HuntingNet.com Forums

Not exactly.

Different tillage operations have different impacts on soil organic matter, which probably the most important component of the soil. Soil organic matter serves some very important functions. It serves as a nutrient bank, storing nutrients in plant available form. It tends to attract and store certain nutrients, as well as providing nutrients as it decays. And since it is largely based on plant matter, it contains most if not all of the essential elements plants need. In addition, it absorbs and holds moisture, and can improve water infiltration rates. It also improves soil tilth, soil structure, and helps to minimize soil and nutrient loss to erosion. The amount buried by the tillage operation and the size of the pieces it leaves has a large impact how quickly it decays. A tiller chops it into fine pieces and buries most of it, making it decay much quicker. It also incorporates more air into the soil, burning off even more OM and drying the soil. On the other hand, a chisel plow or subsoiler appropriately equipped will only bury about 15-20% of the standing OM at a time. The OM left on the surface helps prevent erosion, slows the movement of water, and increases infiltration. And these type implements do not chop the residue, resulting in much slower decay. A larger percentage of the soil organic matter will remain for maturing crops.

Tillers and disks also create much more compaction than something like a chisel plow. It is not a phenomenon unique only to plows, as many gardeners know the effects of “tiller pan”. Take three fields. One is tilled only with a tiller. One with a disk. The other with a chisel plow. Most tillers or disks are used on about the top 4" of soil. If no other tillage method is used, that penetrometer will most likely show a sharp spike in the amount of force required to penetrate the soil at that 4" depth, which is the plow pan you mentioned. On ground that has only had a chisel, the penetrometer will show a slow, steady increase in the amount of pressure required to penetrate the soil. I've done this study myself a few years ago. All soils tested were the exact same type: Bluegrove Fine Sandy Loam. I used a field my dad farmed (he disks a lot), one I farmed (I only used a chisel), and the garden, which only saw a tiller. The readings on the penetrometer did not indicate a plow pan on the field that saw only the chisel (three times with spikes and once with sweeps). Digging to a depth of 12", root growth had no appearance of any hinderance at any depth, although there were no roots growing down the full 12" at the time. On the field that had been disked, there was a spike in the amount of pressure required to penetrate at about that 4" depth. Subsequent digging there showed many roots slowing at the 4" level, with many stopping vertical growth and growing horizontally. Some roots did penetrate and continue growing. That field was chiseled once (with sweeps) and disked three times. I do not know what effect, if any, running over the ground once with the chisel had. I don't know what possessed me to do the garden other than curiosity. I could not get the penetrometer to penetrate passed 4". After it rained (I did this during a prolonged dry spell because that is when the effects are most pronounced), I dug down to about 12”. The roots stopped almost completely at 4”. Now I know why I was having to water my garden so frequently. My plants were not able to develop an adequate root system, and since the closer moisture is to the surface, the quicker it evaporates, it didn’t take them long before they needed water again.

Soil doesn’t have to be perfectly size and perfectly smooth to create a good seedbed. It is also not the entire aim of a tillage program. A good tillage program provides benefits to the plant throughout that plant’s life cycle. Getting a good stand is meaningless if it is not accompanied by good production, which is the ultimate goal of any food plot.