A Comparison of Solid and Liquid Fertilizer for Coastal Bermudagrass Hay Production1
- M. E. Walker,
- T. C. Keisling and
- W. H. Marchant2
Coastal bermudagrass (Cynodon dactylon L. Pers.) response to N, P, and K fertilization has been well documented. Generally, the accepted result of previous work is a fertilization program consisting of either (i) applying a 10-1-4 N-P-K ratio or (ii) fertilizing to increase the acid extractable P and K to 25 and 50 to 70 mg/kg, respectively. Under (ii) N is applied as needed to obtain the desired forage production and protein concentration. Liquid urea-nitrogen solutions have been investigated but little information on liquid P and K is available. An experiment with the objective of comparing liquid N, P, and K to conventional soild fertilization practices on Coastal bermudagrass was conducted on a Tifton soil (Plinthitic Paleudult; fine, loamy, siliceous, thermic) using a well established sod. A split plot design was used. Main plots were physical fertilizer form. Subplots were a complete 3 × 5 factorial with annual applications of 0, 37, and 74 kg/ha P and 0, 93, 186, 279, and 372 kg/ha K. Nitrogen was applied at 336 kg/ha for both liquid and solid forms. All fertilizer was applied each season as four equal split applications. Soil samples were analyzed for P, K, Ca, and Mg and soil pH was measured. Liquid fertilizer containing N, P, and K produced essentially the same forage digestibility as conventional solid fertilizer. Forage yield and N recovery was less with the liquid N source compared to solid fertilizer containing ammonium nitrate. The percentage digestible dry matter decreased as the % K in the forage decreased below approximately 1.5%. At the lower tissue K concentrations, the sod was infested to various degrees by Texas panicum (Panicum taxanum Buckl.), ragweed (Ambrosia artemisfolia L.), and large crabgrass (Digitaria sanguinalis L. Scop.) whose contribution to the forage yield would cause a reduction in digestibility. At 336 kg/ha N, more K was removed in the forage than was added when previously proposed N-P-K ratios were used. This excess removal of K by the forage could result in nutritional imbalances when soil reserves are exhausted. Applying high rates of K did not cause K accumulation in the Ap. Soil pH decreased in the upper and increased in the lower soil profile when using solid fertilizer as compared to liquid fertilizer. Extractable Mg also decreased in the upper and increased in the lower soil profile when using solid compared to liquid fertilizer. Additional work is needed to characterize the relation between forage yield level, K removal on various soils for several years, and Coastal bermudagrass stand characteristics when the soil K reserves are exhausted.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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