Ways through which soil nutrients are lostSoil nutrients are lost in many ways. The most common ways of soil nutrient loss
1. Leaching 4. Erosion
2. Crop removal Burning 5. Oxidation and reduction
(a) Leaching: This is the removal of nutrients out of the reach of lant roots by percolating water. It is common in areas wilh heavy rainfall, loose soil particles and sparse vegetation.
Primary nutrients such as nitrogen, phosphorus and potassium are lost under hash rainfall condition. they dissolve easily in water. So leaching is a natural way whereby the soil losses it's nutrient
(b) Crop removal: Soil nutrients are used by crops for growth and development. Farmers harvest the crops as tubers, seeds, fruits and vegetables. These are used by man for food and other purposes. The nutrients taken up by plants are lost completely from the soil. This is because the harvested parts of crops are not returned to the soil through decay. So harvesting crops and not trying to turn the residue of the crops that are harvested into organic manure or compost farmyard manure tends to lose the nutrients of the soil
(c) burning: The burning of vegetation reduces soil fertility. This is because it exposes the surface of the soil to the agents of erosion such as water and wind.
However, burning during farmland preparation can be used to control weeds. It eases the working condition of new farmland. The soil is sterilized. Soil acidity is reduced due to the presence of ash that contains alkali metals such as potassium, calcium, and magnesium.
(d) Erosion: Soil erosion causes loss of soil nutrients. When the top soil of farmland is removed by water or wind, the available plant nutrients are lost. Erosion is common in soil that is not covered by vegetation.
(e) Oxidation and reduction: Oxidation and reduction reactions in the soil lead to loss of soil nutrients. For example ammonium radicals in the soil can be oxidised to give ammonia gas. Nutrients such as nitrates may be reduced to nitrogen gas or nitrogen dioxide gas. The gases go into atmosphere resulting in loss of fertility.
These are agents or circumstances that hasten or fasten the loss of nutrients from the soil. The Factors affect the ways the nutrients in the soil can be removed. The factors are:
1. The nature of the land or slope of the land.
2. The nature of soil, and
3. Vegetative cover.
4. Cultivation practices.
(a) Slope of the land: The slope determines the speed at which water carries away particles. Soil particles contain nutrients which are used by plants. The nutrients arc removed faster in areas with steep slope than tho'se with gentle slope. In most cases, the nutrients are washed to the lowland or valleys.
(b) Nature of soil: The nature of soil in an area plays a role in the extent of nutrient losses that mav occur. The soil in an area may be sandy, clayey or loamy. Sandy soil has loose particles and little organic matter and therefore easily leached by rainfall Erosion is higher where the soil is sandy.
Clay and loamy soils have more organic matter and cohesion. The nutrients in these soil are not easily leached wind and water erosion are less.
(c) Vegetative cover: When the soil is covered by plants, the rate of nutrient loss is less. This is because the vegetation reduces the impart of rain-drops and wind. The speed of run-off water is reduced thereby preventing the development of gullies. The roots of plants help to bind soil particles. The temperature of the soil is also regulated as a result of the cover. Above all, the dead vegetative cover crop adds organic matter to the soil, which is a major source of plant food. Where the soil lacks vegetative cover, it is exposed to wind and water that can carry away soil particles and nutrients. Micro-organisms in the soil are reduced because of lack of organic matter. The soil is subjected to wide temperature fluctuation.
(d) Cultivation practices: Continuous cropping leads to exhaustion of soil nutrients while over tillage exposes the soil to easy erosion hy water and wind.
3.2 Soil erosion
Erosion is the removal or wearing away of the surface soil by different agents. These agents are:
1. Water 4. Ice
2. Wind 5. Man.
However, water is the major agent of erosion in Nigeria.
The process of erosion involves three stages.
1. Types of soil erosion
There are four types of soil erosion depending on how the erosion occurs. These are:
1. Splash or raindrop erosion.
2. Sheet erosion.
3. Rill erosion.
4. Gully erosion.
(a) Splash or raindrop erosion: This is the first stage of the erosion caused by rainfall. It is the removal of soil particles by little raindrops. The soil particles scattered by raindrops block the soil pores. This will make it difficult for the rain water to the soil. The result is that the water will begin to flow gradually on the surface of the soil.
