Crop Response to Phosphorus Fertilizer in Ohio

Authors: Dr. Manbir Rakkar, Greg LaBarge, CPAg/CCA; Original published in the C.O.R.N. Newsletter

Phosphorus (P) is an essential plant nutrient and P fertilizers are added to supplement the soil’s available P. There are economic and environmental benefits to making informed decisions about P fertilizer use. The under-application of P fertilizer can result in reduced yields, while over-application adds to input costs, with economic losses resulting from both scenarios. From an environmental perspective, excessive P going into streams and lakes can result in toxic algal blooms.Young Corn Plants

A few frequent questions about P fertilizer use are: Does P fertilizer always result in a positive yield response? How much yield increase is expected with applied P? What is the likelihood of yield penalty if P fertilizer is not applied?

A recently published factsheet‘Soil Phosphorus and Crop Response to Phosphorus Fertilizer in Ohio’ (, provides a general overview of soil P and highlights the findings of Culman et al. (2023) to answer these practical questions (Rakkar and LaBarge, 2024). The study summarized 457 replicated field P trials conducted over the last 45 years across 40 counties in Ohio. The robust dataset evaluated corn, soybean, and wheat response to added P fertilizer in trials conducted on farms and at research stations.

Below are some key takeaways:

Does P fertilizer always result in a positive yield response?

No. Out of the 457 field P trials, a significant increase in crop yield was observed in 107 trials with P application. The crop response to added P also varied among crop types. Corn responded to P application in 29.9% of trials, soybean in 14.2%, and wheat in 36.8% (Fig. 1).

Fig. 1. Relation of relative yield and soil Mehlich-3 P for corn, soybean, and wheat across 457 field trials

Fig. 1. Relation of relative yield and soil Mehlich-3 P for corn, soybean, and wheat across 457 field trials (Culman et al., 2023).

How much yield increase is expected with applied P?

It depends on the Mehlich-3 soil test P level. The Mehlich-3 soil P measures the readily available soil P for crop uptake. Culman et al. (2023) classified Mehlich-3 soil P levels into five categories: <10, 10–20, 20–30, 30–40, and >40 ppm to evaluate the yield increase for each soil P category.

The crop yields were presented as Relative Yield, which refers to the yield with no P application divided by the maximum yield obtained across all P treatments. In other words, 100% relative yield means no yield increment with added P. The lower the relative yield, the higher the yield increment.

Generally, as the soil test P levels decreased, the yield increment increased with P input (Table 1). When the soil test P was less than 10 ppm, the median relative yield was 87%. As the soil test P level increased above the critical level of 20 ppm, the median relative yield ranged from 97% to 99%, signifying minimal yield increment with added P.

Table 1. Summary of crop response to P fertilizer by soil P classification. (adapted from Culman et al., 2023)


Mehlich-3 soil P classification (ppm)

Number of trials

Fertilizer responsive trials (%)

Median Relative Yield (%)





















What is the likelihood of yield penalty if P fertilizer is not applied?

We can also determine the likelihood of yield penalty based on Mehlich-3 soil P with the information in Table 1. When the soil P level was less than 10 ppm, 67% of trials showed increased crop yields with applied P. When the P levels were above the critical level of 20 ppm, only 12-14% of trials showed increased crop yields. In other words, the likelihood of yield penalty with no P application decreases as soil P levels go above 20 ppm. If the soil test P level is less than 20 ppm, there is an increased risk of yield penalty with no P application.

For more soil fertility resources, information, and tools, use the link


Culman, S., Fulford, A., LaBarge, G., Watters, H., Lindsey, L. E., Dorrance, A., & Deiss, L. (2023). Probability of crop response to phosphorus and potassium fertilizer: Lessons from 45 years of Ohio trials. Soil Science Society of America Journal, 87, 1207-1220.

Rakkar, M. & LaBarge, G. 2024. Soil Phosphorus and Crop Response to Phosphorus Fertilizer in Ohio. Ohioline. (

Ohio Fruit News – January 2024

The January issue of OFN is attached and also available online. In this issue, you will learn about:

  • Proposed changes to the registrations for Ziram, Thiram, and Ferbam, three fungicides that are critical to fruit disease management
  • The current status of agricultural water standards for the Produce Safety Rule
  • Fruit disease diagnosed in 2023 by the Plant and Pest Diagnostic Clinic

Print version OFN_JAN_2024

Online version 

A Minimalist Approach to Ensuring Fall through Spring Vegetable Harvests

– Matt Kleinhez, Article Originally Posted on Fruit, Vegetable, & Specialty Crop News)

