Cotton growers in Georgia spent an estimated $30.05 an acre on foliar insecticide in 2024, which is $30,050 on 1,000 acres. Foliar insecticide is the kind sprayed on the leaves. That average is a cost, not a proven loss, but it is what a wrong call about spraying puts at stake. You and your agronomist settle that bill spray by spray, and the agronomist’s pay may depend on what you buy. A large California study found that a commission on the sale did not mean more spraying. So who pays matters less than who decides. Write down who pays each agronomist, and keep the purchase and any change of product or rate as your call, in writing.
The study, by Rosenheim and Culshaw-Maurer, used California’s public records of pesticide use, which farms there must file. It covers 592,068 crop-years from 2012 to 2021. A crop-year is one crop grown in one field by one farmer in one year. In this article, an agronomist is the adviser who scouts your fields and recommends what to apply. California licenses them as pest control advisers (PCAs), and it requires a written PCA recommendation before some high-risk pesticides are applied.
The authors sort PCAs into four groups: sales advisers employed by chemical retailers, independent advisers paid a fee by the farmer, advisers employed by one farm, and licensed farmers advising their own farm. Farmers advised by sales advisers used slightly less pesticide than farmers advised by independent advisers, who receive no sales commission.
Is the advice from your input dealer’s agronomist free?
Where the dealer’s agronomist does not charge, the advice costs nothing on the day and is paid for in the product. In California, the sales advisers’ scouting and recommendations are free to the farmer, and their companies earn their income through chemical sales. Independent advisers charge a flat fee per hectare (a hectare is about 2.5 acres) and sell no chemicals.
The dealer also weighs on fertilizer decisions. In a 2005 survey of US corn growers, 41.2 percent based their nitrogen rate on a fertilizer dealer’s recommendation, 17.6 percent on a crop consultant’s and 4.6 percent on the extension service’s. Routine practice was named by 71.7 percent of the growers. A farmer could give more than one answer, so the shares add to more than 100.
In the California records, sales advisers were linked to nearly six in ten crop-years, and independent advisers to fewer than three in ten.
Write down, for each agronomist, who pays them and what they or their employer sell.
Does an agronomist paid on the sale recommend more?
In this study, no. The authors measured pesticide use in three ways for each of 10 crops and compared farmers advised by sales and by independent advisers on each, 30 comparisons in all. In 11, farmers with independent advisers used more; in 16 there was no difference; in 3, farmers with sales advisers used more.
The authors did find one sign of heavier use among the sales advisers’ clients: adjuvants, the additives mixed into the tank with the pesticide. Those farmers used more adjuvants per application, but not more adjuvant in total weight.
The advisers and dealers the authors consulted gave one reason a commission may not push sales: it is paid on the profit from a sale, not on gross receipts, and margins on pesticides are small. A second brake is the farmer, who can decline a spray.
The study has limits. The data record what farmers did. No experiment assigned advisers to farms, and farmers choose their advisers. If farmers who like to spray pick sales advisers, that would push the sales advisers’ figures up, so finding no extra use counts for more, the authors argue. The records list what was applied, not what the adviser recommended, and a farmer may have turned a spray down. The study covers California and pesticides only, not fertilizer or seed.
Older work was mixed. A 1975 study found that farmers advised by sales advisers spent twice as much on pesticides as farmers advised by independent ones. The gap appeared to close over the five years studied, and two later questionnaire studies found no significant difference.
Judge each recommendation by the reason it gives, not by who is paid for it.
Does any kind of agronomist, or any law, remove the conflict?
No agronomist is free of interest; what changes with who pays is the interest. The clearest difference in the California study came from advisers on a farm’s own payroll: more pesticide was used against insects and plant diseases, but not against weeds. The authors tie this, cautiously, to the risk those advisers carry, since they could lose their entire employment if blamed for an outbreak. The records do not show whether the extra spraying protected the crop.
What each kind of adviser stands to lose differs. Only farmers licensed to advise themselves have a direct financial stake in the outcome of each crop. Sales and independent advisers can lose individual clients if they are blamed for damaging pest outbreaks.
