Agriculture: UPSC Previous Year Questions (Geography)

Explanation

Statements 1,2 and 3 are correct: India is the largest producer, consumer and exporter of turmeric in the world. In the year 2022-23, an area of 3.24 lakh ha was under turmeric cultivation in India with a production of 11.61 lakh tonnes (over 75% of global turmeric production). More than 30 varieties of Turmeric are grown in India and it is grown in over 20 states in the country. The largest producing states of Turmeric are Maharashtra, Telangana, Karnataka and Tamil Nadu. India has more than 62% share of world trade in turmeric. During 2022-23, 1.534 lakh tonnes of turmeric and turmeric products valued at 207.45 million USD was exported by more than 380 exporters The leading export markets for Indian Turmeric are Bangladesh, UAE, USA and Malaysia.

Explanation

Drip irrigation is a highly efficient water-saving irrigation technique where water is directly supplied to the plant roots through a network of pipes, valves, and emitters.

Statement 1 is correct: Drip irrigation delivers water only to plant roots, preventing water wastage in surrounding soil areas. Since weeds grow in moist conditions, less water in non-target areas leads to reduced weed growth.

Statement 2 is incorrect: Drip irrigation does not reduce soil salinity. Instead it may lead to salt accumulation near the root zone over time due to limited leaching of salts from the soil. Flood irrigation is more effective in reducing soil salinity as it washes away excess salts.

Statement 3 is correct: Since drip irrigation supplies water at a slow and controlled rate there is minimal surface runoff, preventing soil erosion. Unlike traditional irrigation methods like flood or sprinkler irrigation, which cause water runoff and soil displacement, drip irrigation keeps soil structure intact.

Explanation

Contour bunding is a soil conservation technique primarily employed in hilly or sloping terrains to combat soil erosion and enhance water retention. This method involves constructing embankments, or "bunds," along the natural contour lines of the landscape. These bunds act as barriers that slow down water runoff, promote water infiltration and reduce the loss of topsoil. Options (a), (b) and (c) are incorrect:

Contour bunding is not suitable for desert margins or areas prone to strong wind action. Wind erosion is better controlled by techniques like windbreaks or shelterbelts, not contour bunding. In low-lying flat plains prone to flooding contour bunding is less effective. Flood management and soil conservation in these areas often involves levees, dykes, or drainage systems rather than contour bunds. Contour bunding is not specifically designed for scrublands prone to weed growth. Weed control requires different management practices, such as mechanical or chemical weeding methods.

Explanation

The nitrogen cycle is a crucial process that maintains the soil fertility necessary for plant growth.

Statement 1 is correct: Animals excrete urea through urine containing nitrogen. When this urea is deposited onto the soil, soil microorganisms break it down through a process called mineralization, converting it into ammonium (NH₄ +), which can readily absorbed by plants.

Statement 2 is incorrect: While the burning of coal releases nitrogen oxides (NOx) into the atmosphere, it does not directly add nitrogen to the soil. Instead, the pollutants can contribute to air pollution and acid rain, which may eventually affect soil quality but not in a beneficial way for nitrogen enrichment of soil.

Statement 3 is correct: The death and decomposition of vegetation naturally adds nitrogen to the soil. When plants die, their organic matter decomposes due to microbial activity. During de-composition, nitrogen is released in the form of ammonium and nitrates, which then enrich the soil. This recycling of nutrients is a natural and critical component of the nitrogen cycle.

Explanation

Salinization refers to the accumulation of soluble salts in the soil resulting from irrigation practices where water evaporates, leaving salts behind. This process adversely affects soil structure and fertility.

Option (a) is incorrect: Salinization reduces crop yields as excess salts in the soil create osmotic stress on plants which hin-ders their ability to absorb water and nutrients. This leads to stunted growth and lower productivity.

Option (b) is correct: Salinization causes soil particles to disperse and clog pores which makes the soil impermeable. This is known as sodic soil degradation. This dispersion leads to the clogging of soil pores, reducing permeability and making the soil less capable of absorbing water. Thus water infiltration decreases and the soil becomes impermeable.

Option (c) is incorrect: Salinization generally occurs due to poor drainage but it does not necessarily raise the water table. On the contrary, a high water table can exacerbate salinization by bringing saline groundwater closer to the root zone through capillary action.

Option (d) is incorrect: Salinization does not directly fill air spaces in the soil with water. It can lead to waterlogging due to reduced soil permeability which indirectly affects soil aeration. Waterlogging displaces air from soil pores which deprives plant roots of oxygen.

