The following farming practices have consequences or effects on the soil;
- BUSH BURNING
This involves setting fire to the bushes to clear out the vegetation
MERITS
- It releases potassium and phosphorus as ash
- It has a sterilising effect on the soil
- It stimulates the growth of fresh grass
- It destroys soil-borne pathogens or germs
- It destroys the seeds of weeds
DEMERITS
- It destroys the organic content of the soil
- It reduces the population of the soil’s live organisms
- It oxidises nitrogen and sulphur into gaseous forms
- It exposes the soil to erosion and leaching
- It may raise the PH level of the soil
- It causes environmental pollution
- It destroys the soil structure
- It reduces soil water content
- OVERGRAZING
Overgrazing is a situation where more animals than can be supported on a particular pasture are put there to graze.
MERIT
- More faeces are dropped, which could improve the fertility of the soil
- Weeds can easily be eradicated from such land.
DEMERITS
- It depletes the vegetative cover of the soil
- It causes poor growth and regenerative capacity of vegetation
- It exposes the soil to erosion
- It destroys soil structure
- It leads to soil compaction
- Compacted soil reduces water infiltration
- Pore spaces in the soil in the soil are reduced
- CLEAN CLEARING
This is the removal of the entire vegetation on a piece of land.
MERITS
- It gets rid of weeds from the land
- It may leave the land free of all obstacles
DEMERITS
- It leads to the disturbance or removal of topsoil
- It leads to ian ncrease evaporation of water
- It exposes the soil to erosion
- It leads to a reduction in organic matter
- It leads to a loss of soil nutrients
- It leads to leaching
- It destroys the soil structure
- FERTILIZER APPLICATION
This involves the application of a certain chemical substance to the soil to increase its fertility
MERITS
- It supplements nutrient content of the soil
- It enhances the productive capacity of the soil
- It increases the population of microorganisms in the soil
- It stimulates vegetation growth
DEMERITS
- Excessive application of fertilisers can cause soil acidity
- Excessive application can also reduce the activities of soil organisms
- Excessive application may also hinder the growth of crops
- ORGANIC MANURING
It involves the application of manure, e.g green manure, farm yard manure and compost manure to the soil to improve its fertility.
MERITS
- Organic manuring returns nutrients to the soil
- It improves the texture and structure of the soil
- It encourages the activities of soil organisms
- It improves the water temperature fluctuations in the soil
- It prevents soil erosion
- It improves water water-holding capacity of the soil
DEMERITS
- The process may lead to the introduction of pathogens to the soil
- It may have adverse effects on crops if not properly applied
- CROP ROTATION
Crop rotation is the system of farming whereby different crops are grown on the same piece of land year after year in a definite manner to maintain the fertility of the soil
MERITS
- It adds nutrients to the soil through nitrogen fixation
- It increases the yield of crops
- It controls the growth of weeds
- It maximises the use of available land
- It controls pests and diseases associated with the soil
- If controls erosion
CONTINOUS CROPPING
This involves the growing of crops on the same piece of land every year without the application of manure or fertilisers
MERITS
- It enables different crops to be grown and harvested
- It maximises the use of available land
DEMERITS
- It depletes soil nutrients
- It ensures the spread or multiplication of germs
- It ensures the multiplication of pests and parasites
- It results in low yields of crops
- FLOODING: It is defined as the accumulation of an abnormal large quantity of water in an area which refuses to percolate or flow away.
EFFECTS OF TILLAGE IMPLEMENTS ON THE SOIL
PLOUGHING
- It increases the soil organic matter content
- It helps to mix the soil
- It improves water infiltration capacity
- It improves the aeration of the soil
- It leads to compaction of the soil
- It spreads disease-causing organisms in the soil
HARROWING
- It leads to fine tilth through the mixing of soil
- It increases aeration and water infiltration
- It increases root penetration
- It leads to the destruction of soil structure
- It may lead to soil erosion
RIDGING
- It prevents erosion and improves water penetration
- It collects together rich topsoil
- It improves aeration and root penetration
- It improves water conservation in the soil
- It also facilitates the harvesting of root crops
EVALUATION
- List five effects of bush burning on the soil
- (a) Define Tillage
(b) Explain zero tillage
METHODS OF REPLENISHING LOST NUTRIENTS
- CROP ROTATION: It is a system of farming whereby different crops are grown on the same piece of land year after year in a definite manner to maintain the fertility of the soil.
