Author: Bob Whitney

Regents Fellow & Extension Organic Specialist, Texas A&M AgriLife Extension

What the Haney Test Revealed: Biological Benefits of Cover Crops in Action

Over the past few weeks, I’ve written about what cover crops like Sunn Hemp, Tepary Bean, and Cowpea leave behind in the soil and how their nutrient contributions stack up in standard soil tests. But it wasn’t until we looked at the Haney Soil Test results from March 2025 that we could truly see the biological influence each of these summer cover crops had on the soil. In this post, I’m sharing new insights drawn from those results and why I believe every grower should consider this test when evaluating cover crop performance.

Why the Haney Test?

Unlike standard chemical soil tests that only measure nutrient availability, the Haney Test adds a biological lens. It measures microbial respiration (COâ‚‚-C), available organic nitrogen (Haney N), and gives an overall Soil Health Score. These indicators help us understand how biologically active the soil is and how much of the nutrients are likely to cycle into plant-available forms.

For organic and sustainable systems, this is vital. We’re not just feeding the crop—we’re feeding the soil.

All Plots Started Equal

Just to set the stage: all test plots had a rye cover crop terminated in early spring 2024 and were kept bare and weed-free through summer. The only difference among plots came when Sunn Hemp, Tepary Bean, or Cowpea was planted in August 2024. The check plot remained bare.

The Biological Winners and Stragglers

Here’s what the Haney Test results (click here to see reports) show:

  • Sunn Hemp had the highest COâ‚‚-C (43.21 ppm), strong Haney N (74.74 lbs/ac), and the highest Soil Health Score (9.41). It fed the microbes and left behind a soil system ready to cycle nutrients. If you’re planting a high-demand crop like corn or grain sorghum, Sunn Hemp sets the table biologically.
  • Cowpea followed closely with a COâ‚‚-C of 32.08 ppm, Haney N of 71.50 lbs/ac, and a Soil Health Score of 7.80. Reliable, balanced, and consistent—it’s a solid choice for improving soil function while conserving moisture and nutrients.
  • Tepary Bean, despite good forage quality and tissue N content (3.02%), showed low microbial activity (COâ‚‚-C of 13.75 ppm) and the lowest Soil Health Score (6.43). It may decompose slower or produce compounds less favored by microbes. That’s not necessarily bad—it might serve longer-term fertility, but it’s not the best option for short-term nutrient release.
  • Check Plot (bare fallow) showed high mineral N (83.73 lbs/ac) and decent COâ‚‚-C (37.14 ppm), but that’s misleading. There was no cover crop to feed soil life or cycle nutrients—just unutilized residuals from last year. Long term, this approach does not build soil health.
  • Click here to read a summary report – Summary of Soil Samples

What This Means for Growers

The biological boost from a cover crop can be measured and managed. Without the Haney Test, we’d only be guessing how much nitrogen or biological activity remains from cover cropping. We tell growers: don’t plant blind—use this test to make more informed fertility and management decisions.

Sunn Hemp again proved why it’s a leading summer cover crop for southern systems. Cowpea is a great second choice when water is limited or biological stimulation is still desired. Tepary Bean may have a role in longer rotations but isn’t the best for quick turnover systems.

Final Thought

We use cover crops for more than just erosion control. They’re engines of soil biology, nutrient cycling, and resilience. The Haney Test gives us a dashboard to read those engines.

If you’re not already using it, this is your sign: test for biology, not just chemistry.

Read more:

Personality Plus: Building Resilient Organic Dairy Cows from Day One

I take the Bovine Veterinarian Magazine and appearing in the March/April 2025 edition (picture below) was this interesting article on dairy calf personality by Maureen Hanson. The article rang all kinds of “bells” for me because organic dairy production requires more than just certified feed and pasture. It demands a different kind of cow—one that can thrive with lower intervention, recover from stress without antibiotics, and mature into a productive milking animal under the constraints and values of organic systems. Maureen Hanson wrote her article based on a 2024 peer-reviewed study from the University of Kentucky (Journal of Dairy Science, https://doi.org/10.3168/jds.2023-24257)1 and this study offers a compelling new tool for organic dairy production: personality-based calf selection.

