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4/30/2012 - 5/6/2012

Farmland Rental Rates Show Continued Strength in 2012

By William Edwards and Ann Johanns, Department of Economics

Anyone who is involved with the rental market for Iowa farmland knows that rental rates have been pushed significantly higher by the favorable corn and soybean prices that farmers have enjoyed since 2010. This trend continued in 2012.

Results from the most recent Iowa State University Extension and Outreach rental rate survey estimated the 2012 average cash rent for Iowa corn and soybean land at $252 per acre, an increase of $38 per acre or 18 percent from last year. This is the largest one-year increase since the statewide survey was started in 1994. The second largest increase was in 2011, with an increase of $30 per acre. Average rents were higher in all nine crop reporting districts, with increases ranging from $57 per acre (26 percent) in north central Iowa to $16 per acre (9 percent) in south central Iowa.

High quality land showed the largest increase in rents. Estimated rents for land in the high third of each county increased by an average of 20 percent, but estimated rents on low third quality row crop land increased by only 15 percent. In many counties respondents indicated that typical rents were $400 to $500 per acre or more for the higher quality land.

Typical rental rates for land growing oats and hay were also reported, as well as rental rates for grazing pasture and corn stalks. This year rental rates for allowing hunters on farmland also were included.

The intent of the Iowa State survey is to report typical rents in force, not the highest nor the lowest values heard through informal sources. Rental values were estimated by asking over 3,000 people familiar with the land market what they thought typical rates were in their county. The number of responses received this year was 1,419. Of the total responses, 37 percent came from farmers, 28 percent from landowners, 16 percent from professional farm managers, 16 percent from lenders and 3 percent from other professionals.

The Cash Rental Rates for Iowa 2012 Survey is available online as a downloadable document; from the Ag Decision Maker website, .

Other resources available for estimating a fair cash rental rate include the Ag Decision Maker information files Computing a Cropland Cash Rental Rate (C2-20) and Flexible Farm Lease Agreements (C2-21. Both documents include decision file electronic worksheets to help analyze leasing questions.


William Edwards is an Iowa State University professor of economics with extension responsibilities in farm business management. Edwards can be contacted at 515-294-6161 or by emailing Ann Johanns is a extension program specialist for ag economics. She can be reached at 641-732-5574 or

Progress of Corn Planting and Corn Emergence

Roger Elmore, Department of Agronomy

Two questions about corn
1. Is the corn planting window closing?
2. What about corn that is already planted?

As of Sunday, USDA-NASS reported half of Iowa’s corn lay in seed beds, the other half in seed bags. That rate puts us 18 percent ahead of the five-year average. Forty-one percent of our anticipated crop was planted in one week, with only 4.3 days suitable for fieldwork. If we can use that number for days corn was planted, that’s 5.9 million acres in 4.3 days or 1.37 million acres per day. Proving we can plant a lot of corn quickly in Iowa when conditions are right. Unfortunately, forecast conditions this week aren’t too favorable right now. How should we think about this? 

Corn already planted

By April 22 we had nine percent of Iowa’s corn planted. Four percent of that was planted between April 16 – 22, four percent between April 9 – 15, and 1 percent prior to April 8.  Depending on your specific location, all of the corn planted prior to April 15 should be emerged or very close to emerging now based on average heat unit accumulations across the state.  However, heat unit accumulation (growing degree days or GDD) has been a bit less in the northern third of the state, so corn in those areas planted before April 15 may be close to emergence but not quite there yet. It takes about 90 – 120 GDD’s from planting to emergence.

Corn planted after the April 15, including that planted last week, should be well along in the germination process but not yet emerged. For more information on this, read the article Elwynn Taylor and I wrote about corn’s germination process.

Once emergence occurs, evaluate plant stands carefully – whether you expect good emergence and seedling survival or not. Poor stands and plant-to-plant variability lower yield potential. However, depending on the potential date of replant, keeping the surviving stand may be the best option – even with variable plant heights and development.

There are two situations that may cause you to consider replanting: 

  1.   If corn plants emerged non-uniformly, resulting in different plant developmental stages within a row but plant populations are reasonable, replanting will not likely be of benefit. Although the smaller plants compete with their larger neighbors for resources, only extreme conditions warrant replanting. If half the plants are two-leaves behind the rest of the plants within a row, yields can be reduced by 5 to 10 percent. You can estimate yield loss in fields exhibiting non-uniform development by using a tool on uneven emergence posted at our website.  
  2. If corn populations are significantly lower than desired, replanting may be of benefit. Consider several things and make comparisons when determining if a specific field fits this category:
    • Estimate stands. Measure the existing plant population in several random areas in the field. Use the ‘Replant Checklist’ for steps to evaluate an existing stand in a problem field.
    • Estimate yields. The most important factor in deciding whether or not to replant is to calculate expected yield with the current stand versus what you could potentially have if you replanted. Table 1 provides guidelines for this decision. The data shows relative yield potential for numerous planting dates and plant populations based on recent yield data, planting date trends and modern ranges in plant populations.

