Monday, November 5, 2007
29-2

Increasing Phosphorus Availability to Corn (Zea mays L.) In Tropical Soils Using Vermicompost.

Mona Lisa Banks and Frieda Eivazi. Lincoln University, Cooperative Research Programs, Jefferson City, MO 65102

Highly weathered soils of the tropics are commonly low in phosphorus (P) and are referred to as “P-poor”soils. These soils inherently possess small amounts of phosphate available to plants and correspondingly high capabilities for fixing P. Depending on type of fertilizers applied, then, significant portions of the applied P "retained" as Fe-, and Al-phosphates rendering it unavailable. A greenhouse experiment was conducted to investigate the effectiveness of Vermicompost (VC) amendment on uptake of P growing corn (Zea mays L.). Mixture of soil and sand (500 g of soil, 25 g sand) were placed in plastic container lined with polyethylene bags. Treatments consisted of control; Vermicompost; dicalcium phosphate (DCP); and combination of Vermicompost plus DCP. The experimental design was randomized complete block and replicated four times. The pots were brought to field capacity and kept at that moisture level for the duration of six weeks. Parameters such as seed germination count, and plant height was recorded. Plants were then harvested and dried at 70 0C for dry weight determination. Samples were ground and processed for different chemical analysis. Plant and soil extracts were obtained using microwave digestion with nitric/nitric-hydrofluoric acid mixture. Total elemental analyses of the samples were done using Inductively Coupled Plasma Emission Spectrophotometer (ICP). Pots which received DCP fertilization showed the highest germination rate of 89% ,the highest average plant height, and the highest concentration of P in both soil and plant samples. Results obtained will be presented and the practical application will be discussed.