Yield Goals Could Cost You This Year

Chad Lee, Extension Professor, Grain Crops, University of Kentucky

Recently, I worked with a small group of farmers who were interested in trimming costs, but not yield, in 2015. They provided their soil test values, historical yields, crop history, and intended production practices for 2015. Those producers reported that were applying $124 per acre more for fertilizer than what was recommended by the University of Kentucky. Even if we factored in enough fertilizer for the following soybean crop, they were spending about $100 per acre more. They were using yield goals to make their fertilizer decisions.

Producers enjoy farming based on yield goals. Yield goals are positive thinking. They are a challenge to the producer to try to reach higher yields. Annual budgets have yield goals. Loans require an estimate of income which requires a projected yield. Yield goals are easy to market and easy to understand. Yield goals also could cost you a lot of money in 2015.

Kentucky's No. 1 Nutrient Deficiency in Soybeans: Potassium

Chad Lee, Extension Agronomist, University of Kentucky

K deficient soybean.

Every year we see soybeans somewhere in Kentucky with deficiency to potassium (K). Causes for the deficiency can be dry weather, soil compaction and/or low soil test levels for K. For the fields that I visit or receive calls, the reasons tend to be 1) soil compaction, 2) dry weather and 3) low soil test K. The symptoms in this image seem to generate to most phone calls, text messages and emails, which is why I've labeled it number one for soybean.

Resist Mudding in Corn... or at Least Try to Minimize Problems when you Do

Chad Lee, Extension Agronomist, University of Kentucky

Visible slot from planting.
Undamaged corn in the field is at tassel/silking,
but the plants with sidewall compaction
are not close to tassel.

The wet weather and calendar increase the urge to get back into the fields earlier. Getting into the field "one day too soon" can result in sidewall compaction and/or surface compaction that will put the corn crop further behind all season.

Below are some images that serve as reminders of what happens when fields are planted too wet.

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.

Sidewall Compaction in Corn

Chad Lee, Extension Agronomist, University of Kentucky

  Earlier, we posted about sidewall compaction with the understanding that farmers had to plant when they could plant and in some cases, this meant planting into fields that were a little too wet. Yesterday I visited a field where the farmer was concerned because the corn was "yellow and dying". The county agent and I visited the field at the perfect time because a rain from the night before had kept the soils wet and improved the appearance of the corn.



Corn in a compacted seed furrow. The slit of the furrow is still open. The oldest leaf has brown along the margin and yellow moving toward the midrib of the leaf, which is typical K deficiency symptoms.  



Fertility Considerations/Strategies for Late Planted Corn

Lloyd Murdock and Greg Schwab, Extension Soils Specialists and John Grove, Soils Research
Plant and Soil Sciences, University of Kentucky

At this late stage in the season, priorities should be on planting the corn crop, first, then applying needed fertilizers after planting. Fertilization after the crop is planted is not yield-reducing and, in some cases, can actually cause nitrogen (N) fertilizer use to be more efficient.

Phosphorus (P) and Potassium (K)
There may be a few situations where P and K were not applied prior to corn planting. If the soil test P and K levels for a field were in the medium to high range, any fertility added this year would generally maintain these soil test levels and would have little, if any, effect on yield. This would probably be the situation in a majority of Kentucky corn fields. Therefore, adding P and K fertilizers after planting would not be a problem and, if the field's P and K soil test levels are in the upper part of the medium range or higher, the P and K could be delayed until this fall. If a field tests in the low soil test range, the P and K should be added this season, but can be delayed until after planting.

P and K fertilizers are soluble in water, so they dissolve with rain and move into the soil fairly quickly. They will only move into the top 2 to 3 inches, but this will be enough to make them available to the plant, in most situations. If the field was no-tilled or has a lot of residue on the surface, many corn roots will be close to the surface and will take up added P and K. A clean tilled field might result in reduced uptake. This would more than likely only be a problem if P and/or K were in the low soil test range and there was an extended period of dry weather that resulted in the top few inches of soil becoming very dry.

Nitrogen (N) Management Strategies for Late Planted Corn

Once the optimum planting date has passed, the yield loss from further delayed planting far exceeds the yield loss associated with post-planting N applications. Your goal should be to get corn planted as soon as soil conditions permit. Your corn-N management situation, field by field, falls into one of two categories: a) some or all N has already been applied; b) no N has been applied. Your N loss situation has also shifted. Early N applications should be managed to avoid denitrification loss, while later applications need to be made so as to avoid volatilization loss. Because of the wet spring, the soil will contain less residual N, or N mineralized from organic matter, than normal.

For the full article, go to the Corn and Soybean Science Newsletter.