Soil Degradation & Conservation 3.4.3-3.4.4

3.4.3- Outline the processes that cause soil degradation *A decrease in the productivity of pastures, forests, and cropland used in agriculture which is due to poor land management*

Causes of Degradation What can cause/increase erosion? Overgrazing and intensive farming (soil losses fertility) Use of land that is not fertile (ex:rainforest) Salinization caused by irrigating soils Acidification Compaction

Erosion Possibly the most important means of nutrient loss. Erosion is the washing away of soil by water and wind. Erosion usually washes away the top layer of soil first. This is where nutrients such as Nitrogen, Phosphorus and Potassium are located. Leads to leaching of soil.

Gully Erosion

Stream Bank Erosion Where stream banks widen due to problems such as rain, flood, removal of vegetation protection, etc. 7

Dryland Salinity Salination of Soil is caused by irrigation Water has dissolved salts and dissolves more as it percolates. When irrigation is turned off too soon, saline water rises up towards soil surface. Why? Considered salinized soil when salinity affects plants’ growth or at 2% salinity. Occurs in warm, dry areas where there is not enough rain to flush/leach the soil of salt. Loss of soil productivity 8

Acidification The acid level of soil progressively increases, resulting in interference of plant growth Some chemicals can be the cause of this Aluminum, Phosphoric Acid, Ammonia, and Urea (Where are these found?) It is associated with nitrate leaching, product removal, and inorganic fertilizer use. 9

Soil Compaction Surface crusting of soil Caused by excessive plowing, excessive cultivation and Ranching Results are poor water circulation and oxygen content (needed for seed germination) 10

Many of these can cause desertification – an enlargement of deserts through human activities. Each year, about 11 million hectares of arable land is “lost” from productivity through soil degradation processes.

3.4.4 - Evaluate soil conservation measures 1) Soil Conditioners: Liming What does this do? Adding compost to soils Artificial fertilizers can restore nutrients

2) Wind reduction techniques Windbreaks – rows of trees, shrubs, fences or concrete walls that are planted along the boundaries of windward fields. These slow wind speeds, which help conserve soil moisture and prevent erosion. Shelterbelts – planted perpendicular to prevailing winds (are a type of windbreak)

Wind Breaks (Shelter Belts)

Wind Reduction Techniques Advantages? Provides habitats for animals, pest-eating insects, and pollinators Disadvantages? Long-term planning Can house crop eating animals

3) Water Reduction Techniques Contour plowing – planting crops in long strips that run along a hillside rather than running up and down. Prevents water from making gullies Slows the flow of rain water to increase soil infiltration. Terracing – turning a hillside into a series of ascending terraces Saves soil from being eroded and conserves water.

Water Reduction Techniques Advantages? Very effective Makes slopes usable for farming Reduces erosion by 60-80% Disadvantages? Takes up space Inefficient on large farms with large farm equipment Very expensive!