温度、水分和施肥对甜菜黑土氮素迁移转化的影响

Effects of Temperature,Water Content,and Fertilization on Transformation and Transportation of Nitrogen in the Black Soil with Sugar Beet(Beta vulgaris L.)

以东北甜菜主产区的黑土为材料,采用模拟土柱方法,研究了不同温度（5℃和20℃）、水分（10%,20%和30%）和施肥（尿素）条件对甜菜0—90cm土层土壤无机氮（NH4＋-N和NO3--N）迁移转化的影响。结果表明：在整个培养期内,温度和水分对不同施肥处理、不同土层土壤NH4＋-N和NO3--N含量的影响不同。不施肥土壤NH4＋-N和NO3--N含量在不同水分和温度下均无显著差异。不同温度和水分条件下施肥处理各土层NH4＋-N、NO3--N平均含量均随土层深度增加而下降,在相同温度条件下,土壤水分为20%时为甜菜土壤矿化和硝化作用的最适水分,而10%水分时,0—15cm土层土壤硝化作用受到明显抑制。施肥明显增加0—15cm土层NH4＋-N、NO3--N含量,分别与不施肥相比增加2.71~16.65倍和1.04~9.05倍。5℃时,NH4＋-N、NO3--N在土柱内的迁移距离和硝化作用主要发生在0—15cm土层内;20℃时,主要发生在0—15cm和0—50cm土层内。施肥与不施肥土壤NH4＋-N含量与温度、水分均呈负相关,NO3--N含量和硝化率（Nr）呈正相关,多因素统计分析表明,温度和水分的提高可以增强施肥土壤的氮素转化,温度、水分和施肥三者对土壤NH4＋-N、NO3--N含量迁移有交互作用,但是对土壤氮素的转化没有显著影响。

The study focused on the effects of different temperature（5 ℃ and 20 ℃）,water content（10%,20% and 30%）and fertilization condition（urea）on transformation and transportation of inorganic nitrogen（NH4＋-N and NO3--N）in black soil（0—90cm）.A soil column experiment was conducted on the soil samples collected from the main sugar beet-growing area in northeast of China.The results showed that during the whole culturing period,the effects of temperature and water content on concentrations of NH4＋-N and NO3--N in soil depended on the depth of soil layers and the application of fertilizers.The contents of NH4＋-N and NO3--N in the soil without fertilizers varied with no significant differences along with the changes of water content and temperature.In the fertilized soil,the average contents of NH4＋-N and NO3--N decreased with the increase of depth of soil under different temperature and water conditions.Under the same temperature conditions,the mineralization and nitrification took place at the fastest rate in the soil with a water content of20%,but the nitrification was suppressed significantly in the soil of 0—15cm depth when the water content was 10%.In the soil layer of 0—15cm,fertilization enhanced the NH4＋-N and NO3--N contents by 2.71~16.65 times and 1.04~9.05 times,respectively.At 5 ℃,the transfer and nitrification of NH4＋-N and NO3--N mainly occurred in the layer of 0—15cm in the soil columns.At the temperature of 20℃,those processes took place mainly in the layers of 0—15cm and 0—50cm.No matter the soil was treated with fertilizers or not,the content of NH4＋-N was always negatively correlated with temperature and water content,and the NO3--N content was positively correlated with nitrification rate（Nr）.The multifactor statistical analysis indicated that theincreases of temperature and water content could promote the nitrogen transformation in fertilized soil;meanwhile,temperature,water content,and fertilization had interactive effects on the transfer of NH4＋-N and NO3--N,while they had no significant influence on nitrogen transformation.