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Make conservation system work

What went right? What went wrong? Those are two questions to think about as you evaluate your corn and soybean crops growing in the field after this planting season. How the crop plants are performing, especially if something is going wrong, is often blamed on the type of tillage system being used.

Conservation tillage systems, whether it’s no-tillage or minimum tillage or something in between, need to be used on more acres to save soil and protect water quality. Several things can be done to manage these systems better.

Managing conservation systems at the right field moisture conditions is a critical factor to ensure successful outcomes, says Mahdi Al-Kaisi, an Iowa State University Extension agronomist and soil management specialist.

Plants showing a delay in growth may be explained by improper planting depth, soil surface compaction or side-wall compaction due to planting in wet soil conditions, or nutrient deficiencies, such as phosphorus or potassium. Seedbed preparation, along with tillage or planting equipment settings, has a combined effect on plant performance.

It is very difficult to isolate the exact cause of poor plant performance when soil conditions and management practices aren’t at their best. “While scouting fields and evaluating soil conditions, producers need to check soil moisture below the soil surface at the seed depth, as well as where the nodal root system gets established, at a depth of ¾ to 1 inch deep under normal conditions,” he says. “Adequate soil moisture with adequate nutrient availability and a friable seedbed without sidewall compaction can provide a good growth environment for root systems.”

Meet the plant’s needs

To ensure the successful transition from conventional to no-tillage or minimum-tillage systems, nutrient management considerations including starter fertilizer and timing of nutrient application are critical. A proper fertilizer program is necessary.

The corn or soybean plant’s needs for N, P and K are basically the same regardless of the tillage system, says Al-Kaisi. Research shows the tillage system has little effect on N, P and K crop needs.

However, the timing and method of fertilizer application are vitally important to
no-tillage success, especially in cold and wet soil conditions, where mineralization of soil nutrients is much slower compared to conventional tillage.

“Conservation tillage systems such as no-tillage have a positive impact on soil productivity and profitability, especially under extreme weather events of wet or dry conditions,” Al-Kaisi says. “These systems protect soil, conserve energy, improve soil tilth and soil organic matter, and can reduce the capital costs associated with the tillage equipment used in conventional tillage.”

It’s important to keep in mind, he emphasizes, that conservation decisions made now can affect soil erosion over the next several years.

Comparing tillage systems

Research on soybean production after corn shows no yield or economic return advantages for any conventional tillage system over no-till. Studies show that
no-till economic returns for corn on well-drained soils are much greater than other conventional tillage systems. Even in cold and wet soils with adequate drainage, both no-till and strip tillage performed very well compared to conventional tillage systems.

Al-Kaisi suggests reading “No-till is better choice for soybean after corn” available on the Iowa State University Integrated Crop Management Newsletter website at

It explains the results of six years of tillage system studies at six locations in Iowa. Five different systems (no-till, strip till, deep rip, chisel plow, moldboard plow) were compared.

“In summary, tilling corn residue for the soybean crop year does not improve soybean yield,” says Al-Kaisi. “There may be some challenges in managing corn residue. But simple modification of the planter to include residue cleaners, heavier down pressure springs, or other residue management attachments are far more cost-effective than the expense associated with conventional tillage.”

Some farmers say they till corn crop residue to improve the organic matter content of soil. That reasoning is unsupported by research, says Al-Kaisi. Studies have shown that incorporating residue with intensive tillage will do more damage. This practice accelerates the loss of soil organic matter by mineralizing organic matter and altering the activity of microbes in soil. There’s also a greater potential loss of organic matter associated with conventional tillage due to risk of soil erosion. In a no-till system, crop residue can decompose slowly and release nutrients more efficiently into the soil for crop use.

Source: ISU Extension


NO-TILL BEANS: Results of a long-term Iowa State University study shows soybean yields are not significantly different for five types of tillage systems tested at various Iowa locations.

This article published in the July, 2012 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2012.