AGRICULTURAL SCIENCE NOTES FORM FOUR

nursery is an area or place where seedlings are raised until they are ready for transplanting in the field.

A nursery should preferably be located in a place which has the following characteristics;

(a) Deep, fertile and well-drained soil without risks of water logging.

The concept of perennial crops

Perennial crops are crop plants that stay in the farm more than two years. These crop plants grow very slowly and termed as permanent crops. Most of perennial crops have deep root system. Perennial crops include coffee, tea, cocoa, bananas, palms, coconuts, cinnamon, cardamom, vines, cloves, and cashew-nuts. Perennial crops which are not tree crops include pyrethrum, banana, sugarcane, sisal etc.

After planting perennial crop, you will not plant it again for several years. Others they can live up to 50 years in the field. Coffee and tea for example can live up to fifty years in the field.

Some Importance of Perennial Crops

(a) Because they grow very slowly, they do not need large quantities of manure or fertilizer application. They need only small amount of nutrients per annum.

(b) After the perennial crop is established on the field, it requires less labour force than annual crops.

(d) Others are used as medicine.

(e) Perennial Spices like cloves, cinnamon and cardamom have antimicrobial effect that can be used to cure human intestinal infections. Pyrethrum produces toxic substance that used to manufacture pesticides.

(f) Coffee, tea, cashew nuts, pyrethrum, and rubber are cash crops. They generate foreign exchange when they are sold abroad.

Furthermore, they give raw materials to agrobased industries.

(g) Tree crops create wind-break and shelter to other biota. Also they provide shade to both environment and the farmer. Example coconuts and cashew nuts they give shade near home place of the farmer.

The husbandry practices of tree crops

Nursery

Seedlings of perennial crops require special attention therefore, nursery should be used. A (b) Fairly level ground.

(d) Sheltered from winds.

(e) Light or medium textured soils.

Qn. Why is not recommended to site a nursery in a valley bottoms or under the canopy of a tree?

Land preparation

Land for planting perennial crops must be prepared at least three months before planting time. Ring-bark all trees and cut them down later when they die. Uproot all roots and remove them from the ground. If roots remain in the soil, they may harbour Armillaria root rot fungi. Dig out perennial weeds as much as possible. Plough and harrow the land. After harrowing, mark out the positions for planting holes. The distance between the holes should be equal to the spacing recommended for the crop being grown.

Qn. Why is recommended to leave the holes for planting perennial crops open?

Qn. What is the recommended diameter for holes for perennial crops?

Transplanting

Two to four weeks before transplanting seedlings mix the top soil of each hole with well rotten farmyard manure or kraal manure or compost or phosphatic fertilizer.

After mixing the top soil with manure or fertilizers, return the topsoil into the hole.

At the same time of planting each seedling, open the hole at the centre using a suitable tool. After making the hole inserts the root system of the plant into the hole. Make sure that you do not bend the main root. The main root should be placed pointing downwards. It should be straight as possible, and then cover it with soil gradually. Finally make a basin of soil around each plant.

Mulching and watering

After transplanting each seedling, apply water onto the basin around the plant. Mulching is advisable in order to minimize evaporation of moisture from the soil.

If termites are problem in the area, apply a suitable insecticide example Aldrin, dieldrin onto the mulching materials.

Weed control

Weeds can be controlled by applying mulches, cultivating, planting cover crops, slashing, and application of herbicides or by grazing livestock on fields with weeds.

Manuring

Apply organic manures or fertilizers according to the nutrient status of the soil in the given area.

Irrigation

For some tree crops, it may be necessary to irrigate during the dry season. Irrigation may be done by basin irrigation, furrow irrigation or by sprinkler irrigation.

Example of the tree crops that needs irrigation are citrus, pawpaw, coffee plants.

Pruning

Pruning is essential to tree crops for several purpose; example controlling fruit production, make easy picking of fruits and to modify the environment around the plants, making weeding and spraying of pesticide easy.

