局部灌水施肥条件下玉米根区土壤水分动态变化特征

The dynamic change of soil water content in root zones of maize under localized supplies of water and nitrogen fertilizer

采用分根装置,对传统均匀灌水和根系分区交替灌水2种方式,在作物根区均匀施氮和部分根区施氮2种方式下,对0,0.2,0.4,0.6 g/kg干土4个施氮水平玉米根系不同区域灌水前后的土壤水分动态进行了研究。结果表明:均匀施氮条件下,均匀灌水时玉米两个根区的土壤含水量始终相近,而交替灌水则表现为,两根区呈交错变化,总是灌水区大于非灌水区,且灌水后相差较大,灌水前相近;交替灌水与均匀灌水均表现为,增施氮肥可使灌水前的剩余土壤水含量提高,且增幅及持续时间均随施肥水平的提高而增大;均匀灌水条件下,均匀施氮时玉米两根区灌水前的土壤含水量始终非常接近,局部施氮则不同,施氮区明显大于未施氮区,且尤以高水平施氮表现更为突出;交替灌水局部施肥条件下,交替灌水和局部施肥所造成的作物根区土壤水分状况的不均匀性同时存在,前期和低氮水平下以交替灌水影响为主,中、高氮水平在后期以局部施氮影响为主。

The soil water content in different root zones under localized supplies of water and nitrogen fertilizer was studied with maize grown in split-root containers.Maize was irrigated in both halves of the pot（C） or water was alternatively supplied to two halves of the pot（alternative partial root-zone irrigation treatment,A）.Urea was applied to both halves of the pot（J） or was fertilized to one half of the pot while the other half was kept without N fertilizer（partial root-zone fertilization treatment,P）,all with four levels of fertilization,i.e.zero,low,medium and high.For J-fertilization,the soil water content（SWC） was the same for two root zones under C-irrigation while SWC of two root zones changed alternatively and SWC of the irrigated zone was always larger than that of the non-irrigated zone under A-irrigation,and this was more obvious after irrigation.For both C-irrigation and A-irrigation,N fertilization increased the residual SWC before irrigation.Moreover,both the increment and duration rose with N rates.For C-irrigation,the residual SWC in two root zones was equal under J-fertilization while the residual SWC of the fertilized zone was significantly larger than that of the non-fertilized zone under P-fertilization.Under A-irrigation and P-fertilization,both partial root-zone irrigation and partial root-zone fertilization caused the asymmetry of SWC in two root zones.Moreover,the effect of partial root-zone irrigation was larger than that of partial root-zone fertilization for low N rate and the early time after fertilization,and the effect of partial root-zone fertilization was larger than that of partial root-zone irrigation for medium and high N rates and the late time after fertilization.Higher N fertilization could increase the capacity of soil water conservation for both two irrigation and two fertilization methods.