In the first part of this ­­series we discussed soil sampling.  We learned why we sample our soil, how to sample our soil, and began reviewing ways to use the soil fertility analysis to improve our food plots.  I want to reiterate the importance of working towards a neutral pH in the soil.  If the soil analysis reports a pH lower than 6.5, we use lime to raise the acidity.  If the analysis reports pH higher than 8.0 we will use sulfur to lower the alkalinity.  PH levels 7.5 to 8.0 may not need any altering because planting and fertilization will often lower soil pH to within optimal ranges.  Lime takes three to six months to affect the soil, so start early.

We are now going to look at soil fertility and altering the fertility by applying fertilizers. 

fer·til·iz·er (fûr-tl-i-zr)n .~  Any of a large number of natural and synthetic materials, including manure and nitrogen, phosphorus, and potassium compounds, spread on or worked into soil to increase its capacity to support plant growth.

Most of us are familiar with Triple 13.  Triple 13 is a common reference to a fertilizer that is equal parts (13) Nitrogen(N), Phosphorus(P), and Potassium(K).  In fact, you can purchase fertilizers in a great many combinations of N, P and K.  Lawn fertilizer will generally have more Nitrogen that either of the other minerals.  Different types of plant life have different needs.  A forb, broad leaf, herbaceous plant, will produce nitrogen and release it back into the soil.  For this reason, clovers do not need subsequent applications of nitrogen like other plant varieties do.  When adjusting soil fertility levels, it is vital to know what is currently growing or what you will be planting in order to correctly apply fertilizers.  As was mentioned in Part I, the only way to accurately assess a food plot’s soil needs is to have the soil tested by an accredited testing lab.  A lab’s analysis report will recommend rates of fertilizer based to the type of vegetation that will be growing in the soil that was tested.

Let’s look again at the soil analysis that we were working with in the last issue.  Let us first look at the box titled “What is in the Soil”.  This graph shows the levels of Phosphorus, Potassium, Calcium and Magnesium.  Nitrogen is transferred into a gaseous form or released from soil organic matter so rapidly that Nitrogen is seldom tested for due to the difficulty in obtaining and projecting accurate levels.  This box uses a bar graph to show the level of each mineral in general terms; very low to very high.  In this report, Phosphorus was shown to be very high while Potassium was low. 

Now look at the box labeled “Fertilizer to Apply for Bulk Application”.  Here we see the recommended application rates either by a per-acre rate or lbs./1000sq ft.  Because Phosphorus levels were very high, the recommendation was that no phosphorus be applied.  However, a high application rate of Potash was recommended.  Notice also that the lab recommends 60 lbs./acre of Nitrogen.  This food plot was planted in No Plow after this sample was taken.  No Plow requires an initial application of lime in order to establish quickly.

This all seems simple.  What do you do, however, when you aren’t planting food plots that measure exact acreage?  The Whitetail Institute Soil Testing Services includes a lbs/1000sp ft recommendation.  Not all labs will break things down this far.  In such instances you will have to do some math (or ask your kids to do some math for you).  You’ll need to know the area measurement of your food plot(s); Length times Width.  I don’t come across many square food plots, so do your best.  This plot was just over .75 acres, or 32,760 sq ft.  One acre is 43,560 square feet.  I took my length, 504ft times my width, 65ft and came up with 32,760.  If I divide this by 43,560, I get .752 acres.  I can use these numbers to determine precisely how much fertilizer to purchase.  We know we need 120 lbs/acre of Potash or 2.8 lbs/1000sq ft.  We can either multiply 120 times .752 (90.24lbs) or multiply 2.8 times 32.76 (91.73lbs). 

Buying fertilizer gets difficult because it usually comes in pre-mixed combinations.  You aren’t going to find a 60-0-120 fertilizer.  If you are able to purchase your fertilizer from a Farmer’s Co-operative, you may be able to buy fertilizers in bulk, either pre mixed or as individual types that the Operator will mix for you.  Even bulk fertilizers rarely come as only N, P, or K.  Each mineral has to come in a form that is suitable for handling and working with.  In most cases, your options will contain at least two of the minerals.  Consult with the Co-op owner or operator for options and availability.

