Combining Nitrogen Fertilizer with Poultry Litter in a Binary Mixture of Tall Fescue and Bermudagrass.

A common problem when poultry litter is applied to pastures in the southeastern USA is the buildup of soil P because of the difference in N-P-K ratio of the litter and plant requirements. This 2-yr study tested the theory that if the N requirement of a tall fescue-bermudagrass binary mixture is only partially met by poultry litter, application of fertilizer N would stimulate growth to remove excess soil P and other nutrients. A small-plot study combined 8.9 Mg ha^-1 litter with 150 kg ha^-1 N, using split applications of each N source at various times of the year in order to create differential fertilizer management treatments of ‘Fescue biased’ (autumn-winter), ‘Bermudagrass biased’ (spring) and ‘Optimum management’ (winter-spring). In each of four replicated blocks, three plots of hybrid bermudagrass were overseeded with ‘Jesup MaxQ’ tall fescue (summer-active) and three plots were overseeded with ‘Flecha-542’ (winter-active). Biomass yield and uptake of nutrients were determined at two spring harvests of fescue chiefly and three summer harvests of bermudagrass chiefly. Forage nutritive quality was determined at three harvest dates. For the Optimum Management treatment that provided 4.48 kg ha^-1 litter in January and March, plots overseeded with Flecha 542 produced more biomass in both spring (mean= 3065 kg ha^-1) and summer (mean= 7907 kg ha^-1) than plots overseeded with Jesup MaxQ (means= 2925 and 6490 kg ha^-1, respectively). Results will be discussed in relation to N availability of poultry litter, soil and plant P concentrations, and how to best integrate organic and inorganic fertilizers in a year-round forage production system.