Bovine Veterinarian – March/April 2025

Calf Personality Predicts Future Performance

In the study, 49 Holstein calves were assessed using a series of behavioral tests designed to evaluate their responses to novelty and stress. Through principal component analysis of their behavior, researchers identified three personality traits:

  • Fearful: slower to approach novelty, more time spent being alert but not engaging
  • Active: higher movement across all tests, more physical exploration
  • Explorative: more interaction with objects and environment, less time inactive

These traits were then statistically correlated with detailed data from automatic calf feeders and wearable accelerometers tracking feeding behavior and activity. The results were striking:

  • Active calves consumed more starter grain, reached intake benchmarks earlier, and had significantly higher average daily gain (ADG) across all periods.
  • Explorative calves, surprisingly, had lower starter intake and lower ADG specifically during the weaning period.
  • Fearful calves showed no consistent associations with feed intake or growth but were clearly slower to engage with novel environments—a potential early marker for stress sensitivity.

Implications for Organic Dairy: Observation is Prevention

Organic systems are built on the foundation of preventive health, yet many dairy owners and managers are disconnected from the earliest stages of calf development. Calf rearing is often delegated to extremely capable managers but often few of the decision-makers (probably you since you are reading this) spend the time to observe how calves respond to their first illness, their first separation, or their first group housing experience.

This study confirms that those early responses matter. Calves that are more active adapt better to weaning and start feeding more quickly, leading to stronger growth and rumen development—two key goals in organic dairy management. Explorative behavior, meanwhile, may suggest curiosity but could signal greater sensitivity to changes, especially during stressful transitions.

You Can’t Manage What You Don’t Observe

The beauty of this research is that it doesn’t require high-tech tools to be useful. Yes, wearable accelerometers and automated feeders give precise measurements, but a skilled observer can spot:

  • Calves that hesitate or vocalize excessively when encountering new objects or people
  • Calves that walk their pens often versus those that stand still
  • Calves that seek out grain early versus those that delay

Even 20 minutes per pen per day, using a simple observation sheet for behavior categories like “explores new object,” “approaches person,” or “walks pen,” could help identify high-potential calves for organic dairy production systems.

A Call to Action for Organic Dairy

Early-life behavior should become part of calf selection and culling decisions in organic systems. Just as we select against structural flaws or poor production genetics, we should begin identifying calves whose temperament makes them a poor fit for organic environments. Resilience (something of extreme importance in organic dairying) is not just physical; it is behavioral.

These steps can help producers:

  • Reduce calfhood mortality and illness
  • Improve long-term health and lifetime milk production
  • Target breeding decisions for greater resilience
  • Stay within the boundaries of organic treatment rules

The goal isn’t just healthier calves. It’s to create a herd that is biologically compatible with organic practices. Personality is not just a curiosity. It’s a management tool. And for organic dairy, it might be one of the most important ones we haven’t been using.

Appendix: Early-Life Calf Behavior Observation Checklist

Use this tool I developed during the first 10–14 days of life (or whatever fits your operation) to assess each calf’s temperament and adaptability. Score each behavior during structured (regular) observation sessions or low-stress test scenarios (not when moving to a new pen!). Click: Calf Behavior Tool

Observation CategoryBehavior DescriptionScoring Notes
Novelty ApproachTime to approach a new object (e.g., colored bucket, ball) placed in pen1 = avoids; 2 = cautious/slow; 3 = approaches/touches; 4 = immediate interest
Response to HumanReaction when person enters pen or stands nearby1 = flees or hides; 2 = freezes; 3 = moves away calmly; 4 = approaches or investigates
Pen MovementGeneral movement over 10 minutes1 = mostly stationary; 2 = some walking; 3 = walks frequently; 4 = constant movement
Play BehaviorJumps, kicks, head butts, or frolics1 = none; 2 = rare; 3 = moderate; 4 = frequent
VocalizationsCalf vocalizes when alone or during change (e.g., feeding or handling)1 = silent; 2 = occasional; 3 = frequent; 4 = constant/loud
Feeder InterestTime to discover starter grain or milk feeder1 = delayed; 2 = average; 3 = quick; 4 = immediate curiosity

Score each calf twice during the observation window to account for variability. Calves with consistently high scores in movement, feeding curiosity, and play behavior may be more biologically suited to organic dairy systems. Those with consistently low or fearful responses may require extra care—or may be poor candidates for organic retention.

  1. Woodrum Setser, D., Proudfoot, K., Costa, J.H.C., Marchant-Forde, R.M., Bewley, J.M., & Cantor, M.C. (2024). Individuality of calves: Linking personality traits to feeding and activity daily patterns measured by precision livestock technology. Journal of Dairy Science, 107(5), 4512–4527. https://doi.org/10.3168/jds.2023-24257 ↩︎

What Do Cover Crops Leave Behind? Comparing Sunn Hemp, Tepary Bean, and Cowpea

This past fall, we let our warm-season legumes—Sunn Hemp, Tepary Bean, and Cowpea—grow as long as the season allowed. Since we planted late, we hoped for a long fall, and thankfully we got one. Each crop reached full maturity, including seed set, about two weeks before a freeze finally stopped all aboveground growth. That’s when we collected the forage samples—at peak biomass and nutrient accumulation, just before decomposition began.

These samples, along with earlier soil tests from the same plots, gave us a snapshot of how each forage performed in terms of nutrient cycling and potential soil improvement.

Crude Protein: A Quick Look at Forage Quality

One of the easiest ways to relate cover crop nitrogen content to livestock feed value is by converting it to Crude Protein (CP) using the standard multiplier:

Crude Protein (%) = Nitrogen (%) × 6.25

CropNitrogen (%)Crude Protein (%)
Sunn Hemp3.0419.0
Tepary Bean3.0218.9
Cowpea2.6216.4

All three crops delivered respectable CP levels. Sunn Hemp and Tepary Bean were just under 19%, making them excellent options for grazing, hay, or green manure. Cowpea was slightly lower but still solid at 16.4%.

Nutrient Accumulation: What the Plants Took Up

These legumes not only fixed nitrogen—they also scavenged and stored other critical nutrients. Here’s a quick summary of key nutrients in the biomass at the time of harvest:

NutrientSunn HempTepary BeanCowpea
Phosphorus %0.210.170.15
Potassium %1.621.371.16
Calcium %1.251.410.94
Magnesium %0.470.350.27
Sulfur (ppm)2,4831,7661,603
Zinc (ppm)342116
Iron (ppm)5924368
Manganese302227
Copper1098
Boron241619

What Stood Out

  • Sunn Hemp was the most balanced nutrient accumulator, with strong numbers in phosphorus, potassium, magnesium, and trace minerals like zinc and boron. It had the highest sulfur and copper as well.
  • Tepary Bean stood out for iron, with 243 ppm in the tissue—much higher than the others.
  • Cowpea showed lower uptake in most nutrients but still delivered usable protein and respectable mineral content.

These Cover Crops Don’t Just Grow—They Mine the Subsoil and Feed the Topsoil

Our recent soil tests confirm this. For example:

  • Magnesium and calcium levels rose significantly under Cowpea, even though the forage tissue levels were lower than in Tepary Bean or Sunn Hemp. This suggests slow, steady mineralization of residues.
  • Sunn Hemp left higher sulfur, zinc, and boron levels in the plant tissue, and five months later, those nutrients are becoming more available in the soil, contributing to fertility for the next season.
  • Phosphorus availability dropped slightly, especially in Cowpea plots, indicating that some P may still be tied up in decomposing roots or surface residues—but will likely continue releasing over time.

This delayed but strategic nutrient release is one of the reasons we emphasize cover crops not only as temporary fixes, but as seasonal tools for long-term soil fertility.

Takeaways for Organic Producers

These results highlight how cover crops can build both soil and have forage value. Even after seed production, these legumes held onto good nutrient density. If you’re grazing, cutting for hay, or planning a green manure termination, these crops offer real value beyond just nitrogen fixation.

  • Sunn Hemp may be the best all-around soil builder.
  • Tepary Bean could be ideal where iron uptake is a priority.
  • Cowpea, while slightly behind in nutrient concentration, is still a useful, fast-growing legume that fits well in diverse rotations.

One of the lesser-appreciated benefits of warm-season legumes like Sunn Hemp, Tepary Bean, and Cowpea is their ability to act as biological nutrient pumps. With their deep and aggressive root systems, they draw up nutrients from deeper layers of the soil profile—nutrients that would otherwise remain unavailable to shallow-rooted crops.

What makes this process even more valuable is the timing of nutrient return. These plants don’t immediately release what they’ve gathered. Instead, after several months, the decaying plant material released those deep-stored nutrients onto the soil surface, right where the next crop can use them.

Robotics for Field Crops?

I have had many opportunities lately to present programs that focused on many aspects of organic and regenerative agriculture and one of my favorite slides is one of Greenfield Robotics and their “yellow” robots working through a row crop field. In fact, I have had a few folks asking about a demonstration of these robots or even a tour to the company in Kansas (Texans don’t mind driving if it is to look at farm equipment!).

Greenfield Robotics was the first company I have seen that has a self-propelled piece of equipment that works in row crops which is by far the majority of the crop acres we need this technology to work on. This equipment also works down the row and keeps working night or day. Just check out the company video below they did just 6 months ago.

I am excited that companies are moving in this direction and that we are starting to see more of them develop technology that will change agriculture for row crop farmers. I was asked to visit about another company getting into this area, Aigen AI Generated Robotics has been doing some development work in sugar beets the Dakotas’ and cotton in California. They have reached out about some possibilities for some research/demonstration work in Texas cotton, in particular organic cotton.

Aigen will deliver, run and maintain the robots throughout the season taking the technical hassle out of the growers’ hands. As I explained to a farmer the other day, until these companies get all the ‘kinks’ out of the system and the technology get better and better developed, leasing the service is probably the best option.

Check out the Aigen YouTube channel for what is coming down the road!

Enjoy some of the other pictures of robots working!! Kinda fun to watch and to think about for Texas farmers – organic and regenerative.

Here is another Robotics Company

The picture above is of the Carbon Robotics LaserWeeder G2 1200 designed for row crops. This is a 16-row model if I counted correctly!

Recently Carbon Robotics was the third company to contact me about their new units for row crops.  They are a big player in the vegetable industry in California, but they reached out lately to tell me about their newest addition for row crops.  Carbon Robotics utilizes both lasers and computers to zap the weeds and not the crop. Laser weeders are a great idea but they have typically been slow and very expensive. As with most technology it is getting better and cheaper.  According to the company they believe they can be as competitive as conventional weed control chemicals per acre.

Check out their latest G2 LaserWeeders here: Carbon Robotics

BMR Male-Sterile Sorghum Silage: A Smart Alternative for Dairy Producers

As the High Plains continues to face water scarcity, many dairies are exploring more drought-tolerant forages1. One promising option is brown midrib (BMR) male-sterile sorghum silage, which is now showing strong potential to partially replace corn silage in lactating cow diets. A recent feeding trial2 by Texas A&M specialists Dr. Juan Piñeiro and Douglas Duhatschek conducted at the Southwest Regional Dairy Center in Stephenville, Texas, reveals some key takeaways that dairy producers need to consider before spring planting.

Why Consider BMR Male-Sterile Sorghum?

Photo: SUG R BALE BMR – Hybrid Sweet Sorghum (Male Sterile) Arrow Seed Co., Nebraska

Unlike conventional sorghum, male-sterile types don’t form grain. Instead, they pack sugars into the stalks and leaves. This results in silage with:

  • Less starch but more water-soluble carbohydrates (WSC)—these sugars ferment well and help stabilize the silage.
  • No need for kernel processing, which can reduce harvest costs and time.
  • Higher crude protein (CP) and ash, compared to corn silage.

