Liquid Manure on Grass Hay to Improve Nutrient Use Efficiency, Yields and Quality

Bill Jokela, Sid Bosworth, Jeff Carter, Paul Pfluke, John Rankin, and John Aleong

Duration: 1995 - 1997

Traditionally, the only option available for application of liquid manure on grassland has been to broadcast on the surface. This generally results in large losses of nitrogen via ammonia volatilization, leading to low utilization of manure N. An improved method is the trailing foot or sliding shoe, in which manure is delivered through a series of tubes attached to metal shoes which ride along the surface of the ground. The intent is to place the manure in a band close to the ground below the grass canopy, providing less surface exposure and some wind protection and preventing contamination of foliage with slurry. The objective of this study was to evaluate the availability of nutrients, especially N, from liquid dairy manure applied by different methods (surface application vs. subcanopy banding).

The study was conducted at two sites: a) Shelburne Farms (orchardgrass on a well drained Galway silt loam) and b) UVM farm (reed canarygrass on a moderately well drained Vergennes clay). All manure treatments were applied with a commercial slurry tank spreader equipped with different options for various application techniques. Preliminary results showed that ammonia losses were greatest within the first few hours after application. Losses were also greatest with the high application rates (5000 - 6000 gal/acre) verses low rates (2500 - 3000 gal/acre). Banding manure with a sliding foot applicator reduced ammonia losses by about 25% at the low manure rate and close to 50% at the high rate. Most of the difference occurred in the first few hours after spreading. Overall, the best yield response was from the higher rates of chemical fertilizer, followed by liquid manure; but in 1997, the high rate of banded manure yielded as well as the high fertilizer N treatment. The highest crude protein concentrations were associated with the higher fertilizer N treatments and higher liquid manure rates. The trailing foot technique shows potential to increase manure N use efficiency and reduce odor. The results are helping us to make better estimates of N availability from manure and to recommend better management practices.

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