FAQs about soil and conservation

I often hear about costs to society from erosion?
What does this mean and what are some examples?

Soil erosion is composed of two main categories. One is the direct cost to the farmer and the other is the indirect cost to society. An example of the societal cost would be the decreased life of reservoirs due to increased siltation caused by erosion. Another cost is cleaning roadway ditches because they fill in with soil that has left the field. Increased turbidity in the water makes it difficult for fish to find spawning sights and it makes it expensive to clean the water for those using surface water for drinking. Fertilizer and pesticides can enter the water attached to soil particles. These costs are difficult to measure, but they are substantial. The cost of off-site erosion is estimated at $11 per ton using the average of recent analysis by the USDA/NRCS and estimates published in Science magazine and the International Journal of Sustainable Agriculture.

What are some benefits and concerns with strip-tillage?

Strip-tillage is well suited to poorly drained, wet, cold soils where seed germination is often delayed. Only a narrow portion of the row is tilled, which helps dry and warm soils in the spring, easing planter operation and promoting germination. The system can enhance efficiency when manure injection or commercial fertilizer application is incorporated into the tillage operation, reducing passes over the field. Specialized equipment does not always have to be purchased; most farmers already have the strip tillage equipment accessible (such as in-row chisels and ammonia applicator knives). These benefits must be weighed against a variety of potential concerns. For instance, strip-tillage can induce erosion, particularly in highly erodible soils. Strip-tillage also can contribute to soil compaction between tilled zones when the field soil moisture conditions are at or above field capacity.

For further information about strip-tillage:
Resource Conservation Practices: Consider the strip-tillage alternative PM 1901c
(Mahdi Al-Kaisi and Mark Hanna)


What is an appropriate level of residue cover?

Leaving crop residue on the soil surface can minimize surface runoff and soil erosion, improve water infiltration, and increase organic matter content. Most experts suggest that effective conservation tillage systems leave at least 30 percent residue cover after planting. Additional residue is recommended on soils with steeper slopes where the potential for erosion is greater.

For further information about residue cover:
Resource Conservation Practices: Residue management and cultural practices
PM1901a (Mahdi Al-Kaisi and Mark Hanna)

Residue removal and potential environmental consequences- Integrated Crop Managment article

How residue removal affects nutrient cycling - Integrated Crop Management article


Is it possible to get conservation provisions in a lease?

Yes. It is not only possible, but it is desirable. A tenant and landlord should include soil conservation practices as a part of their lease negotiation. Provisions to cover the interest of both parties can be put in writing in the lease. For examples of areas to consider go to the Ag Decision Maker home page at: www.extension.iastate.edu/agdm. This web site contains a wealth of general information and specific information for leases and lease arrangements.

Iowa farmland is increasingly being owned by older people. How will this change in demographics effect conservation practices?

Approximately one-fourth of Iowa’s land is owned by people over 75 years old. Most of them indicate they will pass the land to their children. This indicates a likely increase in absentee ownership, as the land is divided among the children, many of whom will not live in Iowa. Preliminary studies seem to indicate that an increase in absentee ownership will not automatically lead to a decrease in soil conservation. Most farmers will farm the land in a similar manner whether it is owned or rented.

One of the big differences is that renters will tend to take a shorter term point of view when it comes to implementing conservation practices. Their control of the land is less certain and thus they are less likely to want to make long term commitments. Whether or not landlords are diligent in ensuring their long-term interest is honored remains to be seen. 

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