Wednesday, November 15, 2006
286-24
Polymer Fertilizer Coatings: Can They Increase Phosphorus Efficiency in Rice?.
David Dunn and William Stevens. Univ of Missouri, Delta Research Center, PO Box 160, Portageville, MO 63873
Proper phosphorus (P) nutrition is critical for producing maximum rice grain yields. Not all of the P contained in fertilizers is available to plants. When phosphorus fertilizers are applied to soils P may tightly bonded with soil calcium (Ca)to form insoluble compounds. Surface coating of P fertilizers with polymer additives, which interfere with P bonding to Ca, have been investigated. These materials function by preferentially bonding with soil Ca leaving P free for early season plant utilization. The objective of this study was to compare the response of P uptake and rice yields to fertilization with polymer and non-coated coated triple super phosphate (TSP). In this 2-year small plot evaluation three pre-plant P2O5 rates of polymer coated and non-coated TSP (28, 56, and 112 kgha-1) were compared to an untreated control. Plant tissue samples were also collected at these times. These samples were dried, weighed, analyzed for P content and P uptake was calculated. All data was analyzed using the Proc GLM statement. In both years rice yields were significantly increased by all phosphorus treatments except the 28 kgha-1 uncoated TSP in 2004. This treatment was statistically and numerically equivalent to the untreated check. Each year the 28 kgha-1 coated TSP and 56 kgha-1 uncoated TSP treatments produced statistically equivalent yields (2004 coated 28 = 8770 and uncoated 56 = 8770; 2005 coated 28 = 6653 and uncoated 58 = 6854). In both years the 58 kgha-1 coated TSP treatment produced statistically equivalent yields to 112 kgha-1 coated or uncoated. These yield differences could be due to increased availability of P early in the growing season.