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3/2/2009 - 3/8/2009

Moving to No-tillage: Challenges and Opportunities

By Mahdi Al-Kaisi, Department of Agronomy

Wet conditions last fall and potential wet conditions this spring make this a good time to consider tillage choices. It is a good time to examine the value of no-till or strip-tillage, especially for producers that have not tried these methods. Before making tillage choices in the field, producers should consider their overall approach to tillage management.

No-till and strip-till systems are best if the goal is a conservation tillage program that maintains least 30 percent of the previous year's crop residue after planting. However, every choice requires considerations well in advance of going to the field.

Once a producer has made a management commitment to implement a new tillage system, several steps should be taken to achieve maximum results. Included in those decisions are ones related to equipment and attachments, nutrient management, seed selection, weather and soil conditions, and tillage timing.

soybean in no-till field

Soybeans planted in no-till.


One of the first things producers can do is to take an inventory of their current equipment, especially the planter. It is important to know what attachments may be needed – such as row cleaners and stronger down-pressure springs – when adopting no-till. 

To successfully adopt no-till in cold-wet soils producers should be aware of soil conditions. Field internal drainage is an important factor in making site-specific decisions. In approximately half of Iowa cropland, subsurface drainage is used to lower the water table and improve growing soil conditions. Early spring is an ideal time to identify and check drainage systems for potential problems, such as misaligned, collapsed, or broken tiles. Make sure every terrace drains completely in approximately two days after a normal rainfall. If the water stands too long, check for a plugged inlet or outlet.

Soil temperature is critical in tillage management systems that leave significant amounts of residue on the soil surface. As a rule, the farther north in the state the longer it will take for soil to reach planting soil temperature. Strip-tillage is an excellent conservation tillage system option in areas with cold and wet soil conditions in north central Iowa. The use of no-tillage will be less challenging in area where soils are well drained in the state.

Soil texture variability plays a significant role in crop performance, especially in dry conditions where moisture shortage can affect plant stand variability across the field. Soil texture is a key factor in influencing soil's water-holding capacity and drainage of excess water.

Managing conservation systems at the right field moisture is a critical factor to ensure successful outcomes. Plants showing a delay in growth can be explained by improper planting depth, soil surface or side-wall compaction due to planting in wet soil conditions, and nutrient deficiencies, such as phosphorus or potassium. Seedbed preparation along with tillage or planting equipment settings can have 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 are not at their best. While scouting fields and evaluating soil conditions, producers need to check soil moisture below the soil surface at the seedbed where the nodal root system gets established – at a depth of 3/4 to 1 inch deep under normal conditions. Adequate soil moisture with adequate nutrient availability, less compacted seedbed and sidewall compaction, can provide a good growth environment for these root systems. 

To ensure the successful transition from conventional to no-tillage or minimum tillage systems, nutrient management considerations including starter fertilizer and timing of nutrients application are critical. A proper fertilizer program is necessary. Plant needs for N, P, and K are basically the same regardless of the tillage system; current research shows that the tillage system has little effect on N or P crop needs. However the timing and method of application are vitally important to no-tillage success, especially in cold-wet soil conditions where mineralization of soil nutrients is much slower compared to conventional tillage.

Conservation tillage and no-tillage have a positive impact on soil productivity and profitability, no matter what the weather does. These systems conserve energy, improve soil tilth and soil organic matter, and can reduce the capital costs associated with the tillage equipment used in conventional tillage. Conservation decisions made now can affect soil erosion over the next several years.

Research on soybean after corn shows no yield or economic return advantages for any conventional tillage system over no-till.  Our studies show that no-till economic return for corn on well drained soils is 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. No-till and other conservation tillage systems are very effective systems from both production and environmental perspectives.



Mahdi Al-Kaisi is an associate professor in agronomy with research and extension responsibilities in soil management and environmental soil science.

March 2 Crops and Weather Interviews

By Doug Cooper, Extension communications specialist
Listen to Extension communication specialist Doug Cooper’s March 2 interviews with Iowa State University Extension climatologist Elwynn Taylor, integrated pest management specialist Rich Pope and corn agronomist Roger Elmore.

Taylor reports the National Weather Service (NWS) is looking at more favorable weather for the center of the country during the next few weeks. He says La Niña appears to be weakening, but right now is still impacting Iowa's late winter and early spring weather.

Rich Pope talks about the black cut worm traps being placed in many Iowa locations. He says the traps help farmers plan scouting of their corn fields based on solid information about the presence or not of the pest.

Extension corn agronomist Roger Elmore attended the Commodity Classic in Texas (Grapevine, TX) recently and says farmers are hoping for better weather in 2009.

