Recently, rising energy costs have led to a dramatic increase in the price of synthetic fertilizer (Huang, 2009). Between 2002 and 2007 the cost of synthetic fertilizer N per acre rose by over 200% for pecan (Wells, 2009a). This sharp increase in the cost of a single input dramatically reduces the profit margin for pecan producers. Legumes and manure, produced by cattle grazing the orchards, were commonly used to provide fertilizer N for pecan trees in the early years of the southeastern pecan industry. Synthetic fertilizers were readily available at affordable prices after World War II, which led to their wide-scale use, replacing legumes and manure as nutrient sources for pecans (White et al., 1981). As air-blast sprayers were developed and put into use for pesticide application, grazing cattle in the orchard was discontinued in many areas.
Rising N fertilizer costs have led pecan producers to once again consider the use of various legumes such as crimson clover as an orchard floor cover to supplement tree N requirements. Smith et al. (1996) suggested that a combination of crimson clover and hairy vetch (Vicia villosa Roth) could be used as a cover crop to meet the N requirement of pecan in Oklahoma; however, little research in this regard has been conducted in the southeastern United States. Wells (2011a) suggested that crimson clover could provide up to 75 kg·ha−1 N 2 years after establishment, although it was not available until late in the growing season. In 2005, clover (Trifolium sp.) was used in only 15% of surveyed pecan orchards in Georgia. By 2008, nearly half of all pecan orchards surveyed used clover as an orchard floor cover (Wells, 2009b).
Georgia poultry farmers produce over 10.2 million tons of poultry litter annually in the production of meat and eggs, generating ≈20% of the poultry litter produced in the United States (Dunkley et al., 2011). Proper application of litter to the land as a soil amendment is an appropriate use for the waste product. The organic material and nutrients found in poultry litter are beneficial byproducts that have proven useful in amending agricultural soils (Mitchell and Tu, 2005).
The response of N availability and chemical and biological soil quality indicators to poultry litter and clover use in pecan orchards has been previously reported (Wells, 2011a, 2011b); however, significant questions persist regarding the overall effects of poultry litter and clover on pecan tree nutrition and production. The objective of this study was to investigate the effects of these nutrient sources on orchard soil, horticultural, and nut quality parameters of pecan in the southeastern United States.
Adams, W.E., Stelly, M., Morris, H.D. & Elkins, C.B. 1967 A comparison of Coastal and Common bermudagrasses in the Piedmont region. II. Effect of fertilization and crimson clover on nitrogen, phosphorous, and potassium contents of the forage Agron. J. 59 281 284
Allen, S.C., Jose, S., Nair, P.K.R., Brecke, B.J., Nkedi-Kizza, P. & Ramsey, C.L. 2004 Safety net role of tree roots: Evidence from a pecan–cotton alley cropping system in the southern United States For. Ecol. Mgt. 192 395 407
Dunkley, C.S., Cunningham, D.L. & Harris, G.H. 2011 The value of poultry litter in South Georgia. Univ. Georgia Coop. Ext. Bul. 1386
Havlin, J.L., Beaton, J.D., Tisdale, S.L. & Nelson, W.L. 2005 Soil fertility and fertilizers. Pearson Prentice Hall, Upper Saddle River, NJ
Huang, W. 2009 Factors contributing to the recent increase in U.S. fertilizer prices, 2002–2008. U.S. Dept. of Agr. Economic Research Service., AR-33. 8 Apr. 2011. <http://www.ers.usda.gov/Publications/AR33/AR33.pdf>
Hudson, W., Brock, J., Culpepper, S. & Wells, L. 2011 Georgia pecan pest management guide. Univ. Georgia Coop. Ext. Bull. 841
Kingery, W.L., Wood, C.W., Delaney, D.P., Williams, J.C. & Mullins, G.L. 1994 Impact of long term application of broiler litter on environmentally related soil properties J. Environ. Qual. 23 139 147
Nunez-Moreno, H., Walworth, J.L. & Pond, A.P. 2009 Manure and soil zinc application to ‘Wichita’ pecan trees growing under alkaline conditions HortScience 44 1741 1745
Rowe, E.C., Hairiah, K., Giller, K.E., van Noordwijk, M. & Cadisch, G. 1999 Testing the safety-net role of hedgerow tree roots by placement at different soil depths Agrofor. Syst. 43 81 93
Wells, M.L. 2007 Southeastern pecan growers handbook. Univ. Georgia Coop. Ext. Pub. 1327
Wells, M.L. 2009b Pecan nutrient element status and orchard soil fertility in the southeastern United States coastal plain HortTechnology 19 432 438
Wells, M.L. 2011a Nitrogen availability in pecan orchard soil: Implications for pecan fertilizer management HortScience 46 1294 1297
Wells, M.L. 2011b Response of pecan orchard soil chemical and biological quality indicators to poultry litter application and clover cover crops HortScience 46 306 310
White, A.W., Beatty, E.R. & Tedders, W.L. 1981 Legumes as a source of nitrogen and effects of management practices on legumes in pecan orchards Proc. Southeastern Pecan Growers Assn. 74 97 106
Worley, R.E. 2002 Compendium of pecan production and research. Edwards Brothers Press, Ann Arbor, MI