Coordinating of Root-Water-Fertilizer Relation of Spring Wheat-Spring Corn Intercropping System Under Regulated Deficit Irrigation

Determining coordinating of Root Water Fertilizer relation was studied. Two crops of spring wheat and spring corn intercropped were grown in cement pool with length of 1 m, width of 1 m and depth of 1.5 m. The regulated deficit irrigations (RDI) of 30%, 50% and 70% of soil relative water content(SRW) were performed at later jointing stages for spring wheat(seedling stages for corn). Total seed yield of intercropping system was increased with 50% of SRW under 50% RDI at seedling stages for corn intercropped. The vertical distribution of soil Olsen P and root weight decreased significantly from surface soil layers to deep layers, above 30% of Olsen P and 40% of root dry mass in 0～100 cm soil depths were distributed in 0～10 cm soil layer, but where the water content is always below 10%, so un coordination of soil water with root and soil Olsen P in soil layers reduced nutrition use efficiency(NUE). RDI and deep P supply increased amount of roots of below 40 cm soil depths, which was favorable to absorb nutrient for roots in deeper soil profile at the middle and later growth stage. Spatial distribution of NO₃^--N and NH₄⁺-N were influenced by irrigation, at the first period of growth, NO₃^--N and NH₄⁺-N mainly distributed on the 0～10 cm soil layer, but which gradually moved to deep soil along with crop growth, therefore, nitrogen fertilizer should not be applied at deep soil layer, and should be supplied with several times.