Author: Max Runge

The Land Grant University System has a historic tradition of the combined missions of teaching, research, and extension.  In fact, Southern Ag Today was born out of a collaboration of Extension Economists across the Southern region.  The Old Rotation at Auburn, is a great example of Land Grant history and continued relevance.  As cited from the National Register of Historic Places, January 14, 1988:

 The Old Rotation. 

Established in 1896 by Professor J.F. Duggar, the Old Rotation at Auburn University is: 

• The oldest, continuous cotton experiment in the U.S.
• The 3^rd oldest continuous field crop experiment in the U.S.
• The 1^st experiment to demonstrate the benefits of rotating cotton with other crops to improve yields and utilize nitrogen-restoring legumes in a cotton-production system. It continues to document the long-term effect of these rotations in the same soil.

The Old Rotation has had 128 years of cotton planted in the same soil and provides valuable insight into cover crops and crop rotation, and one of the original objectives of utilizing legume cover crops is significant today.

Table 1 shows yields from 1896 through 2023 from plot # 6 and plot # 8  (there are a total of 13 plots with different treatments). Plot # 6 has been planted to continuous cotton with no additional Nitrogen (N) fertilizer and no cover crop.  Plot # 8 was also planted in continuous cotton with no added N, but included a winter legume cover crop consisting of crimson clover and hairy vetch.  The plots have otherwise been treated the same over the research period.  It is also important to note that these are non-irrigated plots; there are years with very low or no yields; and the yields have increased significantly due to improved management practices and genetics. 

The yield difference over the last 100 years is clear and substantial.  However, the yields between 1896 and 1921 were virtually the same, so it took some time for the net benefit of the practice to accumulate.  Much has changed about cotton production in 128 years, but the history of The Old Rotation suggests the reasonable conclusion that good soil and fertility management (or the lack of) is a long term game.    

With more emphasis on improving soil health and reducing fertilizer costs in the Southern region, looking at long term research helps to provide solutions.

More information about the Old Rotation can be found at: https://agriculture.auburn.edu/research/cses/the-old-rotation/

Runge, Max. “Historic Research Yields Modern Solutions.” Southern Ag Today 3(47.3). November 22, 2023. Permalink

What is the value of the nitrogen, phosphorous, and potassium that is removed when hay is baled and carried away from the field? In March, we looked at wheat straw nutrient removal¹, but the value of nitrogen, phosphorous, and potassium should also be considered in hay production.

Baling and removing 8,000 pounds of Bermuda grass hay over the course of a hay season removes 400 pounds of nitrogen (N), 90 pounds of phosphorus (P2O5), and 345 pounds of potash (K2O) per acre². Prices of $0.71 per pound of nitrogen, $0.73 per pound of phosphorus, and $0.61 per pound of potash³ were used to reflect the approximate value of the nutrients. The table below shows the value of the N, P2O5, and K2O removed on a per acre basis when 8,000 pounds of Bermuda grass hay is removed. The value of the nutrients removed by the Bermuda grass hay is $561.61 per acre per year. Or on a 1200-pound round bale basis, that value is $54.24 per bale. Adding the cost of baling (1200 lbs. round bale) of $14.50⁴ per bale and moving⁴ the bales out of the field at $4.35 per bale brings the total costs to $103.09 per 1,200-pound bale.  Converting these values to a per ton basis (4 tons/acre), the nutrient value is $140.40 per ton, and baling and moving is an additional $31.42 per ton. The total per ton costs are $171.82.

It should be noted that this is just the value of N, P, and K, as there are some micronutrients that are removed as well. 

There are caveats. The amount of hay harvested, costs of nutrients, baling and moving will likely be different depending on numerous factors, including location, yield, type of bales, the efficiency of the baler, and soil type. Check local resources in your area to estimate the value/cost of the nutrients and baling costs. 

Information for the values included in this article can be found in the following resources.

1.    https://southernagtoday.org/2023/03/29/wheat-straw-nutrient-removal/

2.   https://www.aces.edu/wp-content/uploads/2019/01/ANR-0449.REV_.3.pdf

3.    https://www.ams.usda.gov/market-news/production-cost

4.  http://agecon.ca.uky.edu/files/custom_machinery_rates_applicable_to_kentucky_2022.pdf

Baling wheat straw following harvest is seen as a way of utilizing a bi-product, with the only cost being baling and removal from the field. The straw could then be sold as bedding for livestock, mulch, or other uses that provide value. However, the cost may be larger than you think.

The cost of fertilizer and increased focus on soil health makes it essential that we know what nutrients we are removing from the field when we take away the wheat straw. Research has shown that removing 6,000 pounds of wheat straw per acre removes valuable nutrients (6,000 pounds is the approximate amount of straw associated with an 80 bushel per acre wheat yield.) Removing this quantity of wheat straw removes 60 pounds of Nitrogen (N), 10 pounds of phosphorus (P2O5), and 135 pounds of Potash (K2O), per acre¹. This is in addition to the nutrients removed when the wheat grain is harvested.  Putting a monetary value to the pounds of N, P, and K taken away by baling the straw shows that the straw does have significant value. A price of $.86 per pound of nitrogen, $0.70 per pound of phosphorus, and $0.61 per pound of potash² were used to reflect the approximate cost of the nutrients. The table below shows the value of the N, P, and K removed on a per acre basis when the wheat straw is removed. The value of the wheat straw needs to be greater than $125.47 per acre or $25.09 per 1200-pound round bale. Adding the cost of baling (1200 lbs. round bale) of $14.50³ per bale and moving³ the bales out of the field at $4.35 per bale. The total of these costs is $43.94 per bale or $219.72 per acre. It should be noted that this is just the value of N, P, and K. There are some micronutrients as well as the organic matter that wasn’t considered in this analysis that have value if left in the field.

There are caveats. The amount of straw could be different depending on numerous factors, including limited yield, variety of wheat, the efficiency of the baler, and soil type. The value of N, P, and K will vary depending on your location as well. Check local resources in your area to estimate the value/cost of the removal of wheat straw. 

Information for the values included in this article can be found in the following resources.

1. https://www.aces.edu/wp-content/uploads/2019/01/ANR-0449.REV_.3.pdf
2. https://www.ams.usda.gov/market-news/production-cost
3. http://agecon.ca.uky.edu/files/custom_machinery_rates_applicable_to_kentucky_2022.pdf

Runge, Max. “Wheat Straw Nutrient Removal.” Southern Ag Today 3(13.3). March 28, 2023. Permalink