Register for the UK WHEAT PRODUCTION FIELD SCHOOL: Hands-On Training

Edwin Ritchey, Extension Soil Specialists, University of Kentucky

The UK Wheat Science Group with support from the Kentucky Small Grain Growers' Association will offer three hands-on training sessions on managing wheat in Kentucky - GREEN-UP (March 8th) - PRIOR TO FLOWERING (April 26th) - PRE-PLANT (TBA).
These trainings are directed towards crop advisors and farm managers who provide agronomic guidance for wheat production. The sessions will be held on the UKREC Farm (1205 Hopkinsville Street in Princeton, KY) from 9am - 3:00pm CST (Lunch is included). Class size is limited to 30 people per training. REGISTRATION IS REQUIRED - see links below.  

Educational credits for the March 8th “GREEN-UP training” have been approved for the following: Pesticide Credits: 3 General Hours & 1 Specific Hours (Cat 1A, 10, 12) CCA Credits: 2.5 SW, 1 PM, 2.5 CM

Corn Nutrient Deficiency from Sidewall Compaction

Chad Lee, Extension Professor and Agronomist, University of Kentucky

This corn field had numerous plants that were stunted with striped leaves. This field was adequate to high in soil test values and had proper pH. When we dug up some plants, we found that the majority of stunted plants suffered from sidewall compaction. Images of the field, the leaf symptoms and the compacted roots follow.

Field where most of the corn appeared yellow with striped leaves.

Looking Ahead: Expect to See Sidewall Compaction

Chad Lee and Carrie Knott, Extension Agronomists, University of Kentucky

Figure 1. Open seed furrow is a good indicator
of sidewall compaction.

The calendar says we are getting late on planting corn. While the soil conditions are probably more important than planting date, there will be intense pressure on producers to plant corn this week. That means that some fields will likely get planted too wet. Getting into a field too soon is completely understandable given the logistics of planting multiple fields and trying to "sneak in" a field between rains.

Checking for Soil Compaction

Edwin Ritchey, Extension Soils Specialist, University of Kentucky
Lloyd Murdock, emeritus, University of Kentucky

Soil compaction stunted this corn.

Crop yields may be limited by soil compaction. Subsoiling is the most common method used to alleviate soil compaction, but is a time consuming and costly operation. If soil compaction is suspected, it is best to identify the areas in the field where it exists, what depth the compaction begins, and what depth the compaction ceases. The best method to document this information is with a soil penetrometer. Most county Extension offices have penetrometers that may be borrowed to make these measurements.

Great Corn Harvest but Compaction Nipped Some Yields

Chad Lee, Extension Agronomist, University of Kentucky

The ear on the left is on a plant with
roots limited by compaction and the
other is on a plant with no compaction.

The corn yields being reported are excellent to date for Kentucky. With the wet weather at planting, we all were very concerned about compaction problems. The continued wet weather helped a lot of corn roots break through compaction. We dodged a disaster, but corn yields were dinged by the compaction. I walked a field yesterday where we think we may have lost as much as 75 bushels per acre to compaction.

That's the bad news. The good news is that the field went about 250 bushels per acre. That's an excellent yield in most fields and especially in a field with some compaction.

More Corn and Soybean Challenges in Fields

Chad Lee, Extension Agronomist, University of Kentucky

The images from field problems in Kentucky has been updated. Because the file was getting very large, you can access only the May 2012, June 2012 or the full version which includes wheat. If you access the full version, just be aware that it is 23.5 MB... and growing.

The most common symptom in corn is potassium (K) deficiency. In most cases, the K deficiency is the result of root restriction. Most of the root restriction is from compaction, whether it be sidewall or sub-surface. Areas of Kentucky had ample rain during corn planting and getting sidewall compaction would have been very easy to do. The general lack of rain now adds to the problem.

The compaction limits root growth, reducing the root interaction with nutrients. Water is needed for uptake of many nutrients, including compaction. The lack of water reduces the amount of K taken up by the plant. Either dry weather or compaction on their own can cause problem, but having both together causes even more troubles.

Do as I Say not as I Do ... Challenges with Planting

Chad Lee, Grain Crops Extension Agronomist, University of Kentucky

Often this spring, I have warned farmers not to plant one day too early to avoid "mudding in" the corn or soybeans. When we plant just one day too soon, we increase the chances of getting sidewall compaction and run a higher risk of keeping the roots bound within the furrow. Roots trapped in the furrow can lead to some real problems later in the growing season. However, yesterday, I disregarded all of that caution and mudded in soybeans.

Yellow Soybeans and Soil Compaction

Image 1: Yellow soybeans in this field are the result of sidewall compaction.

The spring rush of planting is catching up to the soybean crop in some fields. Surface compaction and sidewall compaction was most likely caused by planting when fields were a little too wet. The compacted soil has restricted root growth on soybeans. Until now, there has been enough water to keep most nutrients within the root zone and the soybeans looked fine. As the soybeans reach full pod development (R4) the plants are rapidly accumulating nitrogen and potassium. The restricted roots are not taking up enough nutrients to sustain plant growth. Plants turn yellow.

Planting all fields in perfect conditions is impossible most springs and especially this one. Timely rainfall now will help move nutrients into the root zone. Yield losses from compaction could be very minor or very sever, depending on rainfall, soil fertility within the root zone and severity of compaction.

Fertilizers at this point will likely have little impact on yields. The soil scientists will address this in more detail.

As more soybeans across Kentucky get closer to full pod and beginning seed development, I expect we will see more yellow soybeans.

Image 2: Soybean roots restricted by sidewall compaction. Root growth is limited mostly to the furrow created during planting.

Image 3: Soybean roots restricted by compaction just beneath the soil surface. Root growth is bending to curve around the compaction. The overall root mass is reduced from the compaction.

Image 4: Soybean roots with little to no restriction. The whole plants are greener and larger. Root mass is greater and there are more nodules per plant.

Image 5: Yellow soybeans have roots with restricted growth while the greener soybeans have little to no restriction on root growth.

Avoiding Sidewall Compacting During Late Corn Planting

Lloyd Murdock, Extension Soils Specialist
Plant and Soil Sciences, University of Kentucky

Sidewall compaction can result from planting a crop when the soil is a little too wet. This damaging effect can be even greater on soils with a relatively high clay content at the surface. It occurs when the double disc opener leaves the side wall of the planting furrow smooth and compacted (slick as opposed to shattered) as it pushes the soil aside. The trailing press wheel then increases the compaction with its downward force. If the soil stays very moist or wet, the roots may be able to penetrate the compacted mud at the sidewall and expand further into the soil. However, if the weather turns dry after planting, the sidewalls then harden, and roots are not able to push through since there are no pores or cracks. This causes the roots to grow within the planting furrow, along the direction of the row. Although plants may look normal at emergence, they will begin to show nutrient and drought stress after the corn is several inches high. This problem may be more common in no-tillage because no-tillage soils have better structure, and it is easier to traffic them in a wetter condition. The old adage of "waiting on no-till" is a good one. Sidewall compaction can also occur with conventional tillage. If you can mold the soil into a ball in your hand and the soil ball will not easily crumble apart, it is too wet to plant.