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.


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.

Holiday Arrangement Class

Last week Williams County Extension hosted a Holiday Arrangement Class. The class was led by Angie Girdham, Horticulturists at Hillsdale College. She taught participants how to make holiday centerpieces or grave saddles. The arrangements were made from White Pine, Fir, and Arborvitae trees. Special Thank you to Mike Weaver for providing the trees. Jessica Runkel, a regular attendee of the event and 4-H Programming Assistant, stated, “I love it. I don’t really know how to make an arrangement. So, I need a self-guided tour. My mom and sister have been coming and making grave saddles for the past 4 years for family members who have passed away. It is a bonding experience for us. that we look forward to every year.” What a wonderful way to spend the Holidays!

If you are interested in this or similar programming please give our extension office a call (419) 636-5608.

Highly Pathogenic Avian Influenza Outbreak

Bird flu, or avian influenza, is a disease caused by influenza type A virus that can infect poultry. Most strains are low pathogenic. Highly pathogenic strains (HPAI) are highly contagious in birds and often cause death in poultry. The recent HPAI outbreak in multiple counties in Ohio has affected over 4 million birds and prompted many questions. Visit  to learn more. This link includes videos, factsheets, and trifold.

It is also important to note that there is an upcoming webinar tomorrow, December 19 at 6 pm. 

Please click the link below to join the webinar:

HPAI Webinar Link (Click for Access)

For more information please contact the OSU Extension Office.

Williams Crop Update – November 29, 2023

All information is representative of the Williams County Area. Based on the Bryan Zip Code, about an inch of precipitation fell over the Thanksgiving weekend into early this week. Corn is around 85% harvested and yields are averaging between 180-200 bushels per acre; however, the quality has been poor, this is due to vomitoxin and low-test weights. Test weight is a measurement of bulk density, or the weight of corn per unit of volume, and is expressed as pounds per bushel. The “standard” test weight for corn is 56 pounds per bushel. Currently, the corn is coming into the grain elevators at 22-23% moisture.

Over the past month, there has been trouble with vomitoxin, resulting in some corn being rejected from grain elevators. Gibberella ear rot is caused by the fungus Gibberella zeae (also known as Fusarium graminearum), the same pathogen that causes stalk rot in corn and head scab in wheat. The fungus causes a pinkish-white mold to develop at the tip of the ear. During infection and colonization of the ear, the fungus produces several mycotoxins, including deoxynivalenol (DON), also called vomitoxin. As a result, high levels of Gibberella ear rot severity and moldy grain are usually accompanied by high levels of vomitoxin. It is the most prevalent of secondary fungal metabolites. The mold grows on wheat, corn, oats, barley, and other grains. This mold develops under wet conditions and enters the plants through silk or wounds during wet conditions during the silking stage (R1 growth stage), which promotes spore production, leading to more infected plants. For more information on vomitoxin please contact your local extension office.

2024 Gardening Roundtables

Join us for a monthly informal discussion series focused on gardening. This series will be a place for gardeners to network, share ideas, and problem-solve with one another about the benefits and issues of growing a garden. The goal of the series is to allow peer learning through networking, problem-solving, and idea-sharing regarding the benefits and challenges of gardening on the farm. Roundtables will be geared toward growers with gardening experience but are open to anyone from novice to master. Each date will be a standalone topic, so attendance of all dates is not required. Topics will be determined before each month’s roundtable to allow for the selection of timely issues. It is hosted on a Monday of each month from 6:00 PM to 8:00 PM. No cost to register. Open to gardeners in Williams County and beyond.

Dates: January 22, February 26, March 4, April 29, June 24

Time: 6:00 p.m. – 8:00 p.m.

Location: 1425 East High Street, Bryan, Ohio 43506 in the Conference Room

Cost: Free

To register, call the Williams County Extension Office at (419) 636-5608 or email Kayla Wyse at To register online, visit

Turfgrass Times

Did you know that the OSU Turfgrass Program publishes informative videos? Turf Team Times publishes videos that include information on grass establishment, turfgrass diseases, and much more. These videos are conducted by professionals within OSU.

Link to Youtube Channel:

Link to Latest Video:

Link to Website:

2023 Vegetable Trials

The 2023 Home Garden Trials are now active. The team is looking for people excited about growing vegetables in their home gardens and then letting us know what they think. Youth and adults are welcome to participate. Each trial contains 2 varieties that you will grow side by side to compare throughout the season. You can select multiple trials. For the trial, you will receive seeds for 2 varieties, row markers, a garden layout plan to prepare your rows or beds, and growing information specific to the crop species.
For more information, visit the website at
The guidelines, cost, and past results are available on this site as well as the new vegetables in the trials. The deadline to order is February 17.