(b) Sheet erosion: Sheet erosion follows splash. It occurs when raindrops cause soil particles to block soil pores. Rain water hen Hows slowly over the soil surface. The soil particles are then removed or carried away evenly. This can also be caused by wind. The wind blowing over the soil that is exposed can carry away soil particles uniformly and deposit them somewhere else
(c) Rill erosion: Sheet erosion develops into rill erosion. This occurs when raindrops on the soil surface cause gradual removal of soil particles in suspension along narrow channels.
The channels may be existing before^They could be caused by the rain water itself. The size of the "channels, or rills becomes larger because of downward cutting. This eventually leads to gully erosion.
(d) Gully erosion: Channels that cannot be smoothened out by ordinary cultivation are referred to as gullies. Gully erosion takes place when rain water does not sink into the soil, it therefore runs off over the land. The soil panicles being carried by the rain water help to cut deeper and deeper into the soil. Sudden drop in slope or channel increases the cutting power of the water. Where the land is very slopy and the soil loose, large gullies are easily formed.
2. Prevention and control of erosion
Prevention and control of erosion can be achieved through the following practices:
(a) Covering the land with vegetation: Covering the soil with plants prevents'the soil from being exposed to agents of erosion such as water and wind. The planting of cover crops is to maintain adequate ground cover. Soil fertility is also increased because of leaf fall. Water infiltration is encourage and run-off is reduced because of the vegetative cover.
(a) Crop rotation: A well designed crop rotation ensures that the land is always protected against erosion. Where legumes are included in the rotation, they help to control erosion because they Miirad over the soil surface.
(c) Application of organic and inorganic manures: The addition of compost and farm yard manures make the soil cohesive and absorb water.' They also add plant nutrients to the soil. The addition of lime fertilizers such as calcium triococarbonate (IV) to the soil causes loose soil particles to be bound together. This improves the structure of the soil and the soil cannot be carried a|way easily whether by water or wind.
(d) Mulching: This involves covering the soil with mulch materials such as papers, grasses and stones. It prevents direct contact tween the soil and raindrops.
Mulching increases water infiltration and reduces sheet erosion. Where mulching is done with plant materials, organic is added to the soil. This helps to bind loose soil particles together.
(e) Preventing bush burning: Setting the bush on fire destroys the coverings for the soil. During bush burning, organic matter and many agriculturally important living organisms are destroyed. The soil is therefore exposed to agents of erosion. Where bush burning is avoided, the organic matter and micro-organisms present help to improve the soil structure and control erosion.
(f) Preventing overgrazing: Overgrazing of pasture or field could occur if animals are allowed to remain for a long time on the same land. Almost every vegetation in such a place is eaten up stud will not have time to grow again. Such land is exposed to piosion agents. The feet of animals also destroy soil structure and cause the formation of hard layers or hard pans below the soil surface. This makes infiltration difficult and increases surface run-off. Overgrazing by farm animals should therefore be avoided.
(g) Establishment of wind breaks: The planting of trees prevents pitision by acting as wind breaks. This is a good erosion preventive measure especially in the Savannah regions and where the soil is sandy.
