Recycling biosolids and lake-dredged materials to pasture-based animal agriculture: alternative nutrient sources for forage productivity and sustainability. A reviewGilbert C. Sigua
Research Soil Scientist, United States Department of Agriculture-Agricultural Research Service Subtropical Agricultural Research Station, Brooksville, FL 34601, USA
Accepted 18 June 2008 ; published online 18 October 2008
Abstract - Domestic sewage sludge or biosolids and lake-dredged materials are examples of materials that can be used to cut fertilizer costs in pasture-based animal agriculture. Sustainable biosolids and lake-dredged materials management is based upon controlling and influencing the quantity, quality and characteristics of these materials in such a way that negative impacts to the environment are avoided and beneficial uses are optimized. This article examines the following two key questions. Is the use of these materials in an agricultural setting harmless and sensible? Is the use of biosolids secure in all climates, in all soils and is it sustainable over the long term? Recycling biosolids and lake-dredged materials to pasture-based animal production is quite productive as alternative nutrient sources for forage production. Perennial grass can be a good choice for repeated applications of biosolids and lake-dredged materials. Although biosolids and lake-dredged materials supply some essential plant nutrients and provide soil property-enhancing organic matter, land-application programs still generate some concerns because of possible health and environmental risks involved. Repeated applications of biosolids and lake-dredged materials indicate no harmful effects on soil quality and forage quality. Beneficial uses of biosolids and lake-dredged materials are both economical and environmental. The concentrations of soil nitrogen and phosphorus following repeated application of biosolids were far below the contamination risk in the environment. The residual effect of biosolids over the long term can be especially significant in many forage-based pastures where only 50% of the million hectares of pastures are given inorganic nitrogen yearly. Long-term studies have demonstrated the favorable and beneficial effects of added lake-dredged materials on the early establishment of bahiagrass in sandy pasture fields. Often these materials can be obtained at little or no cost to the farmers or landowners. Lake-dredged materials can be used as soil amendments (lime and fertilizer) for early establishment of bahiagrass in beef cattle pastures. Bahiagrass in plots that were treated with biosolids and lake-dredge materials had significantly higher forage yield and crude protein content when compared with those bahiagrass in the control plots or untreated plants.
Key words: sewage sludge / carry-over effect / bahiagrass / forage productivity / ecological implication / domestic wastewater / beef cattle / subtropical pastures / lake-dredged materials / forage-based pasture / agriculture / environment / biosolids / dredging
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