Sweet Corn Response to Surface and Subsurface Trickle Phosphorus Fertigation

Abstract High‐frequency phosphorus fertigation may increase the time‐averaged P concentration in the soil solution above that expected from P solubility considerations. Where P is a yield‐limiting factor, frequent P fertigation may increase yield by stimulating P‐uptake by the roots. A field experiment was conducted on a loessial soil (Haploxeralf) high in NaHCO 3 ‐extractable P (0.8 mmol kg −1 soil) to test the hypothesis that subsurface placement of emitters (SSR) is more effective in stimulating P uptake than surface placement (SR). Four concentrations of P in the water (Cp), 0.04,0.16,0.64, and 1.29 mol P m −3 , were applied via surface or subsurface emitters to sweet corn Zea mays (L.) Jubilee. Marketable ear yield increased with Cp, yielding 22.9,24.3,24.9, and 28.9 t ha −1 , respectively. Yield was higher for tricklers placed 30 cm below soil surface (25.2 t ha −1 ) than on the surface (23.5 t ha −1 ). Elevated Cp increased the soil solution P concentration, thereby increasing total P uptake and total dry matter production by the plants. Deep trickler placement significantly increased the fraction of total dry matter allocated to the ears, which resulted in higher marketable yield. Subsurface irrigation also reduced weed growth due to the dry top soil during the experiment.