The Effect of Split Nitrogen Applications on Nitrogen Uptake by Pensacola Bahiagrass from an Aeric Haplaquod

Abstract

AbstractAn experiment was initiated with an established ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) sod on Myakka fine sand (sandy, siliceous, hyperthermic Aeric Haplaquod) that had been used in a 10‐year experiment with N fertilizers. Five lime treatments were used in the previous experiment as main plots, with three N rates (0, 112, and 224 kg of N/ha/year) as subplots, and five N sources (calcium nitrate, ammonium nitrate, ammonium sulfate, urea and ureaform) as subsubplots.The current experiment was established to determine the effect of the number of N applications on N uptake efficiency in Pensacola bahiagrass forage with particular emphasis on rainfall amounts and distribution. The original experimental design was used except that treatments which had 1, 2, 4, 8, and 16 N applications/year replaced the N source variable on the sub‐subplots. Nitrogen rates were retained as in the original experiment. The experiment was conducted for 3 years.Nitrogen uptake in forage was relatively efficient ranging from 64 to 79%. There was little difference among treatments involving number of N applications. Generally, 1 or 16 applications were slightly superior to treatments involving two, four, or eight applications. Nitrate‐ and NH4+‐N concentrations in soil solutions higher than those from the control treatment were found only in March and April 1973 when initial N applications were followed by 202 mm of rainfall within a 12‐day period. This coincided with low N recovery in forage, particularly from treatments involving one or two N applications since all or one‐half of the annual N supply for these two treatments had been applied prior to this relatively intense rainfall.