In this study, replacing 25% or 50% of corn silage with BMR male-sterile sorghum silage (while adjusting the diet to maintain similar nutrient levels) led to:

  • 11% more dry matter intake (DMI) on average,
  • Higher milk yield and energy-corrected milk (ECM), and
  • Improved total digestible intake of fiber and protein at the 25% replacement level.

What’s the Catch?

  • At 50% replacement, digestibility of starch, protein, and fiber was lower compared to a full corn silage diet. This was likely due to the switch from starch-rich corn silage to more dry ground corn, which digests differently in the rumen.
  • DMI dropped in the corn-only group, likely due to higher starch fermentation and heat from silage spoilage during feed-out. This highlights the practical importance of silage management.

Take-Home for Producers

If you’re in a region with limited irrigation or looking to diversify your silage crops, planting BMR male-sterile sorghum could be a great option, especially if you aim to replace around 25% of your corn silage. It offers water savings, improved intake, and sustained milk production—when paired with proper ration balancing.

Keep in mind:

  • Sorghum needs wilting and proper timing for harvest.
  • Balancing for rumen-available starch is key when increasing ground corn in the diet.
  • Avoid silage heating at feed-out—especially with higher starch silages.

As more data rolls in from real-world dairies using this silage, we’ll continue refining how to best use it. For now, this is a promising tool for those looking to stretch water, reduce costs, and maintain high-performing herds.

Footnotes

  1. Bean, B. (2025, March 25). Sorghum Silage: The Rising Star of Dairy Feed. Sorghum Checkoff. Retrieved from https://www.sorghumcheckoff.com/agronomy-insights/sorghum-silage-the-rising-star-of-dairy-feed/ ↩︎
  2. Duhatschek, D., Pilati, A.G., Mittelstadt, J.P., Isasi, J.C., Cabañas, J., Lee, A.M., et al. (2025). Effects of partially replacing corn silage with BMR male-sterile sorghum silage on dry matter intake, digestibility, and milk production in lactating dairy cows. Texas A&M University Dissertation, Department of Animal Science. ↩︎

Summary of Soil Test Reports from Different Cover Crops

In August of 2024 (replanted September 12 but that is another issue!) we planted test plots for cover crops with the objective of determining which works best for the next crop we want to plant. This was really late in the summer to be planting a summer crop but to be honest we were waiting on a rain and finally gave up and irrigated. The individual cover crops were in the less than average range for growth but still all plots grew and ended up putting on a seed crop simply because we had a long fall. The plots were watered twice and then got some rain. We left the plots to grow as much as possible and after a killing frost plowed the cover crop back into the soil. We then took soil samples on March 6, 2025, and submitted them to the Texas A&M Soil Testing Lab.

Below is the plot layout

The soil test reports cover four treatments: Check, Sunn Hemp, Tepary Bean, and Cowpea. Click here if you want to read more about Texas Cover Crops. Below is a summarized comparison of key soil characteristics and nutrients across these treatments which shows how each crop affected the soil it was grown on.

1. Soil pH and Conductivity

  • Check: pH 6.6 (Slightly Acid), Conductivity 91 umho/cm
  • Sunn Hemp: pH 6.5 (Slightly Acid), Conductivity 80 umho/cm
  • Tepary Bean: pH 6.6 (Slightly Acid), Conductivity 138 umho/cm
  • Cowpea: pH 7.1 (Neutral), Conductivity 117 umho/cm

🔹 Observation:

  • Cowpea resulted in the highest pH (7.1), making the soil more neutral.
  • Tepary Bean had the highest conductivity (138 umho/cm), indicating more soluble salts.
  • Sunn Hemp had the lowest conductivity (80 umho/cm), potentially reducing salt buildup.

2. Nitrate-N (Soil Available Nitrogen)

  • Check: 14 ppm
  • Sunn Hemp: 13 ppm
  • Tepary Bean: 17 ppm
  • Cowpea: 12 ppm

🔹 Observation:

  • Tepary Bean had the highest nitrate-N (17 ppm), likely contributing more nitrogen to the soil.
  • Cowpea had the lowest nitrogen levels (12 ppm), possibly due to uptake by the crop.

