KCSE ONLINE

Esoma Online Revision Resources

Soil Fertility - Agriculture Form 1

Soil Fertility: Organic Manures

Lesson Introduction

In the previous lesson you learnt about the supply of water to plants as nutrient.

If one nutrient needed is in low supply, plant growth is limited and crop yield are reduced.

A soil which is able to supply the plant with their nutritional requirements adequately is said to be fertile.

Soil fertility is therefore ability of the soil to support and sustain crop growth in order to get maximum yields in a farming system.


Maize grown in fertile soil





Glossary
Soil fertility
: - ability of the soil to support and sustain crop growth in order to get maximum yields indefinitely
Leaching
:- carrying down of soluble minerals from the top soil by infiltrating water beyond reach by plant roots
Soil erosion
:-carrying away of top fertile soil
Monocropping
:- practice of growing one type of crop on a piece of land over a long time
Crop rotation:- practice of growing different crops on same field in an orderly sequence.
Sequence of crop rotation

Maize 1st season

Beans 2nd season

Potatoes 3rd season

Grass 4th season

Inorganic fertilizers:-chemical compounds that are manufactured to supply specific plant nutrients.
Organic manures:- these are fully decomposed organic substances from plant and animal remains added to the soil to provide one or more nutrients
Humus:- end product of decomposition which is mostly dark in colour.
Green manure:-type of manure made of green plants when fully decayed.
Farmyard manure:- is a mixture of fully decomposed animal waste (urine and dung) and crop residues used as animal bedding in animal houses.
Compost manure:- manure prepared from compost (heaped) organic materials.


Soil Fertility: Organic Manures

Lesson Objectives

By the end of the lesson, you should be able to:-

  • define soil fertility
  • distinguish between organic matter and manure
  • explain how soil fertility can be maintained
  • explain how soil looses fertility
  • explain the importance of organic matter in the soil
  • describe the different organic manure well
  • prepare compost manure.

Soil Fertility: Organic Manures

Characteristic of fertile soil

  • Problems of manures
  • Importance of manures
  • Importance of organic matter
  • Ways in which soil loose/gain fertility
  • Green manure
  • Farm yard manure

  • Compost manure

What is soil fertility ?

Ability of the soil to support and sustain crop growth in order to get maximum yields indefinitely.

Maintaining soil fertility is important for sustaining production in a given field.

Maintaining soil fertility involves balancing plant nutrients using various production practices like crop rotation

What is crop rotation?

Crop rotation is practice of growing different crops on same field in an orderly sequence over given period of time. This is one way of maintaining soil fertility

Soil Fertility

Characteristics of a fertile soil

Good depth


Deep soil gives plant roots greater volume to obtain plant nutrients and provide strong anchorage 

Proper drainage

A well drained soil is properly aerated promoting healthy root development. Well aerated soils allow root respiration and reduce the build up of carbon dioxide to toxic levels. 

Good water holding capacity:-
This ensures that enough water is retained for plant use.
Adequate nutrient supply:-
It should supply the nutrients needed by plants in the correct
amount and in a form that is available to the crop

Correct soil pH:-
Different crops have different soil pH requirements. Certain plant nutrients are only available at a specific soil pH. 

Free from soil borne pests and diseases like



Maize suffering from head smut disease

Ways of maintaining soil fertility

  • Irrigation
  • Crop rotation
  • Proper drainage
  • Weed control
  • Use of manure
  • Mixed cropping
  • Control of soil PH

Use of manure


A farmer supplying inorganic fertilizer in a crop field

Ways of losing soil fertility

  • Soil erosion
  • Leaching
  • Monocropping
  • Salt accumulation
  • Change of soil PH

Burning vegetation


Burning vegetation kills micro organisms and destroy humus

Organic Manures

Soil fertility is usually improved by use organic manure.


 

Humus- end product of decomposition which is mostly dark in colour.

Organic manure.

These are fully decomposed organic substances from plant and animal remains added to the soil to provide one or more nutrients.

 

Advantages and disadvantages of organic manures.
 

Advantages

Are readily available and cheap

Add plant nutrients to the soil

Do not pollute the soil

Improve water holding capacity of the soil

Prevent soil from being overheated

Support life of tiny animals living in the soil.

Disadvantages

Manures are bulky to handle

Some crop diseases, pests and weeds may be spread through manures

A lot of labour is required to apply manure onto a farm

Types of organic manure

There are three types of organic manure namely:

  • Farm yard manure
  • Compost manure
  • Green manure

Farm yard manure

Farm yard manure is made up of animal wastes and bedding from animal houses



Factors which affect the quality of farm yard manure are :-

  • Type of litter used
  • Age of manure
  • Age of animal
  • Method of storage
  • Type of animal
  • Type of feed given to the animal

Havesting materials for green manure
preparation

Factors which affect the quality of green manure

  • Type plant material
  • Age plant growth
  • Fertility of the area where material were grown

Order this CD Today to Experience the Full Multimedia State of the Art Technology!

For Best results INSTALL Adobe Flash Player Version 16 to play the interactive content in your computer. Test the Sample e-Content link below to find out if you have Adobe Flash in your computer.

Sample Coursework e-Content CD

Other Goodies for KCSE ONLINE Members!

Coursework e-Content CD covers all the topics for a particular class per year and costs 1200/- ( Per Subject per Class ).

Purchase Online and have the CD sent to your nearest Parcel Service. Pay the amount to Patrick 0721806317 by M-PESA then provide your address for delivery of the Parcel. Alternatively, you can use BUY GOODS TILL NUMBER 827208 Ask for clarification if you get stuck.

Install ADOBE Flash Player for Best Results

For Best results INSTALL Adobe Flash Player Version 16 to play the interactive content in your computer. Test the link below to find out if you have Adobe Flash in your computer.

Search

Subject Menu