The layout of a four-year crop rotation plan is shown in this table
YEAR | PLOT I | PLOT II | PLOT III | PLOT IV |
1 | Yam | Cowpea | Cassava | Maize |
2 | Cowpea | Cassava | Maize | Yam |
3 | Cassava | Maize | Yam | Cowpea |
4 | Maize | Yam | Cowpea | Cassava |
PRINCIPLES OF CROP ROTATION
- Deep-rooted crops like yams and cassava should not follow each other
- Shallow-rooted crops should not follow each other
- Crops which have the same diseases should not follow each other
- Crops which have the same pests should not follow each other
- Crops of the same family should not follow each other
- Crops which control weeds should be planted
- Legumes should be included in crop rotation
CONDITIONS NECESSARY FOR THE PRACTICE OF CROP ROTATION
- Where land is scarce or limited in supply
- Where the population is high
- The need to have different varieties of crops
- The need to maintain soil fertility
- Where the soil is exhausted of nutrients
- ORGANIC MANURING
Organic manure refers to the decomposed plant and animal products which have been carefully prepared to supply nutrients to plants or crops.
- BUSH FALLOWING
This is the practice in which farmlands are left to lie fallow after one or two years of cultivation to allow the nutrients to revert to the soil.
- COVER CROPING
It is the process of planting certain plants mainly to cover the soil surface to conserve the soil nutrients.
Some common examples of cover crops are: mucuna pueraria, centro, clotalaria, calapogonium and cowpea
- LIMING
It is the process whereby Calcium or magnesium-containing compounds are added to the soil to reduce soil acidity. Some common liming materials are: limestone, quicklime, slaked lime, basic slag, dolomite, gypsum, wood, ash, etc.
- APPLICATION OF INORGANIC FERTILIZERS
Fertilisers are chemical substances in the form of powder, granules, pellets, or crystals which can be added to the soil to increase fertility.
EVALUATION
- What is crop rotation?
- List five principles of crop rotation
FACTORS INFLUENCING NUTRIENTS
Availability in the soil
- Soil PH
- Concentration of other nutrients
- Leaching
- Crop removal
- Oxidation and Reduction of organic materials
- Burning
- Soil Texture
- Erosion
- Soil moisture content
- Level of Organic matter/microorganisms in the soil
WAYS IN WHICH SOIL NUTRIENTS CAN BE LOST
- Crop removal
- Erosion
- Leaching
- Soil Acidity
- Excess of other nutrients
- Oxidation and reduction of organic materials
GENERAL EVALUATION
- What is Bush burning?
- State the merits of bush burning
- What is crop rotation?
- List five principles of crop rotation
- State four effects of ploughing on the soil
WEEKEND ASSIGNMENT
- The following are pre-planting activities except (a) ploughing, (b) bush clearing, (c) harrowing, (d) thinning
- The following are types of manure except (a) green manure, (b) farm yard manure, (c) NPK, (d) compost
- The following are methods of fertiliser application except (a) broadcasting, (b) ring method, (c) Top dressing, (d) erosion
- The following are liming materials except (a) limestone, (b) Ure,a (c) quicklime (d) slaked lime
- Nutrients are lost through the following means except (a) crop removal, (b) Erosio,n (c) leaching, (d) mulching
SECTION B
- (a) State four demerits of bush burning
(b) State four uses of lime in Agriculture
- (a) Define soil organic matter
(b) State five ways in which soil organic matter is important in Agriculture.
See also
PLANT NUTRIENTS AND NUTRIENT CYCLES