Page 132 - Nutrient Management Planning Guide

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Estimating Manure Inventory

Measure Bulk Density of a Pile

Manure nutrients are applied on a weight basis. As a result, the volume of manure in a pile must be converted to weight by using the bulk density of the material. The procedure for determining bulk density of solid manure, poultry litter or compost is simple:

Measure and record the weight and volume of an empty container. Conversion factors for volume and weight 1.

measurements are provided in Table 4.1.3 and 4.1.4. Sample the pile, being sure that the samples reflect the composition of the pile (i.e., proportions of bedding and 2.

manure). Take samples perpendicular to the face of the pile, to get a better representation of the layering profile within the pile. Try to go as deep as possible, at least 50 cm (Figure 4.1.7). Fill the container without excessively packing or compacting the material, trying to achieve a similar 3.

consistency as in the pile. Measure and record the weight of the filled container. Calculate bulk density by dividing the weight by the volume. Repeat this procedure 10 to 20 times (depending on the variability and size of the pile) from various sites on 4.

the pile. Large, variable piles will require a greater number of samples. Determine the average bulk density for the pile from the samples collected.

Table 4.1.3 Factors for Converting Between Units of Volume

Start Units

Multiply start units by factors in the appropriate column to get: ft 3 yd 3 m 3 L US gal Imp gal

Cubic feet (ft 3 ) 0.0370 0.0283 28.32 7.481 6.229 Cubic yards (yd 3 ) 27.0 0.7646 764.6 202.0 168.2 Cubic metres (m 3 ) 35.31 1.308 1000 264.2 220.0 Litres (L) 0.0353 0.0013 0.001 0.2642 0.2200 US gallons (US gal) 0.1337 0.0050 0.0038 3.785 0.8327 Imperial gallons (Imp gal) 0.1605 0.0059 0.0045 4.546 1.201

Table 4.1.4 Converting Between Units of Weight or Mass

Start Units:

Multiply start units by factors in the appropriate column to get:

lb tn kg t

Pounds (lb) 0.00050 0.45359 0.00045 Short tons (tn) 2000.0 907.18 0.90718 Kilograms (kg) 2.2046 0.00110 0.00100 Tonnes (t) 2,204.6 1.1023 1000.0

tip

Due to exposure to the elements, the surface density of a pile is often different than the interior density. If the outer weathered layer is relatively thin (i.e., less than 15 cm), scrape off the surface of the pile until moist material is reached. If the pile has a thick weathered layer, use a core-sampling device such as a manure sampling probe (Chapter 4.2).

tip

Using “book” values for the bulk density of a manure pile, rather than determining the actual density, can lead to large errors in estimated total weight.