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Maquoketa River Watershed, Iowa
The UMRW stakeholder group set a target
of reducing phosphorus, nitrogen, and sediment concentrations
in the river by 50 percent each. TIAER evaluated results of
the models, comparing the effects of the scenarios to the
target and to the baseline. Results demonstrate that several
scenarios show improvement in one or more of the target pollutant
levels. The most sizable improvements in sediment and most
nutrients were obtained with the following scenarios.
- No-till on all cropland
- Contouring on cropland and pastureland
with slopes greater than two percent
- Terraces on cropland with slopes greater
than two percent
- Contour buffer strips on cropland with
slopes greater than two percent
- Enhancing and developing waterways
for all cropland
When those five effective scenarios are
measured for effect on producer profit as cost per acre, terraces,
contour buffer strips, and waterway enhancement are the most
expensive scenarios, creating a negative effect on producer
profit. (The major reason for the cost associated with the
last two listed scenarios is that the land is taken out of
production, and farmers would lose that potential income,
which would be only partially offset by conservation reserve
program (CRP) payments.) No-till and contouring were also
estimated to cut producer profits, but by much smaller margins.
The following scenarios actually result
in profit increases for producers:
- Applying manure at the high P rate,
with manure nutrient crediting
- Ceasing fall crop-removal fertilizer
applications
- Reducing N application on all cropland
- Reduced and split N application on all
cropland
Manure nutrient crediting underlies
the profit-enhancing potential for these scenarios, allowing
reduced application of commercial fertilizers, and thus saving
on fertilizer cost, machinery, and labor.
Do the profit-enhancing scenarios move
stakeholders toward the target or away from it? Applying manure
at the high P rate helps significantly with nitrate and marginally
with soluble P, sediment, organic N, and organic P. Stopping
fall crop removal fertilizer applications helps significantly
with soluble P, has marginal benefit for organic P, nitrate,
and organic N, and no effect on sediment. Reduced N application
also helps significantly with soluble P and with nitrate,
and has marginal benefit for organic P, organic N, and sediment.
Reduced and split N application helps significantly with soluble
P and nitrate. It has very slight benefits for organic P and
sediment, and a very slight negative change in organic N,
i.e., an increase in organic N.
If producers opt, then, for those four
scenarios that would result in the most profit, they would
improve the level of soluble P and nitrate in the river; however
these scenarios would have little effect on the organic nutrient
levels and very little effect on sediment.
These results pose several questions and
decision points for stakeholders and policy makers. If scenarios
with the best potential for reaching the target are too expensive
for the producer, should there be cost share to encourage
such practices? If a scenario shows only marginal improvement
in the condition of the river, should it be pursued? What
about combinations of scenarios? TIAER tested four combinations
of scenarios. For example, the following three combined scenarios
increase profits for producers and have significant benefits
in improvement of water quality in the river:
- No-till, with reduced N application
on all cropland
- Contouring, with reduced N application
on all cropland
- Contour buffer strips, with reduced
N application on all cropland
Thus, by combining a profit-enhancing scenario
(e.g., reduced N application on all cropland) with other options
that yield significant water quality improvements and have
little or no impact on producer profits, the overall result
can be an outcome that both enhances profits for the producer
and results in significant reductions in sediment and nutrient
concentrations in the river.
Finally, even if a scenario shows little
impact at the watershed level, it could still be beneficial
at a smaller scale. For instance, the scenario of phytase-supplemented
rations for swine farms shows only a very marginal soluble
P reduction when the entire watershed is taken into account.
But phytase-supplemented rations at one specific site do show
significant reductions in soluble P in the immediate microwatershed.
Similarly, a scenario could have different impacts on different
parts of the watershed, and thus could be targeted to a specific
sector. For instance, applying manure at the high P rate,
with manure nutrient crediting, is a significant profit-enhancer
for mixed farms and for freestall dairies; however, for beef
pasture operations and calf/heifer operations, it has only
a small impact on profits.
Thus, in an area such as the UMRW, CEEOT
analysis can give stakeholders within watersheds valuable
information to use in their efforts to improve water quality
in their community. At the same time, it can give individual
producers and policy makers valuable information as to which
scenarios would yield the best environmental impact on his
or her particular type of operation, and which would be cost
effective.
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