Page 63 - Nutrient Management Planning Guide

58

Field Assessment

Important Terms

Table 3.1.1 Key Terms and Definitions

Term Definition

Bulk Density, Soil

The mass of dry soil per unit bulk volume. Bulk volume is determined before the soil is dried to constant mass. Deep Ripping

A tillage process aimed at amending/shattering sub-surface compacted soil layers typically at depths greater than 30 cm.

Discharge Site The area of the field over which groundwater and its associated salts emerge at the soil surface. Montmorillonite Clay

Dominant ‘type’ of clay in Alberta soils. Characterized by swelling and shrinkage when wetted and dried.

Recharge Site The area of the field over which water is absorbed and added to the zone of saturation. Runoff

The portion of the total precipitation or surface water that does not enter the soil, rather it flows overland. Water Holding Capacity

The ability of the soil to hold water. The water-holding capacity of sand is considered low, while that of clay is considered high.

The first step in nutrient management planning is to gather information about site characteristics and how they impact nutrient management. Sloping land, problem soils and the presence of water bodies all influence the fate of applied nutrients and must be considered in NMP’s.

Five characteristics to identify during a site assessment are:

Soil physical properties • Slope • Water bodies • Problematic soil conditions • Past and current site management •

Soil Physical Properties

Soil physical properties include texture and structure. Understanding how these properties influence runoff and leaching potential, erosion susceptibility, nutrient retention, crop establishment and growth and the risk of compaction and crusting will enable more site-specific nutrient management decisions.

Soil Texture

Soil consists of four basic components: organic matter, minerals, air and water (Figure 3.1.1). The mineral component of soil is made up of sand, silt and clay particles (Figure 3.1.2). Soil texture is the percentage (by weight) of sand, silt and clay in the mineral fraction of a soil.

Figure 3.1.1 General Composition of Mineral Soils