from subsurface (injected) litter and were
more than 4 times higher from disked-in
litter than from subsurface litter. These results
were very similar to those from research studies
on perennial grassland that also showed subsurface
application of poultry litter prevented
more than 90% of NH3
loss when compared
to surface-applied poultry litter (Moore et al.
2011; Pote et al. 2011). In Sweden, Rodhe and
Karlsson (2002) applied broiler manure in May
1998 after using a harrow to break the soil surface,
and found that about 39% of the NH3
-N
from the surface-applied manure was volatilized
after five days, whereas incorporating the
manure into the soil effectively prevented NH3
volatilization. However, the Swedish study
had more than 3 cm (1 in) of precipitation
and average air temperatures of only 12.3°C
(54.1°F), so the relatively low rates of NH3
loss
they observed may have been largely due to
lower VPD.
Summary and Conclusions
Poultry litter application method greatly
affected the volatilization of NH3
-N from
this conservation tillage system. When compared
to conventional surface spreading of
poultry litter, NH3
volatilization decreased
an average of 67% when the litter application
was lightly disked into the soil surface
and decreased an average of 88% when the
litter was applied below the soil surface using
the Subsurfer prototype. These reductions
in NH3
volatilization were achieved while
retaining average ground cover of 82%, consistent
with conservation tillage needs, so
further development of the Subsurfer technol