I'm not sure what type soil you have but I'd guess its very similar to mine and is basically a sandy loam. If yours is the same then it is what's sometimes called a highly weathered soil and though we have plenty of limestone (calcium) in our soil its not in a form that is available to the plants. However, like I mentioned earlier, this non-useable calcium can be broken down and made available so drought or heat could release it. However there is a lot of chemistry going on so you can't just say its this either but it could be. Could also be the result of moisture conditions or a few other things.
Another thing that is easier to visualize is the buffering capacity of your soil. Weathered soils such as sandy loams tend to have a low buffering capacity. The easiest way to visualize what all this means is to picture a bicycle tire versus a tractor tire. A tractor tire would be a soil with a high buffering capacity and the loss of one pound of air would go unnoticed whereas the loss of a pound of air from the bicycle tire would be seen immediately. Transferring this thought to your soil and with your soil being a loam and having a low buffering capacity you would expect to see changes in the pH more readily than a soil with a higher buffering capacity. These changes can be due to a host of chemical reactions going on in the soil and trying to figure out exactly what's going on would only give you a headache.
A low buffering capacity can be a blessing or a curse. The blessing is that it is easy to amend but the curse is its more unstable and subject to change due to environmental factors or other things. Your goal should be to have a well balanced soil with a high buffering capacity. This can be done but it takes a lot of time and understanding of all these little things that effect your soil's chemistry and structure. The most common suggestion is to add organic matter. This is an over simplification of what's going on but its often suggested without really understanding what's going on. As mentioned, your soil is most likely what's called I a heavily weathered soil so much of the nutrients which help create the buffer are washed out of reach of your plants roots. I'm sure you are familiar with seeing the old timers turning their land. This practice would reach down and pull these nutrients in the buffer zone up to the top where the plants could use them and the crops would do better. However, if your soil is like mine and is heavily weathered and this turning practice has been done for eons then you have a plow line where the plow couldn't go any deeper. Beneath this layer the buffering capacity is most likely higher because all the nutrients have been washed into this layer and they are essentially stored and out of reach. To see how this can effect your grass all you need do is take your front end loader and dig up some of this soil beneath the plow line and spread a scoop of this somewhere in your pasture and within a year you will see a huge difference in the grass color and growth in this test spot. Not only will it be greener and more lush but it will be more drought tolerant and pH stable.
Another thing worth mentioning on soil buffering is there are some snake oil products out there which advertise using minute amounts of this rather than conventional fertilizer or manures. What some of these products can do is mine the buffer from your land just like the turning plow did which is akin to your just digging your grave deeper and not what you need and is only a short term fix can which can hurt your land if done to much. You want to save this reserve and address fixing the 18 or so inches above this layer.
In my view its best to add as much natural organic matter and nutrients as possible just like you are doing with the clover and such. Though you may not see the benefits immediately you are doing what is right for the land and helping yourself in the long run by creating a well balanced soil. You need to also have the awareness that certain chemicals can effect the chemistry or the organisms that help you build your organic layer and your soil's buffer. Sadly, this won't be easy because you are surely correcting many years of soil neglect but I think you are on the right path by trying to figure out what's going on in your soil because soil is after all the foundation of your cattle operation.
Sorry for the long post and I'm sure I've got a few things oversimplified but this is how I look at things. Hope this helps and hope it didn't give you a headache. :lol:
