Planning for inputs to a crop enterprise requires knowledge of whether or not there will be worth in the effort. Since irrigation requires a large commitment of time and money, its worth over the long-term should be evaluated.
Information in the accompanying table uses projected yields based on long-term research and estimated costs and returns calculated by the Mississippi State Budget Generator to assess the projected worth of irrigating soybeans in the Mid-South.
The calculations use 2005 input prices, a diesel price of $2.23 per gallon, and projected yields indicated in the table. Calculations are made for mid-April, mid-May, and early- to mid-June plantings using two soybean prices.
Major inputs/operations used to generate costs are as follows.
All plantings use glyphosate-resistant varieties seeded into a stale seedbed in 20-inch-wide rows.
All plantings receive a foliar fungicide at R3 to R5.
All plantings are treated for stink bugs, and the June planting receives an insecticide treatment for worms.
The April irrigated planting receives 7.5 inches per acre of irrigation water, whereas the May and June plantings receive 11 inches per acre.
Furrow irrigation with rollout vinyl pipe is used.
Projected average yield increases from proper irrigation are 21, 22, and 17 bushels per acre for April, May, and June plantings, respectively. All of these increases are sufficient to increase profits above nonirrigated profits at both $5.50 and $6 per bushel prices.
Increases in returns from irrigation compared to no irrigation are estimated to be greater in April and May plantings.
At soybean prices of less than $6 per bushel, estimated returns from April plantings are the only ones high enough to cover estimated land rent of $50 or more per acre for nonirrigated land and $80 or more per acre for irrigated land.
Larry G. Heatherly is a retired USDA-ARS research agronomist and current crop consultant. e-mail [email protected] 
|Estimated net returns* at ($ per bushel):|
|Planting month||Projected yield||Estimated costs**||$5.50||$6|
|bushels per acre||$ per acre|
|*Returns to land, management, and general farm overhead. **Includes both fixed and direct costs.|