Agriculture- 2 | Geography for UPSC CSE PDF Download

SOIL FERTILITY AND FERTILISERS

Plant Nutrients and Soil Fertility

At least 16 elements, namely carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), boron (B), and chlorine (Cl), are essential for the normal growth of green plants and are hence called essential elements.

• The absence of any of these essential elements hinders the proper growth of plants and can be corrected by the addition of that element, whereas an excess of any of these may be toxic.
• Plants obtain carbon from carbon dioxide in the air, oxygen and hydrogen from water, whereas the remaining elements are sourced from the soil.
• The plant nutrients, based on their relative amounts required by the plants, are termed as macronutrients if required in large amounts, and micronutrients, if required in traces.
• The micronutrients essential for plants are iron, manganese, copper, zinc, boron, molybdenum, and chlorine. The remaining essential elements are macronutrients.
• Continuous cultivation of land leads to the depletion of nutrients in the soil, thus affecting soil fertility and, in turn, crop yields. It is thus obvious that this drain of nutrient supplies will continue to impoverish the soils unless these supplies are replenished by natural or artificial means.
• The principal methods of supplementing and improving the productivity of soils are:
  (i) Addition of organic matter and
  (ii) Application of fertilisers. The use of manures and fertilisers is complementary and not a substitute for each other.

Manures

These are relatively bulky materials, such as animal or green manures, which are added mainly to improve the physical conditions of the soil, to replenish and maintain its humus status, to sustain optimum conditions for the activities of soil microorganisms, and to make good a small part of the plant nutrients removed by crops or otherwise lost through leaching and soil erosion.

They, thus, supply practically all the elements of fertility that crops require, though not in adequate proportions. Moreover, they are bulky with low nutrient content compared to the high and rapid nutrient demand of high-yielding varieties (HYV) and hybrid crops. As of 2025, there has been a notable rise in the use of vermicomposting—using earthworms to convert organic waste into nutrient-rich manure—and bio-slurry from biogas plants, which is increasingly adopted as a sustainable manure option.

Farmyard Manure

It is the most valuable and commonly used organic manure in India. It consists of a mixture of cattle dung, the bedding used in the stable, and any remnants of straw and plant stalks fed to cattle. The value of farmyard manure in soil improvement is due to its content of principal nutritive elements and its ability to:
(i) Improve the soil tilth and aeration,
(ii) Increase the water-holding capacity of the soil, and
(iii) Stimulate the activity of microorganisms that make the plant-food elements in the soil readily available to crops. The supply of organic matter, which is later converted into humus, is a key property of farmyard manure.

Composted Manure

Another method of augmenting the supplies of organic matter is the preparation of compost from farmhouse and cattle shed wastes of all types. Composting is the process of decomposing vegetable and animal refuse (rural or urban) to a quickly utilizable condition for improving and maintaining soil fertility.

Good organic manure, similar in appearance and fertilizing value to cattle manure, can be produced by decomposing waste materials of various kinds, such as cereal straws, crop stubble, cotton stalks, groundnut husk, farm weeds and grasses, leaves, leaf-mould, house-refuse, wood ashes, litter, urine-soaked earth from cattle sheds, and other similar substances. In 2025, composting techniques have been enhanced with microbial inoculants to accelerate decomposition and improve nutrient availability.

Green Manures

Green-manuring, wherever feasible, is the principal supplementary means of adding organic matter to the soil. It involves growing a quick-growing crop and ploughing it under to incorporate it into the soil. The green-manure crop supplies organic matter as well as additional nitrogen, particularly if it is a legume crop, which has the ability to acquire nitrogen from the air with the help of its root-nodule bacteria.

The green-manure crops also exercise a protective action against erosion and leaching. The crops most commonly used for green-manuring in India are sunn hemp, dhaincha, cluster bean, senji, cowpea, horse gram, pillipesara, berseem or Egyptian clover, and lentil.

Sewage and Sludge

The liquid waste, like sullage and sewage, contains large quantities of plant nutrients and is used after preliminary treatment for growing sugarcane, vegetables, and fodder crops near many large towns by operating sewage farms. In many places, the undiluted sullage has been found to be too strong for healthy plant growth, and if it contains readily oxidizable organic matter, its use actually reduces nitrates present in the soil.

