科研之友
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摘要
Despite evidence that forage crops can access P from the Bh horizon, routine soil testing focus only on P concentrations in the top 15 cm. We evaluated the role of the Bh horizon on the overall P budget for 2 yr in a bahiagrass (Paspalum notatum Flugge) pasture grown on a Spodosol. Treatments consisted of three P rates (0, 5, and 10 kg ha(-1)) arranged in a completely randomized design with each plot receiving a basal application of 56 kg N ha(-1) and 47 kg K ha(-1). Phosphorus application had no effect on bahiagrass P uptake (P = 0.2). Average P mass leached below the 45-cm soil depth was 0.08, 0.08, and 0.09 kg P ha(-1) for the 0, 5, and 10 kg P ha(-1) treatments, respectively. In 2007, the net balance of P in the Ap horizon was -10.8 kg P ha(-1) for the control and -0.8 kg P ha(-1) for the 10 kg P ha(-1) treatment. The same treatments had net P balances of -6.6 and 7.2 kg ha(-1) in 2008. When soil P held in the Bh horizon was included in the P budget computation, the net P balance was positive for all treatments including the control. Results indicate that soil P concentrations were sufficient to maintain bahiagrass production with no additional P fertilization required. Phosphorus held in the Bh horizon is a significant supply of P to low-input pastures growing on Spodosols in Florida and should be considered in nutrient management programs for perennial grasses.
- 出版日期2011-6
