Texas A&M AgriLife Sorghum Tips

If it Finally Rains—Late Seeding Sorghum/Sudan for Hay

The drought across Texas is acute.  I travelled across the state July 20-22.  Only near Beaumont did pasture and range look somewhat satisfactory.  Reports indicate forage is in short supply in Texas.  Prices for hay are up and may climb more.  Some livestock producers are reducing herd size or even selling all cattle.

We do not know when it will rain.  The long-term National Weather Service forecast for Texas projects continued dry conditions into Fall.  For the next 7 days of August 1-7 only the Houston region and southeast Texas showing moderate chances of rain.

Q:  Is it realistic that some late forage could still be planted in Texas for 2022?

In a typical year we would not consider this now that July is over.  For years I have suggested—if not recommended—when grazing and especially hay is limited, farmers in the Texas South Plains (Lubbock region) could plant sorghum/sudan as late as August 1.  If moisture is available and the seeding is established, then there is at least 2.5 months of growing season left.  This can allow modest late-season forage production to help alleviate a forage shortage.  AgriLife results from the distant past conducted at Bushland, TX (west of Amarillo) found good forage yields up to 3 tons/acre dry matter planted as late as August 15, but a) there was nearly 5” of rain in August, and b) the first 32⁰F occurred about 17 days later than normal (Nov. 12th).  For this year, in this region of the state, growers could consider late planted sorghum forages to at least August 7th—dryland if it rains (recently received 3” in some areas) or limited irrigation is used.  (See below for other regions of Texas.)

Q:  If I do get some rain (or am willing to use some limited irrigation), how late could I seed sorghum/sudan in 2022?

Texas A&M AgriLife has not tested these late plantings in most of the state.  So, there is some conjecture in these suggestions.  But if you get some starter rainfall, and believe more can and will come, then you could feasibly drill/plant sorghum/sudan as late as:


  • Texas High Plains, August 7, especially for the Lubbock region where the average first heavy frost/light freeze is the first few days of November
  • Rolling Plains to North Texas (Dallas/Commerce region), August 10-15
  • Central Texas to El Paso, August 20-25
  • Coastal Bend to Uvalde region, Sept. 1-7
  • Corpus Christi to Lower Rio Grande Valley, Sept. 7-14


Understand these are guidelines.  We have a special situation, even a crisis.  This could be modest growth at best—if rains occur.  But it could be worth the risk.

What issues could arise?  There could be an early heavy frost that could shorten the window of potential growth.  Often it is not the first frost/freeze that curtails growth rather substantially cool fall weather (highs in the low 70s, lows in the low 40s and lower).  We do not expect growth to be as robust as earlier plantings.  Tropical storm season in coastal Texas could hammer a forage crop.  It remains stifling hot and though you had planting moisture, it remains excessively dry.

Input cost will continue to be high.  Many farmers, especially with no cattle, would rather save inputs, available moisture for 2023.

Q:  What sorghum/sudan hybrids should be considered for late planting?

Use your seed dealer’s basic or typical sorghum/sudan.  This may be called by other names:  sorgo/sorghum-sudan, three-way cross, sudangrass, haygrazer (but not forage sorghum).  The earliest any of these would hit boot stage is about 60 days after planting.  For this situation, you do not need brown midrib (BMR) sorghum/sudan.  It costs more to seed.  Photoperiod-sensitive sorghum/sudan is OK, but it too costs more for seed.  The issue is forage production, any forage production.  The timing of planting and duration of growth can produce 2 tons of dry matter per acre, more if conditions are good.

Q:  What is a suggested planting seed rate/density for late-summer seeding?

Again, AgriLife does not have data, but I suggest a seeding rate of about 2/3 of what you would use if this was seeded under favorable conditions earlier in the year.  If moisture remains marginal but you decide to plant in hopes it rains, a seeding rate ½ of normal is probably adequate.  Typically, those seeding rates range from about 15 lbs./A dryland & 25 lbs./A irrigated in the High Plains to a full bag (50 lbs./A) in Central Texas.  Since this late planting has some risk, we don’t need the high seeding rates.  Perhaps 25 lbs./A for any location is Texas is a maximum.  These suggestions assume seed that is about 15,000 to near 20,000 per lb.  Some seed could be smaller (22,000 per lb. or more) so lbs. per acre seeding could be reduced some.

There are situations it might be better to use a planter (see below) rather than a drill.  If so, then seeding rate could be reduced by 2/3 vs. a drill.  A seeding rate as low as 60,000 (about 4 lbs./A) could be adequate if using a planter.  This will help hold seed cost to a minimum.

Q:  Would a planter be better than a drill in some circumstances?

