Surface-Banding Liquid Manure over Aeration Slots: A New Low-Disturbance Method for Reducing Ammonia Emissions and Improving Yield of Perennial Grasses

and leaching of manure nutrients during winter from forage stands will be less than from bare soil or cover Low-disturbance methods for applying slurry manure on forages crops after harvest of annual crops. are needed that can maximize crop response and minimize loss of The traditional method for spreading liquid manure nutrients to the environment. A new implement [Aerway SSD (subsurface deposition slurry applicator)] that bands manure over aera- on forage crops, surface broadcasting with a splashplate tion-type slots was assessed relative to conventional broadcasting and applicator, is rapid and inexpensive. However, broadsurfacebanding.Thecomparisonwasbasedonimmediateandresidual casting of manure is typically uneven, especially under crop responses to single and multiple applications of dairy slurry by windy conditions (Huther, 1988). Broadcast manure tall fescue (Festuca arundinacea Schreb.) and orchardgrass (Dactylis may also damage grass swards (Christie, 1987; Prins and glomerata L.). Also, ammonia emissions were compared using both Snijders, 1987; Wightman et al., 1997) and contaminate semiopen chamber and micrometeorological (integrated horizontal standing plants with microorganisms that can impede flux)methods. Theaerationslotswithoutmanuregenerallydidnothave silage fermentation (Anderson and Christie, 1995; Stefa significant effect on yield or N uptake. Averaged over all harvests, fens and Lorenz, 1998). Surface-applied manure is also surface banding increased yield and N uptake over broadcasting by prone to runoff into waterways (Uusi-Kamppa and Hei6.9 and 6.8%, respectively. The SSD increased yield and N uptake nonen-Tanski, 2001). Crop response to broadcast appliover surface banding by 4.4 and 7.5%, respectively. The relative effeccation of slurry manure is often inconsistent (Bittman tiveness of the techniques on yield varied among experiments. In the et al., 1999), and this probably discourages farmers from ammonia volatilization trials (micrometeorological method), loss of applied total ammoniacal N in the 2 wk after application ranged from using slurry as a primary nutrient source. Inconsistent 36 to 61% for broadcast manure compared with 17 to 32% for SSD- crop response is largely attributed to volatilization of applied manure. With both micrometeorological and semiopen cham- ammonia,whichisinfluencedbymanureproperties,soil ber, ammonia emissions from applied manure were 46 to 48% lower attributes, and weather conditions (Stevens and Laughwith the SSD than with broadcasting. Emissions from surface-banded lin, 1997; Sommer and Hutchings, 2001). Volatilization manure (chamber method) averaged 33% greater with surface band- of ammonia is reduced by minimizing the surface expoing than with the SSD. The results indicate that the SSD manure sure of manure with the air and improving contact with applicator reduced ammonia loss and increased yield and N uptake the soil (Sommer and Hutchings, 2001). There is more relative to broadcasting and surface-banding techniques. ammonia loss after broadcasting of liquid manure on stubble than on bare soil, particularly if the manure has high dry matter content, because of increased exposure