Signs of Spring: Robins, Vultures, and Planting Corn

Roger Elmore, Department of Agronomy
Spring is imminent.  Last week two robins sang high in one of our neighbor’s oak trees.  Soon  a trio formed! We’ve endured a long, robin-less winter at least in northern Story County, Iowa.  Recent news articles actually suggest though that robins often overwinter in Iowa and that Turkey Vultures are actually a better spring signal! 

With the anticipation of spring comes the thought of planting corn, but not yet.  What must we think about between now and that much-anticipated first day of planting?  Here are some questions to ponder:

• What crop will you plant?  Consider facts and economics not emotions. Watch crop and input prices. Remember the yield penalty for corn following corn hovers around 15 percent in Iowa. 

• Have you ordered seed?  Compare hybrid performance in third-party tests like those conducted by Iowa State University and other land-grant universities in relation to seed company reports.

• Is your soil fertility program planned?  What about, weed, insect, and disease management? Subscribe to the Integrated Crop management  (ICM) News to stay on top of these issues.

• Do you anticipate changing your tillage system? If so, think hard …and fast. Search for ‘tillage’ in the ICM News. 

• Are you staying with the same row spacing?   Rows narrower than 30 inches don’t appear to dramatically increase yields in Iowa but they do not lower yields either. As plant populations increase, narrower rows may eventually be more beneficial than 30 inches. See our web page for information.

• What seeding rate will you target?  Yields continue to increase in Iowa in part because we’re increasing plant populations by over 400 plants per acre per year. Hybrids marketed today thrive with higher seeding rates than before. Although variability exists across locations, most producers should plant corn in the lower to mid-30,000 seeds per acre range given yield trends and economics.

• What are your plans for scouting?  If you don’t know what is happening in your field in 2009 you won’t know what to work on to improve your management in 2010.  The very best managers know what is going on in their fields. ISU Extension’s  Agribusiness Education Program coordinates many programs throughout the year that could improve your scouting skills.

• Is your planter ready? Gather tips from several articles by searching the ICM News site including this one: Equipment maintenance: Planters.

This list includes several practices you have some control over.  Continue to think and study topics that are important for your production system to help bring about a good 2009 season. Think about them as spring flies toward us.

Signs of spring…Turkey Vultures? I prefer to watch for robins and corn planters.


Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production.

Anhydrous Ammonia Applicators Have New Safety Issue

By Mark Hanna, Department of Agriculture and Biosystems Engineering

High nitrogen fertilizer prices have producers and ag-input suppliers searching for ways to reduce costs and gain efficiency. Some anhydrous ammonia applicators have responded by modifying equipment to allow control of flow to individual sections of an applicator, or even to individual knives. These modifications are being made in order to avoid unwanted N application on overlapping rows, near field boundaries, or into waterways. 

Although this is a sound strategy to limit unwanted fertilizer application, individual section or knife shutoff valves on an anhydrous ammonia toolbar can trap pressurized ammonia at various locations within the system. Operators should take care to bleed all lines including those to individual soil injectors that may still be under pressure before attempting any servicing or work on or around the system.


Additional care needed when working around equipment
Installing a small bleeder valve upstream of any section or knife shutoff valve allows an operator to bleed off trapped, pressurized ammonia before working on those sections or lines. Because these systems are relatively new, and bleeder valves may not be present, it is important to empty all lines before working around the equipment.

To bleed pressure from the applicator, operators should:

1. Shut off ammonia flow first at the supplying field nurse tank.
2. Then open individual knife or section valves farthest downstream in the plumbing system.
3. Follow this by opening any upstream section-control valves.
4. Finally, open the main flow valve.

This procedure opens valves successively upstream in the plumbing system allowing system pressure to be released. 


Wear appropriate gear
In addition to bleeding pressure from hoses and fittings, individuals working around the equipment should always wear appropriate personal protective equipment (PPE), gloves and vented or splash-proofed goggles to prevent injury from minor amounts of ammonia that still may be present in the system. Having readily available water is especially important to flush tissue that may be affected by an ammonia release.

Even if the ammonia plumbing system has been properly bled, openings in hoses, lines, or valves should be treated as exit points for ammonia. Heat from surroundings or sunlight can vaporize small amounts of liquid ammonia still contained in the system and cause unexpected release as hoses or equipment is moved. Caution is always of paramount importance.


Working with maximum pressure
Hoses on applicators upstream from shutoff valves must be capable of handling maximum expected pressure within the system at that point.  Maximum pressure is often supply (tank) pressure or that delivered by a supply pump along with an added safety factor.  All ball valves should be rated for use with anhydrous ammonia and vented to the inlet side.  If not properly vented, liquid ammonia can become trapped in the valve’s closed position and later release when the valve is opened. 


Mark Hanna is an extension agricultural engineer in agricultural and biosystems engineering with responsibilities in field machinery.

This article was published originally on 3/9/2009 The information contained within the article may or may not be up to date depending on when you are accessing the information.

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