Integrated Crop Management News

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Heavy Rain, Soil Erosion and Nutrient Losses

June 5, 2008
Image of soil erosion in a conventionally tilled field

By Mahdi Al Kaisi, Department of Agronomy, and Matt Helmers, Department of Ag and BioSystems Engineering

As we write this article spring rains are coming hard and fast causing substantial soil erosion when soils are most vulnerable because of degraded crop residue cover, soil preparation by tillage and no crop canopy.

Late May Weather: A Mixed Message

June 3, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to June 1, 2008

Iowa weather during the last week of May behaved like, well, Iowa spring weather.

For the week, temperatures statewide were close to or slightly below long-term averages, and soil temperatures were general for rapid growth and development of both corn and soybean.

In addition, sporadic rains from “dust settlers” to “goose drowners” led to lots of variability in crop progress, with only a day or two suitable for field work; some areas of northwest and west central Iowa being the exceptions where more work time was available.

How Late Can Soybeans be Planted?

June 2, 2008
Table of the effect of planting date on soybean yields in Iowa

By Palle Pedersen, Department of Agronomy

Whether we like it,or not, there are many areas in Iowa where farmers are still waiting to plant soybeans and now, given the recent weather, many fields are going to need to be replanted. Based on the May 25 estimates from USDA, only 72 percent of our soybean acres were planted compared 80 percent last year. Bottom line: we can continue to plant soybeans until early July but a few management practices may need to be changed.

Effect of Flooding on Emerged Soybeans

June 1, 2008
Image of a flooded Iowa soybean field

By Palle Pedersen, Department of Agronomy

The excessive amount of rainfall that we have received in Iowa over the last 2 months, and particularly the last week, has caused excessive flooding in many areas. River bottoms are completely flooded and will probably not be able to be planted now for the next 2 to 3 weeks or at all this year. For the majority of the fields the water should drain and dry quickly, barring no more excessive rainfall.

Soybean Replant Decisions from Hail Damage and Flooded Fields

June 1, 2008
Image of hail damaged soybean plants

By Palle Pedersen, Department of Agronomy

After talking to many agronomists and farmers around the state today (May 30) it seems that many will have to replant a few fields because of the extensive rainfall that we have received over the last week. Looking at the weather forecast for Iowa today, it just does not seem to give us any relief with chances of rain pretty much every day during the next week.  

Replanting Corn – How Do You Get Rid of the Existing Stand?

June 1, 2008

By Mike Owen, Department of Agronomy

The recent deluge of water has destroyed many corn fields and if the previously applied herbicide requires that corn be replanted, how do you kill the existing poor stand?

If the corn hybrid was a known herbicide resistant cultivar, your options are somewhat limited. If the hybrid was Roundup Ready®, the use of Liberty® or paraquat are not likely to consistently control the emerged corn.

Replant Options in Corn Fields

June 1, 2008
Table of herbicides that can control existing corn stands

By Mike Owen, Department of Agronomy

Given the recent bad weather, it is likely that a number of corn fields will be considered for replanting to soybean. However, before this is considered, two things must be resolved; first, how will you remove the existing corn stand and second, was there a residual herbicide treatment applied to the corn?

Flooded Corn and Saturated Soils

May 30, 2008
Image of ponding in a field with two-leaf corn seedlings

By Roger Elmore and Lori Abendroth, Department of Agronomy

The storms last Sunday, May 25, and again on the May 29 and 30 have unloaded extraordinary amounts of rain in many parts of Iowa. Soils in the majority of the state are likely saturated. Low lying areas of fields whether they are tiled or not, are covered with ponds and areas along streams and rivers are flooded. It is not an attractive sight for producers!

Now Grow! (No, Not You, Weeds)

May 27, 2008
Image of base 50 degree F degree days in regions of Iowa from May 1 to May 26, 2008

The week of May 19 through May 26 was slightly cooler than average.  Favorable field conditions allowed corn and soybean planting to catch up.  About 60 to 70 percent of soybeans are planted statewide.