Some of our sky-blue water turned brown during the past two growing seasons. Fueled by heavy rains over much of the southern part of the state, soil loss has been substantial. Most crop growers clearly understand the importance of keeping the highly fertile topsoil on the landscape.
Research has shown that using some type of conservation tillage system will reduce soil loss. Yet adoption of the systems that have the greatest potential for reducing soil loss has been slow, at best. Over the years there have been several explanations for the slow adoption rate. Many are no longer valid, and it's time to take a new look at planting systems that will minimize soil loss in the corn-soybean rotation.
Conservation tillage can be described as any practice that leaves a certain percentage of crop residue on the surface after planting. The three generally accepted conservation tillage systems used in the northern and western corn belt are no-till, ridge-till and strip-till.
Results from several studies that have compared various tillage systems lead to the general conclusion that yields are reduced slightly with no-till when soils are cold and wet early in the growing season. There is also a general conclusion from the studies that the lowest amount of risk is associated with ridge-till and strip-till planting.
The switch from conventional planting to conservation tillage requires some changes in our thinking about fertilizer use. Recommended nitrogen rates to achieve the expected yield do not change. However, broadcast applications that remain on the soil surface are not a good option. Research has shown that broadcast N that remains in contact with crop residue is subject to loss, probably through volatilization. Thus, fertilizer N applied in a conservation tillage system should be placed below the crop residue.
For application of phosphate, potash and other immobile nutrients our thinking needs to shift from broadcast to banded applications. Most ridge-till farmers place the band in the center of the ridge 4-6 inches deep in the fall of the soybean year. This deep band is used effectively by young corn plants and eliminates the need for starter fertilizer. Also, phosphate and potash rates can be reduced considerably with banding when compared with broadcast applications for conventional planting.
Banding phosphate below the soil surface reduces the potential for movement of phosphorus from the landscape into surface waters, where the phosphorus can increase algae populations and thus reduce water quality.
Conservation tillage also improves the economic bottom line. In a survey in the summer of 2001, several ridge-till farmers were asked via personal interviews to provide their production costs for corn and soybeans, as well as their yields for each crop. Neighbors who farmed a similar number of acres with conventional tillage were asked the same questions.
Average corn yields for the conventional and ridge-till planting systems were 144.9 and 149.0 bushels per acre, respectively. For soybeans, the average yield was 41.5 bushels per acre for conventional and 43.7 bushels per acre for ridge- till.
While yields were similar, there were major differences in cost of production. The conventional system had a corn production cost of $1.94 per bushel, compared with $1.52 for ridge-till. For soybeans, production cost with conventional tillage was $4.13 per bushel, compared with $3.69 for ridge-till. In general, ridge-till production costs were lower for fertilizer, herbicides and fuel.
In the past, some growers have expressed a perception that conservation tillage is best suited to small equipment. However, Iowa and Minnesota crop producers use 16-row ridge-till planters and cultivators successfully. Ridge-till and strip-till planting does not limit equipment size. As with conventional tillage, choice of equipment for conservation tillage is an individual grower decision that is influenced by many factors.
When evaluated from agronomic, environmental and economical perspectives, the adoption of conservation tillage planting systems is a win-win situation for everyone.
Brainerd Dispatch ©2013. All Rights Reserved.