Farming a Flat Function

AAE 320

Overview of Talk

“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 explain or to fix

Farming a Flat Function For many crop production processes,

yield becomes relatively unresponsive to inputs when they are used at near optimal levels

Input

Yield

Farming a Flat Function

As a result, profit also has a “flat” response to the input

Input

Pro

fit

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 Analysis to see if could statistically

observe effect of nitrogen on yield when at high/near optimal nitrogen rates

One Site-Year from Iowa

0.0

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0.8

1.0

1.2

0 50 100 150 200 250 300

N Rate (lbs/ac)

Yie

ld (

% m

ax)

All Site Years from Iowa

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0.2

0.4

0.6

0.8

1.0

1.2

0 50 100 150 200 250 300

N Rate (lbs/ac)

Yie

ld (

% m

ax)

2,200 observations

Average Yield by N Rate

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N rate (lbs/ac)

Avg

Yie

ld (

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ax)

IN

IA

PN

Waseca

Morris

Main Point

Once N rates get above 85-100 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

Online N Tool from Problem Set 1

Current WI Recommendations

N rate (lb/a)

0 50 100 150 200 250

Ne

t retu

rn to

N ($

/a)

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20

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0.050.100.150.20

N:Corn price ratio

CC - High Yield Potential Soils

Source: C. Laboski, UW Soil Science

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

See the same thing for corn seeding rates: very flat returns

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)

Corn Returns for Seeding Density from Problem Set 1

(Lauer)

Soybean Returns for Seeding Density and Seed

Treatments(Gaspar et al. 2014)

Processing Sweet Corn Insecticides

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# Sprays

Net

Retu

rns Pounce

Mustang

Baythroid

Capture

Warrior

Capture on Processing Sweet Corn

(mean with 95% error bars)

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# Sprays with Capture

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rag

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Capture on Fresh Market Sweet Corn

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# Sprays with Capture

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etu

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Capture on Fresh Market Sweet Corn

(mean with 95% error bars)

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# Sprays with Capture

Avera

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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

see with all the variability from other factors

3) Wide range of input levels consistent with profit maximization

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

And Another Issue

Can’t?Costly!

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

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?