The Soil Temp and what it is doing in February  02/24/17 7:41:38 AM

Key Dates

March 8
th—Spring Agronomic Mtg.—Cass Co. Fairgrounds



Refuge in the Bag and Insect Mode and Action.


          DeKalb Genuity SmartStax Corn           =       Orange Bag

          DeKalb Genuity VT Triple Pro Corn     =       Purple and White Bag

          DeKalb Genuity VT Double Pro Corn   =       Brown and White Bag


All traited kernels are green in color, and when in combination with the Refuge in the Bag offering, include the refuge version of the same base genetics in a purple colored kernel.


Example--Genuity VTDouble Pro hybrids will have 95% of the kernels being green and 5% of the kernels being purple within each bag. It will offer you dual mode traited insect protection for European Corn Borer, Southwestern Corn Borer, Corn Earworm, Fall Armyworm along with tolerance to Roundup Ready 2 Technology.  





What is the soil temperature? In February??  Many areas in SE Nebraska have soil temps. at 4” depths in the mid 40’s  This gets many people anxious, jumpy, and generally in motion to do something regardless of calendar date.  Anhydrous applications have begun or resumed in some areas where it is dry enough for it to occur .  When anhydrous ammonia is applied, it reacts with soil moisture to form the ammonium ion (NH4), which can readily attach to clay particles in the soil and is not subject to losses at that point. Over a period of several weeks, NH4 can be converted, through a series of steps known as nitrification, to nitrate (NO3) if soil temperatures are above 50 degrees F.    50 degrees isn’t an “on/off” switch. Yes, as soil temperatures crawl above 50 degree the pace of conversion increases, but, anhydrous is being converted to nitrate even when soil temps are in the 30 degree range.   However, it’s at a very slow rate compared to when the soil temp. is in the 70 degree range. 


A simplified illustration of the process is:


Ammonium à Nitrite à Nitrate

(NH4)           (NO2)     (NO3)


Two groups of bacteria are involved in the conversion process: nitrosommonas in the conversion of ammonia to nitrite, and nitrobacter are responsible for converting nitrite to nitrate. These steps occur in rapid succession to avoid a buildup of nitrite (NO2)  in the soil. The end result, nitrate (NO3),  is the form of nitrogen that is susceptible to leaching. Therefore, ammonia applications when soil temperatures are below 50 degrees, decreases the activity of the bacteria. The more nitrogen that is maintained in an ammonical form, the less chances for losses between now and this planting season.


A couple of additional considerations with NH4 being applied in February--1) consider the use of covering disks on the ammonia applicator if not already using them,  and 2) implement the use of an N-Serve, or urease inhibitor type additive in the anhydrous application. These additives can aid in minimizing anhydrous losses if warmer conditions exist prior to planting.



Additionally, soil temperatures this warm have winter annual weeds actively growing.  When it gets cold again (tomorrow) the plants will simply slow down in their growth activity.  BUT, these weeds will have a “jump” on the season and likely will be present sooner and larger than normal once Spring is here to stay.  Which, leads to this thought:


With the advent of the RR2Xtend system coming to the market this summer weed control topics are repetitive with everyone having ideas or solutions to your weed control challenges.  Marestail as one example, is, and has been, used often in these discussions.  Primarily because it is a chronic weed problem in No-Till Soybeans since the era of No-Till practices began.   It’s proliferation has likely been fostered where Roundup applications “wounded” or failed to kill the plant and the plant continued to grow and reproduce seed for the coming years.  


We won’t argue whether it is Roundup Resistant—we consider it an escape from your post-emergence herbicide application..   Marestail is a product of what may be called an escape or a weed shift in crop production   It is also known as horseweed,  is a winter annual weed that germinates usually in the fall.  The 70 degree weather of the past week has it growing nicely—now!    This spring, it will likely be prolific in number and given the weather patterns of late, thriving early in the season and active in  growth with all of the warm weather and generally full soil moisture profile. 


Marestail, along with other current weed problems such as water hemp, ragweed, or palmer amaranth have posed control issues primarily due to their plant morphology or design if you will.   Although small in size and many in number these species have waxy leaves that make it difficult for post emergence herbicide applications to be absorbed and translocated within in the plant.  This is especially true as the plants increases in size.


Once weeds are  more than 4- 6” in height, higher rates of a Roundup are required and many times the Roundup needs a tank-mix partner to insure good control.    This does not mean it is resistant to Roundup.  It means that an appropriate rate increase along with a tank-mix partner provides the best control when weeds are this big and “out of the range” of labeled control. 

Many of the tank-mix partner treatments increase the chance of crop injury.  Although this injury is relatively minor, leaf speckling can occur and at this stage of development means little to nothing in regard to yield potential.  

An additional option in control is the timing of the herbicide applications that can be made.  Here is where the RR2Xtend part has been mentioned often the past months.  Xtendimax and Engenia are also options here, whether in a PRE application (MOST RECOMMENDED) or in combination with post-emergence tank-mixes.  As mentioned before, marestail is a winter annual by life cycle classification.  Most everyone will agree that weeds are easier the kill when they are the smallest stages of their life cycle.  It is usually easier to kill weeds before you see them and that is why we suggest that spring applications of a number of pre-emergence soybean herbicides such as Authority First, Canopy EX, Sharpen, Sonic and Valor all work well as a spring burn down to a number of other weeds which have become harder to control with post-emergence applications.  They are not in-fallible.  But, a spring herbicide application to fields with a historic weed problems, should give you better control later this year.


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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