Soccerepe : Agriculture

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Monday, 10 September 2018

Agriculture September 10, 2018

Methods of Crop Propagation

Sexual Propagation

Sexual propagation is propagation by means of seed. A seed is a fertilized ovule enclosing a tiny plant and the food necessary for its germination. It is thus a living but dormant plant. A seed will germinate to produce a new plant when given all the right conditions.

Seed Germination

Germination is the process whereby the seed absorbs water, swells, and produces a radicle (embryonic root). This is soon followed by the plumule which later develops into a shoot. Before the new plant develops leaves, it uses the food stored in the cotyledon(s) to grow. Once new leaves are formed the plant uses carbon dioxide from the air and water from the soil to produce its food through a process called photosynthesis.

Recently, we classified crops as either monocotyledons or dicotyledons depending on whether they have one or two seed leaves. In monocotyledons, the single seed leaf remains underground when the seed germinates. In dicotyledons, the seed leave appear above the ground. In some cases they may turn green and carry on photosynthesis before proper leaves are formed.

For a seed to germinate, it must have adequate moisture, oxygen (from the air), and the right temperature. seeds of some crops require light for germination.

Seed dormancy

Seeds of certain crops fail to germinate immediately after maturity even when all the right conditions for germination exist. An example is some varieties of ground nuts. This temporary failure to germinate is called dormancy. Dormancy is caused by a number of factors:

(a) Type of seed coat - A hard or thick seed coat prevents the seed from absorbing water and possibly also oxygen. Under natural conditions the hard seed coat will soften with time.

(b) Immature embryo - In some crops, the embryo has not completed its development at the time of harvest, and so the seed remains dormant.

Dormancy caused by hard or thick seed coat can be broken by two methods:

(I) Presoaking - soaking the seeds in water to soften the seed coat so that it absorbs water. When planted in the field the seed will germinate faster.

(ii) Scarification - This is a process of breaking the seed coat so that the embryo can easily absorb water and oxygen when it is planted.

Seed longevity

Longevity is the ability of the seed to remain viable or able to germinate with time. seeds of some crops remain viable for many years while those of other crops lose their viability after a few years. Onion seeds lose viability very quickly. Cereal grains generally remain viable longer than legumes. Before planting seeds of any crop it is important to know the viability.

Seed quality

Seeds for planting must meet certain minimum qualities in order to get a good crop.

Some of these qualities are that:

I. Seeds must be mature and well filled. Small shrivelled seeds may germinate but they produce small, weak seedlings that may not survive.

ii. The seed must have a high percentage viability.

iii. Seeds for planting must be clean and free broken seeds, dirt, weed seeds and other foreign materials.

iv. They must be free from insects and seed borne diseases.

Treatment of seeds for planting

Although I have defined seed as a fertilized ovule, agriculturists sometimes use the word 'seed' loosely to include things like potato and yam cuttings. Seeds must be dressed with seed dressing chemicals before planting. This I'd to protect them from soil borne pests and diseases. If seeds are not treated they can be attacked by soil fungi. This will cause them to rot and fail to germinate. They may also be attacked by soil borne insects and other organisms. The two most commonly used seed dressing chemicals in Nigeria are :

(I) Fernasan D.

(I) Aldrex T.

There are also many other chemicals tested in our research institutes. If found suitable, they will eventually be recommended to farmers for use in treating seeds before planting.

A chemicals are toxic to a certain degree. You should therefore strictly obey the directions on the packet when using any chemicals.

Asexual propagation

Asexual propagation is propagation by means of vegetative organs. For this reason it Is sometimes called vegetative propagation. In some crops that do not produce viable seeds it is the only means of propagation. In certain other crops it is used because it is easier than growing plants from seed. Asexual or vegetative propagation can be divided into four groups , namely: Division, Cutting, layering and Grafting.

Division - This is propagation of plants from vegetative organs that separate naturally from the parent plant. Such organs include:

(I) Rhizomes - Ginger.

(ii) Suckers - Banana.

(iii) Crowns - Pineapple.

(iv) Runners - Strawberries.