(h) Contour strip cropping: This involves the growing of close ginning plants such as grasses and row crops such as maize in alternate strips across the slope of the land. This ensure adequate cover for the land. It therefore reduces the speed of moving water and its load.
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HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
3. 52. SOIL MICRO-ORGANISMS
4. ORGANIC MANURING
5. FARM YARD MANURE
8. CROP ROTATION
9. GRAZING AND OVER GRAZING
10. IRRIGATION AND DRAINAGE
11. IRRIGATION SYSTEMS
12. ORGANIC MANURING
13. FARM YARD MANURE
16. CROP ROTATION
17. GRAZING AND OVER GRAZING
18. IRRIGATION AND DRAINAGE
19. IRRIGATION SYSTEMS
21. MILKING MACHINE
22. SIMPLE FARM TOOLS
23. AGRICULTURAL MECHANIZATION
24. THE CONCEPT OF MECHANIZATION
25. PROBLEMS OF MECHANIZATION
26. SURVEYING AND PLANNING OF FARMSTEAD
27. IMPORTANCE OF FARM SURVEY
28. SURVEY EQUIPMENT
29. PRINCIPLES OF FARM OUTLAY
30. SUMMARY OF FARM SURVEYING
31. CROP HUSBANDRY PRACTICES
32. PESTS AND DISEASE OF MAIZE- ZEA MAYS
33. CULTIVATION OF MAIZE CROP
34. OIL PALM
35. USES OF PALM OIL
36. MAINTENANCE OF PALM PLANTATION
39. PROCESSES IN COCOA CULTIVATION
HOLING AND LINING
41. LAND PREPARATION FOR YAM
42. DEPT OF PLANTING
43. SPACING OF YAM
44. PLANTING DEPT OF YAM
45. STORAGE OF YAM
46. STAKING OF YAM
47. HARVESTING OF YAM
49. FORAGE CROP AND PASTURE
50. FORAGE GRASSES
53. TYPES OF PASTURE
COMMON GRASSES AND LEGUMES
56. ESTABLISHMENT OF PASTURES
57. 201. FORAGE PRESERVATION
58. HAY SILAGE
59. FORESTRY IMPORTANCE OF FORESTRY 206. FOREST MANAGEMENT FOREST REGULATION DEFORESTATION AFFORESTATION
60. DISEASES AND PESTS OF CROPS
61. MAIZE SMUT
62. RICE BLAST
63. MAIZE RUST
64. LEAF SPOT OF GROUNDNUT
65. COW-PEA MOSAIC
66. COCOA BLACK POD DISEASE
68. CASSAVA BACTERIA BLIGHT
69. BLACK ARM BACTERIA BLIGHT OF COTTON
70. TOMATO ROOT KNOT
71. DAMPING-OFF OF TOMATO
72. ONION DOWNY MILDEW
73. STORED PRODUCE MOULD
74. PESTS OF CROPS
75. STEM BORERS
76. ARMY WORM
77. COCOA MIRIDS(CAPSIDS)
79. WHITE FLY SEED BUGS
80. CASSAVA CULTIVATION
81. CASSAVA MEALYBUGS
82. VARIEGATED GRASSHOPPER
83. GREEN SPIDER MITE
84. COTTON STAINER
86. PESTS OF VEGETABLES
89. LEAF ROLLER
90. BEAN BEETLE
91. RICE WEEVILS
92. . PROBLEMS WITH PESTS CONTROL
93. CROP IMPROVEMENT
94. PROCESS OF CROP IMPROVEMENT METHODS OF CROP IMPROVEMENT
95. HYBRIDIZATION OF CROPS
96. ANIMAL PRODUCTION
97. THE DIGESTIVE SYSTEM OF ANIMALS
98. THE LARGE AND SMALL INTESTINE
99. RUMINANT ANIMALS
100. THE NERVOUS SYSTEM
101. THE NEURONS
102. A SYNAPSE ACTION IMPULSE REFLEX ACTION VOLUNTARY ACTION
103. THE CENTRAL NERVOUS SYSTEM
104. PERIPHERAL NERVOUS SYSTEM
105. THE REPRODUCTIVE SYSTEM MALE AND FEMALE REPRODUCTIVE SYSTEM
106. REPRODUCTIVE SYSTEM OF BIRDS
107. THE CIRCULATORY SYSTEM
108. THE PULMONARY CIRCULATION
109. THE HEART
110. THE RESPIRATORY SYSTEM
111. THE TRACHEA INSPIRATION THE EXPIRATION THE DIAPHRAGM
112. HEAT PERIODS OESTROUS CYCLE
115. MAMMARY GLAND
117. EGG FORMATION IN POULTRY
118. LIVESTOCK MANAGEMENT
119. MANAGEMENT OF GOATS
120. REPRODUCTION IN GOAT
122. POULTRY MANAGEMENT
123. BATTERY CAGE SYSTEM
124. INTENSIVE SYSTEM
125. . SEMI-INTENSIVE EXTENSIVE SYSTEM
PROODING AND REARING IN POULTRY
126. POULTRY SANITATION
127. ANIMAL NUTRITION
131. NUTRIENT SOURCES AND FUNCTIONS
133. PROTEIN FATS
136. FEEDING MECHANISMS IN HOLOZOIC ORGANISMS
137. TYPES OF DIETS
138. FATTENING OR FINISHING DIETS
139. LAYER DIETS
140. BALANCED DIETS
141. LACTATION DIETS
143. DISEASE, CAUSES, SYMPTOM CORRECTION
144. RANGE MANAGEMENT AND IMPROVEMENT
145. LIVESTOCK DISEASES
146. VIRAL DISEASES
147. RINDER PESTS
148. NEWCASTLE DISEASE
149. BACTERIA DISEASES
153. FUNGAL DISEASES
154. PROTOZOAN DISEASES
157. RED WATER FEVER(PIROPLASMOSIS)
158. ENDO PARASITES
159. TAPE WORM
160. ROUND WORM OF PIGS
161. LIVER FLUKE
162. ECTO PARASITES
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