Sampling and analysis protocol

1.0 Introduction

Proper sampling and analytical techniques are critical to accurately determine the nutrient content and other properties of materials applied to the land for the purpose of improving the growing of agricultural crops. Proper techniques have always been important, but they are now a legal requirement under the Nutrient Management Act, 2002. The techniques described in this document are intended to meet the requirements of the regulations under the Act. They can also provide guidance for other sampling and analysis requirements with similar goals.

In this document a nutrient management plan required by the regulation for a Farm Unit will be denoted as an NMP. A nutrient management plan required for the application of non agricultural source materials (NASM) will be denoted as a NASM Plan.

1.1 Background to Act and Regulations

The Nutrient Management Act, 2002 provides for the "management of materials containing nutrients in ways that will enhance protection of the natural environment, and provide a sustainable future for agricultural operations and rural development."

The regulations that have been developed under the authority of the Nutrient Management Act, 2002 provide particulars on how this management is to occur. These regulations apply to land applied nutrients from all sources, including commercial fertilizer, manure and other agricultural source materials, and non-agricultural source materials (NASM) such as sewage biosolids and paper biosolids. A key component of the regulations is the requirement for a nutrient management plan. There are two types of nutrient management plans: NMP and NASM Plans. To complete a meaningful nutrient management plan, it may be necessary to know the concentrations of nutrients and other parameters in both the soil and the materials that may be applied to land.

The regulations lay out what materials need to be sampled and analyzed, how frequently they need to be sampled, and which parameters need to be measured. These are minimum requirements. It may be desirable to sample more frequently, or to analyze for additional parameters, to optimize the management of land applied materials.

1.2 Health and safety

There may be hazards associated with the physical act of sampling or with handling materials that could contain toxic material or pathogens. It is the responsibility of the sampler to have taken all necessary precautions and to act according to all applicable health and safety regulations pertaining to the sampling site and specific situation.

1.3 Sampling frequencies

1.3.1 Soils

Soils may be sampled for two different purposes: to assess the initial nutrient concentration in the soil which will guide the application of nutrient containing materials for agronomic and environmental purposes, and to determine the acceptability of the site for receiving the particular material with respect to, for example, regulated metal content and pH.

1.3.1.1 Soils receiving nutrients

Persons applying nutrients to fields where a NMP or a NASM Plan is required, must collect a representative soil sample from each field (or section of field) as part of developing the nutrient management plan, and then at least once during each five-year period for subsequent NMP. The results from analyzing these samples are entered into the nutrient management plan.

For NASM Plan's the soil samples used to develop the nutrient management plan must have been taken within the previous 5 years prior to the date that the NASM is to be land applied.

As a best management practice, in fields where nutrient levels may fluctuate widely within the five year interval, it may be appropriate to sample the soil more frequently than is required by the O. Reg. 267/03. This situation can occur on sandy soils where crops that are removing large amounts of nutrients are grown. Silage corn, forages and processing tomatoes all remove large quantities of potassium from the soil, therefore, soil test levels can decline quickly to the point where yields are reduced.

Soils must be analyzed for soil pH and, if the soil has a pH below 6.0, for buffer pH. They must also be analyzed for available phosphorus (using the sodium bicarbonate extractant) and available potassium (using the ammonium acetate extractant). In addition, the sample may be analyzed for available magnesium, nitrate nitrogen, or the manganese and zinc availability indices.

It is necessary to know the available phosphorus concentration of a soil prior to applying nutrients so that application rates and setback distances can be properly determined. The soil must have been sampled and tested for sodium bicarbonate extractable phosphorus content and pH within the five years immediately prior to applying the nutrients to land.

1.3.1.2 Soils receiving Non-Agricultural Source Materials

Persons applying non-agricultural source materials must, in addition to the nutrient analyses, have representative soil samples analyzed for the total content of each of the eleven regulated metals (Table 1-2). These soil samples must have been collected within five years prior to the application of non-agricultural source materials, as part of the preparation of the NASM Plan

In the regulation, the maximum allowable metal concentrations in soils receiving NASM are based on the "mean metal content of uncontaminated Ontario soils and approximate an upper level of background concentrations". For some soils, one or more metal concentrations may already exceed the maximum allowed in the regulation. It is therefore necessary that soil testing be conducted prior to the application of NASM to determine the suitability of the soil. Samples collected as per Section 2.1 of this document shall be analyzed for the eleven metals listed in the regulations.

Summaries of acceptable analytical methods are presented in Section 4.

1.3.2 Non-Agricultural Source Materials

Non-agricultural source materials must be of an acceptable quality to be land applied, with respect to regulated metals, and, if required, fats, oil and grease (FOG), boron, sodium and pathogens. Category 2 and Category 3 NASM as defined in O. Reg. 267/03, must be sampled and analyzed at least as frequently as specified in the regulation. Category 1 NASM, as defined in O. Reg. 267/03, does not require sampling and analysis unless the application rate exceeds 20 tonne per hectare per year in which case the sampling and analysis would need to be done for phosphorous and nitrogen to determine the appropriate nutrient application rate.

The requirements to sample and analyse for pathogens apply only to sewage biosolids and NASM containing human body waste (e.g., fecal material). In the case of Category 3 NASM that is not sewage biosolids or contain human body waste, pathogen testing may be done to determine if the NASM is CP1. Category B compost is considered CP1 material. Additional testing for culturable Enteroviruses and Helminth Ova is not required. This material, by definition, meets the treatment and testing requirements set out in the Ontario Compost Quality Standards (PIBS 8412), updated in 2012.

1.4 Averaging of results

Where a material is required to be analyzed for regulated metals or pathogens, the concentration of metals or level of pathogens in the material is considered to be the average, or mean, of the concentrations in the four most recent samples. This allows for any variation that may occur in sampling or analysis of the materials, while maintaining protection of the environment. Metal concentrations are calculated as a simple arithmetic mean^{footnote 3[3]}, where the concentrations of each regulated metal in the previous four samples are added together and the resulting total is divided by four. Pathogen levels are calculated as the geometric mean where the concentrations of each pathogenic indicator in each of the previous four samples are multiplied together and the fourth root of the resulting product is calculated.

Where the mean concentration of any parameter exceeds the allowable concentration, and the generator still intends to land apply the material, the generator has the option of re-sampling the material. This is done by continuing to take representative samples with an interval between samplings of at least two days. The analytical results are then used to calculate the mean value. Sampling can continue on this basis until the mean value of all sample results within the previous 4 months is within allowable limits for all parameters. This method is for use where a large value is skewing the mean, and that value may be due to a spurious analytical result.

1.5 Sampling locations

Samples that are being collected for total solids, nutrients, regulated metals and if required, FOG, boron and sodium analysis must be collected at the location where the material is generated and before it is transported to the land application area or agricultural operation. This could be the generating site or storage. This is to provide the farmer with the best possible representative estimates of concentrations of the parameters measured.

Samples of material that are to be analyzed for pathogens may be collected at a location immediately after the treatment process in the liquid form. Liquid samples are most homogenous at this point. For solid NASM the samples may be taken immediately after the treatment process or later in the process.