Interest in marketing locally-grown, freshly-harvested vegetables fall through spring is strong and increasing among high tunnel growers in the Midwest, Great Lakes, Mid-Atlantic, Mid-South, and Northeast. Scanning the agendas of industry meetings and listening to growers and others in these areas makes clear that fall through spring harvest and marketing of high tunnel-grown crops is an established and increasingly common practice. Importantly, some growers have transitioned to cash cropping their high tunnels only fall through spring and leaving summer to grow cover crops and focus on other priorities, including field-based production. Conversations with and public presentations by these growers and other experts make clear that fall through spring income from high tunnel production can be significant if the correct crops and varieties are chosen and suitable practices are used.

We have long wondered which crops, varieties, and practices may be ideal for Ohio high tunnel growers looking to harvest fall through spring. Much of our previous research focused on a relatively small number of crops and the use of various tools and practices (e.g., films, fabrics, and/or soil heating). Our goal was to describe potential production outcomes when high tunnel growers invested in the process to various levels. Results from those experiments suggest that yields are likely to be greatest when investments are also highest, for example, when soil heating, plastic films, and row covers and the effort to maximize their utility are used. Those studies were summarized previously in this blog.

We are asking a different question in Winter 2023-2024. As the three panels below describe, seven crops were seeded in two high tunnels in October-2023 and grown without any supplemental heating, films, or row covers. This “minimalist” approach explores the worst-case scenario, the minimum that can be expected from these crops under the conditions they have experienced since seeding. This approach may appeal to growers unfamiliar with fall through spring production and/or those who are unwilling or unable to invest much time, money, or effort in it, at least at this time. The test outlined below is one example of what can be expected but many others exist. Of course, different outcomes may be possible when other varieties, planting dates, and growing practices are used. Upcoming evaluations will push the “minimalist” approach further as all crops capable of being grown and harvested fall through spring do not require a high tunnel. Please contact me (Matt Kleinhenz, 330.263.3810, if you would like more information.


Tips to Stretch Short Hay Supplies

– Dr. Jeff Lehmkuhler, PhD, PAS, Beef Extension Professor, University of Kentucky

Below are a few tips to consider stretching limited hay supplies. For additional information contact your local Extension agent. It is recommended to consult with your feed nutritionist or County ANR Agent before making drastic changes in your feeding program.

  1. Inventory hay – know how much hay you have available; weigh a few bales to get an average weight or estimate the weights based on available information from Extension publications.
  2. Minimize storage losses – keep hay off the ground on a surface that will allow water to drain away; keep bales covered or stored inside a barn; if bale grazing limit the number of bales placed in the field to provide 2-4 weeks of feeding to reduce weathering losses.
  3. Reduce feeding loss – consider minimizing feeding losses; using hay rings with skirts / metal on the bottom, tapered ring designs, chains to suspend bales, or cone inserts to keep hay inside the feeder has been proven to reduce hay feeding losses compared to hay rings with openings at the bottom; using an electrified temporary poly-wire placed down the center of unrolled hay will reduce losses from cows laying on the hay, trampling it into the mud, and defecating on the hay; feeding processed hay into a bunk or large industrial tire reduces waste compared to feeding processed hay on the ground.
  4. Cull – consider selling less productive females, open cows, and cows with structural/functional issues to reduce the number you must over winter; consider selling the bull as the market may provide the opportunity to sell a mature bull and replace him with a younger bull next spring.
  5. Limit time access to hay – research has shown dry cows in mid-gestation can be maintained on good quality hay when they have restricted access time to only 6-8 hours a day; the hay savings comes from less waste as feeding behavior is altered; all cows must be able to access hay at any given time; this is not recommended young or thin cows, lactating cows or growing animals.
  6. Substitute hay with grain – calories and protein can be provided from supplements; grain/commodity mixes can be used to replace hay; cows can be maintained on a low hay diet by using grain supplementation that balances the nutrient supply and animal requirements; consult a nutritionist before making extreme feeding changes.
  7. Deworm young animals – animals with an internal parasite burden will have reduced efficiency.
  8. Feed an ionophore – if grain supplementation will be used, consider adding an ionophore to increase the energy efficiency of the feed consumed. Consult your nutritionist to discuss inclusion rates and developing a supplement program. Previous work has shown that feeding 200 mg of monensin allowed cows to maintain body condition on 10-15% less hay.

