MEANING AND ELEMENTS/FACTORS OF CLIMATE
Climate is defined as the average weather condition of a place, measured over a long period of time (over 35 years).
Factors of Climate
Factors or elements of climate include:
- Relative Humidity.
- Radiant energy.
Importance of climate in Agriculture
- Climate affects the duration of a cropping season.
- It determines the yield of crops.
- Climate limits the types of crop to be grown in an area.
- It also affects vegetation distribution in an area.
- It affects the incidence of pests.
- It affects the incidence of diseases.
- Climate determines the yield or productivity of animals.
- Climate limits the type of livestock to be reared in an area.
- It also affects the type of soil formation in an area.
How Climate Determines the Type of Crops and Animals Found in Nigeria
Essential factors of climate which determine the types of crops and animals found in Nigeria are rainfall and temperature.
- Rainfall is defined as the amount and distribution of water precipitated within a given time, in a given area.
- It is brought about by the South West Trade winds which blow from the Atlantic Ocean.
- As the wind blows from the Ocean to inland, it drops the water it is carrying.
- As a result of this, the coastal areas receive more rainfall per annum than the rest of the region.
- As the moisture – laden wind moves further inland, the amount of rainfall decreases.
- By the time this wind gets to the northern part of the country, there is little or no moisture left in it.
- In the northern areas, less rainfall is experienced per year.
- In the coastal areas, rainy season ranges from eight months to all-theyear-round while in the north, rainy season lasts for only three to four months.
- This moisture regime affects crops and livestock distribution.
- In the coastal areas, which are the more humid southern part, crops which adapt to heavy rainfall are predominant, e.g rice, maize, fruit, cocoa, forest trees, yams and banana.
- Much animal rearing does not take place in heavy rainfall areas because of high humidity and tsetse fly infestation.
- Consequently, only animals such as dwarf sheep, goat, poultry, Muturu and N’dama cattle which are resistant to trypanosomasis can be reared.
- In the northern parts, with little rainfall, crops which are drought resistant like guinea corn, millet, cowpea, groundnut, cotton and beniseed are grown.
- These crops normally complete their life cycles within three to four months of rainfall. This area is the animal-rearing zone because of few or no tse-tse fly.
- Animals like donkeys, cattle, sheep, goats, camels and horses are reared here successfully because of sufficient grassland for grazing them.
- Temperature is defined as a measure of the heat energy which a body contains or the degree of hotness and coldness of a place at a point in time.
- There is variance of temperature from the coastal areas to the extreme north.
- During the dry season, temperature is extremely high in the north but not as high in the coastal areas.
- Though many farming activities do not take place in the dry season, the crops found in the north are high temperature-loving plants, like tobacco.
- The average minimum temperature varies from 22°C in the coastal areas, e.g. Calabar, during the coldest month of the year to about 13°C in the northern areas, e.g ., Nguru, during the coldest harmattan season.
- Owing to this coldness, wheat can be successfully grown in the north under irrigation, while it cannot be grown in the coastal areas.
- Animals found in the northern areas are also well-adapted to withstand the severe heat of the sun.
Environmental factors affecting agricultural production
Environmental factors affecting agricultural production are grouped into three major classes. These are:
- Climatic factors.
- Biotic factors.
- Edaphic factors.
CLIMATIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
a) Rainfall: Rainfall is defined as the release of excess condensed water vapour in the atmosphere into the earth.
- It determines the distribution of crops and animals.
- It is necessary for seed germination.
- Excessive rainfall leads to leaching of nutrients and causes soil erosion.
- It helps to dissolve nutrients in the soil, thereby making the nutrients available to crops.
- It determines the type of vegetation of an area.
- It determines the seasons in Nigeria, i.e, rainy and dry seasons.
- It determines the vegetation types in Nigeria – savanna in the north and forest in the south.
- The seasons also determine when crops would be planted.
- The seasons also determine the type of crops to be grown.
- Vegetation types in turn determine the types of livestock that can be raised in the different ecological zones.
- Insufficient rainfall causes crop failure and poor yield.
Ways in which high rainfall affects Agricultural production
- High rainfall prolongs the cropping season.
- It increases the problem of plant diseases.
- It determines the type of crop to be grown.
- It increases the incidence of erosion or flooding.
- It encourages thick forestation, thus increasing the incidence of pest e.g. tse-tse flies infestation.
- It encourages the growth of disease-causing organisms (pathogens).
- It increases leaching of plant nutrients or soil acidity.
- It causes water logging in clay soil.
- It determines the type of crops or livestock grown or reared i.e. distribution of crops and animals.
- It encourages faster or rapid growth of weeds.
b) Drought: This is defined as lack of or insufficient rainfall in an area.
Effects of drought on plant growth and development:
- Delay in flowering/reduction in flowers/flower abortion.
- Poor crop establishment.
- It leads to a reduction in leaf area.
- There is a reduction in cell size and inter-cellular volume.
- Several physiological processes may decrease due to the dehydration of protoplasm.
- Water stress produces important changes in carbohydrate and nitrogen metabolism of plants.
- There is a decrease in the production of green matter.
- There is a reduction in photosynthesis.
- It impairs desired quality, that is, appearance, fibre content, firmness, etc.
- There is reduction in yield.
- Possible death of plants/crop failure.
- Lower resistance/prone to diseases.
- Difficulty in pegging, especially in groundnut.
c) Temperature: Temperature is defined as the degree of hotness or coldness of a place.
