Pre-Plant Review  03/16/17 2:27:17 PM

Thanks to all who attended our Spring Clinic this past Wednesday!
Planting Preview---I know this seems crazy to be talking about.  But, we really are about 4-5 weeks away from active corn planting if the law of weather and averages are correct. Every year we have this discussion, regarding optimal planting dates based on weather and soil temperature conditions.  This is a debatable topic among producers that will last until this fall and it seems the corn planting dates get earlier and earlier every year.
Is it based on current hybrids genetic abilities to emerge faster and more uniform in cooler/wetter environments?  YES. 
Is it the hybrids abilities to withstand dry conditions better in/during pollination since earlier planted corn tends to “beat the heat” sooner?  YES
Is earlier planted corn an agronomically riskier management strategy than later planted corn?  YES.
In the South Eastern portion of Nebraska April 20th in the South and May 1st in the North would be considered to be in the ballpark for the day to plant your corn if you could plant it all on one day.  Time and equipment management, play a role in when you start and when you want to finish.  So it is an on-going debate of when to start and when you need to be finished.  It generally takes about 125 growing degree units (GDU’S) for corn to emerge from the soil.  GDU’S are calculated from the soil temperature, not the air.  Across Eastern Nebraska, corn planted April 20th-30th  historically on average will have the best yield potential.  Prior to April 20th the soil is usually cool (less than 50 degrees) and wet (field capacity) and can have continued establishment problems prior to emergence..  After April 20th the risk factor lessens for many things from the germination and stand establishment standpoint.  THIS YEAR, it appears to be an earlier spring which may tempt you to change your normal strategies.
Planting                population (1000/ac)
  Date         10     15     20     25     30     35
Apr. 1st        62      76    86     92     94     93
Apr. 20        67      81    91     97     99     97
Apr. 30        68      82    92     98    100    98
May   9        65      79    89     95     97     96
May 19        59      73    83     89     91     89
May 29        49      63    73     79     81     79
                         % of maximum yield
from Nafziger,E.D. 1994. Journal of Production Agriculture. &:59-62
Based of research in the Central Corn Belt by the University of Illinois.
We are normal---at least from a soil moisture standpoint.  Most folks who have been in the fields already  with fertilizer applications this spring, state that a good 0.5” “packing rain” would not hurt a thing and we would agree.  However, below the top 1-2” the soil profile is ample in moisture and should make an ideal seedbed.   This is important since corn can root and absorb moisture from a 4 foot depth and an average silt loam which can hold about 2 inches of water per foot of soil----a full soil profile would have about 16 inches of available soil water.   An average corn crop here in Eastern Nebraska can use through transpiration between 25-28” of water per season.  At the present time we need are O.K. BUT we should also try to conserve as much soil moisture as possible.  The main issue as we approach planting is soil moisture conservation—July, normally, is dry in these parts. 
Planting more soybeans?
Commodities prices are causing producers have thoughts of increasing soybean acres as a more economical plan of attack for this year.  Will it make you more money?  That answer seems to change on a daily basis and who is answering the question.  There are agronomical risks in a bean-on-bean rotation--mainly dealing with disease pressures left in the residue of the previous soybean crop.  Bean Leaf Beetles, Bean Pod Mottle Virus,  strains of phytophora  are all concerns especially when soybeans are planted two years in a row on the same acre.  Crop rotation minimizes these issues but will not eliminate them.    If you are considering beans-on-beans, consider varieties with strong emergence capabilities and a good tolerance to SCN, SDS as well.  Seed Treatments would also be a recommendation, especially with Bean on Bean acres. 
Weed and Feed--Most producers using liquid fertilizer applications also implement a tank mix with a pre-emergence or burn down herbicide combination in the tank.  Some combinations can cause coagulation in the tank, plugging of tank filters, screens, and tips.  A time saving tip to save headaches during the fast approaching spray season is to do a small compatibility test prior to mixing 100's of gallons of spray solution only to find the mix is incompatible.
Compatibility Test based on 25 gallon per acre application:
1.         Add 1 pint of fertilizer to each of two jars.
2.         To one jar add 1/4 tsp (1.2 ml) of a compatibility agent and stir.
3.         To both jars add the appropriate amount of herbicide(s).  Add dry herbicides first, flowables second, and emulsifiable concentrates last.  Stir after adding each material.
                        Dry herbicide:  For each pound per acre to be applied, add 1.5 level tsps.
                        Liquid herbicide:  For each pint per acre to be applied, add 1/2 tsp or 2.5 ml.
4.         Shake or stir the contents of each jar thoroughly and let the mixtures stand for 15 minutes.
If either mixture separates but can be readily remixed, the mixture can be sprayed with good agitation.  Comparing the two jars will indicate if a compatibility agent is needed.