Cutting - A cutting is a portion of a plant which when placed in a suitable medium will produce roots and shoots and grow into a new plant. Cuttings are classified in two ways:

(a) The part of the plant from which they are made.

i. Stem cutting - for example casava , sweet potatoes and Irish potatoes.

ii. Root cutting - for example Bread fruit.

iii. Leaf cutting - For example Bryophyllum.

(b) The stage of development when the cutting is made.

i. Herbaceous cutting - these are cuttings made from the stem portion having herbaceous succulent growth. For example coleus.

ii. Softwood cutting - This is also succulent tissue but from new growth. An example is Croton.

iii. Semi hardwood cutting - this contains mature tissue which has not yet hardened. An example is lemon.

iv. Hardwood cuttings - cutting from mature , hardened part of the stem. Examples are grape and fig.

Layering - This is a method of vegetative propagation in which plant parts are made to develop roots while they still attached to thr parent plant. There are sic types of layering.

i. Simple layering - A branch of the plant is buried in the soil at one point. This is cut off from thr parent plant when it has rooted

ii. Serpentine or compound layering - in this case a long branch is selected and layered at may poi ts instead of just one.

iii. Mound or stool layering - The stem is cut off completely and the stump is covered with soil. When the buds start sprouting, more soil is added so they can form adventitious roots.

iv. Trench layering - this is similar to serpentine layering but in this case the whole branch is buried in thr ground. The axial buds sprout to produce new plants that can be separated.

v. Tip layering - Only the tip of s branch is covered with soil. This is possible where the terminal bud sprouts.

vi. Air layering - in air layering the bark is removed from a portion of the stem. That portion is covered with moist saw dust or orther soft material. This is then covered with a polythene film and the place continuously kept wet. When it had rooted, it is cutoff for planting. The stem to be layered should be mature but actively growing. The bark should be easy to remove.

Grafting - This is a method of vegetative propagation in which two parts of different plants are joined together so that they unite and grow as a single plant. The lower part of this union is called the root stock and the part grafted on top is called the scion. When a single but is used as a scion the process is called budding.

Conditions for successful granting include the following:

i. Stock and Scion must be compatible. That is , they must be suitable together in order for their union to be successful

ii. Stock and scion must be in proper stage of growth.

iii. Cambium layers of stock and scion must be well aligned.

(a) Small scion with thin rind

(b) Large stock with thick rind

iv. Cut surfaces must be protected from dying.

v. After budding or grafting adequate time should be allowed to form a union.

Sections of scion or budwood:

i. It should be from a suitable plant of variety

ii. It should be from mature wood of current seasons growth.

iii. Buds on thr scion should be in dormant condition.

iv. A round twig is generally preferred.

There are various methods of budding and grafting.

Method of budding

There are two main methods of budding.

I. Shield or T budding

ii. Patch budding

a. Stock prepared with T- shaped incision

b. Shield bud prepared.

c. Bud inserted in stock.

d. Technique of cutting out patch from bud stick.

e. Bud patch removed.

f. Stock showing preparation of panel with flap and bud patch inserted.

Method of grafting

There are four common methods of grafting

i. Approach grafting - the stock and scion Are brought together as two separate growing plants. The scion is not severed from the parent plant until a successful union has been achieved. Approach graft can be either spliced or tongued

ii. Apical grafting - this is where the top part of the root stock is cut off ad in arching. The difference is that the scion has been detached from the parent plant. There are three common types of apical grafting.

1. Whip and Tongue.

2. Saddle.

3. Wedge or cleft.

Types of apical grafting

a. Scion prepared for whip and tongue graft.

b. Stock prepared for whip and tongue graft.

c. Whip and tongue graft ready for tying.

d. Stock prepared for saddle graft.

e. Scion prepared for saddle graft.

f. Saddle graft ready for tying.

g. Scion prepared for wedge or cleft graft.

h. Wedge or cleft graft ready for tying.

Advantages and disadvantages of different propagation methods

Sexual reproduction

i. In most field crops propagation by seed is the only economic and practical method.

ii. Horticultural crops grown from seed live longer than those propagated by asexual means.

iii. In breeding new varieties, seeds are absolutely essential.

