Research Summary:
How dryland wheat responds to biosolids fertilization at eleven field sites
D.M. Sullivan, A.I. Bary, C.G. Cogger, E.A. Myhre, T.E. Shearin and
T.N. Cramer
Oregon State and Washington State Universities
Conclusions
Grain Yield
- Average yield response from biosolids was 0.4 Mg/ha (6 bushels/acre) greater than for
fertilizer N
- Biosolids = fertilizer N (8 locations)
- Biosolids > fertilizer N (3 locations)
- Biosolids from three different treatment plants produced the higher yields. Similar crop
responses are expected with other sources of anaerobically digested biosolids.
Plant-available N
- Biosolids at an "agronomic rate" of 6 to 9 Mg dry solids per ha supplied more
N than the typical "grower N rate" of 50 to 80 kg/ha
- Indicators of greater N supply were:
- Higher grain N concentrations at 7 locations
- Higher post-harvest soil nitrate-N at 2 locations
- Biosolids were an effective fertilizer N substitute at all locations
- In our wheat-fallow production systems, the value of biosolids as a replacement for 60
kg fertilizer-N/ha is about $37 per ha ($15/acre)
- N fertilizer replacement value for anaerobically-digested biosolids, applied at current
"agronomic rates" is $6 to $7 per dry Mg of solids ($1 per wet ton)
- The reduction in grain test weight associated with biosolids fertilization may result in
lower grain prices, depending on local grain marketing practices.
- Future research is needed to determine the economic value of biosolids for production of
hard white winter wheat. High grain protein is desirable for hard white wheat production.
Newly released hard white varieties have a problem with low protein with inorganic N
fertilization.
Harvest of on-farm test site L-92 near Spokane, WA.
Biosolids application to wheat stubble
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