The disadvantages are still greater if sewage is used on land without preliminary treatment. The soil quickly becomes 'sewage sick' owing to mechanical clogging by colloidal matter in the sewage and the development of anaerobic organisms, which not only reduce the nitrates already present in the soil but also produce alkalinity. Bacterial contamination makes the eating of raw vegetables grown on untreated sewage or sullage a real danger to health. However, under no circumstances should any produce grown on a sewage farm be eaten uncooked.

Concentrated Organic Manures

Some of the concentrated materials such as oil-cakes, bone-meal, urine, and blood are of organic origin and continue to be utilized effectively in Indian agriculture as of 2025.

Fertilisers

Fertilisers are inorganic materials of a concentrated nature; they are applied mainly to increase the supply of one or more of the essential nutrients, e.g., nitrogen, phosphorus, and potash. Fertilisers contain these elements in the form of soluble or readily available chemical compounds. In common parlance, fertilisers are sometimes called 'chemical', 'artificial', or 'inorganic' manures.

Compound Fertilisers

These fertilisers are multiple-nutrient materials, supplying two or three plant nutrients simultaneously. When both nitrogen and phosphorus are deficient in a soil, a compound fertiliser, e.g., ammophos, can be used. Its use does away with the necessity of purchasing two different fertilisers and mixing them in the correct proportion before use.

Mixed Fertilisers

Compound fertilisers contain plant food elements in fixed proportions and are, therefore, not always best adapted to different kinds of soils. Accordingly, the needs of different soils can generally be met most economically by the use of fertiliser mixtures containing two or more materials in suitable proportions. Mixtures usually meet nutrient deficiencies in a more balanced manner and require less labour to apply than straight fertilisers used separately. Mixtures containing all the three principal nutrients (N, P, and K) are termed completed fertilisers.

Fertiliser Use in India (Updated as of 2025)

The use of chemical fertilisers plays an important role in boosting agricultural output. Indian soil, though rich and varied, is deficient in nitrogen and phosphorus, which, together with organic manure, greatly influence crop productivity. Our New Agricultural Strategy is based on the increased use of chemical fertilisers since it is a critical way to augment our food grain production, which is essential for meeting the demand of our rising population.

There has been a considerable increase in the domestic production of fertilisers over the years, from 39,000 tonnes in 1951-52 to approximately 15 million tonnes in 2025, though this is still insufficient to keep pace with the growth in consumption.

Since the adoption of the New Agricultural Strategy in the Sixties, the consumption of chemical fertilisers has been growing rapidly. The Government has been promoting the consumption of fertilisers through heavy subsidies and initiatives like the Pradhan Mantri Kisan Samriddhi Kendra (PMKSK). In spite of this, India's position remains behind other progressive countries.

The fertiliser consumption pattern in India, updated for 2025, reveals:

• Consumption of fertilisers in India per hectare reached 150 kg in 2025, up from 75 kg in 2015-2016. The corresponding figures for some developed countries in 2025 are: South Korea (450 kg), Netherlands (350 kg), Belgium (300 kg), Japan (400 kg).
• Adequate supply of water, which is essential for the application of chemical fertilisers, is lacking over large parts of the country, hence preventing their more rapid consumption in India.
• The rainfed areas, which constitute 60% of the cultivated areas in 2025, consume only 25% of total fertilisers. The Government is taking steps, such as the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY), to increase the consumption of fertilisers in these areas.
• Rabi crops, which account for one-third of agricultural production, account for two-thirds of fertiliser consumption. This is largely due to the more assured availability of irrigation and subsoil moisture for Rabi crops.
• There has been a steep rise in fertiliser subsidies, which is a huge drain on resources, and most importantly, the bulk of these subsidies goes to the more affluent farmers.
• The sharp increase in international fertiliser prices has compelled the government to divert attention to greater use of organic manures, both farmyard manure and urban and rural compost, alongside innovations like nano urea, which reduces urea use by up to 50%.

The major constraints in fertiliser use in India as of 2025 are:

• High prices of fertilisers and shortage of capital.
• Fear of heavy losses in case of failure of crops due to failure of rains.
• Returns non-remunerative in case of inferior cereals.
• Non-availability of fertilisers in remote areas, though mitigated by government distribution networks.
• Regional imbalances due to uneven spread of HYV seeds, variation in availability of irrigation facilities, and infrastructural disparities.

Bio-fertilisers (Updated as of 2025)

Biofertilisers are natural fertilisers. They are preparations of efficient strains of microorganisms capable of fixing atmospheric nitrogen into an available form, solubilising insoluble phosphate, producing growth-promoting substances like vitamins and hormones, and also play a considerable role in the decomposition of organic materials and enrichment of compost. Though biofertilisers cannot replace chemical fertilisers, they can supplement them considerably.

