How Do You Rate This Publication?       

Title:	Optimizing simulated fertilizer additions using a genetic algorithm with a nutrient uptake model
Author(s):	Cropper, Wendell P., Jr.; Comerford, N.B.
Date:	2005
Source:	Ecological Modelling, Vol. 185: 271-281
Description:	Intensive management of pine plantations in the southeastern coastal plain typically involves weed and pest control, and the addition of fertilizer to meet the high nutrient demand of rapidly growing pines. In this study we coupled a mechanistic nutrient uptake model (SSAND, soil supply and nutrient demand) with a genetic algorithm (GA) in order to estimate the minimum addition of phosphorus necessary to meet the initial four-year demand. Optimal P additions were estimated using two pine root length density inputs scenarios, a mycorrhizal scenario, and a grass competition scenario. The low root length scenario required 32.5-35.0 kgP ha-1 (depending on the fitness criteria) to best match the four-year loblolly pine P demand. With higher root length density, only 14.5 kg P ha-1 was required to meet demand. Adding a large fungal length density of mycorrhizae changed the simulated P uptake kinetics so that two separate fertilization amendments were optimal, although the total P added was similar to the higher root scenario. GA fitness functions were adjusted to eliminate SSAND uptake underestimates smaller than loblolly P demand, at the cost of an additional 9 kg ha-1 (higher root scenario) or 1-2 kg ha-1 (mycorrhizal scenario). Optimal GA estimates for P addition with grass competition were 1.5-3 kg ha-1 higher, with a sharp fitness peak associated with decline of grass in the first growing season.
	View and Print this Publication (884 KB)
Pristine Version:	An uncaptured or "pristine" version of this publication is available. It has not been subjected to OCR (Optical Character Recognition) and therefore does not have any errors in the text. However it is a larger file size and some people may experience long download times. The "pristine" version of this publication is available here: View and Print the PRISTINE copy of this Publication (1.02 MB)
Publication Notes:	We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information. This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain. Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS Webmaster, srswebmaster@fs.fed.us if you notice any errors which make this publication unuseable.
	Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility