CLASS : JSS2
SUBJECT : AGRICULTURAL SCIENCE
TERM : FIRST TERM E-NOTE
WEEK : WEEK 3
TOPIC: SOIL FERTILITY AND MANAGEMENT.
Contents: 1. Meaning of soil fertility
2. Methods of soil fertility management
(Advantages and disadvantages of each methods) .
SUB TOPIC 1:MEANING OF SOIL FERTILITY.
Soil fertility is the capacity of the soil to supply soil mineral nutrient or elements to crop in adequate amounts and in suitable proportions to enhance crop production.
A fertile soil is that which contains adequate nutrient elements required by crops .
CHARACTERISTICS OF A FERTILE SOIL.
1. High cat ion exchange capacity.
2. Good water holding capacity.
3. Adequate humus contents
4. Good granular (spheroidal) structure.
5. Good workability.
6. Essential elements available in required amount.
1. Differentiate between soil fertility and fertile soil
2. What are the characteristics of a fertile soil?
SUB TOPIC 2: METHODS OF SOIL FERTILITY MANAGEMENT.
There are several methods that can be used to maintain the fertility of the soil. They include bush fallowing, cover cropping, rotation cropping, application of organic and inorganic fertilizers.
BUSH FALLOWING: This is the practice of leaving a farm land uncultivated for a period of time. This is to allow the soil tore gain its lost nutrients in a natural form.
1.It is an effective method in area with low pressure on land.
2. It protects the soil against erosion.
3. Fallen leaves decompose to increase organic matter content of the soil.
4. The method reduces evaporation of water and leaching of minerals are reduced.
5. Living organisms are build up in the soil which help in soil modification and
1. It is very slow method of maintaining soil fertility.
2. If the period for fallow is not enough ,the adequate replacement of lost nutrients will
not be achieved.
3. It can not be used in places where there is high demand on land.
1. List four methods of maintaining soil fertility
2. Explain the term bush fallowing
3. State two advantages and two disadvantages of bush fallowing
COVER CROPPING: This is the growing of crops purposely to provide a cover for the soil. Crops such as melon, cowpea, groundnut, sweat potatoes can be grown for this purpose. They are grown along side with the main crops to provide a cover for the soil.(pueraria, mucuna, and centrosema can be used in plantation.)
1.They protect the soil against erosion.
2. It reduces evaporation of soil water.
3. It prevent leaching.
4. Cover crops suppress weeds on the farm land.
5. Where legumes are used ,they help to increase the nitrogen content of the soil.
6. Their falling leaves decompose to add organic matter to the soil.
1. Cover crops compete with the main crops for nutrient and water.
2. They increase the rate of loss of water in the soil through transpiration.
ROTATION CROPPING:This is the growing of crops on a piece of land year after year in a definite order.
1. The method make for continuous use of land without rapid loss of essential nutrients.
2. It is an ideal method to use where land is scarce.
3. It is a labour saving method as the same land is used every year.
4. Weed are effectively checked.
5. It reduces erosion.
1. Continuous tillage of the surface soil renders it loose and easily eroded.
ORGANIC MANURING: Manures are plants and animals materials that are added to the soil to supply nutrients needed for the growth of crops. There are three types of organic manure, green manure, farm yard manure and compost manure.
GREEN MANURE: These are un-decomposed green plants parts which are turned into the soil. Plants to be used as green manure should be, easily establish, grow quickly, produce abundant succulent shoots and roots in a short time, easily cover the ground and grow on poor soils.
1. It supply plant Nitrogen and other nutrients
2. It protect the soil against erosion.
3. It reduces the loss of nutrients through leaching.
4. It improve the physical condition of the soil.
1. They may habour diseases and pests of crop plant
2 . It may be expensive to grow green manure plants
FARM YARD MANURE: It is a mixture of animal droppings, urine, food remains and beddings or litter. The materials are heaped under a shed to decompose for sometimes before used.
