Name: ______

Part A: Calculating Losses

Kernels per Square Foot to Equal One Bushel per Acre

Crop

/

Kernels/ sq. ft

Wheat

/ 18-20
Oats / 10-12
Barley / 13-15
Rye / 21-24
Red Clover / 400
Alfalfa / 300
Soybeans / 4-5
Corn / 2

In order to evaluate your efficiency and that of your combine, you need to calculate your losses. The first step in calculating loss is to walk the perimeter of your field and look for losses due to weather, animal damage, disease, or an overripe crop. These losses are not due to the combine or general efficiency so should be subtracted from the final figure. Next combine a small area and count the loose kernels on the ground in an area one ft wide across the width of the rear of the combine. Get an average from three or more locations. Divide the number of loose kernels on the ground by the width of the grain head you are using. This is your average loss per square foot. Divide you loss per square foot by the number of kernels per square foot to equal one bushel per acre. This information can be obtained from the above table. This is your bushel per acre loss.

You can also calculate the percentage of the crop lost if you know what your yield/acre is. The formula for calculating this is as follows:

%loss = (bushels per acre loss / yield per acre) * 100

1.) List the steps to calculating your losses.

1.______

2.______

3.______

4.______

5.______

2.)  While combining a 12 acre oat field you yield 1200 bushels of oats. You have a JD 9500 combine with a 20 ft grain head.. The width of the straw walkers is 5.6 ft. You conclude that there are an average of 200 kernels of oats that lay in the one-foot strip behind the combine. What is your average loss/square foot?

3.)  Using the answer from the previous question, calculate your bushel/ acre loss.

4.)  What is the % loss?

5.)  You are combining soybeans with a machine with a 15 foot head. Your yield is 35 bushels per acre. When checking behind the machine you count 180 beans in a 1 foot strip. The combine is 8 ft wide. What is your bushels/acre loss?

6.)  What is your % loss?

7.)  Calculate the loss/acre for our class example.

8.)  Calculate the percent loss for our class example

Part B: Calculating Effective Field Capacities:

Effective field capacity is a function of field speed, machine working width, field efficiency, and unit yield of the field. Area capacity is expressed as:

Ca = swEf/8.25

where:

·  Ca is area capacity, acre/h;

·  s is field speed, mile/h;

·  w is implement working width, ft;

·  Ef is field efficiency, decimal.

NOTE: Typical ranges of field efficiency and field speed can be found in Table 3.

This information in this document was adapted from American Society of Agricultural Engineers Standards.

Procedure:

With two stopwatches, have

1.  one person measure the length of time the forage harvester is actually harvesting.
______

2.  and another person measure total length of time for this experiment.

3.  Calculate field efficiency:

A) First, change the times measured into seconds

(Minutes * 60) + number of seconds

e.g. 3 minutes 18 seconds = (3*60) + 18 = 180 + 18 = 198 seconds


B.) Second, calculate field efficiency by using the number of seconds calculated in step a and the following formula.

Field efficiency = chopping time /total time * 100


4.  How wide is the combine’s header?

5.  How fast is s/he combining?

6.  What is the theoretical field capacity?

7.  What is the effective field capacity?

General questions:

  1. How could the farmer improve effective field capacity?
  2. What is the combine model?
  3. What is the header model?
  4. How long has the farmer owned this combine?
  5. Does s/he plan to upgrade the machine?
  6. What style combine is it?

7.  What does the farmer like/dislike about the machine?