Tim,
I have been running a Bobcat S650 for the last couple of years on our ranch in the Texas Hill Country clearing mostly mesquite and agarita (not much cedar on our place). I don't grub the mesquite but rather shear and spray it. From your pictures you are doing a great job in clearing the roots etc. The issue where we are if you grub a lot, all you end up doing is bringing lots of rocks to the surface as the top soil is relatively thin. I can cut the tree with the shear at grade level, spray with a mix of remedy and diesel and go to the next one leaving a relatively smooth surface and most of the native grass cover in place. Over the last couple of years I have cleared 100-125 acres with about 225 hours of run time (still have some stacking to do).
The land that I am clearing is generally flat to some slope; some areas are rocky most is not (the areas that I am clearing happen to have my best soil hence the high concentration of mesquite). I have had very little regrowth in the areas that I did a couple of years ago.
One advantage of the shearing is that I leave much of the soil undisturbed. That way I get faster recovery of the native grasses other than where my skid steer wheels chew up the soil. I do tend to grub the agarita using the shear as a grubber.
The land may have been cleared some 40-60 years ago and I suspect in spots there may have been some areas where the pastures were shredded for a time to try to control things. The result is that this mesquite ranges from small new growth but mostly is stuff that is trunks of 3-8 inches in diameter, 20-25 foot tall and some are as much as 24 inches in diameter. Many of the ones that are the 3-8" size are multi-trunk with as many as 20-30 of the things coming from the same root system. Those are a pain to shear. The agarita's are amazingly huge as well; some have branches 3" in diameter and the bushes may be 8-10 feet tall and the size of a small bus. Beautiful yellow wood though if you ever has a use for it.
I also have a bumper crop of prickly pear and other cacti mixed in with the lot. I run it over while doing this clearing but for long term control I have been having a crew come in the spring between the time of the oak leaf drop and the mesquite leaf out and aerial spray for pear with a helicopter (I have way too much for reasonable hand spraying). The section that I had done a year ago has seen about a 75% kill or better in the 12 months; it supposedly takes as much as 2-3 years to get maximum kill.
What have I learned so far:
It takes me about 2-3 hours per acre to cut, spray and stack my pastures that are very densely covered with mesquite, etc. I have seen very little regrowth of brush in areas that I did two years ago.
I go through about two gallons of spray mix per acre; mix is 15-25% Remedy Ultra, the balance diesel. The amount of mix/acre depends on how much mesquite vs. other 'stuff' I have to clear.
If you buy Remedy Ultra in bulk, shop around. A year ago I was tying to buy 75 gallons of the stuff. I found all of the feed stores including TSC would negotiate but some have are more willing than others. TSC (after discount) was still more that $20/gallon higher than some local feed stores. After talking to about 10 or more suppliers in a 100 mile radius I found about a $25-30/gallon variance between high and low price.
I use a Bobcat 72" root grapple to pick and stack. I don't 'scoop' the stuff; I reach down and pick a tree off the ground, go to the next one, drop the load on top of it from about 12 inches and then pick the whole mess up. Repeat and rinse until the grapple is full and head to the brush pile. The more stuff in the grapple (up to a limit) the better job it does picking up the little 'stuff'.
I now use a 16" M&M Hydrasnip to shear with. It has 10 gallons of built in tanks and I have the optional spray system. You MUST spray the sump immediately after shearing. You must attempt to have the stump as clear as possible of dirt and debris when spraying. The cellular structure of the mesquite is such that it starts shutting itself down within minutes of you shearing and spraying later is an exercise in futility; otherwise all you have done is pissed off the mesquite and it grows back worse that before and harder to kill. Read the Texas A&M Agrilife stuff on line about mesquite. It also is interesting to cut a 24 inch old mesquite with a 16 inch shear (think of nibbling)
I used another brand of shear for about a year; it got to a point I was spending as much time repairing it as I was shearing and not getting as good a job done. The blade attachment systems on most of these shears for example are based on through bolts with slots through the blades. Two things; the hard mesquite will have a tendency to cause the blades to slip in the slots (even with 300 ft-lbs of torque) leaving a gap between the blade (tough to cut the small trees then) that you have to then loosen and re-straighten, and second, the bolt heads tend to drag dirt across the stump (see issue above) reducing effectiveness of spray; the M&M shears use a different attachment system that avoids these issues. Also most shears that have sprayers also have smaller tanks requiring more stops to refill. I can't say enough how much more efficient I am with these new shears and how great the owners of the manufacturer are to work with on issues. They are however quite a bit pricier than most.
One thing for certain is, when you are cutting and grappling mesquite you will go through hydraulic hoses and wiring where exposed. You want equipment that shields these things as best as possible; add some of your own protection and you will still be making repairs. That mesquite is tough stuff and finds ways to get to that rubber stuff no matter what. I would strongly recommend having some precut hoses and extra wire, fittings, etc. on hand to minimize downtime. Oh yes, and some extra hydraulic fluid to replace what you sprayed on the pasture through that blown hose.
The shearing method IMO works well in areas that you want to minimize top soil disturbance and you also don't want to spend the time, effort and expense (and pray for rain) to reseed the grass.
