Page 214 - Nutrient Management Planning Guide

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Chapter 5.1

tip

Late summer applications of fertilizer are

recommended for forage seed production to maximize yield, as forages are setting their yield potential in the fall.

tip

Research in Alberta suggests that, based on moisture conditions, fertilizing winter cereals at seeding to meet requirements is an efficient way of fertilizing fall-sown crops.

efficiency. Broadcasting elemental sulphur fertilizer in the fall allows more time for weathering and conversion to crop available forms.

Soil sampling should always occur prior to nutrient application, however, soil analysis results may not be available to plan fall fertilizer applications. A common practice is to split fertilizer application between fall and spring. A base rate is applied in the fall, followed in the spring by an application based on moisture conditions and soil test recommendations from fall sampling. Fall fertilizer application also means an extra field operation. This can add to production costs, reduce snow-trapping capability, and increase a field’s erosion potential.

Since snowmelt is responsible for the bulk of runoff in Alberta, unincorporated fall broadcast nutrients are at risk of being lost. Wet conditions in early spring that occur on fine textured and poorly drained soils in central and northern Alberta can cause significant losses of fall applied nitrogen through denitrification. Fall broadcast applications of N are most subject to loss. Table 5.1.3 shows the relative efficiency of fall and spring broadcast and banded applications under various conditions.

Table 5.1.3 Relative Effectiveness of Different Methods and Timing of Nitrogen Application (yield improvement compared to spring broadcast and incorporation = 100)

Soil Climate Categories Application Method

Dry 1 Medium 2 Wet 3 Irrigated 4

Spring Broadcast and Incorporation

100 100 100 100

Spring Banded

120 110 105 110 Fall Broadcast and Incorporation

90 75 65 95

Fall Banded 120 110 85 110

1 Well drained soils that are seldom saturated during spring thaw. Although spring and fall banded nitrogen were equally effective in research trials, fall banding may be more practical under farm conditions. The extra tillage associated with spring banding may dry the seedbed and reduce yields.

2 Well to moderately drained soils that are occasionally saturated during spring thaw for short periods.

3 Poorly to moderately drained soils that are saturated for extended periods during spring thaw. In research trials conducted in the higher rainfall areas, spring broadcast nitrogen was well incorporated and seeding and packing completed within a short period of time. Under farm conditions, shallow incorporation or loss of seedbed moisture resulting from deeper incorporation may cause spring broadcasting to be somewhat less effective than shown here.

4 Well drained soils in southern Alberta that are seldom saturated during spring thaw.

From Kryzanowski, L., 2004