Ensuring Healthy Herds: The Critical Role of Water Management for Livestock in Winter

– Kate Hornyak, OSU Extension Program Coordinator, Delaware County (originally published on Ohio Farmer on-line)

Water stands as an essential nutrient for beef cattle, much like it does for humans. It plays a vital role in various bodily functions, including growth, reproduction, lactation, and the regulation of body temperature. However, the winter season intensifies the challenge of providing a sufficient and accessible water supply. This difficulty is compounded by the freezing temperatures and changes in the behavior of the livestock during colder months.

Challenges in Winter Water Management

Managing water for livestock during the winter months presents distinct hurdles. The primary issue is the freezing of water sources, limiting cattle’s access to water. Cattle often increase their water consumption in colder weather to meet their heightened energy needs. This requires more focused management strategies to ensure they receive sufficient hydration.

In colder temperatures, cattle consume more feed to maintain body heat. If water availability decreases, feed intake also drops, leading to poorer body condition. This is particularly critical if the birthing season is in spring, as reduced water and feed intake during winter can lead to poor fetal growth rates and lower lactation levels.

Methods to Deliver Water in the Winter

Having electricity at your winter-feeding areas is a huge plus. It unlocks several effective methods to prevent your cattle’s water supply from turning into an icy hazard. A straightforward solution is to use a plug-in heater, which can be installed in the drain plug of a large stock tank. This approach is simple and efficient, ensuring that water remains in a liquid state for your herd.

Large stock tanks with larger capacity are another option that can be considered. Stock tanks need to be checked often to allow livestock access to water and ensure filling purposes. Opting for ones with a larger capacity can make a difference when temperatures drop. To combat ice formation, consider installing a continuous flow valve. This valve will prevent freezing and ice from accumulating in the tank.

In areas where electricity isn’t an option, natural sources like ponds and springs come into play for livestock hydration. However, during winter, these natural waterways can present challenges, especially on extremely cold days when freezing is a concern. To navigate this, one can employ innovative methods such as a collection trench combined with solar-heated devices. These systems often include heat tubes buried deep underground, capturing solar energy to prevent water from freezing. However, it’s important to note that even with these measures, on particularly frigid days, with frequent visits by the herd to the water source, a thin layer of ice may still form. In such instances, breaking the ice becomes necessary to maintain uninterrupted access to water for your livestock.

What is Ideal

Keeping the ideal temperature of drinking water for cattle is a balance – it should neither be hot nor frozen. The sweet spot lies between 40 and 65 degrees Fahrenheit. It’s interesting to note that steers with access to cool drinking water have been shown to gain an additional 0.3 to 0.4 pounds per day compared to those consuming warmer water. This underscores the importance of regularly checking the temperature of water, especially in waterers equipped with heaters, to avoid what’s known as a “runaway” – a situation where the water gets too warm.

To accurately gauge the water temperature, use a thermometer, but remember to keep it suspended in the water rather than letting it touch the bottom of the container. The bottom, especially if heated, might show a higher temperature than the actual water. Conduct these checks over several cold days to ensure consistency. Maintaining water temperatures at least at 40 degrees Fahrenheit is crucial not just for the mechanical aspects of water delivery systems, but also for sustaining optimal animal performance.

Furthermore, according to the “Beef Housing and Equipment Handbook” from 1987, a guideline for water access is that 16 cows should be able to drink from each foot of a water fountain or tank perimeter. This is based on the assumption that cows are penned and have continual access to water throughout the day. Practical experiences often suggest that this number can be exceeded if the water flow is consistently adequate.

Understanding and implementing these insights about water temperature and accessibility can significantly impact the health and growth rates of cattle, especially in controlled environments like pens. Regular monitoring and adjustments as per weather conditions are key to ensuring the wellbeing of your livestock.

2023 eFields Booklet Now Available!

The 2023 eFields Book is now available in local Extension Offices. The eFields booklet is a free publication that highlights on-farm research from around the state. The topics in this year’s copy are Corn, Soybean, Small Grain, Forages, Water Quality, Tech, and Other. Each of these sections highlights research conducted during the 2023 growing season. This booklet hosts a lot of exciting information that can assist agriculturists in their management decisions. Stop into the Extension Office to pick up your copy today!

The companion copy of this book for livestock is eBarns. The 2022 copy of this report is available at this link. This publication also covers on-farm research from across the state in the areas of Forages, Dairy, Beef, Small Ruminant, Manure Nutrients, Swine, and Poultry.