CROP PRODUCTION

Climatic factors include:

 Rainfall

 Poor rainfall distribution results to wilting of crops

 Excess rainfall can cause soil erosion

 Excess rainfall can result to crop failure due to flooding.

The four aspects of rainfall which affect agricultural production include: -

a) Rainfall Amount

Rainfall amount refers to quantity of rainfall received in a given area for a period of one year. Rainfall

amount is measured using a rain gauge in millimeters per annum. The amount of rainfall determines the crops grown in an area.

b) Rainfall distribution 

This refers to the spread of rainfall over the year. Rainfall distribution is very poor in Kenya and therefore irrigation is necessary to supplement the short supply. 

c) Rainfall reliability

This refers to the certainty with which a given amount of rain is expected in a given place in the year.

d) Rainfall Intensity  

This refers to the strength with which rain falls; it is therefore measured in terms of amount per hour. Rainfall of low intensity is preferred as it improves water infiltration into the soil and causes less soil erosion.

 Temperature

 Temperature is the coldness or hotness of a place.

 Temperature is measured in degrees Celsius using a thermometer.

 Temperature is influenced by altitude and topography.

 Temperature decreases with increase in altitude, such that for every 300 meters rise in altitude above sea level temperature decreases by1.7-2.2 degrees Celsius.

 Each crop has a temperature range within which it can grow referred to as the cardinal range of temperature.

 For crops to grow well and produce high yields, they require a narrow temperature range within the cardinal range referred to as optimum range of temperature

Effects of temperature on agriculture

Low temperature

 Slow growth rate.

 High incidences of disease such as CDB in coffee.

 Improvement of quality in crops such as tea and pyrethrum.

High temperature

 High evaporation rate hence wilting in crops.

 Hasten the rate of maturity due to increased growth

Rate.

 Improvement of quality in crops such as pineapples and oranges.

 Increase incidences of diseases such as leaf rust in coffee.

 Increased incidences of pest infestation such as aphids in vegetables.

Effects of altitude on agriculture

 Kenya is divided into three ecological zones which include;

 Low altitude zone o - 1500 meters above sea level

 Medium altitude zone 1500 - 2500 meters above sea level

 High altitude zone above 2500 meters above sea level Crops perform differently when grown in each of these ecological zones and therefore each crop has its most suitable zone for maximum performance as illustrated below.

  Wind

Wind refers to air in motion.

 Below is a list of effects of strong wind on agricultural production.

a) Blowing and bringing rain bearing clouds

b) Destruction of farm structures

c) Strong wind may course lodging in weak plants.

d) Wind erosion on bare land

e) Increases rate of moisture evaporation

f) Increase spread of pests and diseases

g) Agent of dispersal.

h) Pollination in crops.

i)  Light

 Light is the source of energy which plants require for

Photosynthesis.

 During photosynthesis, plants manufacture food using water and carbon dioxide in the presence of sunlight and chlorophyll.

Aspects of light that influence agriculture

i). Light intensity.

 This is the strength with which light hits the surface of the earth.

ii) Light duration

 This is the period of time the plants are exposed to light recorded using a Campbell sunshine

recorder

Photoperiodism

 This is the response of plants toward light duration.

Long day plants

 These are plants which require more than 12 hours of lighting to flower and produce fruits or seeds e.g.

Some wheat varieties

Short day plants

 These are plants which require less than 12 hours of lighting to flower and produce e.g. Maize

Day neutral plants

 These are plants which produce flowers regardless of the duration of lighting they have been exposed to e.g. Tobacco.

iii) Light wavelength:

 This refers to the type or quality of light. A wavelength is the distance between two corresponding points of a light wave.

 Chlorophyll absorbs certain wavelengths of light which are not present in artificial light unless it is ultra violet or infra-red.

NB/ Greenhouses can be used to control the temperature, relative humidity and light duration and intensity.

 Relative Humidity.

 This is the amount of water vapor held by air at a given temperature.

 At high humidity the rate of evaporation is low and vice versa.