EFFECT OF SURFACE AND SUBSURFACE DRIP FERTIGATION ON SWEET CORN ROOTING, UPTAKE, DRY-MATTER PRODUCTION AND YIELD

Subsurface (SS) drip fertigation may increase sweet corn ear yield relative to surface (S) fertigation, because immobile nutrients are delivered at the center of the soil-root volume rather than on top of the soil. A container (1 x 1 x 1 m) experiment was conducted on a loessial soil (Haploxeralf) to test this hypothesis. Marketable and total ear yields were higher for tricklers placed 30 cm below the soil surface (3.22 and 4.90 kg m-2, respectively) than on the surface (2.86 and 4.30 kg m-2, respectively). Total fresh weight, dry matter production and plant height during the growing season were also greater for subsurface emitters. Deep trickler position significantly increased P and K content at the center of the root zone. The enhanced concentration apparently stimulated plant rooting which, together with the higher nutrient activity in the soil solution, increased P and K uptake rates, which in turn facilitated the higher dry matter production and commercial yield relative to surface trickler placement. The higher root activity in SS than in S fertigation was reconfirmed by soil air CO2 concentration measurements which showed significant differences between the two treatments during the growth season.