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I have heard that some of the seed sizes for corn could be large again this year.  If you receive those larger seed corn sizes, is your planter going to properly meter and plant those seeds or will adjustments to the planter need to be made?

 

University of Illinois conducted a four year crop rotation study with 12 site years of data showing the following results:

 

1. 
    Soybean growth after 2^nd year corn was 6% better than a corn-soybean rotation.
2. 
   2^nd year corn after soybeans yielded 7% less than the first year corn after soybeans.
3. 
   Continuous corn yielded 10% less than the corn in a corn-soybean rotation.

                                           

The three principal nutrient uptake pathways as reported by Barber (1995) are generally described as:

        1.     Root Interception – roots grow in a nutrient location

        2.     Mass Flow – nutrient moves with the soil water to the plant

        3.     Diffusion – nutrient movement is from higher to lower concentrations

The relative contribution for each nutrient uptake pathway for corn is shown in Table 1.

            Table 1                    Nutrient Uptake by Corn Roots__________________________

                                         _________% of Nutrient Uptake by Method_______
Nutrient                          Root Interception           Mass Flow                  Diffusion

Nitrogen                                     1                                 79                                20

Phosphorus                              3                                  5                                 93

Potassium                                 2                                18                                80

Most of the macronutrient nutrients move to the roots by either mass flow or diffusion.  For P&K, most of the nutrients move to the roots by diffusion.

The data in Table 2 compares the time it takes for P&K to move 1 cm. in two different soils in Indiana (Silborbush & Barber, 1983).

          Table 2            Travel Times for P & K Movement in a Soil__________________________

                                                    Time to Travel 1 cm.                       K Diffusion Rate, Expressed as a

                                                        P                      K                              Multiple of the P Diffusion Rate

                                                                                                                           times as fast as P

                                                       ———year——–                                       ———————
       Soil_   _

Raub Silt Loam                         3.45                 0.42                                                     8.1
Chalmers Silt Loam                1.89                 0.41                                                     4.6______________

 

I have found it interesting that the National Agricultural Statistics Service for the state of Illinois has reported the late season corn stand counts are leveling off based on the 2008 to 2012 data.  The data for the state of Illinois shows the number of plants to be relatively constant at approximately 30,000 plants per acre.  However, for the period 2008 thru 2011, 97.3% of the reported plants had ears.  But in 2012, only 81.5% of the plants had ears.

                                                       

 

Western corn rootworms are reported to overcome our trait resistance in Cry3Bb1, when used in a continuous corn rotation.  Entomologists were surprised at how quickly (6 yrs.) this insect adapted to overcome this transgenic rootworm technology.

You might ask “What can be done?”  Rotate to soybeans.  Even in continuous corn rotation, every 4-6 years soybeans should be grown.  This management step will dramatically improve the performance of your corn rootworm management.

Secondly, add a pyramided corn rootworm transgenic trait, such as Smart Stax (Cry3Bb1 and Cry34/35Ab1) or Agrisure 3122 (Cry34/35Ab1 and mCry3A) to your corn rotation.  These pyramided traits should be rotated every 2-3 years.

Third, as a soil insecticide on non-rootworm Bt corn. 

Fourth, rotate single Bt corn rootworm traits.  Start with the Cry3Bb1 (Genuity VT Triple Pro) or mCry3A (Agrisure RW) then switch to Cry34/35Ab1 (Herculex Xtra).  Generally, rotate single Bt traits annually or every two years.

 

Strip till corn offers significant benefits to the farm.  First, more residue can be maintained on the soil surface for erosion control. 

Secondly, a long term (7 year study) conducted by Dr. Tony Vyn, demonstrated equal yields for strip till and a chisel system.  Dr. Vyn also found that the greatest yields were grown when the seed was planted directly over the P&K fertilizer band.  However, caution needs to be exercised when nitrogen applications are considered.  Some nitrogen can be applied under the seed row, but larger nitrogen applications need to be 5 inches off the row.

 

During a normal mid-summer, July and August, stored moisture is taken from the top 5 foot of soil.  This sub-soil moisture helps the plant meet its daily moisture requirements.  Generally, a foot of silt loam soil will contain 2 inches of plant available water.  In eastern Iowa, the 20 year plant available moisture has generally been 9 to 10 inches of water on 15 April.  In early December 2011, we received about three inches of rain just prior to the soil freezing.  So far, for November and early December 2012, little rain has fallen.  Iowa State University (ISU) has reported in eastern Iowa, sub-soil moisture availability to be from 2.8 to 8.8 inches per 5 foot of soil.

The three driest water years, October 1 thru September 30, since 1950, has been in 1956, 1988, and 2012 in the Central Iowa Crop District.  With these important faces in mind, Dr. Elwynn Taylor, ISU Extension Climatologist, points out that the subsequent years also received below normal rainfall and experienced below trend line corn yields in Iowa.

It is a question asked more often today than in the past by farmers.  The answer is generally yes.  The plant needs sulfur to properly utilize nitrogen.  Sulfur will enhance nitrogen use efficiency and promote higher protein values.  Factors that influence the need for annual sulfur applications:

1. High yields
2. Cleaner atmosphere – less sulfur from coal burning utilities
3. Less impurities in the fertilizer and ag chemicals

In Table 1, the unit removal for sulfur is shown.

Table 1: Sulfur Removal Values

Crop	Sulfur Removal (lbs/unit)
Corn Grain	0.07/Bu
Corn Silage	1.10/T
Corn Stover	3.00/T
Soybeans	0.18/Bu
Alfalfa	5.40/T

Source: Plant Food Update & Removal, Int’l Plant Nutrition Institute (IPNI)

With today’s higher crop yields, I am recommending annually 15 lbs. S/A for corn and 10 lbs. S/A for soybeans.

In a corn soybean rotation, tillage might not be necessary every year.  But, for the 2^nd year corn and continuous corn, some form of tillage or stalk removal is necessary.  Multiple year data at the ISU research farm are showing some interesting results.
                            Influence of Tillage on Corn Yields in Till Soil_________________

                                                               ————————-Bu/A———————–
Type Tillage                                         CSB Rotation                      2^nd Year Corn

Moldboard Plow                                        193.0                                     178.0

Subsoil                                                        188.2                                     167.6

Chisel Plow                                                192.2                                     171.0

Strip-till                                                        174.7                                     156.0
No-till                                                           169.6                                     148.2__________

2^nd Year Corn – 5 site years of data              Source:  Balancing tillage, soil loss and profitability

C-SB – 10 site years of data                                           Mark, Hanna & Matt Helmers

                                                                                              2012 ICM Conference, Ames, IA

                                        

As you begin the farm budgeting for the crop 2013 inputs, I would suggest a review of your current seeding rates for soybeans.  After examining the current data, I would suggest planting one bag of soybean seed per acre, unless planting is occurring quite late.

                                                        Suggested Seeding Rate______________________________

   Row Width (In)_    Seeds per Acre      Seeds per Foot of Row       Distance Between Seeds (In)

            30                         130,000                         7.46                                               1.6

            15                         130,000                         3.73                                               3.2
             7                          130,000                         1.71                                               6.9_____________