Examples of crops that require pruning are bananas, tea and coffee. Cashewnuts and citrus trees need very little pruning.

Pests and diseases control

Pests can be controlled by use of insecticides, proper pruning of trees, planting resistant plant materials, observing field hygiene, also by collecting or cutting away pest infested parts of the plant.

Fungi, bacteria, nematodes, mycoplasma or virus cause diseases in crops. Crop disease or pest cause direct and indirect damage/effect to the crop plant.

Qn. Give any five direct effects and four indirect effects of diseases to crop plant.

Qn. Where the coffee was originated and who and when coffee introduced in East Africa?

Harvesting

Fruits from the crops are harvested when they are ripe. Every crop has its method of harvesting. Example tea crop is harvested by picking the tea leaves.

Processing

Processing is the preparation or conversion of plant product into a form that is good for use and storage.

Every crop has its procedure of processing.

Example; when ripe, coffee Arabica berries are harvested then processed firstly by pulping, followed by fermentation in water and then dried on the sun.

Revision Question

1. Write any four importances of perennial crops to the farmers.

2. State any four perennial crops which are cash crops.

3. Write any three perennial crops which are not tree plants.

4. List all perennial crops which do not require nursery for the establishment of seedlings.

5. State the methods of harvesting the following perennial crops; Coffee, Tea, Pyrethrum, Banana, Cashewnut, Sugarcane and Sisal

6. Write the planting materials used in the propagation of the following perennial crops; Tea, Sisal, Banana, Coffee, Cashewnuts, and Pyrethrum.

7. How coffee, sisal, pyrethrum and tea are:

Harvested and Processed?

Production of Coffee (Coffee arabica)

Introduction:

The crop is grown mainly for its seeds, commonly referred to as beans, which contain 1 – 1.5% caffeine, a stimulating beverage. There are two types of branches in coffee tree, the horizontal and the vertical branches. The inflorescences are produced at the leaf axils of the horizontal branches.

Flowering usually occurs in flush and is stimulated by the onset of rains following a dry period. Arabica coffee is self – pollinated crop, and from flowering to maturity of the fruits takes 8 – 9 months. The fruit is a drupe and is commonly referred to as the berry. Each berry normally contains 2 beans.

Types of coffee grown in different parts of the world There are three major types of coffee commercially cultivated. These are Coffee Arabica, Coffee Robusta and Coffee Liberica.

Coffee arabica

About 60% of the total world production comes from the original species of coffee, Coffea arabica, considered to be light and sweet in taste. The major producers of arabica coffee are Brazil, Columbia, Guatemala, Mexico, Ethiopia, Peru, Honduras, Coast Rica, India, and El Salvador. Also farmers in Tanzania they cultivate this type of coffee.

Coffee grown areas in East Africa

Coffee is the leading cash crop in East Africa. Uganda is the leading country in East Africa in the production of coffee, followed by Kenya and then Tanzania.

In Tanzania, coffee is grown on the slopes of Mt. Kilimanjaro and Arusha and Oldeani. Coffee Robusta is grown near Bukoba. Other areas in Tanzania where coffee arabica is grown are Kigoma, Mbeya, Iringa, and Songea.

Requirement for the growing of Coffee arabica

Rainfall: The ideal annual rainfall requirements of coffee range between 1500 mm, evenly distributed throughout the year. A dry period of 2 – 3 months is, however necessary to stimulate flowering. Where this amount of rainfall is not tenable, watering is necessary.

Altitude: In East Africa, arabica coffee is grown without irrigation in areas with an altitude between 1400 m to 1900 m above sea level, or at 1200 m a.s.l with irrigation.

Soils: The best soils are medium loam soils. The soil should be deeper than 1.8m and it should be fertile with a pH between 5.3 to 6.

Fig. Coffee Arabica

Varieties of coffee arabica

There are several varieties of coffee arabica. Some of these include: Bourbon, Blue mountain, KP 532, K.7, S.L 28, S.L. 34, French mission, Kents and hybrids.

