With our short winters here in the mid south, fall soil amendments play an important role in determining the yield and nutritional content of our spring grass and we pay a lot of attention to the nutritional profile of our forages, including both pasture and hay. As a general rule if the soil is deficient in nutrients, so the forages grown on that soil will also be deficient in nutrients and this is particularly true of trace minerals. This fact is widely overlooked in production agriculture today as it’s considered easier and more cost effective to supplement additional minerals in the diet. I agree with mineral supplementation if it is done in a nutritionally correct way; it is a form of “cheap” insurance against nutritional deficiency. But I don’t like to rely solely on my insurance policy to provide adequate mineral nutrition. To that end, we amend our soils in order to produce healthy mineralized forages which will require minimal additional mineral supplementation.
Perhaps the most important fall soil amendment is applying lime to adjust the pH. Most Middle Tennessee soils are naturally pretty acidic, varying from pH 6.5 all the way down to pH 4.5 dependent on location and parent material. Soils that fall below pH 6 need to be limed often enough to raise the pH high enough so that pH dependent trace minerals can be efficiently uptaken by plants. We’re lucky in this respect. Our soils are naturally pretty fertile, at least by Tennessee standards, and they maintain pH values between 6 and 6.5 without the addition of lime. Potassium (K) fertilizer can also be spread in the fall where it is necessary. Our soil tests indicate that we don’t need to worry about spreading additional potash which is good news for us !
Nearly all middle Tennessee soils are naturally very high in elemental sulfur. Even if the pH is correct, high soil sulfur will bind necessary minerals like magnesium and calcium as well as necessary trace minerals like copper, zinc, selenium and more. Where it’s possible to do so, I amend the soil by applying mineral and trace mineral fertilizers as the most cost and labour efficient way of ensuring that forages grown on that soil will have a decent mineral profile.
Because trace minerals and lime tend to get released fairly slowly, and because early spring is often wet in these parts, I like to apply trace minerals late in the fall with the thought that some will get used this winter and most will get used next spring and early summer when they are most needed.
I’m going to insert an important caveat here. In terms of equine mineral nutrition, getting the basics right is really important but it won’t save you in every case. There are always going to be situations and animals that require more time and effort in order to put them right and this farm is no different than any other in that respect.