Biofertilisers include the following:

• Symbiotic nitrogen fixers, e.g., Rhizobium spp.
• Asymbiotic free nitrogen fixers, e.g., Azotobacter, Azospirillum, etc., with new strains developed by 2025 enhancing their efficacy in cereal crops.
• Algae biofertilisers, e.g., blue-green algae or BGA in association with Azolla.
• Phosphate-solubilising bacteria, e.g., Bacillus megatherium, Aspergillus awamori, Penicillium digitatum.
• Mycorrhizae (a symbiotic association of fungi with roots of plants), increasingly used in 2025 for phosphorus uptake.
• Organic fertilisers (organic waste resources which include animal dung, urine, bone-meal, slaughterhouse wastes, crop residues, urban garbage, sewage/effluent, etc.).

Rhizobium is useful for leguminous plants, Blue Green Algae for paddy, and Azotobacter and Azospirillum for cereal crops. Biofertilisers enhance soil structure and texture, water-holding capacity, supply of nutrients, and proliferate beneficial microorganisms. They are cheaper, pollution-free, and renewable.

Mechanisation of Agriculture (Updated as of 2025)

Meaning

Mechanisation of agriculture refers to the extensive application of power-driven machinery to agricultural operations, starting from the opening of land to sowing, harvesting, threshing, winnowing, and storage stages. The machinery used includes bulldozers, graders, tractors for ploughing, seed drills for sowing, cultivators, rollers, fertiliser distributors, combined harvesters for reaping and harvesting, and other light farm machinery.

Need for Mechanisation

Mechanisation of agriculture is often associated with an increase in agricultural production and reduction in costs. It is also useful in reclaiming barren lands. Thus, the prosperity and richness of the peasantry in Western countries have been due, largely, to the extensive use of farm machinery as agriculture there is commercialised and only a small proportion of the population is engaged in it.

Whereas in India, the case is completely different because here agriculture is a way of life and a means of livelihood. As of 2025, of the total workforce in India, approximately 50% are agricultural workers, down from 67%, of which 31% are women. Therefore, in India, some regard mechanisation of agriculture as desirable and necessary, while others are against it.

For Mechanisation of Indian Agriculture

• Machinery increases the speed of agricultural operations and thus saves time.
• Machinery helps in performing heavy works like ploughing, land reclamation, carrying of earth, jungle clearance, drainage, cane crushing, oil extraction, thus reducing drudgery.
• Reduces cost of production.
• Increases productivity of land and labour, thus increasing total agricultural production to meet the demand.
• Increases income level of farmers.

Against Mechanisation of Indian Agriculture

• Mechanisation will aggravate the unemployment problem by creating surplus agricultural labour; but it can be more than offset by an indirect increase in employment opportunities caused by the introduction of machines.
• Availability of adequate land is essential to adopt mechanisation, but in India, the majority of land holdings are small and scattered.
• Widespread illiteracy, ignorance, and poverty of farmers prevent them from adopting mechanisation on an extensive scale.
• High fuel prices and shortage of mineral oil prevent Indians from using extensive oil-based farm machinery.
• India does not have an adequate machine manufacturing capacity, and there is a scarcity of mechanical skill. This argument is less valid in 2025 as domestic industrial capacity is gradually building up; the argument of non-availability of skill also does not seem to be true with training programs in place.

Selective Mechanisation

Farm mechanisation in India is inevitable for the reclamation of land, conservation of forest land, ploughing of barren lands, etc., besides increasing agricultural production and removing socio-economic disparity among farmers. However, the small size of holdings and large surplus of labour in India call for limited or selective mechanisation (such as the use of machines suitable for small farms and large cooperative farms) so that the labour displacement effects are minimised.

The policy of selective mechanisation has been a great success in absolute terms, especially in states like Punjab and Haryana, where mechanisation levels reach 80% and 70%, respectively, by 2025. However, it does not compare well with advanced countries and with the size of the Indian agricultural sector, which stands at an overall mechanisation level of 45%. Moreover, whatever mechanisation has taken place in Indian agriculture is largely confined to richer farmers. The small farmers, who constitute the overwhelming majority of the Indian farming population, remain by and large untouched by the process of mechanisation, though initiatives like Custom Hiring Centres (CHCs) and the Sub-Mission on Agricultural Mechanisation (SMAM) are bridging this gap.