- Temperature is necessary for germination of seeds.
- It also affects the distribution of crops and animals.
- Too hot or too cold temperature does not favour plants and animals growth.
- Unfavourable temperature may result in seed dormancy.
- High temperature affects evapo-transpiration, and reduces the performance of livestock.
- It affects the wilting of field crops, ripening and maturity of crops.
- Temperature affects microbial activities in relation to mineralization of organic matters.
- High temperature leads to loss of soil nutrients through volatilization.
- High temperature may be harmful by causing premature dropping of fruits and sudden death of livestock, e.g, heat-stress in poultry.
- High temperature reduces the performance of livestock.
d) Wind: Wind is defined as air in motion.
- High wind velocity may cause wind erosion.
- It aids seed and fruit dispersal.
- It can aid pollination and spread of diseases.
- It helps in the distribution of rainfall. and changes in seasons, e.g. rainy and dry seasons.
- High wind velocity causes damage to crops e.g lodging.
- It determines seasons in Nigeria. For example, South West Trade wind brings rain while North East Trade wind brings harmattan or dry season.
- Wind affects evapo-transpiration.
- Wind can cause serious damage to crops in form of lodging, e.g wind storm.
e) Sunlight / Sunshine: Sunshine is the amount of heat and the period the sun’s rays are received at a place.
- Sunlight is necessary for photosynthesis.
- It affects evapo-transpiration.
- It affects the productivity of crops due to length of day, i.e, photoperiodism. In other words, light divides plants into three photo periods: Long Day Plants: These plants require longer day light of between 13 – 15 hours of sunlight, e.g ., millet, sorghum (guinea corn). Short Day Plants: These plants require shorter day light period of between 8 -10 hours of sunlight, e.g ., cocoa, kola and oil palm. Day-neutral Plants: These plants require equal period of day and night; that is, about 12 hours of sunlight and 12 hours of darkness, e.g. tomato.
- Light affects the rising and roosting of animals.
- It affects the rate of production in poultry.
- It determines the productivity of cultivated crops.
f) Relative Humidity: Relative humidity is defined as the amount of moisture in the atmosphere.
- It results in the formation of rain.
- It affects the performance of crops and animals.
- High humidity in poultry houses causes mouldiness of feed and litters.
- Low humidity causes aridity or dryness.
- It determines the type of crops grown in an area.
- Low humidity leads to heat stress in animals, e.g, cattle, poultry, pig.
- It determines the type of crops grown in an area, e.g ., wheat in the north during harmattan.
- It affects the growth rate of crops. For instance, cocoa will not grow well under low relative humidity.
- High relative humidity affects food intake and productivity of farm animals.
- Relative humidity determines the type of pests prevalent in an area.
- High relative humidity favours the growth of disease pathogens.
g) Solar Radiation: Solar radiation is the amount of heat or sun rays radiated to the atmosphere.
- High intensity of radiation causes heat stress in animals, and this reduces their growth, production and reproduction.
- It increases the cost of production because shade has to be provided to protect animals and some crops from direct rays of the sun.
- Solar radiation assists photosynthesis in crops.
- Solar radiation assists in drying of crops.
- Solar radiation is a source of farm power.
BIOTIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
a) Soil Organisms
- These include bacteria, fungi, earthworm, rodent and termite.
- Some, like bacteria and fungi, can cause diseases.
- Some aid aeration of soil, percolation and fertility.
- Some, like the root nodule bacteria can fix nutrients directly to plants and soil.
- Some open up wounds on plants or animals for other pathogens to enter.
- Some reduce the quality and quantity of crops, e.g, potato and yam.
- Some help in the decomposition of plant materials to form humus.
- These include insects, rodents, birds and some mammals.
- They reduce the yield of crops and animals.
- They also reduce the quality of crops and animals.
- Some are vectors or carriers of diseases.
- They reduce the income of the farmers.
- The cost of their control increases the cost of production.
- They include ticks, liverflukes, tapeworms, dodder, mistletoe and lice.
- Some transmit diseases.
- They reduce the quantity or yield of produce.
- They also reduce the quality of produce.
- They may cause the death of plants and animals.
- They reduce production capacity of livestock or crops.
- Cost of control increases cost of production.
- They may be external or internal (i.e ecto or endo-parasites)
- They may be diseases caused by viruses, bacteria, fungi, protozoa, etc.
- They cause reduction in yield of crops and animals.
- They can cause the loss or death of plants and animals.
- The cost of control increases the cost of production.
- They cause reduction in farmer’s income.
- They compete with crops for space, water, nutrients and sunlight.
- Some weeds can harbour diseases and pests.
- They reduce the yield of crops.
- Weed control increases the cost of production.
- Weeds cause poor growth of crops.
- These are birds, rodents and praying mantis.
- Some are beneficial in agricultural production.
- Some are used to control some harmful pests of crops and animals.
- Some feed on farm animals. For example, hawks feed on chicks.
g) Human Activities
Human activities include the influence of man on the production of plants and animals.
- His activities may improve the fertility of the soil if he uses fertilizers and manure.
- There could be increase in yield if he practises crop rotation.
- There could be increase in yield if he controls pests and diseases.
- Increase in yield or production can also be enhanced if he gets rid of weeds from his farm.
- Continuous cultivation bush burning and inability to control erosion can lead to lower agricultural output.