Propagation

Coffee is propagated by seeds. Seeds are sown in a nursery. Hybrids have to be propagated by vegetative propagation.

Nursery

Prepare nursery seedling beds, each bed should be 1.2 m wide. Leave paths 60 cm wide in between the beds. Then cultivate the beds deeply and remove all weeds, stones and roots. If the soil is not fertile, apply manure or phosphatic fertilizers according to the nutrient status of the soil.

Sowing seeds

Spread a thin layer of seeds between two hessin sheets in the sun. Keep them in the sun and water them frequently.

Watch out the seeds to see if they germinate. Take away seeds which have germinated and sow them into the nursery seedling beds. The spacing in the beds should be 15cm by 15cm. Provide full shade over seedling beds in the first month.

Qn. What is the importance of planting trees in the coffee plantation?

Qn. Give three tree species which are recommended in tree plantation.

Qn. What is the spacing of permanent trees on coffee field?

Qn. What is the importance of pruning the roots of coffee seedlings?

Spray the seedling with Aldrin to control cutworms and dimethoate to control scales and copper fungicide to control leaf rust.

Transplant the seedlings when they are one year to one year and half old. However, a few weeks before transplanting harden off the seedlings.

Land preparation

Prepare the land seven months before planting. Cultivate the soil and remove all perennial weeds. Dig plant holes after cultivation (dig the holes about three months before planting) in which the size of each hole should be 60cm by 60cm deep. Heap the top soil and subsoil of each hole separately.

Distance between holes should be 2.7 m x 2.7 m or 2.7 m x 1.4 m or 3 m x 1 m.

About three to two weeks before planting, mix the topsoil of each hole with cattle manure or DAP. Use the mixture to refill the hole.

Planting

Plant the coffee seedlings at the beginning of the main rain season. Re opens each hole and then place the root system of the seedling into the hole. Return the soil gradually and compress it around the roots.

After planting, put some mulch on the basin of soil around the plant.

Pruning

The ultimate aim of pruning coffee is to regulate the quality and quantity of the berries produced.

Pruning of coffee is important because it helps to remove old and unproductive branches thus bringing fresh vigour to the trees. Again pruning help to open up the tree bush to light for better flowering and fruiting.

If coffee trees are not pruned, it becomes difficult to pick the fruits. The plants produce fruits irregularly i.e. it produces a heavy crop one season and light one in the next season, spraying also become difficult and some pests and disease causes serious damage on the coffee trees.

Two systems of pruning coffee

(i) Single-stem pruning and (ii) Multiple stem pruning.

Single stem pruning

In this system of pruning, each tree is allowed to have one permanent stem. This stem is allowed to grow to a maximum height of 1.8 m only before it is capped back to 165 cm.

When the young tree reaches a height of 68 cm, it is cut back to 53 cm. After this; one sucker is allowed to develop from the stem below the first capping.

When this sucker reaches a height of 125 cm it is capped back to 110 cm. Finally, one sucker is allowed to develop from the stem below the second capping.

When this sucker reaches a height of 180 cm it is cut back (capped) to 165 cm. This is the final height of the tree.

Write advantages and disadvantages of single stem pruning

Multiple stem pruning

In this type of pruning, two or three main stems are allowed to grow permanently on each plant. When the young tree reaches a height of 68 cm, it is capped back to 53 cm.

Two stems are allowed to develop. The lateral branches (skirt) below the two stems are removed. The two stem are allowed to bear crop for four to six years before they are replaced by new stems from the developing suckers.

Write the advantages and disadvantages of multiple stem pruning

Mulching

Spread grass mulch on the surface of the soil. Spread the mulch before rains begin. Mulch is beneficial; it suppresses weeds and conserves moisture in the soil.