Independent does not mean neutral. French government inspectors, in a 2023 report on the law that split pesticide sales from advice, write that independent advisers want to keep their clients, and so put the farm’s economic success first. That does not always match the priority of using fewer pesticides, and in doubt they might prefer to limit the risk and advise using the products.
A law that separates selling from advising has not settled the matter either. California considered one in 1971, and the bill failed, so sales advisers remain the largest group in the state. France passed one: a 2018 act and a 2019 ordinance separated the sale of plant protection products from advice on them, in effect since 1 January 2021. Specific advice must be in writing and justify why the recommendation is appropriate.
Two years later, the inspectors heard from everyone they interviewed that sales technicians kept advising only orally and wrote no document, leaving the whole responsibility for using the products on the farmer. The federation of French farm cooperatives denies this.
The French law applies only in France. What carries over to your page is one part: each recommendation, and the reason for it, ends up on paper in the farmer’s hands.
Ask each agronomist to send every recommendation that changes a product, a rate or a purchase in writing, with the reason.
Which decisions are the agronomist’s, and which stay yours?
The agronomist scouts, diagnoses and recommends; the purchase, and any change of product, rate or program, stays with you. That split is this article’s proposal, not a finding. In the California study, some farmers accepted virtually all of their adviser’s recommendations, while others weighed the adviser’s judgment against their own and could decline a spray. Farmers are fully aware of their sales advisers’ commissions and may provide a balancing counterinfluence.
In a guide from the UN Food and Agriculture Organization, David Kahan tells advisers to balance their responsibility with the understanding that it is the farmer who decides how the farm should be managed.
Some decisions are shared by nature. The California authors suggest that a farmer with crop insurance, in close consultation with the adviser, could decide together to accept a small risk of a pest outbreak in exchange for lower input costs.
Another article, on what your hired farm manager decides alone, sorts decisions into four levels. They fit the agronomist too: the agronomist (1) decides alone, (2) decides and tells you, (3) consults you first, or (4) leaves it to you. A decision you share has no level of its own. You hear the agronomist and have the last word, so it sits on level 4.
The page you write with each agronomist has six items, an arrangement proposed here and not taken from a contract template. Item 1 goes first because it is the one most often left unwritten. Anyone can write it without accusing the agronomist, because it applies to every agronomist, the farm’s own included.
| Item | What you write | Why |
|---|---|---|
| 1. Who pays and what they sell | The payer and the pay: a fee per acre, a salary, or built into the price of what you buy; and the products the agronomist or the employer sells | You see which interest weighs on each recommendation: the sale, the client or the job |
| 2. Visits | How many visits a season, and what calls for an extra one | You can tell an agreed visit from one that did not happen |
| 3. The agronomist’s decisions | The types of decision the agronomist makes alone, such as scouting dates and which fields to walk first | You know in advance which calls you will not be asked about |
| 4. Your decisions | What to buy, how much and from whom; any change of product, rate or program | These are the decisions that spend your money |
| 5. In writing | Every recommendation that changes a product, a rate or a purchase reaches you in writing, with the date, the field and the reason; you get copies of the scouting notes and recommendations the agronomist keeps on your fields | Without paper, nobody can later show what was recommended and why |
| 6. Dates | The date the page starts and a date to go over it again, signed by both | The review date is when you decide whether the arrangement goes on |
To check which soil test a fertilizer recommendation rests on, read the article on the soil test report.
List last season’s decisions on one sheet, and mark each one as the agronomist’s or yours.
What should the first hour with your agronomist produce?
One signed page. Set aside about an hour with each agronomist before the season’s first visit, with last season’s invoices and recommendations at hand.
When you and the agronomist disagree about a product, paper will not settle it. A field can, with an untreated strip beside the treated one, and a separate article covers what your on-farm trial tests. Once who pays is on paper, you judge each recommendation by its reason, not by a suspicion. With the page signed, you have settled two questions of how the farm is managed: who advises on what, and who decides. More written documents for the crop side of the farm are in the production section of the library.