|Watts, Donald - Don|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 8/20/2007
Publication Date: 4/7/2008
Citation: Novak, J.M., Szogi, A.A., Watts, D.W. 2008. Copper and zinc accumulation in sandy soils and constructed wetlands receiving pig manure effluent applications. In: Schlegel, P., Durosoy, S. and Jongbloed, A.W., editors. Trace Elements in Animal Production Systems. The Netherlands:Wageningen Academic Publishers. p. 45-54.
Technical Abstract: Pig production across the USA has undergone a massive centralization over the past few decades. Small animal production facilities have been replaced by concentrated animal feeding operations (CAFOs). This management practice has also centralized manure production into limited geographic areas. In the North Carolina Coastal Plain region, CAFOs generate massive quantities of manure that is typically applied to crop fields to recycle their contained plant macro (N, P, and K) and micro nutrients (Cu, Zn, etc.). Crops require very little amounts of micro nutrients, so continuous pig manure application may cause Cu and Zn accumulations in soils to levels that might cause crop yield reductions. In most fields, Cu accumulations usually are far below critical threshold levels for plant toxicity. However, Zn concentrations in some cases are approaching phytotoxic threshold limits for some Zn-sensitive crops. There are two possible alternative strategies to reduce the agronomic impact of land-applied Cu and Zn: i) optimize mineral supplementation of pig feed stocks and ii) develop alternative land treatment systems. Micro nutrient imbalances in manure-treated fields can be reduced if trace mineral supplementation of swine feedstock is optimized. The best possible trace mineral supplementation levels in pig feed stock should result in both an environmental and economic benefit because soil quality is sustained while lowering the cost of adding trace mineral supplements. Attention has focused on using on-site constructed wetlands to sequester nutrients in pig manure effluent. Preliminary research showed that constructed wetlands treated with pig manure effluent over a 2-yr period were highly effective at sequestering Cu and Zn. Reductions were achieved in Cu and Zn concentrations of between 82 and 86% among annual inflow vs. outflow values.