Explanation

Statement 1 is correct: Coffee plant requires a hot and humid climate of tropical areas whereas tea can be cultivated in both tropical and subtropical areas. Coffee thrives in a hot and humid tropical climate, requiring temperatures between 15°C and 28°C with well-distributed rainfall. Traditional coffee producing regions include the southern states of Karnataka (largest producer), Kerala, and Tamil Nadu. Non-traditional regions consist of Andhra Pradesh and Odisha, located in the Eastern Ghats of India. Tea can grow in both tropical and subtropical with temperaturerange 20-30°C requiring high humidity and well-distributed rainfall (100-200 cm) areas. For example, it is cultivated in Assam (tropical) and Darjeeling (subtropical) regions. Assam is the largest producer of tea in the country.

Statement 2 is incorrect: Coffee is propagated by seeds but tea is not propagated by stem cuttings only. Coffee is primarily propagated by seeds, but vegetative propagation methods like cuttings and grafting are also used. Tea is propagated both by seeds and vegetative methods, including stem cuttings and grafting, depending on the desired plant characteristics. In tea cultivation, cuttings are planted either upright or at a slight angle, ensuring that the leaves do not come into contact with the soil. After developing roots, they are transferred to the field approximately 12 months later. Seeds, on the other hand, are sown at a depth of 1.5 to 2.5 cm.

Explanation

Soil conservation techniques aim to prevent soil erosion, improve soil fertility, and maintain ecological balance.

Option 1 is correct: Rotating crops helps maintain soil fertility by alternating nutrient-exhausting crops with nitrogen-fixing ones, reducing soil degradation and pest infestations. Legumes are rotated with cereals to fix nitrogen in the soil in states like Punjab and Haryana.

Option 2 is correct: Sand fences are barriers made of wood or other materials to trap sand and stabilize soil in areas prone to wind erosion, such as coastal or desert regions. It is practised in arid regions like Rajasthan, where wind erosion is a problem.

Option 3 is correct: Terracing involves creating step-like structures on slopes, which slows down water runoff, prevents soil erosion, and conserves moisture, making it highly effective in hilly areas.

Option 4 is correct: Wind breaks are rows of trees or shrubs planted to reduce wind speed and protect soil from erosion, especially in open fields. It is commonly used in hilly regions like the Himalayas and Western Ghats.

Explanation

The National Development Council (NDC) in 2007 adopted a resolution to launch a Food Security Mission comprising rice, wheat and pulses to increase the annual production of rice by 10 million tonnes, wheat by 8 million tonnes and pulses by 2 million tonnes by the end of the Eleventh Plan (2011-12). Accordingly, a Centrally Sponsored Scheme, ‘National Food Security Mission’ (NFSM), was launched in October 2007. Initially, NFSM (2007-08) focused on rice, wheat, and pulses only. The objectives of NFSM are:

Increase production of specific crops through area expansion and productivity enhancement. Ensure sustainability by focusing on improved technologies and efficient resource use. Enhance farm profitability and rural livelihoods.

Explanation

Statement 1 is correct: Paddy fields are typically flooded, creating anaerobic (oxygen-deprived) conditions. Soil saturation in wetland rice fields restricts oxygen transport, creating anaerobic conditions due to submergence. This environment supports the activity of methanogenic bacteria, which produce methane (CH₄), a potent greenhouse gas. Rice cultivation is a significant source of methane emissions globally.

Statement 2 is correct: Nitrogen-based fertilizers, which enhance crop yield, stimulate soil microbes to convert nitrogen into nitrous oxide (N₂O), another potent greenhouse gas. Microbial processes like nitrification and denitrification in the soil release nitrous oxide, especially in poorly drained, waterlogged soils. Nitrous oxide has a global warming potential 265 times greater than CO₂ over 100 years.

Explanation

Energy crops, also called agroenergy or bioenergy crops, are cultivated specifically to generate biomass for renewable energy production. These crops can thrive on degraded, waste, saline, or waterlogged lands. In addition to providing a sustainable energy source, energy crops contribute to reducing greenhouse gas emissions. They also play a role in enhancing water quality and supporting wildlife habitats.

Option (a) is incorrect: Jatropha is primarily cultivated for biodiesel, as its seeds contain oil that can be converted to biodiesel. It is not used for ethanol production.

Option (b) is correct: Maize (corn) is a major crop used for ethanol production. It is rich in starch, which is fermented by yeast into ethanol.India is expanding maize-based ethanol production as part of the Ethanol Blending Program (EBP) to reduce petrol imports.

Option (c) is incorrect: Pongamia (Indian beech) is mainly used for biodiesel production due to the oil content in its seeds. It is not used for ethanol production.

Option (d) is incorrect: Sunflower, with very low sugar content, is primarily grown for edible oil production. It is not a significant crop for ethanol production.