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Crop Development in 2014

Development for our crops is progressing, but several different factors are affecting the relative development for this crop.

Development factors

  • Moisture availability.
  • Previous crop.
  • Maturity rating for the crop.

All of these factors will affect our perception of how this crop is developing.

This week I looked at samples from our Agronology 10 Research plot where the previous crop was corn. Those ears weren’t at the roasting ear stage (R2). A second sampling two days later, with corn two day earlier maturing (110 vs. 112) and on soybean ground, was at late milk (R3) or early dough stage (R4).

The corn crop will reach physiological maturity (32% moisture corn) approximately 60 days after mid-tasseling.

 

Late July Observations

 

In late July you are able to see the fruits of your labor in your corn and soybean fields. Now is the time to evaluate your fields with a critical eye. Determine what is working and what needs possible revision or change.

Potential items to consider

  • What corn varieties are giving you the greatest ear girth and length?
  • What is my final stand count in my fields?
  • What varieties are using nitrogen efficiently in this year with its many stresses?
    • Look at the stalk girth at ear height level.
  • Was green snap a problem with any varieties?
  • With the amount of wind and rain received this growing season, what varieties have no lodged corn?
  • By the last week of July, have my soybeans reached the R4 growth stage (began filling the seed pods)?
  • Are my soybeans waist high or better yet (up to mid chest)?
  • Have my herbicide programs controlled the weeds?
  • Why do certain fields have a lot of volunteer corn?

 

WOW – 1 July

Starting at about 4:00 p.m. thru 9:30 p.m. on June 30, 2014, the weather in Walcott dealt a blow to our corn crops.

We experienced long periods of 40-to-60 mile/hour winds, from 3-to-6 inches of rain, and a lot of lightning. As a result of this weather event, a few trees were lost, lots of tree branches ended up on the ground, and a significant amount of corn fields were flattened.

Weather effects on crops

My immediate concern is with the corn which was ready to begin tasseling. I had not seen any tassels yet, but expect to see some in the next five days. With the corn lodged—flattened—the pollen grains can have a difficult time falling on the corn silks at pollination time. When this happens, some of the ovules will not be pollinated.

Therefore, the quicker the corn straightens up, the less yield loss we could experience.

 

Summer Solstice

On June 21, the Summer Solstice occurs. The Summer Solstice is the longest day of the year in the northern hemisphere. The days that follow will begin to shorten by about 2 minutes per day.

Significance of the Summer Solstice

The significance for the Summer Solstice is its effect on photo period sensitive plants, such as soybeans. With the onset of the day length decreasing, soybean plants shift growth from vegetative to a reproductive growth phase.

On June 20, I found the first flower on my soybeans at the Agronology 10 Research Center. I normally would advise farmers to have their soybean post spraying completed by Independence Day, July 4. Many soybean post emergence herbicide labels indicate “no spraying after flowering.”

Green Snap

On June 16—Monday evening—a storm front that moved through various regions of Iowa. This caused some green snap in some of our corn fields. Green snap can be a problem from V5 to V8—10-to-20 inch tall corn—and again from V12 thru tasseling.

Green snap is caused by

  • High winds.
  • Selected growth stages where the corn plant is dramatically increasing size (height).
  • Herbicide applications where a growth regulator was applied.

The early green snap damage will be less damaging to overall yield since the surrounding plants will have a greater opportunity to compensate than later growth stage damage.


Photo by Ohio State University Extension

10 June 2014 Observations

 

On the 10th day of June, a lot of cornfields looked great. However, there are still some really bad looking cornfields. I would consider these problem fields to have some or most of the following situations present.

Problem observations

  • Nodal root system development is too small or developing slowly.
  • Planting depth was too shallow or too deep.
  • Kernel energy and nutrients have been used up.
  • Drought or flooded conditions are present.
  • Compaction layers are limiting root growth or sidewall compaction is restricting root distribution.
  • Nutrient uptake is compromised and the plant’s growth is being retarded.
  • Some corn varieties are not performing as well as expected in spring 2014 conditions

 

Soybean Planting Date

Observations

In late May, I was surprised at the large percentage of soybean acres still to be planted in the three “I” states.

Generally, those late planting dates—late May—significantly impact your final soybean yields and gross income per acre. A 2 bu/a-to-5 bu/a yield loss due to late planting could be costing you $25 to $60 per acre or more.

Recommendations

It is important to analyze your farming operation and determine how to have your soybeans planted by May 15.

Early June 2014

Observations

Many of the cornfields are looking great. However, there are some cornfields that have significant problems.

The following is a summary listing the various factors that could be creating the growth and nutrient uptake problems.

Problems

  • The corn plant could be transitioning from the kernel supplying its nutrient requirements to one that relies on the nodal root system—secondary roots—for its nutrients and water.
  • Soil compaction could be limiting root development, growth, and nutrient uptake.
  • Shallow planting which could have caused the secondary root system to be placed too close to the soil surface.
  • Cold weather and dry soils can be limiting overall root growth and nutrient uptake.
  • Tillage that is diagonal to the direction of planting could be showing if the soil was worked too wet.
  • Direction of last year’s soybean harvest could be showing where the crop residue wasn’t spread across the entire harvested area.

 

 

Corn Stands in 2014

On May 5, 2014, we planted seven different corn varieties at our Agronology 10 Research Center. All varieties came from the same seed company.

I am limiting my remarks, at this time, to the five corn varieties planted on ground where soybean were the previous crop in 2013.

Observations

What I am finding is a 15% plant population difference, about 6000 plants/a—between the best and worst corn stands—all planted on the same day.

With this large variation in this year’s corn stands, I would advise you to check on your emerged population—now!

Determining plant population per acre

To determine your plant population/a, measure several locations throughout your field at the following distances and multiply the average by 1000.

Row Width (inches)                    Measurement for .001 A

30                                           17.424 ft. (17 ft. 5 in.)

20                                           26.135 ft. (26 ft. 2 in.)

15                                           34.848 ft. (34 ft. 10 in.)


 

20-0-4-2s for Sidedressing Corn

Question

Why would I apply 20-0-4-2s instead of 32% N at side dressing?

Answering the question

The following is a list of agronomic reasons why 20-0-4-2s is a better investment for the corn crop.

  • You would be applying N, K, and S to your current crop instead of just N.
  • Many times N isn’t the nutrient most limiting for the developing plant. Frequently, K is the nutrient in most short supply even though soil test values are good.
  • To your basic 20-0-4-2s blend, additional micronutrients can be added to your side dress mixture.
    • Boron – .2 to .4 lbs. B/A
    •  Zinc – 1 pt. to 1 qt. chelated zinc/A
  • The density for 20-0-4-2s is 10.5 lbs. per gallon.

Rate (gallons 20-0-4-2s/A        lbs. N/A       lbs. K20/A       lbs. S/A

10                                    21                    4.2                2.1

15                                  31.5                   6.3               3.15

20                                    42                    8.4                4.2

25                                  52.5                 10.5              5.25

30                                   63                   12.6               6.3