Last week’s article focused a little on what average litter looks like from a fertilizer value standpoint. This week will look more at how it’s applied and how it affects forage growth.
As mentioned last week, most litter contains approximately equal parts of the big three primary macro nutrients we’re concerned with in soil fertility and growing forages (3-3.5-3). However, very rarely does a soil actually need equal parts of N, P, and K to bring its nutrient concentrations up to an optimum level. Just as an application of 17-17-17 commercial fertilizer is an inaccurate means of fertilizing to the soil’s needs year after year, so too can the use of only litter be a practice that isn’t cost effective. It’s also not very environmentally responsible.
Part of the reason that our soils don’t need this nice, little neat ratio of N, P, and K is because of the utilization of those nutrients by our forages and human’s own history of fertilization. Both bermudagrass and fescue use about the same N and K per ton of grass produced, but P is another story. Most forages only use about 15-20 lbs. of P per ton of forage. They’ll use closer to 50 lbs. of N and K. So, years of poultry litter application will typically result in astronomical levels of P in relation the N and K levels.
Keep in mind, grazed pastures and hayfields are treated completely differently from a P and K standpoint because of the nutrient cycling that goes on in grazed fields. In grazed pastures, a field that already has optimum levels of P and K shouldn’t have P and K applied year after year. There’s no need. Hayfields are different because of the removal of nutrients via the hay bale.
Don’t get me wrong. Litter can be great if you’ve got a good source and someone you trust to possibly pull you an accurate sample. However, if you’re applying to satisfy the N and K needs in the soil and you don’t have a great phosphorus need, then you’re paying for a lot of P you might not need. On the other hand, if you’re just putting out enough to satisfy the P, then you’re not getting enough N to produce anymore forage versus no application at all. The best practice for using litter as a fertilizer is to have a soil test and a litter test in hand when figuring on what your application will be. Soil tests are free, and litter tests run around $30. Both samples will only be as good as the job done by the sampler, too. Once we get the results in, I’ll be glad to sit down with you to figure it all out and come up with an application that is economical and environmentally friendly without excess P.
For more information on soil or litter sampling, call (870) 425-3301 or come by the Baxter County Extension Office.
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