like the one pictured here could produce compost tailored to remediate excess
phosphorus in soil. Click the image for more information about
Designer Composts May Combat Phosphorus
Overload By Sharon Durham February 25, 2005
There are designer handbags and designer shoes, so why not designer
compost? Agricultural Research Service
scientists are studying environmentally friendly composts that help keep
phosphorus from seeping into water supplies.
Applying manure and composts as nitrogen fertilizer often adds more
phosphorus than plants need. This extra phosphorus can then leach or run off
into water. But specially formulated composts can make the phosphorus less
soluble in water, thus minimizing the chance that it will wash away.
Codling have been searching for inexpensive ways to make phosphorus less
water soluble, or to increase the ability of manure, biosolids and composts to
hold onto the phosphorus.
Chaney and Codling, with the ARS
Manure and Byproducts Laboratory in Beltsville, Maryland, found that
composts high in iron could markedly help the manure and compost retain
phosphorus. Both iron and aluminum oxides increase adsorption of phosphorus.
These can be added as chemical additives or by mixing byproducts rich in iron
or aluminum with the manure or other feedstocks before composting.
Because phosphorus runoff can damage streams, lakes, rivers and other
waterways, limits on soil phosphorus are being proposed. Many states have
implemented manure management regulations aimed at preserving groundwater
quality and the health of major water sources.
A management tool called the Phosphorus Index (PI) is used to assess
the risk of phosphorus loss from agricultural fields to surface waters. In some
states, the PI is based on plant-available phosphorus, but the scientists found
that adding iron and aluminum oxides to manure or composts reduced the water
solubility of phosphorus much more effectively than the PI test indicates.
The findings should help livestock producers limit phosphorus runoff a
time when they face tougher restrictions on this valuable soil nutrient.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.