Sustainable Manure Management - Sustainable Animal Agriculture - page 90

off-site transport of manure nutrients (Sharpley
et al ., 2003; Delgado and Follett, 2011). Such
tools offer strategic decision support for land
application of manure. More recently, advances
in the weather forecasting models have been
used to develop prototype tools that provide daily
decision support on whether sites are suitable to
receive manure based upon pollution potential
(Dahlke et al ., 2008; Melkonian et al ., 2008;
Buda et al ., 2013).

conditions. Barriers to the adoption of these spe-
cialized technologies often revolve around the
capacity and speed of application relative to
broadcast application and perceived cost.
However, Rotz et al . (2011) demonstrated that
the cost of adopting some low disturbance appli-
cators on small dairy farms in the north-eastern
USA was either neutral to slightly profitable in
comparison with traditional broadcast methods.
A comprehensive review of low-disturbance
manure application technologies and their asso-
ciated impacts on surface residue, nutrient loss,
erosion, odour and crop response is offered by
Maguire et al . (2011).
Poor accounting for manure nutrients
often results in excess application of manures
for crop production. Manure application rate is
strongly tied to fugitive losses of nutrients to air
and water over the short term (Thompson et al .,
1990; Kleinman and Sharpley, 2003). Over the
long-term, repeated applications of manure in
excess of crop requirement can overwhelm the
soil's natural buffering capacity, resulting in
chronic contributions that cannot be readily
controlled with manure management options
(Kleinman et al ., 2011). Sustainable manure
management must consider realistic yield expec-
tations and credit existing sources of nutrients
(past manure application, recent legume crops).
Testing of manure and soil are necessary to opti-
mize manure application rates, although use of
topic values may represent a significant improve-
ment over the status quo in many instances.
Application rates should be adjusted to account
for the significant differences in manure nutri-
ent use efficiency of different application methods.
For instance, immediate incorporation of manure
may conserve more than 60% of the plant avail-
able N in manure that would be lost with broad-
cast application (Beegle, 2012).

Manure application methods

The fate of manure constituents and the impact
of land application on crop, soil, air and water
quality can be profoundly affected by manure
application methods. Broadcast application of
manure is the most ubiquitous application
method of both liquid and dry manures alike.
Much of the reported inefficiency in delivering
manure nutrients to crops stems from the preva-
lence of broadcast application. Generally, broad-
casting manures exacerbates emissions of NH 3
(Dell et al ., 2011; Pfluke et al ., 2011) and odour
(Brandt et al ., 2011) and losses of P in runoff
(Johnson et al ., 2011), and promotes severe
vertical stratification of nutrients in soil.
Incorporation of manure into soil at time of
application generally improves nutrient use rela-
tive to broadcast application. However, incorpo-
ration has historically been accomplished by
tillage, conflicting with no-till and perennial
forage management systems. In recent years, an
array of low disturbance technologies has
emerged from Europe and the USA that place
manure below the canopy of a perennial crop or
into the subsoil with minimal disturbance to
surface cover. Low disturbance technologies
range from those that band manure below the
canopy of perennial forages (trailing hose, trail-
ing shoe) to those that inject manure into the
soil (chisel injection, disc/coulter injection,
high pressure injection) to those that lightly till
or perforate the soil to improve infiltration of
applied manure into the surface (aeration, low-
disturbance vertical/strip tillage). Many config-
urations of these technologies exist, such that
there are considerable options to adapt low-
disturbance applicators to handle the specific
requirements of existing machinery/manure
handling systems, cropping systems and soil

Timing of manure application

Timing of manure application represents one
of the most difficult logistical aspects of land
application programmes for manure recycling.
Application of manure shortly before crop plant-
ing is recommended to ensure that manure
nutrients are employed by the growing crop.
Long periods between manure application and
crop growth lower the nutrient use efficiency as