Compatibility of mixtures can often be improved by 1) mix the dry fertilizer with water before addition to the mixture 2) add 1/2 the compatibility agent to the fertilizer; the other 1/2 to the emulsifiable or flowable herbicide before adding to the mixture.
General mixing procedure:  Fill the spray tank 1/4-1/2 full with liquid fertilizer and start the agitation.  Add a compatibility agent if needed.  Add the dry herbicide to the spray tank.  Dry herbicides and flowables often mix more readily if mixed with a small quantity of water before addition to the fertilizer.  Continue filling the tank with liquid fertilizer until it is 90% full.  At this point add the flowable herbicide.
Burning Down?
A few important points to keep in mind when using glyphosate based treatemnets for spring applications:
  • The better the growing conditions, the better the performance.
  • Hold off spraying until night time temps are above 40°F and daytime temps are 50-60°F range
  • Best if there are a string of warm days rather than spraying on the first nice day of spring
  • Ideally, target applications between mid-morning and early afternoon
  • Adding 2,4-D or dicamba improves burndown performance on marestail, dandelion, chickweed, others.  See label for plant back restrictions.
  • Always add AMS to the spray solution (full rates)
  • Don’t cut rates….
SLOW Down.  Historic results from Purdue University and others show a 3 bu/acre decrease for planting at 6-7 miles per hour vs. 4-5 mph. If you can manipulate your planter to provide consistent drop/spacing and uniform depth at higher speeds—great!  Most success with even spacing and depth has been found between 4-5 mph.
Uneven seedling emergence (another affect of fast planter speeds) can cause grain yield losses ranging from 7 to 20 percent (Carter & Nafziger, 1989; Nafziger et. al. 1990). 
Example: If 25% or more of a stand is made up of plants that emerged 7 to 10 days late, yield losses will approach 7 percent.  If corn is planted less than 1 inch deep, then the nodal root will be just below or on the soil surface making it vulnerable to rooting problems and drying out.  If the seed is planted too deep (3 inches or more), extra seed energy is needed to push the coleoptile to the soil surface.  Under these conditions, the coleoptile may split, causing the plant to leaf out under the soil surface.  Cold, wet, conditions, soil compaction, surface crusting, and applications of soil insecticides or certain herbicides can increase this problem.  Optimal planting depths for corn are generally between 2-2.1/4” in depth.
Days to 50% Corn Emergence from a 2-inch soil depth
Soil Temperature Days to 50% emergence
50°F 20 days
60°F 10 days
70°F 5 days
80°F 4 days
Monitoring “The Drop” is a common daily occurrence during planting. What is “dropped” during planting, what emerges, and what you harvest rarely, if ever, are the same.  Document these numbers in order to gain stand information and relate you success rate based on planter speed, calendar date of planting, hybrid used, etc.  This can give you further insight of potential dollars per acre lost/gained as a result of your current planting processes.
Seeding Rate. See our website under “Corn Population Data” for the historic data over the past years of we have found to be successful.  There is no “right” number.  We will tell you that these days, dry land populations at our around 30-32,000 have been the most profitable.
Don't Cut Corn Population to Reduce Input Costs
It sounds like a good idea, but it is a bad practice. Ideal corn planting populations that maximize yield are the same whether commodity prices are high or low. For example, cutting populations by 3,000 to 4,000 seeds/a may save about $12/acre, but may cost you 6 to 9 bu/a in yield.  Even at $3 corn—you have lost money.   The table below shows the percent yield reduction associated with reducing planting populations.
Yield Impact of Reducing Populations — Corn
Established Planting Date
Stand April 20 - May 5 May 20 June 1 June 10
plants/a ———————— Relative Yield, % ————————
26,000 to 30,000 100 90 81 67
22,000 96 86 78 64
18,000 91 82 74 61
14,000 80 72 65 54
10,000 65 59 53 44
* Table adapted from Iowa State University
Reducing your nitrogen rates can prove to be more detrimental to crop development since nitrogen is the largest element required for active growth.  The following table represents what both corn and soybeans require to gain average yield goals in a normal corn/soybean rotation.  (Remember you get fertility credits from the previous years crop.)
  Nutrient requirements per bushles of grain
Figures based on soil type, season, and previous soil fertility
      Corn   Soybeans
      Lbs/Bushel Lbs/Bushel
  Yield Goal 150 bu./acre 40 bu./acre
Nitrogen     135   150
Phosphorus   53   35
Potassium   40   55
Sulfur     10   4
Magnesium   8   7
Maganese   0.09   0.05
Calcium     2   7
Zinc     0.15   0.04
Copper     0.06   0.04
Oxygen     atm   atm
Carbon     atm   atm
Hydrogen   atm   atm

*Purdue University Soils Extension
**atm = fixation from the atmosphere
If you are looking to decrease fertility costs, consider elements not used in large amounts by the crop.  Some trace elements are supplied by the soil and may not be require additional application every year.
