Learning target: I can graph and analyze orchard data to find how pollination affects a harvest, and use replacement-cost reasoning to estimate what a pollination service is worth and what that number leaves out.
This sheet uses two teaching datasets. The numbers are invented to be realistic for a California almond orchard, but they were not measured on a real farm. In Part A, graph the harvest data and calculate what each extra colony of bees is worth. In Part B, calculate what it would cost to do the bees' job by hand, then think about what that number does not capture. Show every calculation with units.
You will need: This worksheet, Pencil, Ruler, Calculator
A grower divided her orchard into eight test blocks of the same almond varieties, soil and watering. During bloom she placed a different number of rented honey bee colonies per acre in each block, keeping the blocks far enough apart that bees mostly stayed in their own block. The block with no colonies still received a few visits from wild bees that nest nearby. At harvest she recorded how many flowers had become nuts and how many pounds of almond kernels each acre produced.
| Colonies per acre | Flowers that became nuts (%) | Harvest (pounds of kernels per acre) |
|---|---|---|
| 0 | 4 | 350 |
| 0.5 | 14 | 1050 |
| 1.0 | 21 | 1550 |
| 1.5 | 26 | 1900 |
| 2.0 | 29 | 2100 |
| 2.5 | 30 | 2180 |
| 3.0 | 30 | 2200 |
| 4.0 | 31 | 2220 |
| Extra harvest (lb per acre) | Extra income ($ per acre) | Extra rent ($ per acre) | Net gain or loss ($ per acre) |
|---|---|---|---|
| From 1.5 to 2.0 colonies | |||
| From 2.0 to 3.0 colonies | |||
| From 3.0 to 4.0 colonies |
Imagine honey bees could not be rented at all. A crew could still pollinate almond flowers by hand, dabbing pollen from the second variety onto each flower with a small brush or puffer. The cost of doing a natural job with human labor or machines is called its replacement cost. Use the teaching numbers below.
| Quantity | Value |
|---|---|
| Almond trees per acre | 110 |
| Trees one trained worker can hand-pollinate in an 8-hour day | 4 |
| Labor cost per worker per hour | $25 |
| Pollen collected and prepared for hand use, per acre | $150 |
| Working days during bloom | 15 |
| Honey bee rental: colonies per acre and price per colony | 2 colonies at $200 each |
| Price the grower receives for kernels | $2.50 per pound |
Worker-days per acre = trees per acre ÷ trees per worker per day. Worker-hours = worker-days × 8. Labor cost = worker-hours × $25. Add $150 for pollen. For q7, total worker-days for the orchard = worker-days per acre × 100, then divide by the number of days in bloom. Check that every number you write has a unit (trees, days, hours, dollars).
Suppose planting strips of native wildflowers along the orchard edges costs $25,000 to establish and $2,000 a year to maintain, and lets the grower rent 1.5 colonies per acre instead of 2.0 with the same harvest, because native bees nesting in the strip do some of the pollinating. For a 100-acre orchard, how many years would it take for the rent savings to pay for the strips? Then describe one benefit of the strips that does not show up in your calculation and one risk the grower takes by relying on wild bees.