Toward Quality Biosolids Management: A Trainer's Manual

Training Module 5:
Land Application: Nutrient Management

5.1 Introduction
5.2 Calculation of Agronomic Rates
5.3 Soil Testing

Training Module 5.1. Land Application
Nutrient Management--Introduction

Module overview

Biosolids application rates usually are based on supplying adequate nitrogen for crop needs without excessive losses to the environment. In this module, participants will be introduced to the forms, transformations, and movement of nitrogen in the environment. The module also highlights the role of biosolids in supplying other nutrients for crop production. Biosolids effects on soil chemical, physical, and biological properties (soil quality) also are described here.

Training suggestions

The nitrogen cycle can be used as a springboard for discussion of nitrogen forms, transformations, and losses. The calculation of fertilizer replacement value of biosolids demonstrates the difference between "total" and "available" nutrient content of biosolids.

This session introduces the need for soil testing, which is covered in greater detail in Training Module 5.3, "Nutrient Management-Soil Testing."

Need-to-knows--Nitrogen in the environment

What forms of nitrogen are found in biosolids, soils, and the environment?

• List the forms of nitrogen commonly found in biosolids and in soils.
• List the forms of nitrogen taken up by plant roots.

What nitrogen transformations are important for biosolids management?

• Explain the process that transforms organic N to ammonium-N.
• Explain the process that transforms ammonium-N to nitrate-N.
• Identify and describe the processes that transform biosolids nitrogen to gaseous nitrogen.

What are the objectives of biosolids nitrogen management?

• Explain why nitrate in ground water is a public health concern.
• Describe how heavy winter precipitation or excess irrigation affects nitrate in the soil.
• Describe the causes of excess nitrate-N in ground water.

Need-to-knows--Other nutrients

What plant-available nutrients are supplied by biosolids?

• List three plant-essential macronutrients, and four plant-essential micronutrients supplied by biosolids.
• List two nutrients that accumulate in the soil when biosolids are applied at agronomic rates based on nitrogen.
• List a macronutrient that declines in the soil when biosolids are applied at agronomic rates and the crop is removed from the field via harvesting.

What is the fertilizer replacement value of biosolids?

• Describe the difference between total nutrient content and the plant-available nutrient content of biosolids.
• Identify the data needed to estimate the fertilizer replacement value of a biosolids application.

How do biosolids affect soil quality?

• Identify a method for monitoring changes in soil nutrient status at biosolids application sites.
• List three ways that a biosolids application can improve soil quality.
• Describe the expected change in soil pH after application of biosolids stabilized with alkaline materials. Will soil pH increase or decrease?
• Describe the impact of the decomposition of biosolids organic N and S compounds in the soil. Over time, will decomposition of these compounds increase or decrease pH?

Topics and activities for extended training

There are a number of soil/nutrient-related topics that might be of interest for an advanced workshop, such as: biosolids effects on soil health/quality, managing biosolids phosphorus to protect water quality, and the economic value of biosolids nutrients.

Other topics/methods for advanced workshops can be found in Training Module 5.2, "Calculation of Agronomic Rates" and Training Module 5.3, "Soil Testing" that follow this module in Land Application: Nutrient Management.

Oregon Short School Example

Activity description

Lecture (50 minutes)

Speaker description

Soil scientist (university or private)

Handout materials

Fertilizing with biosolids. Pacific Northwest Extension Publ. 508. Oregon State University Extension Service, Corvallis, OR.

Presentation materials

Overheads illustrating the nitrogen cycle, and selected tables from "Fertilizing with biosolids"

Training resources

Publications

Fertilizing with biosolids. Pacific Northwest Extension Publ. 508. Oregon State University Extension Service, Corvallis, OR.

Chapters 1-3 in: Managing nitrogen from biosolids. (In Press) Northwest Biosolids Mgmt. Assoc., Seattle, WA.

World Wide Web

Oregon State University Extension and Experiment Station Communications
http://eesc.orst.edu/
Fertilizing with biosolids (Adobe Acrobat PDF file)

Training Module 5.2. Land Application
Nutrient Management--Calculation of Agronomic Rates

Module overview

Accurately matching the biosolids application rate to site-specific nitrogen needs is important for producing high-yielding, high-quality crops, and it is critical for compliance with biosolids regulations. In this module, participants will learn how to calculate agronomic biosolids application rates. They will learn how information on biosolids processing/stabilization methods, biosolids nitrogen analyses, crop nitrogen requirements, biosolids application methods, and application site data are used to calculate an agronomic rate.

