Physical factors: Terrain, topography, climate, and soil. which determine agriculture

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Physical Factors:

(a) Terrain, Topography, and Altitude

  1. dependent on the geo-ecological conditions; terrain, topography, slope and altitude.
  2. paddy cultivation requires leveled fields, tea plantations perform well in the undulating topography in which water does not remain standing.
  3. Orchards of coconut are found at low altitudes, preferably closer to the sea level, while the apple orchards in the tropical and sub-tropical conditions perform well above 1500 metres above sea level.
  4. Cultivation of crops is rarely done 3500 m above sea-level in the tropical and sub-tropical latitudes.
  5. highly rarified air, low-pressure, low temperature, and shortage of oxygen at high altitudes are the serious impediments not only in the cultivation of crops, but also in keeping dairy cattle.
  6. soils of high mountainous tracts are generally immature which are also less conducive for agriculture.
  7. topographical features also affect the distribution of rainfall.
  8. the windward side gets more rainfall than the leeward side.
  9. Apart from altitude and aspects of slope, the nature of the surface also affects the agricultural activities.
  10. gullied land is least conducive for cropping.
  11. The Chambal ravines in Madhya Pradesh, Rajasthan, and Uttar Pradesh have put over thousands of hectares of good arable land out of agriculture.

(b) Climate

(1) Temperature:

  • The crops to be grown, their patterns and combinations controlled by the temperature and precipitation conditions.
  • each crop has a specific zero temperature below which it can not be grown.
  • also an optimal temperature in which the crop is at its greatest vigour.
  • For each stage of crop life, i.e. germination, foliation, blossoming or fructification a specific zero and optimum can be observed in temperature.
  • The upper limit of temperature for plants growth is 60°C under high temperature conditions, i.e. at over 40°C, crops dry up, if the moisture supply is inadequate.
  • In contrast to this, the chilling and freezing temperatures have a great adverse effect on the germination, growth and ripening of crops.
  • Crops like rice, sugarcane, jute, cotton, chilli and tomatoes are killed or damaged at the occurrence of frost.
  • minimum temperature for wheat and barley is 5°C, maize 10°C, and rice 20°C.
  • impact of temperature on cropping patterns may be seen from the fact that the northern limit of the regions in which date-palm bear ripe fruit coincides almost exactly with the mean annual temperature of 19°C.
  • essential factor in the limit of grape orchards seem to be temperature. Grapes ripen only in those countries in which the mean temperature from April to October exceeds 15° C.
  • Crops like winter-wheat and barley perform well when the mean daily temperature ranges between 15°C and 25°C.
  • tropical crops like cocoa, coffee, spices, squash, rubber and tobacco require over 18° C temperature even in the coldest months, while crops like wheat, gram, peas, lentil, potato, mustard, and rapeseed require a temperature of about 20°C during the growth and development, stage and relatively higher (over 25°C) during the sowing and harvesting periods.

 

(2) Moisture:

  • All crops need moisture.
  • Take water and moisture from the soil.
  • Available from the rains or from irrigation systems.
  • Within wide temperature limits, moisture is more important than any other climatic factor in crop production.
  • There are optimal moisture conditions for crop development just as there are optimal temperature conditions.
  • Excessive amount of water in the soil alters various chemical and biological processes, limiting the amount of oxygen and increasing the formation of compounds that are toxic to plant roots.
  • Excess of water in the soil, therefore, leads to stunted growth of plants.
  • The problem of inadequate oxygen in the soil can be solved by drainage practices in an ill-drained tract. Heavy rainfall may directly damage plants or interfere with flowering and pollination.
  • Cereal crops are often lodged by rain and this makes harvest difficult and promotes spoilage and diseases.
  • Heavy rainfall at the maturity of wheat, gram, millets, oilseeds, and mustards cause loss of grains and fodder.
  • Indian farmers all over the country have often suffered on account of failure of rains or fury of floods.

(3) Drought:

  • Devastating consequences on the crops, their yields and production.
  • Soil drought has been described as a condition in which the amount of water needed for transpiration and direct evaporation exceeds the amount of water available in the soil.
  • Damages the crops when plants are inadequately supplied with moisture from the soil.
  • drought prone areas of India lie in the states of Rajasthan, Gujarat, Madhya Pradesh, Chhattisgarh, Jharkhand, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Orissa, Bundelkhand (U.P.), Uttarakhand, H.P.J&K, south-west Punjab and Haryana.
  • Where the average annual rainfall is less than 75 cm, agriculture is considered a gamble on monsoon.
  • The incidence of drought and its intensity can be determined from the annual, seasonal and diurnal distribution of rainfall.
  • drought prone areas of India, dry farming is practiced, while in the more rainfall recording regions, intensive agriculture of paddy crop is a common practice.

(4) Snow:

  • Occurrence of snow reduces the ground temperature which hinders the germination and growth of crops.
  • Land under snow cannot be prepared for sowing because of permafrost.
  • Melting of snow may cause hazardous floods in the summer season, affecting the crops, livestock, and land property adversely.

(5)Winds

  • Have both, direct and indirect effects on crops.
  • Direct winds result in the breaking of plant structure, dislodging of cereals, fodder and cash crops and shattering of seed-heads.
  • Fruit and nut crops may be stripped from the trees in high winds.
  • Small plants are sometimes completely covered by wind-blown dust or sand.
  • The indirect effect of winds are in the form of transport of moisture and heat in the air.

(c) Soils

  • Important determining physical factor.
  • Determines the cropping patterns, their associations and production.
  • Fertility of soil, its texture, structure and humus contents have a direct bearing on crops and their productivity.
  • The alluvial soils are considered to be good for wheat, barley, gram, oilseeds, pulses, and sugarcane; while the clayey loam gives good crop of rice.
  • Regur soil is known for cotton, and sandy soil for bajra, guar, pulses (green-gram, black-gram, red-gram, etc.).
  • The saline and alkaline soils are useless from the agricultural point of view unless they are reclaimed by chemical fertilisers and biological manures and fertilisers.

 

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