Dec 16, 2011

Plan ahead before planting crops on marginal land

A fairly common situation involves a landowner wishing to establish crops on unprepared, marginal land. Owner goals vary widely, and often include producing food crops for local sales, home gardening or establishing wildlife food plots. Regardless of the proposed goal, the problems are often similar. The landowner’s choice of field location may be limited to sites with very challenging problems, including problematic existing vegetation, undesirable soil pH (usually very acidic), poor soil fertility and drainage issues (often very sandy, drought-prone soils).

People, especially newcomers to crop production, are often eager to get started and envision a smooth transition from what currently exists at their field site to what they desire as a final result. However, there are some important questions regarding site preparation that should be carefully considered before getting started.

Are you open to the use of appropriate herbicides and synthetic fertilizers, or will you be using organic growing techniques? What extent of preparation will your site need before production can begin? Have you identified affordable sources for seed and other inputs? Do you have access to adequate machinery to perform tillage, planting, mowing and other mechanical tasks? Do you have enough time and labor capacity to follow through with the plan? If you are working on a distant site, can you make timely trips to take care of the necessary tasks? Do you have enough money for all of this?

Plan ahead

For the best long-term results, a soil preparation plan should be developed and followed. The plan should include components that will provide for control or elimination of existing, undesirable vegetation, improvement of soil pH, improvement of soil fertility and increased levels of soil organic matter.

On many challenging soils, the following basic plan has proven effective.

Year 1. Take a soil test to determine the need for lime, current soil fertility levels and soil organic matter baseline (if desired). Eliminate existing vegetation using herbicide (i.e., glyphosate + ammonium sulfate), summer fallow or other techniques, such as solarization.

Year 2. In the spring, sow buckwheat, sorghum and sudangrass, millet, oats or some other spring-seeded annual crop with adequate lime and fertilizer.

Work this crop into the soil before weeds set seed, or in early August. It may need to be mowed before tilling.
Sow fall rye in mid- to late August. If the spring crop was tilled into the soil early and weeds have germinated, soil should be worked again before planting rye to destroy small weeds. Rye will be very attractive to wildlife and re-grow vigorously in spring. Rye is an excellent “scavenger” crop and will be able to extract plant nutrients unavailable to many other crops. These nutrients will become available to the following crop as the rye residue decomposes later.

Year 3. Work the rye into the soil in May. Mowing before tillage may be necessary.

At this point you can repeat the process for another year, or prepare the soil for planned crop production.
This plan allows for the addition and incorporation of lime prior to the seeding of green manure crops. Where large amounts of lime are recommended by soil test, the total amount may be applied over several tillage events.

Similarly, major deficiencies of soil phosphorus or potassium can be corrected gradually. The breakdown of green manure crops over at least one year, and preferably more, will add to soil organic matter, improving soil tilth and water-holding capacity.

By Jim Isleib, Michigan State University