The replant decision rarely comes easy. Numerous factors determine a field’s yield potential. Consider data like that presented in Table 1 as a tool to use in approximating what may result — based on our best available research data. Please realize though that actual yield losses may be greater or less than what is shown.

Corn not yet planted: is the window closing? 

Optimum Iowa corn planting dates range from mid-April to the end of April in north central and northeast Iowa and to the first or second week in May in other parts of Iowa. The table in my March 27 article, Best planting dates for Iowa, summarizes the recommendations for various regions of Iowa. So, what is there to say the first week of May when only half of Iowa’s corn is planted? Here it is in a nutshell:

Be patient if corn is not yet planted. It is far better to wait for good soil conditions than to ‘mud in’ corn.

There is little question based on our research trials that, on average, yield potentials begin to drop after May 2 in north central and northeast Iowa; after May 13 in southwest, south central and southwest Iowa, and after May 18 in northwest, west central, central and  east central Iowa.  Those are average responses and we don’t know what 2012 will offer. If  2012 provides ‘average’ growing conditions, Table 1 contains some ideas on potential yield reductions associated with delayed planting. For example, if you target 35,000 plants per acre and you are able to plant between May 5 and May 15, you may experience 96 percent of the original yield potential.

Certainly it is time to plant if soil conditions allow. ‘Mudding in’ corn could be trouble the entire growing season. Soil temperatures are back to normal for this time of year across most of the state; normals are about 50 F. Soil temperatures point in our favor for planting corn. The calendar clearly shows we should not think too hard about planting, but the call for more rain this week will – and should – slow planting progress.

When soil conditions are favorable, it is time to plant corn. Is the window for planting corn closing? Not yet!

Figure 1. Corn planted April 4 emerged April 23, right on schedule with about 124 GDD accumulated from planting. R. Elmore photo April 23, 2012.

Figure 2.  Corn planted on April 11 on schedule with about 80 GDD accumulated and 12 days in the soil. R. Elmore photo, April 23, 2012.


Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at or (515) 294-6655.

Nineteen Species of Pythium Associated with Damped-off Soybean Seedlings in Iowa

Alison Robertson, Department of Plant Pathology and Microbiology


Soybean seedling disease survey

During the 2011 growing season, extension soybean pathologists from the north central states conducted a seedling disease survey to identify oomycete pathogens that cause damping-off in soybean. The survey is part of a larger project that is being funded by USDA NIFA. 

In the first year of this study, 54 Pythium species and two Phytophthora species, including Phytophthora sojae, were recovered from damped-off soybean seedlings collected from throughout the north central region. In Iowa, 19 Pythium species and Phytophthora sojae were recovered. Many of the species recovered have been reported as pathogens of soybean seedlings, but some of the species have not. To determine if these other species are pathogenic on soybean, we will have to do “Koch’s postulates.” This is the accepted scientific method for identifying the causal agent of a disease. 

Further research will include comparing the pathogenicity and aggressiveness among and within species, and assessing the sensitivity of each species to fungicides used in seed treatments.

In 2012 this survey will continue, with additional funding from the United Soybean Board used to identify fungal pathogens (Fusarium spp. and Rhizoctonia species); pathogens associated with damping off of soybean.    

Data from these studies will add to our knowledge of soybean seedling disease and lead to enhanced management through improved use of seed treatment fungicides and use of resistance.

Saturated soils favor seedling disease caused by Pythium species.


Locating soybean fields with damping off

This growing season, I am again looking for soybean fields that have damping-off. I need to collect 50 diseased seedlings from the field and bring them back to the lab for processing.

If you know of a field with damping-off, please email me at or call me at 515-294-6708, so that we can coordinate sampling of the field.



Alison Robertson is an associate professor in the plant pathology and microbiology department with extension and research responsibilities; contact her at or phone 515-294-6708.