Iv. Root stocks are mostly grown from seed without which budding and grafting cannot be done.

V. Seedlings are easier and cheaper to raise from seed.

Disadvantages

I. Some seedlings raised from seed are not true to type. This is important in horticultural crops.

ii. Plants grown from seed are not always uniform in growth, maturity, yield and other characters.

iii. Some plants produce very few seeds. Seed germination may also be poor.

iv. Seeds may not germinate because of dormancy.

v. Plants grown from seeds take a longer time to produce fruits.

Asexual reproduction

Advantages

I. Plants are true to type and uniform in quality, growth habit and yield.

ii. All plants propagated at the same time by vegetative means start bearing at almost the same time.

iii. It is the only way of propagation for plants that cannot produce seeds.

iv. Plants mature and start bearing early.

v. A plant that is susceptible to certain soil conditions can be grafted onto a root stock that is resistant to these conditions.

Disadvantages

I. Plants do not live long and they are not vigorous.

ii. It is not possible to produce new varieties.

iii. Budding and grafting requires special skills

Dr. Patrick Ejike Chibike 0

Agriculture September 10, 2018

Prevention and Control of Water and Nutrient Losses in Soil

In Water and nutrient Losses we learnt how water and nutrient losses occur and the factors governing them. In this Writeup You shall Consider how to prevent and control these losses.

Prevention and Control of water Vapour Losses

1. Mulching - a mulch is any material such ad straw, leaves , saw dust or plastic film spread over the soil to reduce or prevent evaporation.

2. Crop cover - Keeping a Dense crop cover, such as by close spacing of crops, will reduce direct evaporation from the soil. Removal of weeds by cultivation or killing them with herbicides will eliminate loss of water by transpiration from the leaves of such weeds.

Prevention and control of liquid water losses

1. Organic matter - incorporation of organic matter In the form of crop residue, green manure or farmyard manure will improve the soil structure and increase permeability. Organic matter will also increase the water holding capacity of sandy soils and, therefore, reduce deep percolation.

2. Sub soiling - This is the breaking of compact subsoil without turning , using a special type of implement (chisel). This will improve the rate at which water penetrates the soil and reduce runoff.

Prevention and control of soil and nutrient losses Nutrient losses

All measures taken to control water losses by deep percolation will also control nutrient losses through leaching. Similarly measures that control runoff will control losses of nutrients with the runoff water. Other methods that can be used to control loss of nutrients from the soil include:

Avoiding burning , Returning crop residues to the soil, controlling erosion.

Soil Losses

The prevention and control of soil losses depend on the type of erosion. Erosion is the loss of the surface soil due to washing away by runoff water or blowing away by wind. These are called water and wind erosion respectively.

1.Water erosion is of three types.

i. Sheet erosion : it is the removal of fairly uniform layer of soil from the land surface by runoff water. The effect of raindrop splash AIDS sheet erosion in that the soil is loosened and becomes easier for runoff water to wash it away.

ii. Rill erosion : it is the process by which soil is removed through numerous small channels. This type of erosion accompanies sheet erosion. Both sheet and rill erosion can be controlled by :

(a) Contour Cropping - Planting crops along the contour so that they cut across the slope. This could be in the form of contour strip cropping or contour furrowing.

(b) Terracing - building terraces along the contours will reduce the slope length. The water is caught in the terrace channels and conducted away from the field at a gentle grade.

(c) Gully erosion - When rill erosion is not controlled, the small channels become bigger until they form gullies. More soil is lost in the process. This type of erosion can only be controlled with heavy earth moving machinery.

2. Wind erosion is most common in dry areas but can also occur in humid regions where there is a well marked dry season. The factors governing wind erosion are:

I. Moisture - The drier the soil the more easily it is carried away by the wind.

ii. Speed of the wind - Soil loss increases as wind speed increases.

iii. Surface conditions - Wind erosion is greater when the soil surface is smooth.

iv. Soil characteristics - Loose sandy soils are more easily eroded by wind erosion than clayey soils.

