By Stan Smith
Have you fertilized your hay fields yet this year? In the spring issue
of the Ohio Cattleman we suggested once first cutting is harvested it’s a good time for an annual fertilizer application. If that opportunity was missed, fall is another opportune time to replace soil nutrients removed during hay harvest.
Considering we may have experienced lower than hoped for yields throughout parts of Ohio, it adds insult to injury that in some cases Mother Nature forced us to harvest mature, rained on, or otherwise poor quality first cutting hay this spring. Regardless, that hay still took with it lots of soil nutrients.
Fact is, each ton of hay that’s removed from a field during the harvest process takes with it roughly 12 pounds of P2O5 (phosphorus) and 49 pounds of K2O (potash). That’s regardless the calendar date and with little regard for quality of the forage that’s harvested. In fact, many are surprised to learn since corn grain only removes about 0.20 pound of K2O per bushel, it would take a yield of over 600 bushels of corn to remove the same amount of potash that an average Ohio hay yield removes annually!
To maintain productivity and plant health, fertility that’s removed needs to be replaced. Since P and K move slowly through the soil profile – perhaps only an inch or two a year – it’s probably best that what’s removed is replaced annually. And fall is an excellent time to replace those nutrients removed this year in the form of harvested hay.
Because nearly all the phosphorus sources presently available include some nitrogen, when fertilizing in the fall we also enjoy the benefit to grass based hay fields from the nitrogen that comes along with phosphorus based fertilizers. Nitrogen, when applied in mid to late fall after the top growth of cool season grasses begins to stop, helps store energy in the roots preparing the plant for winter. Enhanced fall root growth aids in the uptake of water and nutrients and carbohydrate buildup in the stem bases, promoting winter survival and spring regrowth.
The basics of fertilizing permanent hay fields are simple:
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! Contact your local OSU Extension office or fertilizer dealer for help finding a soil testing lab.
b) Read the soil test report carefully or get help reading it. I’d discourage anyone from blindly accepting the fertilizer recommendations that sometimes are returned along with a soil test report. I’m not even certain I believe the little graphs sometimes found 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 Ohio’s 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 typically 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 and other Midwest university research might suggest is appropriate as published in the new OSU Extension Bulletin E-2567, Tri-State Fertilizer Recommendations.
Ask your 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 of a hay field, or if you know your present fertility levels meet or slightly exceed critical minimum levels, then it’s prudent to base fertilizer application rates on actual or expected crop removal. As was mentioned earlier, each ton of hay removed takes with it 12 pounds of P2O5 and 49 pounds of K2O. No matter how you slice it, that’s a ratio of roughly 1 to 4, phosphorus to potash. Without benefit of a soil test to tell us otherwise, fertility needs to be replaced in that ratio to fields where hay has been harvested.
To put it into a little different perspective, consider the average hay yield in Ohio is, and has been for decades something less than 3 tons per acre per year. At roughly a 1 to 4 ratio, 12 and 49 pounds respectively, multiplied times perhaps 3 tons of crop removal, it equals 36 pounds of P2O5 and 147 pounds of K2O removed annually per acre.
To recap . . . you can’t starve a profit into any animal or crop, sometime before winter dormancy is an excellent time to apply fertilizer to a hay field, and one ton of hay removes P and K in a ratio of roughly 1 to 4, or 12 pounds P2O5 and 49 pounds of K2O. To maintain fertility, health and the productivity of your forages, P and K must be replaced with either fertilizer or manure nutrients . . . in a ratio of 1 to 4 or, 12 pounds of P2O5 and 49 pounds of K2O, per ton of hay removed!Source : osu.edu