Feeding a growing population requires more food from each hectare and more land for farming. Intensive farming has increased yields enormously, but it can deplete the resources on which future farming depends.Soil: ploughing, removing hedgerows and leaving soil bare expose it to wind and rain, causing soil erosion. Growing the same crop year after year removes the same mineral ions each time and reduces organic matter, so soil fertility and structure decline. Soil forms extremely slowly, taking hundreds of years to make a few centimetres, so it is effectively non-renewable on a human timescale.Water: irrigation uses about 70% of the fresh water taken by humans. Pumping groundwater faster than it is replaced lowers water tables, and in dry regions evaporation of irrigation water leaves salts that make soil infertile (salinisation).Land: forests, wetlands and grasslands are cleared for crops and grazing, destroying habitats and carbon sinks. Overgrazing can strip vegetation and lead to desertification.Other inputs: artificial fertilisers are made using fossil fuels, and phosphate comes from rock reserves that are finite.More sustainable practices include:
• crop rotation, including legumes whose root nodules contain nitrogen-fixing bacteria;
• less ploughing and planting cover crops to protect the soil;
• adding organic matter such as manure;
• efficient irrigation, such as drip irrigation;
• keeping hedgerows and field margins.These can lower yields or raise costs in the short term, so there is a conflict between maximising food production now and protecting resources for the future.
• crop rotation, including legumes whose root nodules contain nitrogen-fixing bacteria;
• less ploughing and planting cover crops to protect the soil;
• adding organic matter such as manure;
• efficient irrigation, such as drip irrigation;
• keeping hedgerows and field margins.These can lower yields or raise costs in the short term, so there is a conflict between maximising food production now and protecting resources for the future.