Reduce Potential Soil Erosion Early in the Spring

By Mahdi Al-Kaisi, Department of Agronomy and Mark Licht, Extension Field Agronomist

Spring rains come with unexpected quantities and force, causing significant amounts of soil erosion to unprotected cropland. Spring is the most critical time for soil erosion because of degraded crop residue, tillage in preparation for planting and lack of crop canopy. Residue cover is not only good for preventing soil erosion, but it will cut down sediment transport to water bodies and contribute to the improvement of water quality.

Raindrop splash and displacement of soil particles. Source: USDA Natural Resources Conservation Service.

Why is rainfall so destructive to bare cropland? In a normal rainfall, raindrops range in size from 1 to 7 millimeters in diameter and hit the ground going as fast as 20 miles per hour (see photo). The impact of millions of raindrops hitting the bare soil surface can be incredible, dislodging soil particles and splashing them 3 to 5 feet away (Figures 1 and 2). A heavy rainstorm may splash as much as 90 tons of soil per acre. However, the majority of the soil splashed is not immediately lost from the field. Most of the splashed soil particles don't leave the field; they clog surface pores which in turn reduces water infiltration, increases water runoff, and increases soil erosion.

Figure 1. Sequential profile of a raindrop splash pattern. (Source: Environmental Soil Physics, Hillel)


Figure 2. Raindrop splash pattern from a sloped landscape. Source: Environmental Soil Physics, Hillel)

After a rainfall event, soil crusting is a significant problem, particularly on soils with low residue cover. The surface crust is caused by a breakdown of soil aggregates due to raindrop impact. The raindrop splash detaches particles that fill soil pores. When rapid drying occurs, a hard crust layer can form in the top 2 inches of the soil. Soil crusting is troublesome when it develops prior to seedling emergence. Additionally, soil crusts create conditions that are extremely conducive to soil erosion during following rainfall events.

The use of a well-designed conservation system can limit exposed soil and rainsplash erosion. An effective conservation system also depends on the planning, observation and timing of operations. Spring is a good time to make observations and develop a new, more comprehensive conservation system.

Conservation systems to reduce raindrops' effect

Tillage and cropping management systems are critical components for reducing raindrop impact on soil particles due to the availability of crop residue to protect the soil surface. Excessive tillage can damage soil structure, leading to increased soil sealing and soil erosion. Conservation systems promote soil aggregates, infiltration, and soil tilth. Additionally, the improved soil structure of no-tillage and other conservation tillage systems stands up better against raindrops. A conservation system that includes high amounts of crop residue such as corn or fall cover crop traditionally provide abundant residue cover to protect the soil surface from spring rains.

Farmers are encouraged to assess residue cover since last fall's harvest and ask themselves the following questions: Was surface residue enough to prevent soil erosion? Is the surface residue cover distributed evenly across the field? Is there enough residue cover left after winter decomposition? If these questions can be answered no, then fall tillage passes and fall manure or anhydrous application need to be considered based on the amount of residue and the residue distribution in the field. Remember that spring is the best time to evaluate conservation systems for their impact on improving soil and water quality.

Options for adjusting spring field operations

With spring weather and the most susceptible field conditions for water erosion here, what options remain before planting? Farmers should consider the effect of any additional tillage on remaining crop residue. If residue cover should fall below 30 percent, adjust your field operations to minimize potential soil erosion due to early spring rain. Options for steep slope areas include cover crops, permanent vegetation, strip cropping, and planting on the contour, all of which can reduce the speed of water runoff and slow soil erosion. If soil crusting occurs, consider using a rotary hoe to allow seedling emergence to occur unrestricted. The faster the crop is growing, the sooner a crop canopy will develop; a partial crop canopy is better than none at all.

Conservation structures such as terraces, grassed waterways, and field buffers are good components of a conservation system, which help in slowing water flow, settling out sediments, and directing water away from the field to a suitable outlet.

Remember that field observations in the spring can help in developing a more comprehensive conservation plan that greatly improves soil and water quality.

This article originally appeared on pages 57-58 of the IC-494 (8) -- May 2, 2005 issue.


Mahdi Al-Kaisi is an associate professor in agronomy with research and extension responsibilities in soil management and environmental soil science. He can be reached at or 515-294-8304. Mark Licht is an ISU Extension field agronomist located in central Iowa. He can be reached at or 515-382-6551.

This article was published originally on 5/7/2012 The information contained within the article may or may not be up to date depending on when you are accessing the information.

Links to this material are strongly encouraged. This article may be republished without further permission if it is published as written and includes credit to the author, Integrated Crop Management News and Iowa State University Extension. Prior permission from the author is required if this article is republished in any other manner.