增加而呈增加态势,在N500下迁移趋势更明显。封冻前0~30 cm土壤硝态氮的相对累积量随灌水量增加而降低,30~60 cm土层则增加。冻结期,随施氮量的增加,0~30 cm土层硝态氮相对累积量增加,30~60 cm土层则降低。消融期0~30 cm土层硝态氮相对累积量随施氮量的增加而增加,随灌水量的增加而减少,而30~60 cm土层则呈现相反规律。

In order to study the influences of irrigation and nitrogen treatments on soil nitrate migration and accumulation during freezing-thawing period,nitrate transfer experiment was conducted in freezing-thawing period under six irrigation×nitrogen treatments of two irrigation levels( 375,750 m^3·hm^(-2)) and three levels of fertilizer application( 100,300,500 kg·hm^(-2)). The results showed that fertilizer and irrigation significantly increased the nitrate accumulation of the 0 ~ 60 cm,and the accumulation was significantly different. In unfrozen and frozen stages,accumulation amount at 0 ~ 60 cm layers increased with the increase of irrigation level and nitrogen rate,and increased with the increase of the fertilizer during thawing period. Nitrate accumulative area moved down from 0 ~ 30 cm to 30 ~ 60 cm in the prophase and anaphase of freezing. Nitrate migration amount was increased with the increase of irrigation level and nitrogen rate,and the migration effect was obvious at N500. Pre-period of freezing,with the increase of irrigation level,relative nitrate nitrogen of soil in 0 ~ 30 cm layer decreased,and that of soil in 30 ~ 60 cm increased. Relative nitrate nitrogen of soil in 0 ~ 30 cm layer increased with the increase of nitrogen rate in freezing period,but decreased in 30 ~ 60 cm depth. In thawing period,relative accumulation of nitrate nitrogen in 0 ~ 30 cm soil increased with the increase of nitrogen rate,but decreased with the increase of irrigation level,while the 30~ 60 cm soil layer showed the opposite laws.