The measures to control wind erosion are :

(a) Leaving a vegetation cover on the soil such as cover crop or stubble mulch which is the remains of the previous crop after harvest.

(b) Wind breaks - a row of shrubs planted perpendicular to the wind direction.

Dr. Patrick Ejike Chibike 0

Friday, 7 September 2018

Agriculture September 07, 2018

Water and Nutrient Losses

Nutrients are elements that are required by crops in other to grow and complete their life cycle. When they are not available in the soil in adequate amounts, they can be added to the soil in the form of fertilizers. The soil nutrients required by crops are nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, boron, molybdenum, copper, zinc and chlorine.

Losses of water from soil

There are two forms in which water can be lost from the soil:

1. Losses in vapour form

2. Losses on liquid form

Losses in vapour form

Losses of water in the form of vapour occur when the water evaporates from the soil surface. The factors that affect evaporation from the soil surface are :

(I) Sunshine - more water is evaporated from the soil and surface on sunny days because of the heating effect of the sin.

(ii) Temperature - the higher the temperature of the atmosphere the greater the evaporation.

(iii) Humidity - less water is evaporated when the atmospheric humidity is high, and more water is evaporated when the atmospheric humidity is low.

(Iv) Wind - increases the amount of evaporation from the soil and from plant surfaces.

(v) Crop cover - a dense crop cover reduces the amount of direct evaporation from the soil but the more dense the cover the more water is used by the crop through transpiration ( a process by which water vapour passes to the atmosphere from plant cells). Water that is used by weeds is lost through transpiration and can no longer be used by the crop.

(vi) Water Supply - more water is evaporated from the soul when it is very wet than when it is just moist.

Losses in liquid form

There are two ways by which water in liquid form is lost from the soil.

(a) Deep percolation - percolation is the vertical movement of water through the soil. Deep percolation occurs when water moves down the soil and out of the crop root zone.

(b) Runoff - Water moving on the surface and out of the area on which it fell as precipitation or was applied as irrigation.

Several factors govern losses of liquid water from the soil:

(I) Soil Texture - in a sandy soil, water moves down the profile very fast because of the large air spaces. In a clayey soil water does not percolate fast enough and may be lost as runoff.

(ii) Soil structure - a soil that has a well granulated structure takes in more water than a puddled soil. A puddled soil will have more runoff.

(iii) Organic matter - A soil that has a high organic matter content has a stable structure. The granules will not break up and close the air spaces when the soil is wetted. Water loss through runoff will therefore be less.

(iv) Slope - Slope is land that lies in a slanting position. Both the length and degree of slope affects runoff.

(v) Crop cover - Less water will runoff from a bare soil than when there is a crop. The crop roots tend to prevent percolation.

(vi) Water supply - When rain falls at a faster rate than the soil can take in, the water collects and begins to run off.

Nutrient Losses

The thirteen nutrient elements listed at my previous write up are found in the soil in various forms. Nutrients are either absorbed I.e attached to the surfaces of the soil solids or they occur in solution in the soil water. There are four basic ways in which nutrients are lost from the soul. There are Leaching, Crop removal, Burning and Erosion.

1. Leaching - All conditions that enhance deep percolation also lead to loss of these nutrients that are present in the soil water. Such removal of materials in solution from the soil is called leaching.

2. Crop removal - Any growing plant take up nutrients from the soil. When such crops are harvested and taken away the nutrients are lost.

3. Burning - When crop residues are burnt, most of the nutrients remain on the soil surface in the form of ash. Only sulphur and nitrogen are oxidized to the gaseous form and lost directly from the soil. The ash may however be lost before a crop can use it. It maybe washed away by run off water or leached through deep percolation.

4. Erosion - This is the removal of soil by water or wind. Thus it is the lost of the soil itself with any nutrients contained in it.

Dr. Patrick Ejike Chibike 0

Wednesday, 5 September 2018

Agriculture September 05, 2018

Fertilizers

When ever a crop is harvested there is considerable loss from the soil. Nutrients may also be lost from the soil die to erosion or leaching. The best and quickest way of replacing plant food lost from the soil is by adding manure which maybe in the form of animal and plant refuse (organic manure) , or chemical manures which are known as inorganic fertilizers. To derive maximum benefit from manure, it should not be left on the soil. If manure is exposed, the heat of the sun may change it and reduce its value as a plant food.

