Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2014
Publication Date: N/A
Interpretive Summary: Tall fescue (cool-season) and hybrid bermudagrass (warm-season) have high growth rates under high fertility and extensive rooting systems, making them valuable in nutrient recycling systems; the nutrients taken up by the crop are removed when the hay is harvested. Growing these perennial forage grasses in a binary mixture provides opportunity to extend the growing season, and thereby maximize uptake of nutrients that might leave the field where they are applied and negatively impact water quality. A team of scientists conducted field studies to determine the effect of nitrogen (N) fertilizer and poultry manure application timing on tall fescue forage yield and persistence in binary mixture with bermudagrass, and on nutrient uptake and soil test phosphorus levels. Three applications of N fertilizer (34-0-0) were combined with two applications of broiler litter, each at various times of the growing season (October – July), to compare ‘N-timing’ treatments of ‘Fescue Bias’ (autumn-winter), ‘Bermudagrass Bias’ (spring) and ‘Optimal’ (winter-spring). Because tall fescue and bermudagrass biomass responded in opposing directions to year-long treatment differences, their combined biomass was similar in Fescue Bias and Optimal N-timing treatments and least in Bermuda Bias. Approximately 0.89 Mg (0.4 tons) less hay was produced with Bermuda Bias treatment, probably due to smaller contribution from winter hay crop. Enhanced growth of tall fescue in spring may offer environmental benefit, as crop uptake of N at each harvest date was greatest when litter and fertilizer N were applied in autumn-winter. The Fescue Bias treatment also offered significantly greater uptake of P, particularly in the binary mixture of summer-active, Jesup MaxQ, tall fescue and bermudagrass; however, final soil P levels did not differ among N-timing treatments. Combining broiler litter and fertilizer N in a year-round forage production system should help producers who often have insufficient land area for spreading litter at agronomically and environmentally acceptable rates.
Technical Abstract: The nutrients in broiler litter, especially N, should be applied in phase with crop demands to reduce the potential for nutrient loss. A 2-yr field experiment studied broiler litter and inorganic N application timing effects on seasonal dry matter (DM) yield, total nutrient uptake, and soil P in mixed tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] and hybrid bermudagrass [Cynodon dactylon (L.) Pers.] swards. ‘Flecha MaxQ’ (summer-dormant) and ‘Jesup MaxQ’ (summer-active) tall fescue were drill-seeded into small plots of ‘Russell’ and ‘Tifton 44’ bermudagrass in 2007. Three fertility treatments, differing in when litter or inorganic N was applied, were each comprised of 8.60 Mg litter ha-1 (as-is basis) split into two applications per season plus 168 kg N ha-1 (ammonium nitrate) split into three applications per season. Based on two harvests in spring, avoiding N applications beyond April resulted in fescue DM yield of 7.0 Mg ha-1 (mean of 2 yr), accompanied by fescue stand count of 76% in May 2010; whereas, applying litter in January and March and inorganic N in May and July resulted in fescue DM yield of 3.0 Mg ha-1 and stand count of 61%. Based on five harvests each year, avoiding N applications beyond April resulted in the highest cumulative N uptake of 189 and 182 kg ha-1 in 2009 and 2010, respectively, and P uptake of approximately 44 kg ha-1 in both years, and values were slightly greater in Jesup-bermudagrass than Flecha-bermudagrass. Nitrogen management to favor the cool-season grass increased the utilization of applied nutrients.