Soil
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How does aeration by ploughing and drainage affect soil fertility ?
• Makes soils more aerobic, this increases rates of nitrogen fixation, nitrification and decomposition of dead organic matter
How do soil nutrient levels affect soil fertility ?
• Farmers increase nutrients by adding inorganic fertilisers, organic matter or by supporting natural processes such as bacterial nitrogen fixation • Farming can also depleate soil nutrient levels due to erosion, biomass removal, inhibeting natural processes that increase nutrient levels
How does irrigation affect soil nutrient levels ?
• Increases the fertility of the soil where water is a limiting factir for growth • Having sufficient water allows plants to keep their stomata open and continue gaseous exchange when the soil would otherwise be dry
How does soil compaction affect soil nutrient levels ?
• Excess use of heavy machinery or high livestock densities can cause soil to become compacted. this reduces aeration and makes waterlogging more likely
How does pH control affect soil nutrient levels ?
• Controlling soil pH helps ensure nutrients are soulable but not too easily leached
What are some activities that reduce the rate if soil erosion ?
• Vegetation acts as a natural windbreak, reducing wind velocity • Vegetation cover reduces impact of raindrops on the soil surface so particles are less likely to be dislogged • Soil organic matter such as humus helps bind soil particles together • Plant roots hold soil together
What human activities increase the rate of soil erosion ?
• Vegetation removal • Ploughing vunerable soils • Overgrazing • Reduce soil biota • Soil compaction • Cultivating steep slopes
What are some effects od accelerated soil erosion ?
• Reduced productivity • Sedimentation in rivers and reservoirs • Increased atmospheric particulates • Desertification
What are some methods of reducing soil ersion ?
Long term crops: - Does not require frequent management that would disturb soil Zero-tillage cultivation: - does not remove top soil Contour ploughing: - Ploughing across 90 degree to the slope reduces erosion as the water is stopped by the ploughed furrows and loses its kinetic energy Tied ridging: - Uses land that is flat, devided into criss-cross of interecting ridges that retain water when it rains Terracing: - slope is cultivated on a series of narrow fields Rows of stones: - slows runoff Windbreaks: - Reduces velocity of wind Multicropping: Increased soil organic matter: - Creates humus as it decomposes binding soil together Livestock management - Can increase trampling where soil erosion is likely to occur