Possibly.  If you can get to moisture for an initial stand with a planter but not with a drill, then consider row-cropping the sorghum/sudan.  This is especially true if you have row-crop spacing of 32” or less, and even better if you have planting capability at 20” spacing.  Also, if you may face planting into a lot of residue (a recently harvested corn or grain sorghum crop).  If a planter can save you a major tillage operation ($$), then plant into that stubble without tillage.  And if you gather some stubble from a summer 2022 crop in your hay, we won’t be picky this year.  If you have a no-till drill this may not be a consideration.  What will give you good seed placement?  If it rains more than difficult seed placement with a drill is less of a concern.

Q:  What are herbicide options for late sorghum/sudan?

Weed issues may be less for late-season planting.  If the sorghum/sudan has the right safener (Concep III, etc.) then s-metolachlor (Dual products) are a good choice.  This is often paired with atrazine, but due to rotational considerations you may not consider atrazine.  Typical options for grain sorghum herbicides could be suitable.  But some of these products may not be labeled for forages in the sorghum family.  Consult your chemical dealer or AgriLife Extension weed specialists in College Station, Corpus Christi, or Lubbock.

Watch for possible residual herbicide issues that might preclude seeding sorghum forages now.  This is especially true if you have had little rainfall since application thus herbicide residual is more likely present.

Q:  Will I need to apply expensive N fertilizer?

I view this as a limited input situation.  There will be no N application unless you get a good stand established and only then if moisture prospects are favorable.  (You got additional rain, or you are committing limited irrigation.)  Otherwise, rely on residual fertility to start this late crop.  If conditions are favorable, I would suggest a maximum of 50 lbs. of actual N per acre.  N prices are still near $1 per actual unit of N.

Q:  Are there other possible late-season forage crop species?

Hybrid pearl millet might be considered, but seed will likely cost more per acre to plant.  The forage performs similarly, but it is probably a less fitting option.  The seed is much smaller (70,000-90,000 per lb.) than sorghum/sorghum sudan so planting depth is limited to about 1”.  Legumes species like forage cowpea are more expensive to plant.

Q:  Why not wait several weeks and plant late summer/early fall wheat or triticale?

These small grains will not deliver the forage production to help alleviate an immediate short forage crisis.  Remember—wheat, triticale, oats, etc. are cool-season crops.  They are less efficient in hot weather.  There can be heat-induced dormancy issues in some wheat varieties (though we are not sure which ones).  Some industry staff consider triticale suitable for early (August) drilling due to relatively better gemination and establishment in hotter conditions.  But that does not mean you should do it.  These crops possibly use limited moisture too early in the season leading to inefficient water use and lower yield.

Q:  If I get good growth when would I start grazing?  When would I cut for hay?

For most sorghum/sudans, a general height for initial grazing is about 30”.  But do not grub the field as sorghum/sudans, if there is time, will regrow.   If baling for hay then boot/late boot stage is a good balance of forage quality and tonnage.  The dry weather we are in may preclude the preferred growth stage for haying.  There is more tonnage if it heads out, but the forage quality is less.  Do not allow grain development.  The goal is forage biomass.  Supplemental protein and other nutrition can be added, if desired.

Q:  Are there any downsides to baling current corn and sorghum stalks?

 Potentially, yes.  Animals that graze a field leave most nutrients on the field through urine and feces.  But haying is different.  Forage removal is a pathway of significant nutrient loss from your cropping system.  For example, if corn or grain sorghum stalks have low 5% crude protein on a dry weight basis, that is about 0.8% nitrogen.  A ton of this hay removed from the field would contain about 16 lbs. of N.  It costs about $1.00-1.10 per unit of actual nitrogen to replace.  This is $16-18 per ton to replace the N.  Then the value of phosphorus, potassium, and other minerals is usually about 25-33% (1/4 to 1/3) the value of the N.  This suggests full replacement cost of the nutrients could be $20-25 per ton of hay.  Is the price you are getting high enough to compensate you for this nutrient loss?  Often it is not.  Farmers don’t factor in this replacement cost.  $40 a ton might seem pretty good—free money—especially if someone else is paying for cutting, baling, hauling.  But actually, less than half of those $40 is real profit.  That is not such a good deal.

Q:  What about potential nitrate and prussic acid poisoning in late-planted sorghum forages?

This is a valid concern.  There is not different consideration than regular sorghum/sudan production for grazing and hay.  Some of our understanding of prussic acid potential and actual threat to animal health is evolving with further research (possibly less an issue than often believed?).  A recent summary from United Sorghum Checkoff program is entitled “Avoiding Prussic Acid (cyanide) and Nitrate Poisoning in Drought Stressed Sorghum in Livestock.”  It is found at Avoiding-Prussic-Acid-and-Nitrate-Poisoning-in-Drought-Stressed-Sorghum-Final-Rev-2_FINAL.pdf (sorghumcheckoff.com)



Dr. Calvin Trostle, Extension Agronomy/TAMU Dept. of Soil & Crop Sciences, Lubbock, (806) 746-6101, ctrostle@ag.tamu.edu


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