1. It contain all the required plant nutrients.
2. It is cheap.
3. It has a lasting effect on the soil.
4. It binds loose sandy soil together.
5. It loosens compact clay soil.
6. It enables the soil to absorb and retain moisture easily.
1. It is very bulky.
2. It can encourages rapid growth of weeds
3. It required much labour during application.
COMPOST MANURE: This is the decayed plant and animal remains in heaps or stacks or pit, used as manure on the farm. The materials needed for compost making include grass cutting, hedge trimmings, weeds, vegetable wastes leaves and other organic wastes from kitchen. Ash, lime or animal dung ,old compost and chemical activators such as sulphate of ammonia are also added. Young succulent plant parts should be used instead of woody and tough parts. This is because decomposition is easier and contains much nutrients for healthy plant growth.
METHODS OF COMPOST MAKING: There are two methods of making compost, pit method and heap (stack) method
The pit method is used in area of low rain fall or in the dry season while the heap method is used in high rainfall areas or during the rainy season. In both method, however, the same processes as well as the materials used remain the same.
PROCESS OF COMPOST MAKING
1. Dig four pit or peg out four areas.
2. Add kitchen wastes, yam peelings, orange skins and pulp, rotten fruits and anything that can rots easily. (starter)
3. Add grass cuttings, hedge trimmings vegetable wastes and compress.
4. Repeat this process until the pit is filled or the desired height is reached
5. Cover the top with soil to prevent the entrance of flies.
6. Insert a stick at one end or at the centre in case of pit method(tester). It detects weather the decomposition is going on or not. The stick will be hot if the there is decomposition after about five days.
7. Turn materials or the content of the pit A or heap A into B after two weeks. Repeat this step until pit or heap D is reached and the desired quantity obtained.
8. Cover the final product with suitable materials until it is needed for use.This will prevent the loss of important nutrients due to strong sun or rain water.
ADVANTAGES OF COMPOSE MANURE.
1. It adds nutrients to the soil for increased crop yield.
2. It improves the structure and texture of the soil.
3. It help to maintain equal amounts of acid and base contents of the soil.
4. It help to conserve soil moisture and prevent soil erosion.
5. It provides sources of food to living organisms in the soil. E. g earthworms, termites and microbes.
6. It has a modifying effect on soil temperature.
1. It involves much labour in preparation.
2. It could cause scorching if applied when not fully mature.
3. It may introduce disease causing agents.
4. It is time involving and not economical for use in large farms.
APPLICATION OF INORGANIC MANURE(FERTILIZER)
Inorganic manure are chemical substances in form of powder, granules or crystals which are added to the soil to provide nutrients that are deficient. Fertilizers are manufacture in the industry from rocks and other materials.
TYPES OF FERTILIZER
There are two types of fertilizer
1. SINGLE/SIMPLE/STRAIGHT FERTILIZERS: These are fertilizers that contain one of the major plant nutrients in the form plants can use. They contain one primary element such as nitrogen , potassium and phosphorous in their composition.
2. MIXED / COMPOUND/COMPLEX FERTILIZERS: These are fertilizers that contain two or more primary nutrient elements plus filler materials.
METHODS OF APPLYING OF FERTILIZERS
1. Broadcasting : This is where fertilizer is evenly spread on the farm land. It could be done during tillage operation to incorporate it into the soil .
2. Side dressing: This is where small quantity of fertilizer is placed on one or two sides of individual crop.
3. Ring placement: Here a shallow trench is dug round individual crop a few centimetres away from the stem ,fertilizer is then sprinkled in the trench and covered with soil.
4. Row placement: These is where fertilizer is applied in row few centimetres away from the crops. It is suitable when crops are planted in rows.
ADVANTAGES OF FERTILIZERS
1. They help to increase crop yield thus the farmer`s income.
2. They increase productivity of poor soil.
3. They are used on large scale farms.
4. They are ease to handle compared to organic manures.
5. The nutrients in fertilizers are readily available to crops.
Disadvantages of fertilizers:
1. Fertilizers are easily leached in the soil.
2. Some leave acidic residues in the soil.
3. They do not improve the structure of the soil.
4. They are expensive to produce.
5. Some of the nutrients may escape as gases under intense heat of the sun.
a) What is the difference between organic manure and inorganic manure?
b) List three methods of applying fertilizer.
c) Explain how to make compost manure.
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