Rice, Wheat and Corn: Prices, Yields and Growing

How grain yield per acre is measured

In the US, grain yield is reported in bushels per acre. A bushel was originally a volume, but grain is traded by weight, so each crop has a standard bushel weight: 60 pounds for wheat, 56 pounds for shelled corn and 45 pounds for rough (unmilled) rice. Most of the rest of the world reports tonnes per hectare instead.

Moisture matters as much as weight. Grain is priced at a standard moisture, 15.5% for corn for example, and wetter grain is discounted or “shrunk” to that standard. When you compare yields between farms or years, make sure they’re on the same moisture basis. For national figures, USDA NASS publishes yield by year for each crop; its corn yield chart and winter wheat yield chart show the long-run trend. Over the past decade, average US wheat yield has mostly sat between the mid-40s and low 50s of bushels per acre, with irrigated and high-rainfall fields well above that. Our article on corn yield and farm income by state breaks the figures down further.

Estimating yield before harvest: a simple wheat and corn yield calculator

Every pre-harvest estimate uses the same idea: count how many kernels the crop has set on a known area, then divide by how many kernels make a bushel. The weak point is kernel weight, which isn’t settled until grain fill ends, so treat any estimate made before maturity as a range.

Corn

The yield component method used by many extension services counts ears in 1/1,000 of an acre (17.4 feet of row at 30-inch spacing), then kernel rows per ear and kernels per row on a sample of ears. Yield in bushels per acre is roughly ears × rows × kernels per row ÷ 90, where 90 stands for about 90,000 kernels per bushel. Use a higher divisor if grain fill was poor, because the kernels will be lighter.

Wheat

Count heads per square foot in several spots, count kernels on a sample of heads, then multiply heads × kernels per head × 43,560 (square feet in an acre). Divide by the number of kernels per pound for your variety, then by 60. Your seed supplier or extension office can give a sensible kernels-per-pound figure. Our crop yield calculator guide covers the general formula for other crops.

Hand counts cover a few square feet. Satellite imagery covers the whole field, which is useful for seeing how much of the field looks like your sample. Our satellite crop monitoring includes a yield estimate and expected harvest date for each field.

Converting between bushels, tonnes and hundredweight

That last column answers a common question, how much a bushel of rice costs. US rough rice is usually quoted per hundredweight, so multiply the price per hundredweight by 0.45 to get a price per bushel. Milled rice in the shop is a different product with a different price.

Working out cost and profit per acre

“Corn price per acre” usually means what it costs to grow an acre. Costs fall into two groups: operating costs (seed, fertilizer, crop protection, fuel, repairs, drying, interest on operating money) and overhead (land rent or ownership cost, machinery ownership, labor, general farm overhead). Revenue is yield times price, plus any program payments or insurance indemnities. Profit per acre is the difference.

The USDA Economic Research Service publishes commodity costs and returns for corn, wheat, rice and other crops, which is the best public benchmark for US farms, and state extension services publish crop budgets you can adapt. Our article on corn seed cost and profit per acre walks through the numbers by USDA quartile. A useful habit is to work out your break-even price (total cost per acre ÷ expected yield) and break-even yield (total cost ÷ expected price) before planting.

Rice, wheat and corn: how growing them differs

Corn is the hungriest of the three for nitrogen and the most sensitive to heat and drought around silking, and its development is tracked in growing degree days. Wheat comes as winter wheat, sown in fall and harvested early the next summer, and spring wheat, sown in spring where winters are too harsh; its key stages are tracked on the Feekes or Zadoks scale, which our wheat growth stages guide explains. Rice is mostly grown flooded, which controls weeds but uses a lot of water. Alternate wetting and drying, where fields are allowed to dry partly between floods, is one of the main ways growers cut water use and methane emissions. Rice is also the crop where yield comparisons most often go wrong, because figures may be quoted for rough rice, which still has its hull, or for milled rice, which weighs roughly a third less. Check which one a statistic refers to before comparing countries or farms.