Training suggestions

This session should include both the "how-tos" and "whys" involved in an agronomic rate calculation. It is important to remind participants that the agronomic rate calculation is an estimate based on available data. The calculated agronomic rate should be regarded as only a rough estimate if there is little data on:

• Crop N requirements for the site and management practices planned
• N availability for a particular biosolids stabilization/processing method

The presentation should include an example demonstrating the calculation of agronomic rates. Participants need to know how to do the calculation with minimal assistance. If there is time available, ask participants to calculate an agronomic rate for given set of biosolids and site information.

When it comes to conversion factors to get from a biosolids analysis to an agronomic rate in field application units (e.g., gallons per acre), there are many "paths through the woods." Providing agronomic rate problems with answers will help participants practice their calculation skills. Getting the correct result with good documentation should be stressed, rather than a rigid calculation scheme.

A discussion of the nitrogen cycle and nitrogen forms should precede discussion of agronomic rate. These subjects are addressed in Training Module 5.1, "Nutrient Management-Introduction." Participants should be aware that trace element concentrations should be considered prior to a calculation of an agronomic rate based on nitrogen. Trace element calculations are addressed in Training Module 2.1, "Biosolids Quality-EPA Part 503 Requirements."

Need-to-knows--Calculation principles

What is an agronomic rate?

• Define agronomic rate.
• Explain when agronomic rates are required for biosolids applications.
• List agencies in your region that can assist with agronomic rate calculations.

What data are needed to estimate an agronomic rate?

• Describe sources of information on crop nitrogen requirements, and their relative reliability.
• List the laboratory analyses needed in calculating a biosolids application rate based on nitrogen.

What other sources of nitrogen besides biosolids should be included in the calculation?

• List potential sources of plant-available nitrogen for a crop, in addition to fertilizer or biosolids.
• Explain what happens to nitrogen returned to the soil as crop residues.
• Explain how previous organic fertilizer applications (manure, biosolids, etc.) affect agronomic application rates.

Need-to-knows--Making calculations

How is the amount of plant-available N per unit of biosolids calculated?

• Describe the relationship between percent total solids and the moisture content of biosolids.
• From a laboratory analyses data sheet, determine whether nitrogen concentrations are reported on a dry-weight or wet-weight ("as-is") basis.
• From a biosolids analysis, calculate organic N content in units of lb/dry ton.
• Describe the effects of tillage after biosolids application on the amount of biosolids ammonium-N retained after application.
• Discuss how the biosolids stabilization/processing methods used at the treatment plant affect projected mineralization rates for biosolids organic-N.

How is the agronomic rate calculated?

• Given data for a particular site, calculate N supplied from sources other than biosolids.
• Given biosolids analytical data and site management information, calculate the quantity of plant-available nitrogen (PAN) per dry ton of biosolids.
• Given data on crop N requirement, N supplied by other sources, and plant-available N per dry ton of biosolids, calculate an agronomic rate.
• Describe how agronomic rates change over time when biosolids are applied annually to the same site.

Topics and activities for extended training

Practice calculations

You can construct more complicated calculation scenarios for agronomic rate calculations with site variables such as: nitrogen provided by irrigation water or starter fertilizer, credits for previous biosolids applications at the site, fall biosolids applications, application to very sandy soil, etc. You could also vary the kind of biosolids applied (liquid, solid, lime-stabilized, etc.).

Oregon Short School Example

Activity description

One lecture session (50 minutes)

Speaker description

Agronomist: private consultant or university

Handout materials

Worksheet for calculating biosolids application rates in agriculture. 1999. Pacific Northwest Extension Publication 511. Washington State University Cooperative Extension.

University fertilizer guide(s) for selected crops.

Presentation materials

Excel spreadsheet with the same format as the handout. Both spreadsheet and handout demonstrate step-by-step agronomic rate calculations

Training resources

Publications

Worksheet for calculating biosolids application rates in agriculture. 1999. Pacific Northwest Extension Publ. 511. Washington State University Cooperative Extension, Pullman, WA.

Process design for agricultural and application sites; Process design for forest land application sites. Chapters 7 and 8 in: Process design manual, land application of sewage sludge and domestic septage. EPA-625-R-95-001.

World Wide Web

Oregon State University Extension and Experiment Station Communications Web site
http://eesc.orst.edu/
Worksheet for calculating biosolids application rates in agriculture. 1999. HTML version with on-line calculator and downloadable Excel spreadsheet (for IBM compatibles).

Training Module 5.3. Land Application
Nutrient Management-Soil Testing

Module overview

Soil testing is a tool to assess the potential for crop response to applied nutrients, and to monitor changes in soil nutrient availability over time. Although soil testing is often not required by federal or state regulations, it can provide valuable information for site selection and for fine-tuning of agronomic biosolids application rates. In this module, participants will become familiar with appropriate protocols for collecting and handling soil samples, appropriate procedures for soil sample analyses, and factors to consider in choosing an analytical laboratory.

