Effect of defoliation frequency and N-P-K fertilization on maidencane

Abstract

Maidencane (Panicum hemitomon Schult.), an important grass on Florida and southeastern Gulf Coast fresh-water marsh range, was cut on 3-, 6-, 9-, 12- and 24-week intervals (T) from June to December 1982 and 1983. Half the plots were fertilized every 6 weeks with 56, 12, and 22 kg/ha N, P, and K, respectively. Dry matter yield (DM), tiller density (TD), rhizome total nonstructural carbohydrate (TNC), crude protein (CP), and in vitro organic matter digestibility (IVOMD) were determined. DM was reduced with frequent clipping, especially every 3 weeks, and 2-year average DM was described: 1981 + 660T -22T2, where T is weeks between harvest. Fertilized grass yielded more DM (6,270 kg/ha) than unfertilized (4,410). TD increased as harvest interval increased. For example TD in April 1983 was TD = 40 + 19.1T. TNC was affected by cutting interval (7.2 + 0.61T - $0.016T2) but not fertilization. CP and IVOMD declined about 0.5 and 3.0 units, respectively, for each week forage remained on range. Fertilization improved 2-year average CP (yes = 13.3%, no = 11.9%), but IVOMD was unaffected. Defoliation of maidencane every 3 to 6 weeks reduced stands and yield, and defoliation intervals longer than 3 to 6 weeks resulted in reduced protein and digestibility. Fertilizer rates and timing of application used in this study did help to maintain yield and tiller density at a higher level than unfertilized grass in the second year.