Field irrigation experiments were conducted in the Hetao Irrigation District of Inner Mongolia,China,to study the effects of irrigation regimes on salt leaching in the soil profile.The data were used to calibrate and ...Field irrigation experiments were conducted in the Hetao Irrigation District of Inner Mongolia,China,to study the effects of irrigation regimes on salt leaching in the soil profile.The data were used to calibrate and validate the HYDRUS-1D model.The results demonstrated that the model can accurately simulate the water and salt dynamics in the soil profile.The HYDRUS-1D model was then used to simulate 15 distinct irrigation scenarios.The results of the simulation indicated that irrigation amount did not have a significant effect on soil water storage but that increases in irrigation amount could accelerate salt leaching.However,when the irrigation amount was larger than 20 cm,the acceleration was not obvious.Compared with irrigating only once,intermittent irrigation had a better effect on increasing soil water storage and salt leaching,but excessive irrigation times and intervals did not improve salt leaching.In addition,we found that the irrigation regime of 20 cm,irrigated twice at 1-d intervals,might significantly increase salt leaching in the plough layer and decrease the risks of deep seepage and groundwater contamination.展开更多
文摘调查和分析了山东省设施菜地土壤次生盐渍化特征和影响因素。2014年全省设施菜地(含瓜类)总面积(日光温室、大拱棚含棚间面积)为64.98×10^(4 )hm^2,占全省菜地面积的35.45%,其中,日光温室25.06×10^(4 )hm^2,大拱棚20.94×10^(4 )hm^2,中小拱棚18.98×10^(4 )hm^2。山东省设施菜地土壤盐分离子组成中阴离子以SO_4^(2-)离子为主,阳离子以Ca^(2+)为主。全省设施菜地约39.73%出现不同程度的盐渍化现象,其中,轻度盐渍化为28.64%,中度盐渍化为8.37%,重度盐渍化为2.29%,盐土为0.43%。在不同设施类型中,盐渍化发生程度为:日光温室>大拱棚>中小拱棚;全省17个市设施菜地次生盐渍化发生程度表现出聊城、莱芜、东营相对较高。全省化肥平均施用量(折纯)为1 624 kg hm^(-2),氮肥(N)、磷肥(P_2O_5)、钾肥(K_2O)施用量(折纯)分别为559.5、465.2、599.3 kg hm^(-2)。通过分析设施菜地土壤次生盐渍化影响因素发现,化肥的高投入是可溶性盐分增加的一个重要原因,但在实际生产中受各种因素影响,未表现出完全线性相关关系;可溶性盐分增加与种植年限密切相关。典型对应分析发现,施肥数量、种植年限均会影响盐渍化程度,但影响各不相同。氮肥、磷肥和钾肥对K^+和Na^+的影响较大;Ca^(2+)和SO_4^(2-)含量受种植年限影响较大,K^+、Na^+、HCO_3^-和Cl^-受种植年限的影响较小;Mg^(2+)受氮磷钾肥和种植年限的影响均较大。
基金supported by the National"Twelfth Five-Year"Plan for Science & Technology Support Program(2011BAD25B07)the State Natural Science Fund(51279142)the Fundamental Research Fund for the Central Universities of the Ministry of Science and Technology,China.(2012206020206)
文摘Field irrigation experiments were conducted in the Hetao Irrigation District of Inner Mongolia,China,to study the effects of irrigation regimes on salt leaching in the soil profile.The data were used to calibrate and validate the HYDRUS-1D model.The results demonstrated that the model can accurately simulate the water and salt dynamics in the soil profile.The HYDRUS-1D model was then used to simulate 15 distinct irrigation scenarios.The results of the simulation indicated that irrigation amount did not have a significant effect on soil water storage but that increases in irrigation amount could accelerate salt leaching.However,when the irrigation amount was larger than 20 cm,the acceleration was not obvious.Compared with irrigating only once,intermittent irrigation had a better effect on increasing soil water storage and salt leaching,but excessive irrigation times and intervals did not improve salt leaching.In addition,we found that the irrigation regime of 20 cm,irrigated twice at 1-d intervals,might significantly increase salt leaching in the plough layer and decrease the risks of deep seepage and groundwater contamination.
