Long-term fertilization effect on corn nutrition and on P and K residuality on a calcareous Mollisol

Miguel Fernández del P.1

Field experimenté were performed on a calcareous Mollisol located on the irrigated central region of Chile, with the purpose to study the influence of a periodical PK fertilization on crop nutrition and on soil fertility. The site involved a sandy loam soil, with a variable depth from 0.6 to 0.85 m, Iying over a gravelly and stony alluvial material; pH 8.2; 1.9% organic matter; 1.0 ds m-1 electrical conductivity; 3 mg kg-1 Olsen-P and 75 mg kg-1 available K. A monoculture of grain maize was cropped for four years, with a late hybrid sown at 76,500 plants ha-1. Three treatments were included: T0, or control; T1 , with 26 and 66 kg ha-1 of P and K and T2 , with 52 and 132 kg ha-1 of P and K, respectively. Triple superphosphate and potassium sulphate were broadcasted, together with 350 kg ha-1 N as urea, which were mixed with the upper soil layer immeditely before sowing. At each harvest time, grain and all aereal plant material produced was removed, dried and ground for N, P and K analysis. Soil samples were taken at the beggining of each cropping period and analyzed for avilable P and K. Fertlization increased both avilable-P at arate of 0.5 and 1.0 mg kg-1 yr1 and available K at arate of 4 and 7 mg kg-1 yr1 on T1 and T2, respectively. On control treatment, only a small increase on available K was observed. Fertilized plots highly increased grain and dry matter yield according with internal requirement of P and K. Apparent P and K recovery and nutrient removed in plant material were calculated.

Keywords: corn, long-term fertilization, P and K fertilization, soil P and K removed, apparent P and K recovery, fertilizer P and K residuality
1 Centro Regional de Investigación La Platina (INIA). Casilla 439, Correo 3, Santiago, Chile.