Types of Organic manures

Green manuring

In one of my write up on fallows and cover crops, we learnt that leguminous plants such as beans, mucuna and peas have swellings on their root which are called nodules. These nodules contain bacteria which can make nitrogen. Land which has become deficient in plant food is planted with green manure plants. Before the next crop is to be planted, the green manure plants are uprooted ad covered with the soil. The green manure then rots and forms humus.

Moisture availability is essential for rapid decomposition of green manures. Thus, under stable rainfall conditions green manuring can be useful in the maintenance of soil fertility.

A major disadvantage is that this method is short lived, consequently , green manure crops must be frown frequently in the rotation programme to maintain crop yields. It is also not practicable to maintain fertility with green manure crops alone, hence other methods are used to supplement their effect.

Farmyard Manure

Farmyard manure consist of faeces, or excreta, urine and other waste product of domesticated animals. These are know n as animal droppings. Together with a bedding of grass, animal droppings are deposited in a shaded place which has been specially prepared for this purpose. New layers of grasses and droppings are continually added until a heap of a mixture of droppings and grass refuse has been formed. In the course of time, decomposition and rotting occurs through bacterial activity and eventuality a rich, cheap source of manure is formed.

Farmyard manure contains all the plant nutrients. It can be produced cheaply and easily on the farm. It last long in the soil , improves soil structure and readily absorbs and retains moisture. Preparation, however , requires much labour during spreading on the farm. It can also encourage rapid growth.

Composting

The best manure consists of rotten anima and plant refuse and is usually prepared in compost pits. To make compost, all refuse including crop residues from the farm SNF household refuse are thrown into a pit which is covered with a layer of soil and watered. When this pit is full, more pits are dug and filled in the same manner. The compost heap should be turned three times at intervals 2-4 weeks to get all the materials decomposed. Each heap should be kept moist to encourage rapid decay by bacteria. Compost pits should be sheltered from the strong heat of the sun and heavy rain. When the refuse is well rotten it is dug up and used in the farm. Composting is a worthwhile practice became of the nutrients it supplies to crops. Compost also promotes the activities of earth worms, terminates and microbes in the soil.

Inorganic chemic fertilizers

Inorganic fertilizers are chemical substances which are usually prepared in the forms of liquids, powders, granules , pellets or crystals. Two kinds of fertilizers can be identified according to whether they contain either one or more of any of three major nutrients namely, nitrogen. (N) , phosphorus (P) and Potassium (K). When they contain only one of the three major nutrients, they are referred to as single, simple or straight fertilizers.

These fertilizers are further divided into 3 classes according to the major nutrient they contain. When nitrogen is the major nutrient it is called nitrogenous. When it is phosphorus it is called phosphatic fertilizer. When potassium is the major nutrient it is called potash or potassium fertilizer.

The second kind of fertilizers are usually referred to as compound or mixed fertilizers such as a combination of nitrogen, phosphorus and potassium, shortened to NPK. When only two of the major nutrients are mixed we ha e NP or NK or PK.

Examples of nitrogenous fertilizers are :

Ammonium sulphate, ammonium nitrate, urea, sodium nitrate, potassium nitrate.

Examples of phosphatic fertilizer are :

Single superphosphate , triple superphosphate.

The major potash fertilizers are :

Muriate of potash (KCI), sulphate of potash, potassium nitrate, potassium magnesium sulphate.

Storage and Handling of fertilizers

Fertilizer Application

Fertilizers are generally applied to the soil before sowing or planting and during crop development at intervals of 14-22 days. This time interval depends on the type of soil and the requirements of the plant.

There are two main methods recommended for the application of fertilizers.

(a) Broadcasting , and

(b) Localized placement in the row or in a circle around the plant.

