WALT: How modern farming methods can effect the ecosystem

 Intensive farming practices include growing high-yield crops, using fertilisers and pesticides and keeping animals indoors. Food production is increased but there are unwelcome side effects.  Organic farming bans chemical inputs and has a less harmful effect on the environment but often produces less, more expensive food.  Hydroponics is the production of food using nutrient-rich solution rather than soil.

Intensive Farming Food production in this field has been increased by growing high-yield crops, removing other plants and pests and adding fertiliser to the soil. Other intensive farming practices include keeping animals indoors, often in restricted spaces. Many of these practices have unwelcome side effects.

ActionTreatmentExplanationSide effect Remove competing plants from the crop growing area Herbicide sprayAllows more energy to be transferred to the crop Reduces biodiversity. May have harmful effect on health. Remove animals that feed on the crop Pesticide sprayPrevents energy being transferred from the crop to consumers Reduces biodiversity. May poison helpful organisms. Keep animals indoors ‘Battery’ farmingReduces energy transferred to environment so more energy available for growth Increased risk of disease. Lower quality product. Ethical concerns.

 The effects of insecticides  Insecticides like DDT don't break down quickly. It's been responsible for a large reduction in bird numbers since intensive farming became widespread. DDT accumulates in food chains - as consumers eat large numbers of prey containing the insecticide. High levels of DDT have been found in birds of prey.  Alternatives to pesticides  Biological control is an alternative to using pesticides. By releasing a natural predator into the crop growing area, the number of pests can be reduced. This can have unforeseen consequences as the numbers of different organisms in the food web are changed. There have been examples of the predator becoming a more serious pest than the original problem.

Organic Farming An alternative way to produce food is to ban the use of fertilisers, herbicides and pesticides, and replace these with more ‘natural’ methods. Some believe this produces higher quality food, and that it doesn't raise as many ethical concerns as there's less environmental impact. Food produced organically tends to be more expensive as the yield is lower than intensively produced food.

TechniqueReplacesAdvantageDisadvantage ManureFertiliserRecycles waste, improves soil structure Difficult to apply and cannot control mineral content Crop rotationSingle cropReduces disease and damage to soil composition Less productivity. Less efficient to grow different crops. WeedingHerbicidesLess environmental damage, or health risk Labour intensive Nitrogen-fixing plants Nitrogen fertilisers Cheaper, longer lasting Reduces area available for growing crops if part of a crop rotation

Food production Some food products have been grown in artificial environments to increase productivity. Examples include growing tomatoes in glasshouses and salmon in fish farms. The benefits of this method are that the growing conditions can be monitored and controlled to improve productivity. Hydroponics An extreme form of growing crops in glasshouses is called hydroponics. Soil is replaced by a mineral solution pumped around the plant roots. Removing the soil means there's no risk of soil organisms causing disease but the plants have to be supported. Monitoring and adjusting the concentrations of minerals in the solution enable the grower to control growth. It allows crops to be grown in regions where there's no soil. Due to the costs involved, hydroponics is used only for high-value crops.