Course: BFM 101 Biofuels Fundamentals

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CRP and Marginal Land Conversion Impacts

Intense planting of bioenergy crops may result in removal of land from the Conservation Reserve Program (CRP) or the use of non-cropped marginal lands. This may result in ecosystem niche loss and less desirable land use. Marginal lands were generally not cultivated because they were poor farming sites. They may have steep, erodible slopes, nutrient poor soils or low moisture retaining abilities. Bringing these lands into production may increase fertilizer and pesticide inputs, crop production costs and environmental risks.

Marginal lands converted to bioenergy crops may lead to lower economic productivity when compared to previous usage. Conversion may cause increased soil erosion and sedimentation in the watershed. Increased tillage may lead to increased runoff, which may cause greater erosion and sedimentation in the watershed. Public drinking water reservoirs could be affected. Water storage structures may be silted or contaminated by leaching and runoff. Increased growth of organisms because of nutrients entering public surface water supplies add costs to municipalities required to treat the excessive contaminants. This may require more chlorine to be used, resulting in trihalomethanes (THMs) and disinfection by-products (DBPs). These also increase costs because they must be removed before the water can be distributed [8,9].

If the bioenergy crop requires more fertilizer, nitrites, nitrates and phosphorus contamination of water may occur. Nitrites and nitrates are highly water-soluble. Nitrate contamination of groundwater and phosphorus contamination of surface water are common fertilizer mismanagement problems. High phosphorus content in surface water leads to overgrowth of plant life, which may cause loss of fishing and other recreation, as well as production of toxins by certain algae and decreased wildlife habitat quality.

Soil texture affects the movement of both nutrients and pesticides, with high clay soil being more prone to runoff and sandy soil being more prone to leaching. Planting on marginal lands with low water holding capacity soil may result in increased weed competition, which may lead to greater herbicide use resulting in non-point source pollution from pesticides. If bioenergy crop production leads to greater pesticide usage, the risks for groundwater and surface water contamination may increase. Pesticides vary in water solubility and persistence in the environment. Highly soluble and persistent pesticides are high water quality risks. The chemical characteristics of the pesticide will determine whether it will be highly leachable, or easily leave a field in runoff. Highly leachable chemicals pose a greater risk to groundwater, while those that adhere to soil leave a field dissolved in runoff water and pose a risk to surface water. Water contamination from runoff or leaching is difficult and expensive to clean up.

Depending on how the land is used, bioenergy crop conversion can be positive or negative. If conservation practices and good management strategies are used, then bioenergy crops may increase infiltration, decrease runoff and improve the watershed. This is particularly true if perennial bioenergy crops can be planted on a large scale. Nutrient concentrations in streams in the Ozark Plateau were greater in areas with agricultural land use. Nutrient concentrations in groundwater were higher in areas with greater agricultural land use than in forested areas. Coliform bacterial contamination of waters, however, might decrease if manure and animal pasturage is decreased with conversion to a bioenergy crop [10]. Water quality monitoring can help identify changes when producers begin raising bioenergy crops. Site factors, such as endangered species, wildlife corridors, watershed recharge areas, etc., should also be considered when changing the land use of a site.

Resources provided by the eXtension Farm Energy Community of Practice at http://www.extension.org/ag+energy

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