Broadcasting involved mixing the fertilizer thoroughly and uniformly with the topsoil. It maybe left on the soil surface or ploughed into it. Broadcasting could be done before ploughing and planting. The fertilizer should not come in contact with the plant roots because it can Burn them. For larger crops such as cocoa or oil palm and citrus, localized placement of fertilizers is usually recommended.

The use of fertilizers brings about an increase In the yields of crops and subsequently more food becomes available for consumption.

Dr. Patrick Ejike Chibike 0

Monday, 3 September 2018

Agriculture September 03, 2018

Fallows and Cover Crops

Fallows

Fallows is the word used to describe a piece of land that is left unplanted for a season or more. This system is adopted in many parts of west African where land is abundant. Bush fallowing on the other hand involves growing crops on a piece of land until the land is no longer productive. The land is them abandoned and allowed to go back to bush for six to twelve years before it is used again. The farmer then moves to other areas to make new farms.

There are many advantages and disadvantages in this type of system. During fallow periods, plant nutrients build up ad a result of formation of organic matter.

Fallowing is designed to clean the land , leaving it free of pests, diseases and weeds. It is also relatively cheap because no extra expenses on fertilizers are involved.

The system , however , encourages repeated land clearance which involves energy , time and in the process valuable forest areas will be destroyed. During clearance, loss of humus and soil fertility results from burning. After clearing , the soil is left bare and this encourages soil erosion.

Bush fallowing is nevertheless becoming rare with the increasing population pressure on land, and with improved agricultural technology because of the introduction of crop rotation is and chemicals for destroying weeds before or during the cropping of the land.

However, the system may continue to persist in those parts of tropical Africa where land tenure system encourages people to temporarily acquire land for farming.

Cover crops

These are crops that are planted to protect the soil surface from being washed away by the rain. The soil is thereby protected from the mechanical action of rain by stopping and breaking up the rain drops before they hit the soil. This prevents surface runoff and leaching of the soil. The crops also prevent rays of the sun from overheating the soil surface which may lead to water evaporation from the soil surface. When a piece of land is lying fallow before the next crop, cover crops are usually planted to occupy such land.

Many cover crops are leguminous (legumes) e.g beans , mucuna, centrosema, pueraria. Many grasses and short lived trees are Also used as cover crops. The legumes are able to make nitrogen In their root nodules and this nitrogen is released into the soil to improve soil fertility. Short lived trees act as wind breaks and cut down wind movement thus reducing erosion, rates of transpiration from crops and evaporation from the soil. Cover crops enrich the soil with their fallen leaves, when these leaves decay.

Dr. Patrick Ejike Chibike 0

Agriculture September 03, 2018

Crop Rotation

From an agricultural point of view, it is unwise to grow the same kind of crop in the same farm year after year. When a farm is cropped continuously, its nutrients become completely used up. This situation is similar to an individual who withdraws money continuously from his savings account without putting some money back into the savings. Eventually, his account will become exhausted and empty. A system of crop changing (rotation) is therefore necessary and must be planned in such a way as to ensure that the nutrients are not completely used up. The planting of crop must follow a definite scientific sequence because different crops require different amounts of food. Some crops use many nutrients and are referred to as "heavy feeders " e.g millet and vegetables. Some plants can actually add nutrients to the soil e.g legumes. Crop rotation can therefore be defined as the planting of different crops on the farm as successive years in a scientific sequence without seriously reducing the soil nutrients.

Principles of crop rotation

(I) In planning crop rotation, deep rooted plants e.g, ground should be followed by shallow rooted ones, e.g . maize. This enables all the nutrients in every part of the soil to be used. A deep rooted plant draws its nutrients from deep down the soil profile, whereas shallow rooted plants derive their nutrients from the surface of the soil.

(ii) the growth of certain crops is favoured by certain nutrients. For example , repeated growth of maize uses up most of the nitrogen, whilst cassava uses up most of the potash.

Example of crops rotation plants are as follows:

Crops to plant

(a) Yams, cassava, potatoes (tubers).

(b) Maize , sorghum (grains crops)

Order to follow

(a) Grain crop should be planted after root crops.

(b) Legumes should be planted before tubers like yams, cassava and maize.

