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Making cropping system
recommendations on dairy operations is complex. Many agronomic decisions can
impact feed production, feed quality, nutrient management, milk production and
profitability. On top of that our variability in weather from year to year
makes assessing the best option difficult over the long term. Using a computer
simulation of a dairy farm might be one alternative to approaching these
problems.
During the last year I have worked with
Dr. Al Rotz at the Pasture Systems and Watershed Research lab and some our
colleagues to use Al's dairy farm simulation model called DAFOSYM (http://pswmru.arsup.psu.edu/DAFOSYM/dafosym.htm)
to address several crop production issues on dairy farms. I have been
reasonably impressed with the results.
Basically, the model simulates the
performance of a dairy farm under several management alternatives. The user
enters all of the characteristics of the farm- soils, cows, crops, and
equipment. The program then simulates the growth of the crops, the timeliness
of harvest, the forage quality of the forages, balances the ration, and then
estimates milk production, nutrient losses and the economic performance of the
farm. It does this over a 30-year period using log term weather data. You can
then adjust some of the predicted results to match records of actual farm
performance.
In the first part of this effort we
found the corn and soybean yield models seemed to predict actual yields fairly
well. The model gives you a prediction of all crop yields for the last 30
years.
We conducted several simulation
projects during the last year. In our first trial, we looked at the economics
of adding soybeans to a corn/alfalfa rotation in Centre or Franklin
County.
We found that soybeans are a profitable
addition on farms that have excess land available for grain production and low
corn prices. They weren't profitable when you needed all the corn for silage.
The model also suggested that soybeans were more valuable when sold as a cash
crop rather than fed on the farm. Soybeans had little impact on environmental
benefits.
We have done other simulations with
adding additional acres, adding cover crops and substituting small grains for
corn. As with all models, the results must be evaluated carefully but it does
allow you to test possible scenarios without doing extensive field
research.
I'm excited about working with the
model more because its difficult to do cropping system studies when you have to
measure actual yields. Often actual yields vary considerably from year to year
and field to field and then you need lots of years or locations to say anything
meaningful.
Eventually we should also be able to do
simulations of different grain crop rotations for grain producers. That should
be interesting as well. |
