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河套灌区土壤盐分对化肥氮素转化过程的影响研究
陶健宇1, 杨劲松1, 姚荣江1, 王相平1, 刘广明1, 陈 强2
1.中国科学院南京土壤研究所;2.杭锦后旗农牧业技术推广中心
摘要:
土壤盐渍化严重影响土壤养分利用与生产力提升,为阐明土壤盐渍化对河套灌区农田土壤肥料氮素转化关键过程的影响。以内蒙古河套灌区不同含盐量土壤为试验材料,通过室内恒温培养试验,分析了不同盐分梯度下土壤中氮素转化的水解和硝化过程。试验共设置了低盐(EC5:1=1.46 dS/m)、中盐(EC5:1=2.19 dS/m)、高盐(EC5:1=3.43 dS/m)3种盐分梯度,分别施用尿素和磷酸二铵两种化学氮肥。研究结果表明:①土壤盐分升高抑制了尿素的水解作用,高盐处理尿素的净水解量较中盐和低盐处理分别降低19.4% 和27.1%,而土壤盐分在中盐时对磷酸二铵的水解表现出促进效应,中盐处理磷酸二铵净水解量较低盐、高盐处理分别提高33.6% 和4.3%。②土壤高盐分会抑制硝化反应的开始,高盐处理相较低盐、中盐处理推迟3 d左右;土壤盐分升高对两种氮肥净硝化量的影响均表现为先促进后抑制的作用,中盐处理尿素的净硝化量,较低盐、高盐处理分别提高了8.6% 和9.1%,中盐处理磷酸二铵的净硝化量,较低盐、高盐处理分别提高了19.1% 和5.1%。③在等氮输入条件下,各土壤盐分梯度下磷酸二铵处理转化产生的铵态氮、硝态氮、无机氮均高于尿素处理。土壤盐分含量对化肥氮转化影响显著,不同肥料种类其影响存在差别;土壤盐分升高对肥料养分的释放存在抑制,适量的土壤盐分会促进硝化作用,这增加氮素淋溶损失的风险。
关键词:  内蒙古河套灌区  土壤盐分  土壤氮素  氮肥转化
DOI:10.13758/j.cnki.tr.2020.04.021
分类号:S156.4+4
基金项目:国家重点研发计划项目(2016YFC0501300、2016YFD0200303),中国科学院重点部署项目子课题(KFZD-SW-112-03-02),巴彦淖尔市博士科研工作站项目(BKZ2017)和巴彦淖尔市五万亩“改盐增草(饲)兴牧”试验示范项目资助。
Effects of Soil Salinity on Nitrogen Transformation in Hetao Irrigation District of Inner Mongolia, China
TAO Jianyu1, YANG Jinsong1, YAO Rongjiang1, WANG Xiangping1, LIU Guangming1, CHEN Qiang2
1.Institute of Soil Science, Chinese Academy of Sciences;2.Inner Mongolia Hangjinhouqi Centre of Agricultural Technology Extension
Abstract:
Soil salination seriously affects the availability of soil nutrients, which restricts the development of agricultural productivity. The objective of this study is to elucidate the effects of soil salinity on nitrogen transformation of fertilizers applied conventionally in Hetao irrigation district of Inner Mongolia, China. Soils of different electrical conductivity [EC5:1, 1.46 dS/m (L), 2.19 dS/m (M) and 3.43 dS/m (H)] and added two chemical nitrogen fertilizers (urea and diammonium phosphate) were used to conduct the indoor thermostatic incubation experiment, and then the hydrolysis and nitrification of soils were determined. The results showed that, 1) inhibiting effect was found on the hydrolysis of urea when soil salinity increased, the net hydrolysis amount of treatment H decreased by 19.4% and 27.1% respectively compared with those of medium and low salt treatments. While medium salt showed a promoting effect on the hydrolysis of diammonium phosphate, and the net hydrolysis amount of treatment M increased by 33.6% and 4.3% respectively compared with those of low and high salt treatments; 2) high soil salinity postponed the beginning of nitrification, the nitrification of treatment H was delayed for about 3 days compared with L and M treatments. The effects of increasing soil salinity on the net nitrification amount of two nitrogen fertilizers were identical, first was promoted and then suppressed. The net nitrification amount of urea of treatment M was 8.6% and 9.1% higher than those of treatment L and H, respectively, while the net nitrification amount of diammonium phosphate of treatment M was 19.1% and 5.1% higher than those of L and H treatments, respectively; 3) in all soil salinities, diammonium phosphate was transferred more to mineral nitrogen than urea under the condition of equal amount of nitrogen input. In conclusion, soil salinity has a great impact on the transformation of nitrogen fertilizers, but the effects are different to different fertilizers. Increasing soil salinity can inhibit the release of fertilizer nutrients; However, appropriate amount of soil salinity may stimulate nitrification, and then can increase the risk of nitrogen leaching loss.
Key words:  Hetao irrigation district of Inner Mongolia  Soil salinity  Soil nitrogen  Nitrogen fertilizer transformation

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