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Title: The Crop Growth Model in the Wind Erosion Prediction System

Author
item Van Donk, Simon

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/12/2006
Publication Date: N/A
Citation: N/A

Interpretive Summary: Poster Presentation only.

Technical Abstract: The primary purpose of the crop growth submodel (CROP) in the Wind Erosion Prediction System (WEPS) is to obtain realistic estimates of plant growth so that the influence of vegetative cover on wind erosion can be properly evaluated. Most crop growth models focus on estimating final crop yield. CROP needs to make reasonable estimates of crop biomass at any time between planting and harvest. CROP was adapted from the Erosion Productivity Impact Calculator (EPIC) crop growth model. Like EPIC, CROP is a generic crop growth model, meaning that one model simulates many crops. The crops are differentiated by different parameter values only. Currently there are more than 60 parameters in CROP which has deviated from EPIC to meet the need for predicting the effects of a growing crop on wind erosion. Phenological development of the crop is based on heat unit or growing degree day (GDD) accumulation. A crop grows from the planting date to the date when the accumulated GDD equal the total GDD required for that crop. Emergence occurs when the GDD accumulation from date of planting equals a certain percentage (typically 5%) of the total GDD. Biomass is converted from solar radiation and partitioned to root and shoot. The shoot mass is partitioned into leaf, stem, and reproductive masses. The latter is partitioned into grain and chaff. The partitioning is done because not all plant parts are equally effective for protection against wind erosion. Stems of young plants are roughly 10 times more effective than leaves in depleting wind energy. Also, leaves are more sensitive to sandblast damage than stems and leaf residues decompose faster. Potential growth is seldom achieved, because of stress caused by sub-optimal conditions. CROP adjusts daily growth for water and temperature stresses. The USDA Natural Resources Conservation Service is the most important user of WEPS and will implement it, including CROP, throughout the USA with its wide range of climates and soils.