Through the series of drought, escalating price, managing dynamic change, and every other type of 'stress' meeting we've hosted in Ohio during recent years, it's apparent that the message regarding fertility is getting out. While not a new story, simply put, fertilizer is expensive yet we all know you can't starve a profit into a cow, and likewise, you can't starve production or profit into a forage field either.

This past year I'm seeing significantly more interest in soil testing, as well as receiving questions about interpreting soil tests and developing efficient fertilizer recommendations. It's also apparent some of those who make fertilizer recommendations for a living may not have attended our meetings, or perhaps do not subscribe to the concepts contained in the Tri-State Fertilizer Recommendations, OSU Extension bulletin E-2567!

Hence, let's review:

a) Soil Test, always soil test! Fertilizer is too expensive to apply if it's not a yield limiting factor. If we don't know what we presently have, we can't possibly know what we might need! Here's a link to a fact sheet with a list of soil testing labs.

b) Read the soil test or get help reading it. I'd discourage anyone from blindly accepting the fertilizer recommendations that sometimes come back with a soil test. I'm not even certain I'd believe their little graphs that I sometimes find on the soil test results which indicate a sample might be high, medium or low in a certain nutrient. What I was told by one of the labs when I asked how their recommendations are generated is that after they establish the nutrient levels in the soil through their laboratory procedures, the recommendations are often generated based on the opinions of the company who might have submitted the sample for the land owner. This means, unless you send in the sample yourself, you may get back a recommendation based on data other than what Ohio State's (or other midwest universities') research might suggest as published in OSU Extension Bulletin E-2567. Ask you local Agriculture Educator for help in developing a recommendation if you have questions.

c) If one insists on fertilizing without the benefit of knowing the present fertility levels, or if you know your present fertility levels meet or slightly exceed critical minimum levels, then it's prudent to base your fertilizer application rates on expected crop removal. If you are harvesting hay from the field, Bulletin E2567 tells us every ton removed (regardless of quality) takes with it 13 pounds of P2O5 and 50 pounds of K2O. No matter how you slice it, that's a ratio of 1 to 4, phosphorus to potash. Without benefit of a soil test to tell us otherwise, fertility needs to be replaced in that ratio when harvesting hay.

To put that into a little different perspective, consider that the average hay yield in Ohio is and has been for decades about 3 tons per acre per year. At 1 to 4, that's 13 and 50 pounds respectively multiplied times 3, or 39 pounds of P2O5 and 150 pounds of K2O per acre. As an FYI, since corn grain only removes about 0.27 pounds of K2O per bushel, it would take a yield of over 555 bushels of corn to remove the same amount of potash that an average Ohio hay yield removes!

To recap . . . you can't starve a profit into a crop or critter, immediately after first cutting is removed is an appropriate time to apply fertilizer to a hay field, and one ton of hay removes P and K in a ratio of 1 to 4, or 13 pounds P2O5 to 50 pounds of K2O. To maintain current fertility levels in your soils, it must be replaced with either fertilizer, manure nutrients, or some other form of fertility . . .1 to 4, 13 to 50, per ton of hay removed!

Source: Stan Smith, PA, Ohio State University Extension, Fairfield County