Balancing Yield and Biodiversity 

• Growing population = increased demand for food.
• Farmers aim to increase yield per hectare (a hectare is a unit of area 100m x 100m).
• This often comes at the expense of biodiversity.

Monoculture

• Growing a single crop over a large area.
• Decreases species diversity:
  
  • Fewer plant species: fewer food sources.
  • Also reduced habitat diversity.
  • Leads to decline in herbivores, predators, and pollinators.

Increasing Field Size

• Hedgerows and field margins are the areas around the edge of the field. They provide important habitats for animal species as well as areas for wild flowers to grow. 
• Hedgerows and field margins are removed to make room for larger machinery like tractors, and to grow more crops.
• Removing hedges may also help to remove any natural pests that are potentially damaging the crop and reducing its yield.
  
• Removing hedgerows and field margins leads to:
  
  • Loss of habitat for birds, insects, and small mammals and reduced plant diversity.
  • Fewer nesting sites and food sources.
  • More soil erosion.

Cereal Crops and Ploughing

• Cereal crops (like wheat and oats) are sown (planted) in the autumn and harvested the following July.
• The land is ploughed between harvest and sowing, this loosens the soil making it easier to sow crops. It also aerates the soil to maintain oxygen concentrations.
• Ploughing exposes the insects living in the soil and are an important food source for birds and other animals.
• Fields only remain ploughed for 1 month reducing the time that the soil invertebrates are available as a food source.

Draining Wetlands

• Wetland areas are drained for farming- to graze animals and grow crops.
• Destroys aquatic and semi-aquatic habitats.
• Reduces biodiversity of species adapted to wet conditions (e.g., frogs, dragonflies, aquatic plants).
  

Pesticides and Fertilizers

• Pesticides:
  
  • Kill pests to reduce damage to crops, but also non-target species like pollinators (e.g., bees) and natural predators (e.g., ladybirds). These natural predators may have been useful as a form of biological pest control- killing pests that damage the crops and reducing the need for chemical pesticides.

• Fertilisers:

  • Harvesting removes biomass from the field, important mineral ions (such as nitrates and phosphates) are not recycled into the soil by decomposition.
  • The mineral ions can be replaced by using fertilisers. 
  • Mineral ions (especially nitrates) run off into water - Eutrophication:
    
    • Algal bloom - blocks sunlight - death of aquatic plants.
    • Decomposition of dead plants uses up oxygen - death of aquatic animals.
      

Organic Farming 

• Avoids synthetic chemicals.
• Uses organic fertilisers (e.g., compost, manure which contain organic molecules from decomposing waste material).
• Nutrients are released slowly as material decomposes:
  
  • Less runoff / leaching - reduced eutrophication risk.
• Encourages natural pest control (e.g., ladybirds, birds).
• Supports higher biodiversity but lower yields.

Biodiversity vs Profit

• Farming practices that reduce biodiversity often increase short-term profits.
• However:
  
  • Loss of pollinators and natural pest control can reduce long-term sustainability.
  • Biodiversity is essential for ecosystem stability and resilience.
• Sustainable practices (e.g., maintaining field margins) can balance biodiversity and yield.