Training suggestions

Soil testing is not required by EPA regulations, and requirements vary from state to state. There currently is also much debate about appropriate soil testing methods, and the interpretation of soil test data. Therefore, to adapt the training program to your audience, consult your local permitting authority for local soil testing requirements.

A general discussion of nutrient management principles and the calculation of agronomic application rates should precede this session. In this training manual, these topics are addressed in Training Module 5.1 and Module 5.2.

This topic can be presented in a "hands-on" format. Consider bringing in materials for your presentation such as sample collection and preservation tools, blocks of field soil (12 x 12 x 12-inch), soil test results and interpretations, or field sampling maps.

Need-to-knows--Test selection and sample collection

Why monitor nutrient availability via soil testing?

• List a local source for accurate information on soil testing requirements at biosolids application sites.
• Describe the goals of a voluntary soil testing program.
• Tell why pre-application soil testing is valuable, even if it is not required by the regulatory agency.
• List your state land-grant university and a soil scientist that can be contacted for information on soil testing.

How are soil samples collected?

• List the number of soil cores that should make up each composite soil sample.
• Identify acceptable tools for collecting soil samples for nutrient analyses.
• List the appropriate soil sampling depth for routine nutrient analyses like soil pH, and plant-available phosphorus and potassium.
• Describe the protocol for collecting soil samples from a large field with distinctly different soil types that occupy areas large enough to be fertilized separately.
• Describe the tools available for collecting deep soil samples (samples 2 to 6 feet in depth), and their advantages and disadvantages.

How are soil samples handled and preserved?

• Describe the expected changes in soil nitrate-N if a soil sample is stored under moist, warm conditions.
• Describe approved soil sample preservation techniques for samples to be analyzed for nitrate-N.

Need-to-knows--Soil testing methods

What soil analyses should the laboratory perform?

• List the soil analyses you should request prior to the first biosolids application at a site.
• Describe the difference between the total concentration of a nutrient in soil and the "plant-available" nutrient concentration.
• List a state or regional reference document that gives the details of appropriate sample extraction and analytical methods for soil testing.

What factors should be considered in choosing a laboratory?

• Discuss the differences between agricultural testing laboratories and environmental testing laboratories.
• Describe what "laboratory proficiency testing" or "laboratory sample exchange programs" are.

Topics and activities for extended training

A number of group activities can be developed to give participants a chance to use their skills with actual sites and/or data. If possible, take a short field trip to collect a representative soil sample. Alternatively, ask participants to design a sampling strategy for a site identified on a soil survey map. Specify fence lines, crop rotations, and important grower management practices (tillage, harvest, irrigation, etc.). For group involvement in data interpretation, ask participants to make nutrient management recommendations, given soil test results from a potential application site, and a university nutrient management guide.

Oregon Short School Example

Activity description

One lecture session (50 minutes). Includes demonstration of sampling tools and composite sampling technique.

Speaker description

Private consultant or university

Handout materials

How to take a soil sample...and why. EC 628. Oregon State University Extension Service. Corvallis, OR.

Site Monitoring. Chapter 9 in: Biosolids management guidelines for Washington State. Washington State Dept. of Ecology Publication 93-80. Olympia, WA. (Revised edition available in 1999.)

Presentation materials

Overheads prepared by private consultant

Training resources

Publications

How to take a soil sample...and why. EC 628. Oregon State University Extension Service. Corvallis, OR.

Site Monitoring. Chapter 9 in: Biosolids management guidelines for Washington State. Washington State Dept. of Ecology Publication 93-80. Olympia, WA. (Revised edition available in 1999.)

Agronomic application rates. Chapter 1 in: Policies for biosolids land application, Oregon Dept. of Environmental Quality, Water Quality Division.

A list of analytical laboratories serving Oregon. FG 74. Oregon State University Extension and Experiment Station Communications. Corvallis, OR.

Soil test interpretation guide. Pub. EC 1478. OSU Extension Service. Corvallis, OR.

Mahler, R. and T. Tindall. 1994. Soil sampling. Bulletin 704. University of Idaho Cooperative Extension. Moscow, ID. 8 pp.

Westermann, R. L. (ed). 1990. Soil testing and plant analysis. Soil Science Society of America. SSSA Book Series No. 3. Soil Science Society of America. Madison, WI.

World Wide Web

Oregon State University Extension and Experiment Station Communications
http://eesc.orst.edu/
Adobe Acrobat PDF files:
A list of analytical laboratories serving Oregon. FG 74.
Soil test interpretation guide. EC 1478.

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