agriculture

What are the main components of soil composition?

Mineral particles (sand, silt, clay), organic content (living and dead matter), air, and water.

How do particle sizes differ among sand, silt, and clay in soil?

Sand has the largest particles, silt has medium particles, and clay has the smallest particles.

Which major mineral ions are required for plant growth and what are their ionic forms?

Nitrogen as nitrate ions (NO3-), phosphorus as phosphate ions (PO4 3-), and potassium as potassium ions (K+).

How do sandy soils and clay soils compare in drainage and aeration?

Sandy soils have rapid drainage and high air content; clay soils have poor drainage and low air content.

How do sandy soils and clay soils compare in nutrient retention and ease of cultivation?

Sandy soils are easy to cultivate but leach nutrients quickly; clay soils retain nutrients well but are heavy and difficult to cultivate.

Define arable, pastoral, and mixed farming.

Arable: Growing crops. Pastoral: Rearing livestock. Mixed: Combining crop growing and livestock rearing on the same farm.

What is the difference between subsistence and commercial agriculture?

Subsistence: Producing food primarily to feed the farmer's family. Commercial: Producing crops or livestock for sale and economic profit.

What techniques are used to increase agricultural yields?

Crop rotation, fertilisers, irrigation, chemical and biological pest control, mechanisation, selective breeding, GMOs, and controlled environments (greenhouses and hydroponics).

What is the difference between chemical insecticides, herbicides, and biological control?

Insecticides kill insect pests, herbicides kill competing weeds, and biological control uses natural predators or parasites to control pest populations.

What are the negative environmental impacts of overusing fertilisers in agriculture?

Excess nutrients leach into nearby freshwater bodies, causing nutrient enrichment, algal blooms, and eutrophication.

How does the mismanagement of irrigation lead to salinisation and waterlogging?

Over-watering causes groundwater levels to rise, drowning plant roots (waterlogging) and leaving toxic salt deposits on the soil surface upon evaporation (salinisation).

What are the main causes of soil erosion?

Removal of natural vegetation, overcultivation, overgrazing, and wind or water action on bare soil.

What are the key impacts of severe soil erosion?

Loss of fertile topsoil, habitat destruction, desertification, silting of riverbeds, displacement of communities, malnutrition, and famine.

How do terracing and contour ploughing reduce soil erosion on slopes?

Terracing cuts flat steps into slopes to slow water runoff; contour ploughing creates ridges along natural land contours to trap water.

What are bunds and windbreaks, and how do they protect soil?

Bunds are low earth/stone walls that retain water and soil on fields; windbreaks are rows of trees/shrubs planted to reduce wind velocity and wind erosion.

How do maintaining vegetation cover and adding organic matter protect soil?

Vegetation cover anchors soil with roots and shields it from rain impact; organic matter improves soil structure and water retention.

What are key strategies for sustainable agriculture?

Using organic fertilisers (manure/crop residues), managed rotational grazing, pest/drought-resistant crops, trickle-drip irrigation, and rainwater harvesting.