(iii) All crops have their range of weeds , pests, and diseases. Certain weeds, pest and diseases also thrive very well with certain crops. If some crops are planted repeatedly , such diseases, pest and weeds will become a common feature in that area and will contribute to serious yielded losses. For example if yams are planted repeatedly in an area , the population of yam nematodes builds up, but if yam is alternated with maize, tobacco or cotton which are not affected by the yam nematodes, their population will be controlled.

(iv) The use of leguminous plants e.g. cowpea, mucuna and groundnuts is desirable in crop rotation. Leguminous plants are Important sources of soil organic matter, and they also have the ability to make nitrogen in their root nodules which are released later to enrich soil.

Crop rotation is advantageous to the farmer in that it provides a variety of food items throughout the year. Crop rotation helps the farmer to control pest and diseases and increase soil fertility. In situations where land is not abundant, crop rotation provides a solution to such problems.

Dr. Patrick Ejike Chibike 0

Thursday, 30 August 2018

Agriculture August 30, 2018

Types of Soil

The different types of soil are sand, silt, loam and clay. Soil texture is the relative proportion of these components in a given sample of soil. A soil which contains chiefly sandy soil. If a sample of soil contains more than 25% of clay, it is said to be clayey. Between the two, there is a type soil with plenty of sand and clay. Such s soil is called loam. A soil texture can also be referred to as light, medium or heavy depending on the combination of the different particles in the soil.

Soil particles

Soil particles are classified on the basis of their size groups and particles size diameter as follows:-

Types of soil particles - particle size diameter (mm)

Stones and gravel. - 2.00 and above
Coarse sand. - 2.00. - 0.20
Fine sand. - 0.20 - 0.02
Silt. - 0.02. - 0.002
Clay. - 0.002 and below

Sand- A sandy soil allows easy movement of water. It is therefore easy to work or cultivate. It is well drained and aerated, producing early crops but tends to suffer badly from drought and is poorly supplied with minerals needed by plant. Leaching of mineral salts goes on at excessive rate. Addition of small amounts of humus can improve the condition of sandy soils.

Clay - Unlike sand, clay retains plenty of water therefore remains water logged, badly drained and aerated. It is a heavy soil which is difficult to cultivate. Addition to humus can also improve the condition of clay soils.

Loam - soil containing a balanced mixture of large and small particles with adequate humus is classed as loam. Loam is therefore the best soil for agriculture.

Apart from the different soil types already mentioned, the soil is further characterized by the presence of plant and animal remains at various stages of decay. These are referred to as humus. The humus gives the soil its characteristic dark colour and helps to improve soil fertility.

Soil structure

Soil structure is the name given to the physical appearance of the soil depending on how individual soil particles or components are packed. Soil particles are usually arranged into aggregates or units owing to tgr mixing together of different soil types like sand and clay. The different units may be classified as very coarse , coarse, medium, fine and very fine.

Soil structure has a direct effect on crop yield and when choosing a site for farming , the structure of the soil must be taken into consideration. For example , a good soil structure has the following characteristics:

(I) It must be well aerated I.e. good air circulation. This us generally an advantage to plants because water logging is prevented;

(ii) A good soil has adequate soil organic matter (humus) . The humus improves the stability of the soil and prevents the soil from bring broken up into clumps. A stable soil structure encourages good plant growth, because water and mineral components of the soil are retained.

The structure or the stability of soil can be preserved by planting green cover crops or grass vegetation and by mulching ( covering with dead grass) or by the addition of certain chemicals such as lime.

Peony Trading Incoperated 0

Monday, 27 August 2018

Agriculture August 27, 2018

Definition and Composition of Soil

Soil is the top layer of the earth crust in which plants have their roots and from which they obtain water and mineral nutrients. When soil is being formed during the process of weathering, the mineral rocks is broken down into particles of various sizes by the action of weathering agents such as water and wind. Humus or organic matter derived from the dead remains of animals and plants are latter added to the mineral particles to produce soil which is suitable for good plant growth.

The soil is divided into three layers.

