Statewide
This concludes a series of Sorghum Tips discussing production yield of grain sorghum vs. corn in relation to varying levels of available water as well as water use efficiency of grain sorghum vs. corn. All previous tips can be found at http://texassorghum.org/sorghum-tips. Previously Parts IV & V depicted simple corn/sorghum comparisons of 1) yield vs. seasonal water use (equal at about 18”) and 2) crop value vs. seasonal water use (equal at about 15” at current prices).
And finally…
• What is the relative net crop value among variable expenses (no fixed costs included) vs. seasonal water use?
One could also calculate the per-unit production costs and produce yet another graph.
To determine net crop value I used Texas A&M AgriLife Extension grain sorghum and corn enterprise budgets for the South Plains (you can find other crop budgets for your region of Texas at http://agecoext.tamu.edu/resources/crop-livestock-budgets/budgets-by-commodity/ )
Then using the same unit of sorghum or corn production per 1” of water (Tip IV) and the recent grain prices for determining the crop value per 1” of water, I used adjusted irrigation water (inches), yields (which automatically adjusts harvest costs), seeding rate, and N & P fertilizer inputs for corn and grain sorghum across a range of total crop water use up to ~38”. The results are noted in the Figure below.
We now see that the relative favorable comparison of grain sorghum in lower water conditions shifts back to the right, or more favorable, than corn at lower water. This is a combination primarily related to 1) the relative ability of grain sorghum to produce the first bushel of grain sorghum with several inches less water than corn, and 2) lower production costs than corn.
The “cross-point” (black arrow) has moved back to the right and is at 19” based on the budgets used. This suggests that in the South Plains a producer with less than 19” total moisture (projected irrigation, rainfall, stored soil moisture) available to the crop, the net income favors grain sorghum. Your farms may provide different results than this graph, and the calculations used can be no better than the budgets constructed by ag. extension colleagues, but this gives you the producer more information to consider when you are debating which fields, crop rotations, etc. should consider grain sorghum or corn.
The principles here apply to the Coastal Bend, Central Texas, Concho Valley, and the Panhandle as well (there are different budgets from Extension for those regions).
This concludes the Sorghum Tips on grain sorghum and corn water use.
In our next tip we will review the major changes in the Huskie herbicide label for grain sorghum.
