Page 37 - Nutrient Management Planning Guide

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Chapter 2.1

Plant uptake

Soil solution Ca/Mg

Sorption Desorption

Plant release and residue

Weathering

Precipitation

Dissolution

Ca

Ca/Mg minerals

Clay

Mg

Ca

Erosion

Crop removal

Exchangeable pool

of Alberta. Volatile S losses can sometimes occur, but for most agricultural soils these losses are thought to be insignificant.

Calcium and Magnesium

Ca and Mg are essential for plant and animal growth. Most soils in Alberta have adequate supplies of Ca and Mg because the parent materials from which Alberta soils were developed are rich in these nutrients.

Calcium is a vital structural component of cell walls and influences membrane permeability. It also plays a role in N metabolism as it enhances plant uptake of NO

3

- . Other important functions of Ca include the movement

of carbohydrates and other nutrients within the plant and cell elongation and division.

Magnesium is a critical component of chlorophyll, and therefore essential for photosynthesis in the plant. It acts as a catalyst and co-factor for many important enzyme systems within plants and also appears to play a role in the production of oils and fats.

Ca and Mg Cycling in Soils

Figure 2.1.12 represents the basic processes involving Ca and Mg in soils. Plants absorb Ca and Mg as positively charged ions from the soil solution and they are replenished from the exchangeable pool. Weathering of Ca and Mg minterals with time results in crop available

Adapted from Korb and Jacobsen 2002

Figure 2.1.12 Calcium and Magnesium Cycling