Effect of Phosphorus Fertilization on Early Growth of Corn on Six Alluvial Soils in Louisiana.

The effect of phosphorus (P) fertilization on corn (Zea mays L.) growth and development on highly diverse soils in the alluvial plain of Louisiana needs to be documented. A greenhouse trial was conducted to evaluate early growth response of corn to P fertilization on six Mississippi River alluvial soils. Soil samples were collected, air-dried, processed and analyzed for all major and minor plant nutrients. All nutrients, except P, were applied to the soils at optimum levels based on soil test. Samples of soil weighing 2.5 kg were fertilized with five P rates (0, 15, 30, 45 and 60 ug P ml^-1), homogenized, placed in 1-gallon pots, and arranged in a randomized complete block design with four replications. Seeds were sown two weeks after P fertilization and were allowed to grow for six weeks after sowing. A laboratory incubation method (1:1 w/v soil/P solution shaken for six hours at 50 rpm, incubated for 10 days at 30°C and analyzed for Mehlich-3 extractable P) estimated that 49% to 100% of P applied to these soils was extracted with Mehlich-3 solution. Relationships among Mehlich-3 soil test P values, P rates applied and plant variables such as biomass, P concentration and uptake for each soil series were examined. A precise and efficient P management scheme that would reflect spatial differences in soil properties affecting P uptake and nutrition of corn is an integral part of environmentally sound and sustainable corn production systems in Louisiana.