EFFECTS OF LAYI NG HEN MANURE APPLICATION RATE ON WATER QUALITY

Abstract

Excessive use of animal manure on agricultural lands can impact the quality of surface and groundwaterresources. A threeyear study (19982000) was conducted on nine 0.4ha plots and on six 2.1m 2 lysimeters to investigatethe effect of two nitrogen (N) application rates from laying hen manure and one N application rate from urea ammoniumnitrate (UAN) fertilizer on surface and groundwater quality. Experimental treatments included N application rates of168 kgN/ha from UAN fertilizer, and 168 kgN/ha and 336 kgN/ha from laying hen manure to corn plots. Subsurface drainand runoff water samples were collected and analyzed for nitratenitrogen (NO3N) and orthophosphate (PO4P). Resultsof this study indicate that application of hen manure at 336 kgN/ha resulted in the highest average NO3N and PO4Pconcentrations in subsurface drain water in comparison with the application of 168 kgN/hafrom either hen manure or UANfertilizer. Application of manure at 168 kgN/ha resulted in significantly lower NO3N loss with subsurface drain water incomparison with NO3N loss from the other two N treatments. Manure application at a rate of 336 kgN/ha resulted in a higherconcentration of PO4P in surface runoff in comparison with manure application rate of 168 kgN/ha. Application rate ofmanure had no significant effect on NO3N concentration in surface runoff water. In addition, higher PO4P losses wereobserved with surface runoff water in comparison with subsurface drain water. The use of manure at both low and highapplication rates in field plots resulted in significantly higher corn and soybean yields in comparison with the use of UANfertilizer. Results of this study led to the conclusions that application of hen manure at a lower rate of 168 kgN/ha can resultin higher crop yields and minimal water pollution in comparison with same amount of UAN fertilizer or higher manureapplication rate.