(I) Topsoil (soil surface), where most most plants roots are found. The top soil is much darker brown than the soil beneath it, I.e. the subsoil. It contains many parts of dead plants and animals, which latter form the humus. It is this humus that gives the top soil its characteristic dark colour.

(ii) Below the top soil is the sub soil. This is relatively infertile layer.

(iii) Underneath the subsoil is the parent rock.

These three layers I.e. topsoil, subsoil and the parent rock together form the soil profile. A soil profile can be examined by making a vertical section through the soil down to the parents material I.e. the rock

Composition of soil

A good agricultural soil is made up of a mixture of the following substances; the numbers representing percentage by volume.

Solid particles.....................40%

Air.........................................25%

Water....................................25%

Humus..................................10%

These percentaged vary with different types of soil found in different places.

Experiment 1: to determine the composition of garden soil.

The composition of a garden soil can be determined as follows:

Method: fill a glass jar with soil to a depth of 10cm and then add water. Shake the jar thoroughly and allow both the water and the soil to settle. What do you observe? Measure the depth of the sand and clay and calculate the percentage of each. The amount of humus and plant remains cannot be determined in this way. Make a chart showing the results.

Results: sand particles being being heaviest will sink to the bottom first. There will be a clear line between between the bottom layer I.e. sand and next layer, clay. Some of the plant remains will float on top.

Experiment II: to demonstrate the presence of air in the soil.

Method: turn an empty tin, which is open at one end, and press firmly into the ground until the tin is filled completely with soil. Gradually scrape the soil from the tin into water in a cylinder.

Result: as this being done, there will be bubbles of air in the water as the soil is falling into the cylinder of water. This experiment demonstrates the presence of air in the soil.

Use of air, water and solid particles in the soil.

Air- air is present in the pore spaces in the soil which are not occupied by water. Air provides oxygen for the respiration of living organisms in the soil, and without air, seeds cannot germinate.

Water- the major source of water in the soil is rainfall. Other sources include supply from irrigation and underground water. The water in the soil is held is held by many forces , on the basis of which soil water can be classed as (I) free (drainage) water, (ii) capillary water, and (iii) hygroscopic water. Only capillary water is available to plants.

Water in the soil may be lost by evaporation from the soil surface, transpiration from the opening ( pores and stomata) in plants and runoff from Soil surface in to streams and rivers.

Soil water is important to plants in the following ways:

(a) it is an important ingredient in the manufacture of food for plants (photosynthesis);

(b) water is used for transporting many food nutrients such ad starch, protein and fats to their parts of the plant where they are needed;

(c) the mineral nutrients in the soil are carried by water to other parts of the plant where they are absorbed to perform various metabolic and physiological functions.

(d) Enzyme activities in the soil and plant takes place in the presence of water in the soil;

(e) All living organisms in the soil require some amount of water for survival and to Carry out life activities. Water is an important constituent of the plant cell. without water, plants cannot grow.

Solid particles - the soil is a mixture of solids such as sandstone , gravel , clay and limestone. The largest particles in the soil are the stones and with many such large particles, the soil cannot retain water for agricultural purposes.

Sand also forms coarse soil particles and therefore does not retain much water. Crops grown in such soils sometimes suffer from lack of water. The coarse solid particles however, prevent soil erosion because they are not easily washed away by water or blown away by wind. Sandstone contains silica which gives the soils its strength. Because of their large air spaces, coarse particles are well aerated and therefore extremely light. Clays on the other hand are not as coarse as sandstone or gravel. They retain water tenaciously. Crops grown on such soil are usually poor and tend to ripen slowly. Clays , however supply some mineral to the soil like kaolin and montmorilonite. Limestone contains lime and when present, gives the soil its alkaline reaction.

Dr. Patrick Ejike Chibike 0

Monday, 10 September 2018

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Prevention and Control of Water and Nutrient Losses in Soil

Friday, 7 September 2018

Water and Nutrient Losses

Wednesday, 5 September 2018

Fertilizers

Monday, 3 September 2018

Fallows and Cover Crops

Crop Rotation

Thursday, 30 August 2018

Types of Soil

Monday, 27 August 2018

Definition and Composition of Soil

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