Jay W. Johnson
1. Is deep chisel plowing better for the soil than regular plowing? Why or why not? In what cases will it be most beneficial?
Chisel plowing is a tillage system that fractures the plow layer with a minimum amount of incorporation of surface residue. For maximum effectiveness, the soil must be relatively dry at the time of chisel plowing.
Most chisel systems used in Ohio will provide tillage to a depth of approximately 10-12'. This is the same depth to which most moldboard plow systems are designed to till; thus, depth of tillage usually does not differ greatly between the two systems.
Because a chisel plow system leaves residue near the soil surface, it can help to prevent the formation of surface crusts, thereby improving water infiltration. On soils that have a tendency to crust, this effect can often lead to increased productivity. On the other hand, use of a chisel system together with surface application of immobile nutrients sometimes results in poor plant uptake due to stratification of fertilizer nutrients in the top few inches of the plow layer. To minimize this effect, we recommend that on low fertility soils, immobile nutrients be deep placed with the planter.
2. How do we determine if we have soil compaction and how bad it is as far as its effect on yield?
The simplest way to determine whether or not you have a compaction problem is to go out into your field with a shovel. If you find that the soil is hard to dig, it is safe to assume that you have soil compaction. Other indicators of soil compaction may also be present: slow drainage, N deficiency problems, and shallow rooting of crops are all possible signs of compaction.
The effect that soil compaction will have on yield depends on the particular growing season. During years in which adequate water and nutrients are present, compaction will not have any impact on yield. On the other hand, when a crop is stressed by too little water and nutrients, or even by too much water, compaction will tend to decrease yields. Soil compaction may cause as much as a 15-50 percent decrease in yield.
Reference: Steinhardt, Gary C. 1985. "Basic Considerations of Soil Compaction, Tillage, and Crop Problems.' Proceedings of the Fifteenth North Central Extension-Industry Soil Fertility Workshop. Bulletin #729.
3. What are some practical methods to reduce soil compaction? How can you get jobs done on time without compaction?
To avoid compaction, one should always be sure that the soil is relatively dry when you are performing field operations. Another good method to reduce soil compaction is crop rotation. In particular, the root systems of forage crops (e x. alfalfa, clover, grasses) are often useful in breaking up compaction zones. There are also deep tillage tools (e.g. subsoilers or paraplows) that can go below compacted regions and mechanically loosen them. In cases where mechanical tools are used, the soil must be relatively dry in the compacted zone for adequate shattering to occur. Other methods for reducing soil compaction include improving drainage and decreasing the load on equipment that is hauled into the field. Finally, soil compaction can be decreased by using a controlled traffic system where the same wheel tracks are used for every field operation; often the use of such a system will allow the timely performance of field operations.
4. If shallow tillage is the only tillage method used in a corn/ soybean/ wheat/ meadow rotation, can increased biological activity be expected to release nutrients previously unavailable to plants, thus decreasing the need for commercial fertilizers?
With a shallow tillage system, the amount of organic matter that accumulates in the upper region of the soil profile often increases with time. As the organic matter content increases, usually so does the amount of biological activity. The net result can be an increase in the availability of some nutrients in this surface zone.
In many cases, however, this increase in the biological activity of the surface layer will result in less organic matter and thus reduced biological activity deeper in the soil profile. Therefore, the net effect of shallow tillage may or may not translate into greater nutrient release and improved availability since many crops have roots that feed deep in the soil profile.
More specifically, whether or not use of a shallow tillage system will result in reduced fertilizer needs will depend on such factors as the crop grown, the mineralogy of the soil, and the distribution of nutrients in the soil profile. Also, some nutrients will tend to be more affected than others. For example, the nitrogen concentration of a soil is closely tied to the activity of soil microbes while the potassium level of a soil depends more on inorganic cycling.