1. Farming a Flat Function
AAE 320

2. Overview of Lecture “Farming a Flat Function”
What is it? (Give Examples)
What does it mean? (Implications)
In my opinion, this problem underlies a lot of complaints about farmers and the environment
It’s not a simple problem to fix

3. Farming a Flat Function
For many crop production processes, yield becomes relatively unresponsive to inputs when they are used at near optimal levels
Yield
Input

4. Farming a Flat Function
As a result, profit also has a “flat” response to the input
Profit
Input

5. Mitchell (2004)
Assembled data from experiments examining corn response to nitrogen
Most from late 1980’s and early 1990’s
Seven states (IA, IL, IN, MN, NE, PN, WI)
Almost 6,000 individual observations
Analyzed to see if could statistically observe effect of nitrogen on yield when used at high/near optimal nitrogen rates

6. One Site-Year from Iowa

7. All Site Years from Iowa
2,200 observations

8. Average Yield by N Rate

9. Main Point
Once N rates get above lbs/ac, expected (average) corn yield very flat, but lots of variability around this average
Makes identifying yield effects of nitrogen on corn statistically difficult/impossible
Change in yield with changing N rate hard to see with all the noise from other factors

10. Online N Tool from Problem Set 1

11. Current WI Recommendations
Source: C. Laboski, UW Soil Science

12. Main Point
WI nitrogen recommendations for corn give the range of N rates that are within $1/ac of the maximum return
Notice how wide the range of N rates is
Over the range of application rates the recommendations give, expected net returns vary less than $1/ac
Returns from applying nitrogen to corn are very flat when near optimal levels

13. What about other inputs?
1) Economic analysis of Seeding Rates
2) Economic analysis of processing and fresh market sweet corn and the value of insecticide sprays for controlling European corn borer (ECB)
Mitchell et al. (2005)

14. Corn Returns for Seeding Density (Lauer and Stanger 2006)
Source:

15. Soybean Returns for Seeding Density and Seed Treatments (Gaspar et al

16. Processing Sweet Corn Insecticides

17. Capture (bifenthrin) on Processing Sweet Corn (mean with 95% error bars)

18. Capture (bifenthrin) on Fresh Market Sweet Corn

19. Capture (bifenthrin) on Fresh Market Sweet Corn (mean with 95% error bars)

20. Main Point
Farmers are “Farming a Flat Function” for several of main inputs
Implications
1) Small profit change over wide input range
2) Impact of inputs on returns is hard to notice with all the variability from other factors
3) A wide range of input levels will be and will seem consistent with maximizing profit

21. And Another Issue Under use of inputs is often obvious
See weeds, insects, diseased plants, yellow or purple crop, wilted crops
Over use of inputs is often invisible
How many farmers leave an untreated check strip?
When Farming on a Flat Function,
How do you know if you put on too much Fertilizer? Fungicide? Insecticide? Water?
Over use of inputs often an invisible cost
Can’t!
Costly!

22. Main Point
Implications of Farming a Flat Function when under use of inputs is obvious and over use is invisible
Wide range of input levels consistent with profit maximization (and risk management)
Some inputs turn out to not be used/needed afterwards, but cannot tell when put them on
Some of the “extra” inputs end up as pollution
Farmers accused of using too many inputs

23. In my opinion
This problem underlies a lot of complaints about farmers and the environment
It’s not a simple problem to explain to the public: Why do farmer use so much fertilizer, pesticide, water, etc.?
Would farmers waste money on purpose?
Most farmers make an honest effort to be good stewards
But farming is messy and variable and it is expensive to find out where you are or will be on some flat function
What’s the answer? More/better technology? Try to better match “natural” systems? Both? Something else?