CROP PRODUCTION

1. CROP ECOLOGY

CROP ECOLOGY

Specific Objective

At the end of the topic, the trainee should be able to:

a. Define crop ecology

b. State the biotic and abiotic factors that affect crop production

c. List various agro ecological zones in Kenya

d. List the crops grown in each agroecological zone

1. CROP ECOLOGY

Definition-A branch of Biology dealing with the relationship of organisms with their environment and with

each other. OR

The study of various phenomena within the crop field e.g., Predator/prey relationship or crop/weed

competition

1.1. ABIOTIC/ CLIMATIC FACTORS

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.

1.2. BIOTIC FACTORS

BIOTIC FACTORS.  

These are living organisms that affect agricultural production.  

Biotic factors influencing agriculture can be divided into the following classes.

 Crop pests: stalk borer damaging maize in the field

 Decomposers: Cause rotting of organic matter there by releasing nutrients for crop growth.

They help in improving soil structure through incorporating organic matter into the soil.

 Nitrogen fixing Bacteria: Nitrogen fixing bacteria are found in root nodules of leguminous

plants. Improve crop production through increasing soil nitrogen content which crops require

for proper growth.

 Livestock parasites: suck blood and transmit diseases to animals

 Pollinators: Bee pollinating maize flower. Pollination in crop production increases yields and viability of seeds.

 Predators: Eagles can eat chicken, rabbits among other livestock. Eagle can also eat insects and pests for example rats, moles and birds which destroy crops.

 Pathogens: Causes diseases in livestock and crops thereby lowering quality of produce.

Increase cost of production when control measures are implemented. Introduce toxic  substances into agricultural products thereby lowering the quality of the produce. Can cause death to crops and animals.

Effects of Biotic Factors on Agricultural Production

1. Pests  Feed on crops thereby lowering quantity of agricultural produce.

•Feed on grains thereby affecting viability of the seeds

•Act as disease vectors

•Lower palatability of crop produce

•Increase cost of production when control methods are applied

•Create entry points for disease causing organisms

2. Parasites Irritate livestock

• Causes anemia in livestock

• Some block alimentary canal

• Lower rate of production in livestock

• Increase cost of production when controlled

• Some lower quality of hides and skins

• Some absorb food meant for the livestock thereby lowering the level of production.

• Some for-example ticks transmit disease causing organisms. 

2. LAND PREPARATION

LAND PREPARATION

Specific objective

At the end of the topic, the trainee should be able to:

a. Name the tools and implements used in land preparation

b. Explain the importance of land preparation

c. Explain the methods of land preparation

TOOLS AND IMPLEMENTS USED IN LAND OPERATION

a. Mould board plough

b. Harrow

c. Jembe

d. Machete

e. Slashers

f. Mowers

g. Rakers

h. Axes

LAND PREPARATION

Land preparation involves all the activities that make land suitable for planting such as  

–ploughing/digging  

-harrowing  

-ridging  

-rolling etc.

A piece of land that has been prepared for planting is called seedbed. In a seedbed the planting materials germinate and grow to maturity and are harvested from same place. 

IMPORTANCE OF LAND PREPARATION

• To kill the weeds.

• Encourage water infiltration into the soil. 

• To aerate the soil.

• Incorporate manure and other organic matter into the soil.

• To destroy stages of crop pests such as eggs, larvae, pupa or adults burying them, exposing them to the suns heat or predators and starving them.

• To encourage root penetration into the soil.

• To make subsequent operations possible e.g. planting, fertilizer application, rolling and ridging.

OPERATIONS IN LAND PREPARATIONS

They include;

A. Land clearing.

B. Primary cultivation.

C. Secondary cultivation.

D. Tertiary operations.

2.1. LAND CREARING

This is the removal of vegetation cover from the surface before tillage. This is done to prepare land for cultivation and as method of land reclamation. Land clearing is necessary under the following conditions.

1. When opening up a virgin land.

2. Where a stalk growing crop was previously planted such as maize.

3. Where land was left fallow for long time.

4. Where the interval between primary and secondary cultivation is long such that the land has reverted to the original virgin state.

Methods of Land Clearing

• Tree felling. Axes, pangas and power saws are used to cut down trees. Bulldozers and root rakers are used in felling trees on a large scale. Removal of stumps and trash later follows.

• Burning. The vegetation cover is set ablaze. The method should be discouraged as it destroys the soil organic matter, soil microorganisms and plant nutrients.

• Slashing. This is done to cut small bushes and grasses using slashers, pangas or tractor drawn mowers.

• Use of chemicals. Chemicals used to kill weeds are called herbicides.

2.2. PRIMARY CULTIVATION

This follows land clearing,

• Small scale farmers use jembes or fork jembes during hand digging.

• In Large scale framing ploughing is done using moldboard or disc plough.

• Other farmers use ox ploughs.

• Primary cultivation should be done before the onset of the rains. This ensures that all other subsequent operations are done in good time.