Agricultural Practices and Techniques (Updated as of 2025)

In order to increase agricultural productivity and production to meet the ever-increasing demand for agricultural products, it is necessary, though difficult, to bring changes in traditional practices and techniques.

Traditional techniques have evolved over generations; they are continuously adjusted within a rather restricted frame to changing circumstances. Farmers are reluctant to change to new modern techniques due to the following main reasons:

• The pursuit of traditional techniques involves less uncertainty, and
• Since traditional techniques are passed on from one generation to the other, there is practically no material cost and relatively less uncertainty of output.

But a successful Green Revolution, as experienced in India, cannot be achieved with the help of traditional agricultural techniques and practices alone. A change in them is almost essential. A number of agricultural techniques and practices have been evolved over the years, and by 2025, modern methods have been integrated. The more important amongst these are:

• Fallowing and crop rotation,
• Double cropping,
• Multiple cropping,
• Mixed cropping.

Fallowing and Crop Rotation

• Both these practices are used for maintaining soil fertility. Continuous cropping drains away soil nutrients; fallowing is evolved to avoid this.
• Fallowing practices, therefore, vary depending on the supply of soil nutrients by individual crops.
• In extreme cases of light soil, with a scarce supply of soil nutrients, land is left fallow for as many as seven years after each harvest.
• On the other hand, in fertile soils, land is allowed to rest every third, fourth, or even fifth year.

• Crop rotation involves growing different crops in a definite sequence on a piece of land to preserve its fertility. The most common crop rotations include growing legumes in one season, which help fix nitrogen in the soil, followed by growing crops such as cereals, cotton, etc., in the next season, which remove nitrogen from the soil.
• Heavily manured crops like sugarcane or tobacco are rotated with cereals to take advantage of the manurial value in the soil leftover from the previous crop.
• The practice of crop rotation is evolved to avoid fallowing of land. However, rotation of crops is not a complete substitute for fallowing in all regions.
• Fallowing is included in the scheme of crop rotation once in three or five years in some cases. Where crops included in rotation supply the nutrients removed from the soil, the need for fallowing may be postponed for a long time, or where soil nutrients can be supplied from outside in good quantities, fallowing may be completely eliminated.

Mixed Cropping

• In mixed cropping, crops are grown mixed in such a way that soil nutrients removed by some are replaced by others, at least partly. Since the different crops mature at different time periods, the practice of mixed cropping enables growing two crops that are sown together but harvested at different times.
• They are so combined that the total output is larger than what it would be if only one crop was sown. Early-maturing crops may be mixed with groundnut, cotton, or pulses, which mature late.

• The different crops grown together have varying susceptibility to variations in weather. Besides, the price variability of these crops is also different; in some cases, crops mixed together are so selected that their prices do not move parallel, or the extent of their variation differs.
• When crops are mixed under these conditions, the farmer is able to reduce yield and price uncertainties. The proportion of crops mixed varies from region to region and also according to the practice of mixing crops.

Double Cropping

• Double cropping involves growing two crops in a year in sequence (as in crop rotation). It is mainly practised in areas where irrigation facilities are available or where rain is heavy enough for adequate soil moisture to be retained.

In regions of perennial water supply, even three crops are taken if resources permit. In double cropping, as in crop rotation, the aim is restoring soil fertility, and hence the second crop is often one that fixes nitrogen, but the actual soil conditions decide the second crop.

Multiple Cropping

With the introduction of short-duration varieties and water management practices, the trend is even towards growing more than two crops in a year, called multiple cropping. An American variety of short-duration cotton, for example, can be grown in rotation with wheat. Similarly, short-duration varieties of wheat, rice, pulses, oilseeds, etc., have also been evolved.

A great many cropping sequences have been evolved from which the farmer can choose according to the marketability of the produce, profitability of the rotation, soil and climate conditions, and his input-mobilising potential. It has been found that by introducing package measures, cultivation is able to resort to multiple cropping and, at the same time, harvest better yields. There is scope for extending multi-cropping practices to all areas where farmers have already been attuned to a higher level of technology through the HYVP.

Modern Techniques (2025)

By 2025, precision farming techniques, such as the use of drones for crop monitoring and the application of fertilisers and pesticides, along with remote sensing and GIS for crop planning and management, have been widely adopted to enhance productivity and sustainability.