Model for estimating feedlot manure quantity and nutrient content - Saskatchewan references

Manure production

There have been several attempts to quantify feedlot manure production in Saskatchewan (table 1). These studies may be regarded as “extension projects” rather than peer-reviewed academic data. In all cases, mass was estimated by weighing trucks as manure was removed from the feedlot. In all cases, data represents fall manure removal once each year. Both moisture content and manure production in Saskatchewan are greater than that predicted by American references (table 5).

Table 1.  Saskatchewan manure production, as-removed, wet-basis, average.

Nutrient concentration

Far more data is available on nutrient concentration than manure production. Manure removal studies in Saskatchewan provide several values for nutrient concentration, and data is also available from Alberta (table 2).

Table 2. Nutrient concentration of feedlot manure in Saskatchewan and Alberta, average.

Two feedlots were involved with the forage project, one near Lethbridge, Alta., and the other near Airdrie, Alta. Samples from the Alberta forage project were collected over a period of five years. The Battersea project was conducted in the fall of 2010 and 2011.

Table 2 presents the average value for each project. In the full dataset: moisture content ranges from about 30 to 70 per cent; nitrogen concentration ranges from about 4 to 15 kg t-1 (8 to 30 lbs ton-1); and phosphorus concentration generally ranges between about 1 to 5 kg t-1 (2 to 10 lbs ton-1) with a maximum concentration of 9 kg t-1 (18 lbs ton-1).

Nutrient production

Nutrient production may be calculated from manure production and nutrient concentration (equation 1). Only Feedlot B, Feedlot C, and “Manure Properties” (Table 2) have both manure production and nutrient concentration available. In any individual pen, nitrogen production ranged from 51 to 155 g head-1 d-1 and phosphorus production ranged from 10 to 37 g head-1 d-1 (table 3). This data represents typical manure production in Saskatchewan with manure being removed once each year. The diet is unknown.

Nutrient production is calculated by equation 1:

NP = MP – NC

Where:

• NP is nutrient production (g head-1 d-1);
• MP is manure production (kg head-1 d-1);and
• NC is nutrient concentration (kg t-1).

Table 3.  Nutrient production by pen as observed in Saskatchewan.