3. Phosphorus (P)

  • Check: 40 ppm
  • Sunn Hemp: 34 ppm
  • Tepary Bean: 35 ppm
  • Cowpea: 32 ppm

🔹 Observation:

  • Check treatment maintained the highest phosphorus level (40 ppm) likely due to residual P from previous crops or fertilizer applications.
  • Cowpea depleted the most phosphorus (32 ppm), requiring the highest Pâ‚‚Oâ‚… recommendation (35 lbs/acre).

4. Potassium (K)

  • Check: 300 ppm
  • Sunn Hemp: 301 ppm
  • Tepary Bean: 319 ppm
  • Cowpea: 316 ppm

🔹 Observation:

  • Tepary Bean (319 ppm) accumulated the most potassium suggesting a strong potassium cycling effect.
  • Check had the lowest potassium (300 ppm), indicating less uptake or retention compared to the legumes.

5. Calcium (Ca)

  • Check: 817 ppm
  • Sunn Hemp: 815 ppm
  • Tepary Bean: 818 ppm
  • Cowpea: 1,122 ppm

🔹 Observation:

  • Cowpea significantly increased soil calcium (1,122 ppm), likely due to deeper-rooted nutrient mining.
  • Other treatments had similar calcium levels (~815-818 ppm).

6. Magnesium (Mg)

  • Check: 149 ppm
  • Sunn Hemp: 157 ppm
  • Tepary Bean: 163 ppm
  • Cowpea: 174 ppm

🔹 Observation:

  • Cowpea led to the highest magnesium levels (174 ppm).
  • Magnesium followed a trend similar to calcium, with legumes slightly increasing Mg levels.

7. Sulfur (S)

  • Check: 15 ppm
  • Sunn Hemp: 12 ppm (Needs 5 lbs S/acre)
  • Tepary Bean: 14 ppm
  • Cowpea: 17 ppm

🔹 Observation:

  • Cowpea maintained the highest sulfur level (17 ppm), possibly through decomposition.
  • Sunn Hemp had the lowest sulfur (12 ppm) and was recommended for an additional 5 lbs of sulfur per acre.

8. Micronutrients (Iron, Zinc, Manganese, Copper, Boron)

NutrientCheckSunn HempTepary BeanCowpeaCritical Level
Iron (Fe)17.518.915.915.24.25 ppm
Zinc (Zn)0.760.650.730.670.27 ppm
Manganese (Mn)10.39.78.910.31.00 ppm
Copper (Cu)0.710.680.660.590.16 ppm
Boron (B)0.260.170.230.301.30 ppm

Some General Observations

  • Sunn Hemp had the highest Iron (18.9 ppm), suggesting enhanced Fe availability.
  • Cowpea had the lowest Copper (0.59 ppm), which may warrant monitoring in future crops.
  • All treatments were below the critical Boron level (1.3 ppm), but Sunn Hemp had the lowest (0.17 ppm). A boron application of 1 lb/acre was recommended for all treatments.

Final Takeaways & Recommendations

  1. Cowpea improved pH stability and significantly increased calcium and magnesium levels.
  2. Tepary Bean led to the highest nitrogen and potassium levels, making it beneficial for nutrient cycling.
  3. Sunn Hemp had the lowest sulfur and boron levels, suggesting it may require supplementation.
  4. The Check treatment retained the highest phosphorus level, while Cowpea depleted the most phosphorus.
  5. All treatments except Check had slightly reduced Zinc, Copper, and Manganese levels, but still above critical levels.
  6. Use these results to help you plan for your next crop and then monitor that crop! This is what we plan to do by planting a Sorghum Sudangrass crop that we will collect both soil samples and plant samples.

Best Option for Long-Term Soil Improvement?

  • Cowpea appears to be the best option for improving soil pH, calcium, and magnesium.
  • Tepary Bean is ideal for nitrogen retention and potassium accumulation.
  • Sunn Hemp had the least impact on conductivity and may be better suited for salinity-sensitive crops.

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