Corn Response to Conventional Versus Alternative Phosphorus Fertilizer Sources in Five Different Soils.

Composting and anaerobic digestion of organic wastes to mitigate excessive storage, greenhouse gas emissions and odors, generates considerable amounts of phosphorus (P) rich material which, when well utilized, may serve as a valuable P fertilizer. However, effective use of these materials requires an understanding of the P release capacity, crop response and how different soils influence P availability. A pot experiment, with corn (Zea mays) as a test crop, was conducted using five different soil to compare differences in P availability, soil P chemistry and crop response.  Treatments consisted of four P fertilizers and five different soils replicated five times in a randomized complete block design. The P fertilizer sources were chicken manure compost, vegetable matter compost, anaerobically digested dairy manure and MAP, plus a no fertilizer control treatment. The five soil ranged from sand to clay texture and from 6.1 to 8.0 pH. Every two weeks 125 pots (5 soils x 5 fertilizer treatments x 5 replicates) were destructively harvested for a total of 9 harvest dates over 134 days after planting. Aboveground crop biomass increased from weeks 2 -14 with all soil and fertilizer combinations (P < 0.001).  Growth was least in the Houston black clay soil throughout the trial, but the highest plant biomass was found with different soils throughout the trial (P < 0.01).  There was no difference in aboveground plant biomass with fertilizer treatment until week 6, but differences by soil, fertilizer, and the interaction between soil and fertilizer were found through the week 14 sampling period.  Early in the growing season, biomass increases were greatest with the composted chicken manure.  By week 14, all fertilizer treatments had significantly greater aboveground biomass than the control and composted vegetable product.  This presentation will also discuss differences in shoot P concentration in relation to soil and fertilizer treatments.