Starters and Salt Indexes--Virtually all fertilizer materials are salts. As they dissolve in the soil they increase the salt concentration of the soil solution. An increase in salt concentration can increase the osmotic potential of the soil solution. The higher the osmotic potential of a solution, the more difficult it is for seeds or plants to extract soil water they need for normal growth.
Why are we talking salt??  Renewed interest in placing fertilizer in or close to the seed row makes it important to remember that an increase in salt concentration in the fertilizer band can cause seed and seedling injury. Placing fertilizer at least two inches away from the seed can usually prevent injury. Excess fertilizer application in a starter band can still produce injury, especially under dry conditions. Crop tolerances vary widely to increased osmotic potential from fertilizer near the seed. Wheat is moderately tolerant of high-salt conditions while soybeans are very sensitive. Corn is intermediate in tolerance. Dry soil conditions as well as fertilizers that produce free ammonia (urea, UAN, DAP) which can significantly increase seed and seedling stress leading to injury.
Greater caution should also be exercised when applying starter fertilizers in coarse textured/dry soils, especially when applied directly to the seed.  While starter fertilizers encourage good early season growth, any fertilizer containing nitrogen (N), potassium (K) or sulfur (S) has the potential to cause germination problems if applied in too high of rates, in too close of proximity to the seed. These three elements are “salts”, which can be thought of as anything that will dissolve in water. These salts will compete with, and have a higher attraction to water, than seed. As a result, too much salt can result in reduced germination, especially in dry or light textured soils. The table below gives guidelines on limits for N, K, and S fertilizer rates on corn.
Total N+K+S limits for fertilizer placed directly with seed
Row spacing                           36”      30”      15”
Total lbs/acre of N-K-S           7         8         16
(Reduce rates by 1/3 in sandy, or dry soils. Do not place urea or ammonium thiosulfate directly on the seed)
Total N+K+S limits in 30” rows
Placement                    Fine texture soils         Sandy soils
Directly on seed               5-8 lbs/acre                  5 lbs/acre
½ inch from seed             7-15                             8
1 to 2” from seed            20-40                           15
> 2” from seed                              40+                            20+
(Do not place urea or ammonium thiosulfate directly on the seed)
Innoculants?    If you are like us, you have bombarded in the past year of two with a multitude of bacterial based seed treatment products that make claims surrounding soil health, nodulation and the like.  Importance of Nodulation. Nodules that form on soybean roots after seedling emergence contain an important type of bacteria. The bacteria, called Bradyrhizobia japonicum, receive a source of carbohydrates from the soybean plant. In turn, these beneficial bacteria convert nitrogen (N) from the air to a
useful form of N (ammonia) for soybean. Nitrogen fixation is critical for achieving high soybean yield potential. Soybeans can obtain up to 50 to 75% of their required N from nitrogen fixing bacteria. Active nitrogen fixation begins in the V2 to V3 stage of soybean
When to Inoculate? Fields that have grown healthy-looking soybeans during the past three years are not likely candidates for inoculation. If a field is new to soybeans, has been taken out of Conservation Reserve Program, or has grown continuous corn for three or more years, then a response to inoculation is likely.
Is Inoculation Beneficial in Other Scenarios? Other situations where inoculation may be considered include soil with pH below 6.0, soil with a high sand content, and fields that have been flooded for more than a week, creating anaerobic conditions. Studies by several Midwestern universities examined the use of inoculants in a corn-soybean rotation. An 11-year study by Purdue University showed an average yield increase of 1 bushel per acre when using an inoculant. The University of Illinois has seen very little yield response to use of a soybean inoculant following corn in a corn/soybean rotation. Iowa State University results were inconclusive in showing whether specific inoculants consistently provided higher soybean yieldsin a corn-soybean rotation .
2017 Plot Work—Providing you with the most viable data for your operation is a main focus for us during each summer season.  We want to provide you data in a “real world” scenario across as many growing environments in our area as possible.  Below is a list of projects we will look at this coming season.
  • 12 MD Corn Sites and 12 MD Soybean sites—Our current lineup across your environments
  • 12 Soybean Treatment Sites—We will include these tests in the MD soybean sites.
  • 6-8 Foliar Fungicide Corn and Soybean Sites
  • In-furrow corn starter and fungicide trial
  • Starter Fertilizers for Soybeans.

John W. McNamara
Wiles Bros. Inc.
606 Wiles Road
Plattsmouth NE. 68048
(402) 298-8550--Office
(402) 499-3870--Cell
(402) 298-7174--Fax
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