Be on the lookout for light green (chlorotic) areas in your alfalfa fields this coming crop season. These areas most likely occur in patches rather than over the entire field.

Monitor sulfur status of forages“If you see these areas, get a tissue analysis done on both the normal-appearing and chlorotic areas,” says Ev Thomas with the William H. Miner Agricultural Research Institute in Chazy, N.Y.

If the affected areas test less than 0.25 percent sulfur, apply a sulfur-containing fertilizer such as calcium sulfate, potassium sulfate or sulfate of potash magnesia, Thomas says.

Rely on a tissue analysis, rather than a soil test, Thomas says. That’s because there’s not a good correlation between soil and tissue status for sulfur. A forage analysis may be useful as an early-warning sign, but be sure to confirm it with a tissue analysis.

Your efforts will be rewarded.

“Midwest university agronomists found yield increases of over 50 percent when they fertilized sulfur-deficient alfalfa (with a tissue analysis of 0.16 percent) with 24 pounds of sulfur per acre, costing about $14.00,” Thomas says. “That’s a big return for a modest investment!”