5.3.4: Soil Conservation

95% of our food depends on soil

Need to prevent threats to food security + production

Need to reduce wind + water erosion + salinization

Need to manage nutrients + limit grazing

Reduce Water Erosion

to reduce loss of fertile land

to reduce flooding, clogging of waterways, and pollution

Use vegetation to intercept rainfall

Use water catchment methods

Improve soil structure + water retention of soil to increase infiltration

Water Capture Methods

Terracing: steps down a hill

Furrow Diking: furrows (trenches) with ridges

Contour Ploughing: plowing down a slope along its natural contour

Strip Cropping: alternating crops between strips, follow contour of land

Buffer Strips: permanent vegetation at edges of fiels

Methods to Improve Soil Structure + Infiltration

Manure: adds nutrients back to the soil (green manure, compost)

Mulch: improves infiltration + reduces evaporation

Conservation Tillage: leave last seasons crops to decompose into soil + protect from erosion

Avoid Compaction: move cattle around, use less machinery

Tilling Methods

Conventional Tilling

• loosens up soil structure

• soil is aerated + moist

• no weeds

• leftover crops are plowed into soil

• land is clear for debris

• CONS: labor intensive, leaves soil exposed to erosion

Conservation Tilling

• crop residue left to mulch

• prevents erosion

• reduced evaporation

• increased infiltration

• no till = no plowing

• reduced labor

• CONS: increased herbicide use, difficult to break from traditional practices

Wind Erosion Reduction

Windbreaks

• reduces velocity + captures soil

• tall trees to break wind

Shelterbelts

• creates habitat for birds + other tree dwellers

• blocks of trees + shrubs at right angles to deflect wind/reduce velocity

Salinization Reduction

Avoid overwatering (especially when hot)

Water plants at night to prevent evaporation

Improve drainage

Manage nutrient levels

Replace nutrients lost to plants + amend soil pH

• grow green manure (crops that add nutrients)

• carefully use synthetic fibers

• add OM (manure, compost, conservation tillage)

• bring pH back to neutral (5.5-7.5)

  • too acidic soil → plants can’t grow bc excess aluminium ions

  • raise pH with limestone

Crop rotation on a 3-4 yr cycle

Control grazing

Restrict number of animals in an area

Allow vegetation to recover

Use grassed waterways + windbreaks to prevent erosion