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By Staff | Apr 9, 2010

The first week of April is now history. It contained days that were up into the mid 80s and days that were wet and cool.

When those warm days came it looked like we might have a very early start to the 2010 planting season. Now that the cool and cloudy weather has returned it looks like we will have to bide our time and wait for the ground to dry and warm up.

The speed at which the deep snow cover and large drifts disappeared surprised everyone. In fact it seemed highly possible that winter was going to be with us until mid April. Recent history, such as in the 1991-92 seasons, tell us that when growers are delayed in their planting one year they will push as hard as they can to be early with field work and planting the next year.

So if the sun shines and the fields dry by April 15, don’t get in anyone’s’ way.

Much publicity was given to the intended acreage report. Most of the acreage figures given were about in the middle of the trade expectations, so prices should not have moved very much.

What was a surprise was the pronouncement that Iowa farmers would raise fewer acres of corn.

Growers with their feet on the ground listened to that announcement and said such a prediction was already outdated as the surveys had been done in early March when everyone was anticipating a much later arrival of spring weather and a delayed planting season.

Only time will tell how the planting season will turn out. Hopefully the fog day predictions don’t prove to be accurate.

The Major League baseball season is now here and the always signals the start to the growing season.

GDUs and PAR light

Last year the number of growing degree units that fields and crops in different parts of Iowa received were as much as 570 behind normal.

That constituted about 22 to 23 percent of what is normally expected.

Over the rest of the state crops were planted early in southwest Iowa and they ended up having one of the best seasons they have ever had. The corn crop in northwest Iowa was planted in the middle part of April, which is in the early side, but ended up being very slow and late in maturing.

Over the rest of the state the GDU deficit ended up being 400 to 500 assuming a May 1 planting date.

Many fields were planted after that date, thus the plants in many fields seemed to be on schedule to tassel as of late June.

But it turned cooler by the end of the month and the crop never caught up.

This year we will all being watching the GDU tables to see how the season is unfolding and hoping that we receive the warmth we need without any heat being excessive.

One other weather measurement that we will be able to make will be the units of photosynthetically active radiation light that is received. PAR is the light that falls into the wavelength that actually produces photosynthetic activity.

Will we be far behind in our PAR light accumulation like we were in 2009 or will the accumulation be back to normal?

I kept an eye on the sky during the weeks I was down in Brazil and Argentina. I noticed that when it was not cloudy and raining they always had a very bright, blue sky with none of the wispy trails that we seem to always have covering our skies. Their sunlight units had to be much greater than ours to the benefit of the crops. That is the third year in a row that I have paid attention and noticed this. What is going on?

Gauges are now available from Spectrum Technologies at several price levels that would let you measure PAR light levels. The lowest priced one is now down around $30.

The soils

In the last few seasons colder than normal temperatures were the rule with quite a few days of open soils. This past winter the temperatures were very cold from Thanksgiving through early March, but there was a deep snow cover during that entire time. Anyone digging in the snow or driving through the fields found that the frost had not gone very deep with many fields actually being thawed out during February. We were wondering if the soils had gone through enough freeze thaw cycles to break up the shallow compaction left from last season plus the deeper ruts formed during the harvest. What is everyone finding?

I have visited with guys and gals who have been out doing fieldwork along Iowa Highway 3 who have commented that the soils are soft and mellow. What I have seen along U.S. Highway 30 with limited field inspections is that the soils seem hard and cold. I have wanted to take my penetrometers into those fields and quantify soil densities.

I will try to get that done if the rainfall amounts are not excessive. Normally this time of year we like to see readings of 180 to 280 PSI. Fields showing test levels above 300 are those that are likely to have problems with developing the deep root systems needed during dry seasons and exploring a high percentage of the soil for nutrients.

Herbicide applications

It sounds like more growers have absorbed Dr. Mike Owen’s message on weed control, which is that a proper weed control program is one which protects yield rather than trying to prove how large of weeds you can control, meaning more residual products will be applied prior to planting both corn and beans.

More two-pass programs will be used in corn with tillage-using growers applying their grass control products close to planting and their broadleaf products after the weeds have emerged.

No-tillers will have to get their products applied shortly as the proper conditions for weed germination are upon us. Strip-tillers, no-tillers and many reduced-tillers, who are hoping to apply both grass and broadleaf control products, will get their best results if they can apply the products slightly before the grass and weed seeds germinate.

Making the applications too early will cause a reduction in the control offered in late summer for the benefit of control in April. That is a rule for nearly every product available.

With last a week’s warm temps growers were starting to see small broadleaf weeds beginning to emerge in protected areas and around buildings.


The fall anhydrous season was cut short with wet field conditions last year. Thus more 28/32 percent and urea will be used this spring. Historically, those two products have their challenges when the April through late early June section of the growing season has a greater-than-normal amount of rainfall.

In the last two years a lot of corn-on-corn acres was hurt both by that factor and the issue of the large amounts of residue from the 2008 and 2009 growing seasons remaining intact in second year corn fields.

In March and April growers need to be formulating their management plan on what stabilizer product they intend to use to mix with their N to stop the volatilization and leaching losses which have hurt corn the past two years. There are now more products available for use.

Soybean management

For top growers soybean yields have continued to increase. Good weather during August and the typically seed fill period is important, but a big factor in what those growers are doing is to manage their bean crop for optimum yields.

That means listening to the new ideas and then finding out more about the few things that consistently add bushels to final yields in the fall.

Those management ideas that have been more universally adopted by growers is to treat the seed prior to planting with an applied fungicide and innoculant.

If your soybean yields have not been in the category that have pleased you now would be the time to rectify that situation by learning about new products or management tools that you should still be using this spring for the upcoming season.

Bob Streit is a crop consultant based in central Iowa. Contact him at bstreit@signatureblue.com.

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