Remediation of Soil Nutrient Accumulations in Orchardgrass following Poultry Litter Application.

Poultry litter can be an excellent source of nutrients for forage production.  If properly managed,
litter can be returned to land; however, one major problem of poultry litter application to land is
soil nutrient accumulation.  Applying poultry litter to land at recommended crop N rates can lead
to an accumulation of P, K, and some micronutrients in the soil.  This study was developed to
observe how soils that contained accumulations of nutrients from poultry litter application could
be remediated through prescription based inorganic fertilizer additions.   Poultry litter application
occurred from 2001-2004, followed by half of the plots receiving the remediation treatments in
2005-2007.  A completely randomized block design consisting of four original  treatments was
utilized.  The original treatments were inorganic N, P, K fertilizer (I), poultry litter applied
according to recommended P rate (PPL), poultry litter applied according to recommended N rate
(NPL), and poultry litter applied at recommended P rate with supplemental inorganic N fertilizer
(NPPL).  Remediation treatments involved using inorganic fertilizers on all treatments based on
soil tests.  These are RI, RNPL, RPPL, and RNPPL in sequence from previous treatments.  Soil
samples were compared between initial nutrient content and content in March, 2007.  Samples
were analyzed for pH, CEC, organic matter and available nutrient content.   Differences between
treatments were found for CEC along with available P, Mg, and Zn.  In each of these
measurements,  the NPL treatment was significantly higher than all other treatments except for
Zn (p<=0.01).   The RNPL treatment was higher in most nutrients than the other treatments,
although less than the NPL (p<=0.01).   Indications are that the remediation process is lowering
some nutrient concentrations, but most are still at high levels when poultry litter application was
originally based on N needs.