We are at the point in far SW Kansas and the OK panhandle that most of the irrigated wheat is starting to stress and needs to be watered.  The 2 week forecast has very little chance of rain and there is really no choice.  This could be setting us up for a spring kill problem.  In some of the past years watering wheat this early in the spring has produced too much growth and made these lush fields less tolerant to the extreme cold that could still occur.  In the Garden City area, we'll be starting to moisture stress within 7 to 10 days.  This same 2 week forecast has nothing alarming from the standpoint of low temperatures.  I see no choice but to water the wheat and hope that winter is over.

There are still numerous fields being strip tilled for corn.  You really need to consider backing off on the NH3 rates this close to planting.  I realize that NH3 is still the best buy but it could actually end up costing you if damage to the corn crop occurs.  From this point forward I would recommend keeping rates at no more than 80 lbs actual N.  The potential for crop injury is a function of rate, time, moisture and soil type.  Obviously the higher the rate, the greater the chance of injury.  The shorter the time interval between fertilizing and planting the greater the risk of injury and the drier the conditions the greater the chance of injury.  The tighter the soil the greater the chance of injury.  This is because on tighter soils nitrate movement is restricted and it will take more moisture to move these salt bands out of the seed and corn seedling root zone.  It takes about 1 inch of moisture to move nitrates 9 inches on a sand while this same 1 inch of moisture will only move nitrates 3 inches on a clay loam.  The damage that typically occurs from this problem is not a reduction in germination, it is a burning to the seedling corn roots.  The corn emerges and looks great until the radical root hits this salt layer.  It burns off and the corn turns purple appears moisture stressed and just sits there until enough irrigation water is applied to disperse the salts.  If you have already applied the full nitrogen requirement with a strip bar and have not had significant moisture on it you really need to consider 2 or 3 inches of irrigation pre plant.  If you haven't stripped the field yet, consider cutting back to 80 lbs of nitrogen and apply the balance as broadcast urea or through the pivot during the season.  You can also get 30 to 40 lbs of nitrogen on with the pre emerge herbicide or burndown application.            

 


Comments

John Lehnert

Thu, 13 Mar 2008 18:58:10

What about dryland wheat with poor stands and 0-2 tillers. In mid February it appeared there would be nothing. Now growers can row the wheat and don't want to give up just yet, however, it is difficult for them to justify spending money to topdress. Some feel with the decreased yield potential there should be enough N available, while others are asking if 10-20lbs might help give the small wheat the boost it needs? Also most of these fields have very light weed pressure at this time but will likely have increasing pressure in the near future. With all that said is now the time to be spraying and topdressing or should they wait another week or two and see how the crop progresses.

 

Fred Fisher

Tue, 18 Mar 2008 04:27:36

It really is impossible to say how much nitrogen is needed on this late / lower potential wheat without more information. You could still delay decisions on rates for a week or two and I would suggest taking a 2 foot soil nitrate to get a better idea. I would use a crop factor of 1.8 to 2.0 lbs of nitrogen per bushel after giving credit for nitrates present in the soil. As for yield potential on this late wheat I would still say if the plant stand is fair it can still yield about 50% of the yields of the better wheat. That might be 20 to 25 bu this year. As for weed control I would delay that as well but keep rotation options open. I would still recommend using Banvel and MCP but needs to be applied prior to joint. In Garden City this late wheat probably won't joint until the 1st or 2nd week in April. Further south it won't joint until April 1st.

 



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