Environmental Engineering Reference
In-Depth Information
Table 13.7 Seed corn yields from sandy loam plots having received
raw and digested dairy manure treatments
Year
Corn yield (dry ton/ha)
Plots treated with raw manure
Plots treated with digestate
2009
4.3
5.2
2010
4.1
4.7
Mean
4.2
5.0
Note: Yields based on dry mass.
Source: Data collected by University of Guelph.
13.3
Corn plots having received raw manure, digestate and inorganic
fertilizer as soil amendments at University of Guelph, Campus d' Alfred
experimental plots.
applied, the plots that had received digested manure demonstrated relatively
small residual N effects, while residual N was higher in the plots that had
received raw manure. Increased crop yields with digestate treatments can be
explained by higher NH
4
+
-N concentrations available for plant uptake;
however, the lower C:N ratio of digestate, compared with raw manure,
results in greater N availability in the soil that can induce N mineralization
(Chantigny et al., 2007).
The effects of digestate application on crop yields have demonstrated
variable results, from no effect to significant increases in crop yield. Further
field studies are needed to better understand long-term yield response under
various cropping, climatic and soil conditions.
13.3.5 NO
3
-N leaching to drainage tiles
Nutrient management planning involves amending soils with sufficient
nutrients to satisfy the needs of crops while minimizing nutrient losses that
can lead to negative environmental impacts. As previously discussed, NH
3
volatilization represents a significant route for N loss during and
immediately after land application of manure or digestate. N losses are
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