Importance of Primary Cultivation

1. To remove weeds.

2. To bury organic matter for easy decomposition.

3. To facilitate water infiltration and aeration.

4. To destroy soil borne pests by exposing them to predators and the sun.

5. To make planting easy.

Methods of Primary Cultivation

1. Hand digging. This is done by use of jembes, mattocks and fork jembes to cut and turn the soil slices.

2. Mechanical cultivation. This is the use of tractor drawn implements such as moldboard and disc ploughs. Subsoilers, cultivators and chisel ploughs are used to break the hard pan. Subsoiling is the process of cultivating the soil with the purpose of breaking up the hard pan. Hard pans may be formed due to continuous use of heavy machinery on the land.

Importance of subsoiling

• Breaking up the hard pan hence improving drainage.

• Improving soil aeration.

• Bringing to the surface leached minerals.

• Improve root penetration.

3. Use of an ox plough. This is the use of ploughs drawn by oxen, donkeys or camels. The method is faster and more efficient than hand cultivation. It’s common in areas where land is fairly flat.

The following aspects should be considered when carrying out primary cultivation.

I) Time of Cultivation

Land should be prepared before the onset of the rains so as to;

• Give enough time for the weeds to dry up and decompose into organic matter.

• To allow CO2 and other gases to diffuse out of the soil while being replaced by oxygen

• Give enough time for subsequent operations to be done hence giving way to early planting.

 II) Depth of Cultivation

This is determined by;

• Type of crop to be planted. Shallow rooted crops do not deep cultivation. Deep rooted crops require deep cultivation.

• Type of the soil. Heavy soils are hard when dry making jembes and fork-jembes to dig shallowly.

• The implements available. Tractor drawn implements give deeper depth than hand operated tools. III) Choice of the Correct Implements This is determined by:

1. Condition of the land. If the land has a lot of stones and stumps, a disc plough is preferred because it rolls over the obstacles without braking.

2. Type of the tilth required. Very fine tilth requires different types of implements.

3. Depth of cultivation. When deep cultivation is required heavy implements are used.

Light implements are used when shallow cultivation is needed.

4. Topography of the land. Tractor drawn implements cannot be used where the slope is very steep.

5. Implements available. A farmer can only use what is locally available.

6. Shape of the land. Some land shapes may not allow tractor drawn implements to be used efficiently e.g. where there are acute corners.

7. Size of the land.

3. PLANT PROPAGATION

PLANT PROPAGATION

Specific objective

At the end of this topic, the trainee should be able to:

a. Explain various methods of crop propagation

b. List advantages and disadvantages of a given method of plant propagation

PLANT PROPAGATION

DEFINITION

 Plant propagation involves the formation and development of new individuals which are utilised

in the establishment of new plantings. 

3.1. SEED PROPAGATION

 Seeds are easy to handle during planting making the operation faster.

 Fertiliser and manure application can be mechanised.

 It is possible to develop new crop varieties due to crosspollination.

 When planting seeds, it is easy to use machines like seed planters and drillers.

Disadvantages of using seeds as planting materials

 Soil borne pests may damage seeds if left for sometimes in the soil before rain falls.

 Some seeds may lose viability if stored for a long time. 

3.2. VEGETATIVE PROPAGATION

The method relies on the use of vegetative structures such as stems, leaves or roots to perpetuate the parent plants. The vegetative parts contain or develop buds which give rise to new individuals.

Advantages of using vegetative materials for planting.

I) Crop originating from vegetative materials mature faster than those from seeds. 

II) The crops show uniformity in such qualities as disease resistance, seed size, colour, keeping or storing quality and chemical composition.

III) It is possible to produce many varieties of compatible crops on the same root stock.

IV) Use of the vegetative materials is easier and faster, especially where seeds show prolonged dormancy.

V) The resulting plant has desirable shape and size for ease of harvesting and spraying.

VI) It facilitates the propagation of crops which are seedless or those that produce seeds which are not viable or have long dormancy.

Disadvantages.

i) Vegetative propagation does not result in new crop varieties.

ii) Keeping the materials free of disease is difficult.

iii) Materials cannot be stored for long.

iv) The materials are bulky and therefore difficult to store and transport.

Plant parts used for vegetative propagation

(i)Bulbils.

These are tiny sisal plants produced in the inflorescence almost at the end of the plant growth cycle.

(ii) Splits.

These are plantlets divided from the existing mother plant with complete leaves and rooting system.

(i) Crowns and slips.

These are materials used to propagate pineapples. Crowns are born on top of the fruits and are broken off and prepared for planting. Slips are born at the base of the pineapple fruit, they take 22 months from planting to maturity.

Crowns and slips are planted in the nurseries first before transplanting to the main seedbed.

(ii) Suckers.

These are small plants that grow from the base of the main stem. They have adventitious roots which grow quickly when planted to form a new plant.

(iii) Tubers (stem and root tubers)

These are underground structures or food organs which are short and thick. They sprout and produce roots for growth.

(iv) Vines.

These are soft wood cuttings which produce roots easily upon planting to give rise to new plants. They are cut from the mother plants and planted directly into the field.

(v) Cuttings and setts.

Cuttings are portions of plant parts which are cut and then planted. They may be from stems, roots or leaves. A stem cutting must have a bud which develops into a shoot. The root cutting must have an eye.