Converting the recommended rate to the numbers describing the fertilizers available to you is, literally, a science.  I was able to find bagged fertilizer in 34-0-0 and 0-0-60.  If the recommended application rate of nitrogen is 60 lbs/acre, using the fertilizer 34-0-0, then the rate is 60 lbs divided by 34 times 100.  (60/34)x100=176 lbs/acre of 34-0-0.  In the same way for Potash, using 0-0-60, 120 lbs divided by 60 times 100.  (120/60)x100=200 lbs/acre of 0-0-60.

It gets trickier when all three minerals are needed, but the concept is the same.  You will often find that it isn’t possible or cost effective to apply fertilizers at the exact recommended rate, especially when fertilizing many small plots.  In these instances, you may want to group similar plots together and apply a fertilizer that meets the average of the recommended application rates.  Or, you may not be able to apply fertilizer at a rate of 60-135-10 and will have to get as close as you can.  If possible, consult with a professional who can help you decipher the analysis report in order to more precisely and economically correct the fertility of your soil.

By Brent Sawyer

TalkHunting Pro Staffer, Brent "Cobrican" Sawyer, was born into a sporting family.  His first couple years of life were spent on the banks of Lake Arthur and around his grandfather's farm in Jennings, La.  Even when his family moved to the city, they visited the farm often.  Brent's parents and Pawpaw spent as many hours as they could find taking him outside to learn how to care for and survive on the land around him.  They camped and hiked.  They gardened.  Brent joined the Boy Scouts as a Bobcat and continued to be involved through his High School days.  There, he learned many new skills to help him belong out of doors.  Brent and his cousins would often sleep out under the stars with only a blanket.  

At the age of 8 he was given his first BB gun.  At 10 he was allowed to hunt with a shotgun.  The family had a lease where they hunted, predominantly, Speckle-belly geese with the occasional snow or duck.  They also hunted doves and rabbits.  Brent learned how to call specks well enough to hunt on his own in only a short time.  About the time Brent went to college, his grandfather dropped the hunting lease.  Fortunately, North Louisiana offers some great opportunities for hunting on public lands.  He spent many hours duck hunting as well as hunting small game.  In 2000 Brent was invited to his first deer hunt.  Since then he has been fully involved in the deer hunting experience.  He also loves to fish.  Lately he has made more opportunities to fish salt water than freshwater but he enjoys both.

Brent Graduated with a degree in Forest Technology and has used his degree as a basis for hunting and recreation properties management.  He joined Talkhunting.com in 2008 and has attended gatherings in Louisiana and Alabama.  He also works for Breathe Safe Environmental Services as a third party monitor for lead and asbestos abatement.  He loves his job but hopes to be able to one day move exclusively to property management and consulting.

Comments(5):

1. There cant be enough said about taking soil samples. Thanks for the info!

   Saturday, May 07, 2011 Robert

2. soil sampling and analysis

   wonderful article filled with great information brent on how to make your plots the best they can be.

   Sunday, May 08, 2011 brad

3. Great article!

   Great information Brent! Sheds a whole new light on the importance of proper soil fertility.

   Sunday, May 08, 2011 Duane

4. Thanks Brent! I did not realize there was so much that could be said about the dirt you are planting in! I will start sampling my soil this year!

   Tuesday, May 10, 2011 Anthony

5. Awesome Soil Analysis Article

   I recognize that Soil Analysis Result... I did something a little different when I sent off for my Soil Analysis this year... I sent in Soil from the same plot in two different soil kits and told them what I had planned on planting... based on what I wanted to plant yielded close but different fertilizer recommendations.. Worth the extra money if you are not sure on what you want to plant.

   Wednesday, May 11, 2011 Dennis