Research Highlights

All poultry litter is not created equal

By Kentucky Soybean Board

As the poultry industry continues to grow across Kentucky, so does the opportunity to use poultry litter. Litter can be used as a nutrient source in crop and pasture production as well as provide additional income for poultry producers from the sale of litter.

With this opportunity comes the question “what is the value of poultry litter?” The answer to this question depends on numerous factors such as the nutrient content of the litter, market price for commercial fertilizer, when the litter is applied, nutrient availabil­ity, cost of transport/delivery and individual soil test data, just to name a few.

The first factor in this equation is nutrient content. Understand­ing the nutrient content of a ton of poultry litter that you are pur­chasing/selling is critical. How are you supposed to determine the value of litter if you don’t know its content? That’s why sampling poultry litter for nutrient content is so important and is the first step in determining the value.

Dr. Edwin Ritchey, Extension Specialist in the Department of Plant and Soil Science at the University of Kentucky, has reviewed over 700 hundred samples of litter across the state, most during projects funded by the Kentucky Soybean Board, and one thing is clear – there is significant variability in nutrient content.

What does this mean? The value of poultry litter will vary and there are risks involved with not testing for nutrient content. The table below summarizes the samples reviewed by Dr. Ritchey, and the range in actual nutrient content is significant. For example, actual nitrogen ranges from 7 lbs per ton (dry) to 186 lbs per ton (dry).

However, not all of the nutrients identified during testing will be available to the crop like traditional commercial fertilizer. Nu­trient loss will occur based on the timing of application, method of application and soil conditions. Nitrogen has the potential for significant loss after application due to ammonia volatilization, denitrification and/or leaching.

Estimates for nutrient availability to the crop can be found in the University of Kentucky’s AGR-146 Using Animal Manures as Nutri­ent Sources. Using the nutrient availability in AGR-146 and today’s fertilizer prices, the value per ton (before delivery and application) are calculated and presented in the table. With this wide range in value also comes risk. Of the samples collected by Dr. Ritchey, 35 percent had a value less than $40/ton (before delivery and ap­plication). However, the value of litter can vary from the above values. The assumed availability of nutrients will change based on when the litter is applied (spring vs. fall application), how it is ap­plied (incorporated vs. non-incorporated) and individual soil test data. This coupled with transportation/delivery costs, application costs, and the variability in fertilizer prices all contribute to the val­ue of poultry litter varying on a site specific basis and year to year.

The discovery and confirmation of the wide fluctuation in nutri­ent content contained in poultry litter led to the Kentucky Soybean Board funding a project with Dr. Jordan Shockley, Assistant Ex­tension Professor and Farm Management Specialist at the Univer­sity of Kentucky, to develop a user friendly but robust customiz­able spreadsheet tool for farmers to determine the nutrient value of litter.

“It’s important to determine the financial risk of not measuring litter for nutrient content,” Shockley explained. “Farmers need to know if the litter they’re buying is worth what they’re paying, and part of that will depend of their management practices. Are they applying litter in the spring or in the fall? That makes a difference in the nutrient quality of the nitrogen, and how much of the nutri­ents will be available to the plants.”

One aspect of the project that Shockley is most excited about is the alignment of the best management practices (BMPs) that this assessment tool will display. “Using the nutrient content of poultry litter combined with the time of application to determine a monetary value will show one of the few times in agriculture that the economic BMP, the agronomic BMP and the environmental BMP all align and none of the three has to suffer in order to meet the other two.”

To underpin the tool, a meta-analysis will be conducted on previous research to determine the nutrient availability from poultry litter for various management strategies. Underpinning the model with the results from the meta-analysis and poultry litter samples collected across the state is a novel approach which will be powerful and the results creditable. The ability of the model to adjust to fertilizer market conditions and individual soil nutrient requirements makes the model flexible for each individual user’s unique situation.

Outputs from the tool will include an estimated $/ton value for litter given the inputs and current management strategy of the user. In addition, the user can adjust litter management practices to determine the gain/loss in $/ton value for litter. The economic risk associated with nutrient content of poultry litter (if unknown) will also be reported. Finally, the maximum distance to econom-ically haul poultry litter will be reported. Statewide extension programming on the tool and management strategies to extract maximum value and reduce risk associated with poultry litter will be conducted.

Farmer-leader Davie Stephens, who raises poultry along with row crops in Wingo, said “Using poultry litter effectively is a three-step process for me. First, we sample the soil, then we sam-ple the litter. Those two tests tell us what the soil needs and what the litter will provide, and that lets us know what other nutrients we need to apply commercially.”

Stephens noted that not all nutrients applied are available to the crop the first year, so the effectiveness of the use of poultry litter is best calculated over the long haul.

“This research is important,” Stephens noted, “because there are so many variables in poultry litter. It depends on how many flocks are raised in the barn before the barns are cleaned out, and even the difference in the size of the broilers when they leave the barns.”

“Different poultry companies also feed different formulations of rations,” Stephens added, “and that can result in variations in litter composition.”

Prices for litter are currently based on supply and demand, and litter is treated as a commodity of its own.

“When poultry barns came to the Purchase area in 1990 and 1991, litter was a liability for some farmers,” Stephens said. “They had these barns, and all the waste was a byproduct, not a source of income. Now poultry farmers can count the litter their barns produce as an extra revenue stream, or, if they apply it to their own crops, it’s a cost reduction. Chicken litter is a viable com-modity for poultry farmers, and of course we are always looking for additional revenue streams.”

Published: Nov 25, 2019

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.