Nutrient supply and fertilization efficiency in midrotation loblolly pine plantations: A modeling analysis.
We simulated the 10 yr macronutrient budgets for 14 installations in a regionwide midrotation loblolly pine (Pinus taeda L.) fertilization study using NUTREM, a simplified model of carbon and nutrient uptake and distribution. Each installation includes 2-4 replications of N and P addition in a two-way factorial design. By approximating the constraints on nutrient use as elements in a linear programming problem, and estimating the parameters of the problem using least squares, we were able to identify baseline soil supply rates and fertilization efficiencies for N and P for each installation. Estimated N supply ranged from 47 kg ha-1 yr-1 to 103 kg ha-1 yr-1, while P supply ranged from 5.5 to 12.4 kg ha-1 yr-1. Fertilization efficiencies were extremely variable, ranging from 23% to 100% for N and 0% to 78% for P. A lower bound to the baseline supply rate was identified for K, Ca, and Mg for each site. While only three sites were P-limited, P limitation was imminent on all sites with operational doses of applied N. While the accuracy of NUTREM is limited by the availability of basic process-level data, the method suggests possibilities for predicting growth response to nutrient amendments.
Society of American Foresters
Ducey, M.J., Allen, H.L. Nutrient supply and fertilization efficiency in midrotation loblolly pine plantations: A modeling analysis. (2001) Forest Science, 47 (1), pp. 96-102.