Page 141 - Soil Degradation, Conservation and Remediation

130 5 Chemical Soil Degradation

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Table 5.3 Nutrient removal by harvested crops (kg ha )
Crops N P K S
Grain crops
Spring wheat 60–75 10–12 15–17 5–6
Winter wheat 60–65 11–13 14–17 7–9
Barley 80–95 15–18 20–25 7–9
Oats 60–76 12–14 15–18 5–6
Rye 60–75 11–14 15–20 5–6
Corn 95–145 18–22 22–28 7–8
Oilseed crops
Canola 85–100 16–20 15–18 12–14
Flax 60–70 7–8 12–15 6–7
Sunflower 65–75 7–8 10–12 5–6
Pulses
Pea 135–145 14–18 30–35 6–7
Lentil 62–74 8–10 27–35 4–5
Other crops
Sugar beets 85–110 16–22 120–150 12–14
Potatoes 125–155 16–20 185–225 11–13
Forage crops
Alfalfa 290–350 30–37 260–320 27–33
Clover 220–260 25–30 175–218 10–12
Barley silage 145–220 22–30 110–130 14–21
Corn silage 170–200 27–35 175–220 12–14
Converted from data compiled by the Canadian Fertilizer Institute from agronomic information
obtained in Canada, 1998;
http://www.cfi.ca/_documents/uploads/elibrary/d161_NU_W_01%5B1%5D.pdf. Accessed 3.1.2012

Table 5.4 Aluminum sensitivity/tolerance of some plants
Categories Plants
Highly Durham wheat, barley, lentils, chickpeas, alfalfa, strawberry, berseem, buffel
sensitive grass, tall wheatgrass
Sensitive Canola, red clover, balansa clover, white clover
Tolerant Whistler, diamond bird wheat, ryegrass, tall fescue, subterranean clover, chicory
Highly Narrow leaf lupins, oats, triticale, cereal rye, cocksfoot, paspalum, yellow and
tolerant slender serradella, Consol love grass

acidity characterized by the predominance of exchangeable H and Al ions on
+
3+
exchange sites of soil colloids. The larger the percentage of exchange sites occupied
by aluminum and hydrogen, the lower is the pH and the higher is the acidity of the soil.

5.3.1 Causes of Soil Acidification

Acidification can occur naturally in soils developed from acidic parent materials
due to release of acid-forming chemical compounds, in high rainfall areas due to