Weed control

Control the weeds that grow between the rows of coffee plants. Cultivate the weeds using forked hoe. Dig out the rhizomes and take them out of the field.

Fertilizers

Coffee requires sufficient nitrogen in the soil. Ask the agriculture extension officer for advice on the type of nitrogenous fertilizer which is suitable in your area.

Pests

Arabica coffee is attacked by many pests. The most important pests of coffee are; leaf miners, antesia, berry borers, thrips, mealy bugs, stem borers, loopers, scales, and berry moths. Control coffee pests by spraying suitable insecticides.

Diseases

The most important diseases of arabica coffee are coffee leaf rust, coffee berry disease (CBD) and armillaria root rot.

Control leaf rust and coffee berry disease by spraying suitable copper fungicides. Control Armillaria rootrot by ring barking wild trees during land preparation.

Harvesting and processing

A coffee plantation begins bearing 2 – 4 years after transplanting.

Harvesting is done by selectively picking the red, ripe berries (commonly called cherries) at intervals of 7 – 14 days.

The cherries are then delivered to the factory for processing on the same day as they are picked. In the factory, cherries are first pulped to remove the exocarp and part of the fleshy mesocarp. This is followed by heaping the beans in a tank to undergo fermentation for 12 – 24 hours. This removes the rest of the mesocarp.

The beans are then washed in clean water, graded, and finally dried to give parchment coffee at a moisture content of 10 – 11%.

The average yield of Arabica coffee in East Africa is about 650 kg/ha of dry parchment coffee. With good husbandry practices, regular yields of about 1250 kg/ha of dry parchment coffee should be obtained.

Questions
		1. Where in Tanzania, coffee arabica is grown? 2. State any three varieties of coffee arabica. 3. Why coffee arabica is much grown than other types of coffee? 4. What are the conditions necessary for the grown of the arabica coffee?
	5.		How can the government assist farmers who grow coffee in our country?
	6.		The first harvesting of coffee begins at what time after planting coffee?
	7.		Explain the uses and problem facing coffee industry in Tanzania.
	8.		Define the following: (a) Cherry (b) Pulping (c) Single stem pruning (d) Armillaria root rot

Production of Tea

Introduction

The scientific name of tea is Camellia sinensis.

In East Africa the first tea was planted in 1900, however, large commercial production of tea was not undertaken until the 1920s. Tea is a cash crop grown for its leaves which may contain as much as 4% caffeine. A beverage known as “tea” is prepared from leaves.

Fig; Tea

Climate and soil

Altitude: Tea grows well in areas with high altitude of 1200 m to 2200 m above sea level.

Rainfall: Tea requires a lot of rainfall. About 1500mm to 1750mm of well distributed rainfall is required.

Tea in Tanzania is growing in Usambara, Iringa, Mbeya and slopes of High mountains like Kilimanjaro and Meru.

Soils: Tea grows well on soils that are acidic (pH 4 to 6). The soil should be deep and well drained. Such soil should have ability to hold and retain a good amount of moisture.

A good supply of nutrient elements in the soil is also necessary. Nitrogen Phosphorus, potassium, sulphur, copper and zinc should be available in the soil.

Varieties of tea

There are two groups of tea varieties which are grown in East Africa that are:

i. Assam varieties

ii. China varieties

Both tea varieties are evergreen perennial trees. Under natural conditions, Assam tea may grow to a height of 9 m, while China tea may grow to height of 4.5m.

The leaves of Assam tea are pale green, long, wide and are either horizontal or point downwards. The leaves of china tea, on the other hand, are dark green, short, narrow and point upwards.

Tea varieties that are grown in Tanzania are Assam varieties. They include TRI 6/8 and BB 35. They are high – yielding, adaptable to wide ecological conditions and produce good quality tea.

Propagation

Tea may be propagated by means of seeds or by vegetative propagation. Vegetative propagation gives much better results than sowing seeds.

Qn. What is clone?

. How rooting medium for planting tea cuttings

is prepared

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