The Yield Plateau on the Irrigated Quarter
A 160-acre center-pivot quarter in the High Plains has averaged 218 bu/acre corn over the last five years, against a county average of 224. The owner believes the pivot is underperforming and wants a recommendation on whether to invest $95,000 in variable-rate fertigation and soil-moisture sensors. You are retained as an independent consultant. Records show uniform nitrogen applications of 210 lb N/acre, a soil test with organic matter ranging from 1.1% in the west half to 2.3% in the east half, and a well capacity of 650 gpm. The owner's son, who manages day-to-day operations, has already obtained two vendor quotes and is pressing for a decision before spring planting in six weeks.
1. What is the first analytical step before evaluating the technology investment, and why?
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Separate the yield gap into its components before pricing a solution. The 6 bu/acre gap to the county average is small, and the field's internal variability (organic matter 1.1% vs 2.3%) suggests the limiter may be water, not nitrogen. Check well capacity first: 650 gpm over 160 acres is roughly 4.1 gpm/acre, which is marginal for full-season corn in most of the High Plains and may cap yield independently of fertility. If the pivot cannot meet peak ET demand, fertigation and sensors address a secondary constraint. The consultant's job is to identify the binding constraint - water, nitrogen, or uniformity - before recommending capital. A defensible answer states the diagnostic sequence: water supply adequacy, application uniformity, then nutrient management, then technology.
2. The son wants a decision in six weeks. How do you structure the recommendation given the timeline?
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Split the recommendation into a no-regret tier and a deferred tier. No-regret actions that fit within six weeks: a pivot uniformity test (catch cans) and a review of the five years of yield monitor data by pivot position. These are low-cost and directly test the uniformity hypothesis. Defer the $95,000 capital decision until the uniformity data and a water-balance check are in hand, and state explicitly that a six-week window is not a reason to skip diagnosis on a capital item of that size. Document the conversation: the client is entitled to a clear recommendation, and the consultant is entitled to name the evidence needed. If the owner insists on proceeding, put the conditional basis in writing.