Posts filed under ‘soil’

Soil Microorganisms Dominate the Soil Ecosystem

UK scientists have analysed their soil to get an accurate assessment of soil biology, and changes in soil biology over time.  Their conclusions show that the top 3 inches of soil there are 12.8 quadrillion (12,800 million million) soil microorganisms and that number has  increased by nearly 50% in a decade. Scientists report that the most likely reason for the increase in numbers is warmer, wetter weather conditions which translates directly into warmer, wetter soil micro environments. The theory is that these warm and wet soil environments encourage faster microbial reproduction. Read the article here: http://www.guardian.co.uk/science/2010/feb/28/soil-biodiversity-invertebrates-countryside-survey

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March 3, 2010 at 8:30 am 4 comments

Identifying Surface Soil Compaction

The top 6-8 inches of soil are approximately 40% clay, which creates management challenges. Surface compaction in the Van Wert County area is commonly seen, but I would argue that surface compaction only plays a role in harming crop development during the emergence stage of a crop. Once the crop is out of the ground, then surface compaction plays less of a role on restricting crop growth and development other than restricting moisture movement from the surface to the subsoil. Subsurface compaction, on the other hand, can prove to be very detrimental to crop growth and development. Especially if the subsurface compaction creates a nearly impervious layer for roots to penetrate.

December 1, 2009 at 8:30 am 2 comments

Selecting the Right Lime Product for Your Farm

A very common question in NW Ohio this time of year is “What type of lime should I apply?” Closely followed by that question is “What about pelletized lime, is it worth the cost?”

Let me first say (and I’ll provide example later) that all lime is good! There is a misconception that ag lime is bad, or that wastewater lime is bad. Not true. The major difference among lime products is effectiveness. On a pound for pound basis, the effectiveness can be rated thusly: pell lime > ag lime > water treatment lime.

Let’s say that your soil test on one of your fields comes back with a recommendation of 3 tons of lime/acre.  This would require 3 ton/acre of pelletized lime, or 6 tons/acre of calcitic ag lime, or 12 tons/acre of wastewater lime.  I did have to make a few assumptions in this example. I assumed that the ENP of pelletized lime was 2000 lbs/ton, calcitic lime was 1000 lbs/ton and water treatment lime was 500 lbs/ton.  These products are all good, and all do the exact same thing. But as you can see, some products are more effective than others.

So, how do you best  use this information? Use this information to compare cost and go with the less expensive product.  For example, water treatement lime may only cost to truck.  Determine which product has the lowest per acre cost, and there is your winner.

I did not go into the Calcium to Magnesium ratio, since it is not a determining factor for lime selection in this area. If you wish to read more on this ratio, please visit: http://ohioline.osu.edu/agf-fact/0505.html

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August 19, 2009 at 8:10 am

Yellow Soybeans: What is the Cause?

You don’t have to drive too far to see patches, or small areas, within a soybean field that show yellow soybeans.  Here are the typical symptoms:

1. Generally, the areas in the field are small–perhaps a circular area with a diameter ranging from 25′ to >75′

This is a typical yellow area currently observed in some soybean fields.

This is a typical yellow area currently observed in some soybean fields.

2. The uppermost leaves are affected–that is, the symptoms show up only on the newest growth on the soybean plant

The newest growth of soybeans clearly shows the symptomology.

The newest growth of soybeans clearly shows the symptomology.

3. The uppermost leaves have interveinal chlorosis–the veins are green or dark green and the leaf area between the veins is yellow or very light yellow.

Interveinal chlorosis: green veins and yellow leaf tissue.

Interveinal chlorosis: green veins and yellow leaf tissue.

Robert Mullen, Keith Diedrick and Ed Lentz wrote an excellent article in the July 7, 2009 CORN Newsletter providing an overview of yellow soybeans and diagnosis. There are a few things you can do to verify the presence of a nutrient deficiency.  Mullen recommends the following: tissue sampling, soil sampling, and root observation.

  • Tissue sampling: sample the uppermost, fully-expanded trifoliate and discard the petioles (small stem that connects the trifoliate to the main stem). Collect samples from an unaffected area as well as the affected area.
  • Soil sampling: collect corresponding soil samples from the unaffected area and the affected area at a depth of 8″, unless in no-till or severely reduced tillage.  In no-till or very minimum tillage operations, sample the profile at the 0-4″ zone and at the 4-8″ zone.
  • Root observation: By doing a root observation, we are specifically looking for soybean cyst nematode (SCN). These SCN structures will appear as tiny, lemon-shaped objects on the roots that range in color from white, yellow, tan and brown. They are easy to see with slight magnification (a field lens works fine). The cysts are about the size of a pinhead and considerably smaller than nitrogen nodules. You must carefully remove the soil as not to dislodge the SCN structures.

So what to do? In some cases an application of 1-2 qt. per acre of a liquid manganese product can alleviate the visual symptoms.  However, this may not translate in to a positive return on yield.  Research was conducted in 2004 examining this very problem.  Research results are available here: http://farmfocus.osu.edu/Foliar_Mn-Beans-04.pdf

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July 22, 2009 at 8:00 am

Identifying Surface Soil Compaction

I had the opportunity to do a little field work, and came across a classic example of surface compaction.  Please note, try as I might to get good images, the pictures just don’t adequately convey the concept.  I’ll supplement the photos with textual description.

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I pulled a core with my push tube soil probe.  The probe shows about 14″ of exposed core, and I used the knife to ‘pick’ at the core to show soil structure.  The knife is placed at the breakpoint between surface compaction and structured soil.  Above the knife, the soil structure is lacking with no clearly defined soil peds.  Below the knife I can distinctly see peds that form medium to fine subangular blocks.  Again, the difference was much more striking in person.


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This is the same photo, but I’ve cropped the image to focus on the break in soil structure differences. Above the knife tip is structureless; below the knife is developed structure..

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You’ll notice how well the surface horizon holds together when I try to form a ball; this is due to moisture remaining in the surface layer.  The subsurface layer has a lower moisture content; notice how I cannot form as smooth of a ball without the soil crumbling. Implications? There are many implications, but most obvious is that the surface is retaining moisture, which may delay field work.


March 31, 2009 at 7:30 am


Notice

This blog is no longer being maintained. Information on this blog may still be relevant, but for the latest agronomic information and farm management information please visit http://corn.osu.edu and http://ohioagmanager.osu.edu, respectively.

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