Date of Graduation

12-2011

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Nathan A. Slaton

Committee Member

Edward E. Gbur Jr.

Second Committee Member

Jason P. Kelley

Third Committee Member

Richard J. Norman

Abstract

Nitrogen (N) availability in poultry litter (PL) applied in the fall as a nutrient source for winter wheat (Triticum aestivum L.) has not been adequately characterized. Our objective was to determine a potentially available N (PAN) coefficient based on the inorganic-N fertilizer equivalence (FEQ) of fall-applied PL to winter wheat via field and laboratory research. Wheat grown at six site-years received 0, 84 and 168 kg N ha-1 as PL applied preplant and/or at-planting. The FEQ of PL-N was based on growth and yield responses of wheat fertilized with 22 to 191 kg N ha-1 applied in late winter as a urea-ammonium sulfate blend (UASB) which was used to calculate PAN. Tiller number, aboveground N uptake, and grain yield responses to UASB-N were characterized using linear and quadratic models. Soil amended with PL or urea was incubated at 5, 15, and 25°C to supplement field research results. Wheat receiving PL-N produced N uptake and yields that were 11 to 43 kg N ha-1 and 297 to 1474 kg ha-1 greater (p<0.10) than the no N control. Application of 168 kg PL-N ha-1 increased tillering and yields above that of 84 kg PL-N ha-1 at only three site-years. Applying litter at planting resulted in greater wheat yield at only one of six site-years. The average PAN coefficients for PL-N were 0.35, 0.30, and 0.39 kg UASB-N kg-1 PL-N for tiller number, N uptake, and grain yield, respectively. Incubations conducted at 15 and 25°C showed that 19 to 31% of total-PL N was recovered as NO3-N with recovery reaching a plateau in 44 and 28 d, respectively. Based on these results plus other Arkansas research, a grain-yield based PAN coefficient of 0.31 kg UASB-N kg-1 PL-N provides a reasonable approximation of the availability of PL-N to winter wheat.

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