Winter application of manure and other agricultural source materials

Introduction

Manure and other agricultural source materials (ASMs) are valuable commodities. They are rich in nutrients and organic matter that are important for productive, healthy soil. However, those same nutrients can be detrimental to water quality if they make their way into lakes and rivers.

Winter is not an appropriate time for manure application. Water can’t effectively infiltrate frozen soil. Water from melting snow, often combined with precipitation, moves off the field and carries nutrients with it. Research in Ontario indicates that 67%–98% of phosphorus lost from agricultural land leaves during the non-growing season.

The increased risk of nutrient loss or displacement means that fewer nutrients from winter-applied manure are available for crop production. Winter application is widely recognized as unsuitable and can result in negative public perceptions of agriculture.

This fact sheet describes manure management strategies that can prevent situations where manure must be applied during the winter and ways to minimize risks when winter application is the only option.

Manure management is a year-round job

The traditional manure application windows of spring and fall are a busy time for farms. Wet soils and unpredictable weather combined with the pressures of planting and harvesting crops can result in delays to manure application and necessitate spreading in less than ideal conditions. Changes to your operation can reduce the pressure during these busy times.

Diversify crop rotation: Growing cereal crops that are harvested early can provide enough time to apply manure into ideal soil conditions. Forage crops are harvested several times during the season and allow application of manure between cuts (Figure 1).

Invest in storage: Constructing additional liquid manure storage capacity or roofing over an existing storage to keep rainfall out can help store manure through the winter.

Invest in removing water: Diverting clean water (from roofed areas and areas of the farm that are not in contact with manure) away from manure storages helps avoid diluting manure. Consider roofing over liquid storages to minimize collection of rain.

Expand timing windows: Applying manure after planting and/or investing in equipment that allows manure to be applied to growing crops (Figure 2) expands your options.

Consider a custom applicator or broker: Hiring custom applicators to apply your manure quickly and efficiently can allow you to focus on other important tasks. Brokers can ensure that excess manure is put to good use.

Explore economic opportunities through agreements with others: Selling or trading manure for straw or other agricultural products that you need can benefit both parties. Include the value of nutrients in land rental agreements.

Acquire access to more land: Owning or controlling additional land through an application, rental or other agreement may provide additional manure use opportunities, including transporting manure to fields farther from the storage where agronomic needs may allow higher application rates.

Plan for the unexpected: A contingency plan is a written plan of what to do if a nutrient management strategy or plan cannot be followed and addresses what will be done if:

• weather or equipment conditions delay planned storage or application
• more nutrients are available than the nutrient management strategy (NMS) or nutrient management plan (NMP) have addressed
• more nutrients are generated than the storage design capacity
• there is a spill

All farms that are required to have an NMS or NMP are also required to have a contingency plan. Even on farms that are not required to have one, contingency plans are valuable tools for reducing the need for winter spreading and any adverse environmental effects.

Options for excess manure during the winter

Alternatives to winter spreading include:

• temporary field nutrient storage sites for solid manure (Figure 3)
• transferring materials to a broker or other neighbouring storage facilities with extra capacity
• keeping manure in “pen packs” or mounded bedding packs in outdoor feeding yards for longer periods of time, reducing the need to spread during winter conditions

When spreading during winter is the only option

Current regulations

There are several laws that protect the quality of surface and drinking water. These include the Environmental Protection Act, 1990, the Ontario Water Resources Act, 1990, and federally, the Fisheries Act, 1985. If manure enters surface or ground water at any time of year, there is the potential for charges under one or more of these laws, depending on the nature of the impacts that result.

O. Reg. 267/03 provides standards for the application of manure between December 1 and March 31 (known as the restricted period) and any other time when the soil is either frozen or snow‑covered. Frozen soil is defined as any 5 cm layer of frozen moisture in the top 15 cm of soil. Snow-covered soil is defined as soil with a layer of snow on the surface with an average minimum depth of 5 cm.

Farms with an NMP must follow the standards outlined in O. Reg. 267/03. For all other farms, these standards are recommended as a minimum standard. The standards are summarized in Table 1.

Table 1. Winter application restrictions for agricultural source material (ASM) (O. Reg. 267/03 Part VI)

* A minimum setback from the top of bank of surface water must include a minimum 3-m vegetated buffer.

Prohibitions for vulnerable land

No prescribed materials can be applied from December 1 to March 31 or when the ground is frozen or snow covered on land:

• subject to flooding once or more every 5 years
• where water collects during a rainstorm or thaw and flows directly into surface water (Figure 4)