soil fertility lecture in Zamzam University

This Agriculture Science presentation especially Soil fertility

1. Zam-zam university
Soil fertility
Date: 26/02/2024
Lecturer: sakeriye
09/19/24 Lecturer: sakeriye sh qasim
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2. Welcom
e back
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3. Introduction
Soil fertility is a vital aspect of agriculture and
plays a crucial role in determining the
productivity and sustainability of agricultural
systems. It refers to the ability of soil to provide
essential nutrients and favorable conditions for
plant growth and development. Soil fertility is a
complex and dynamic property influenced by
various physical, chemical, and biological
factors. Understanding soil fertility is essential
for farmers, agronomists, and researchers to
optimize crop production, conserve natural
resources, and promote sustainable agriculture.
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4. Definition of Soil Fertility
Soil fertility can be defined as the inherent
capacity of soil to supply essential nutrients,
water, and other favorable conditions necessary
for plant growth, reproduction, and overall
productivity. Fertile soil contains an adequate
and balanced supply of essential nutrients,
favorable soil structure, good water-holding
capacity, optimal pH levels, and a diverse and
active soil microbial community. These factors
contribute to the overall fertility of the soil and
support the growth of healthy and productive
crops.
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5. Importance of soil fertility in
agriculture
Nutrient Supply: Soil fertility is crucial for
providing an adequate supply of essential
nutrients to plants. Nutrients such as nitrogen
(N), phosphorus (P), and potassium (K) are
necessary for plant growth, development, and
overall productivity. Fertile soils contain a
balanced and sufficient supply of these
macronutrients and micronutrients, ensuring
that crops have the necessary elements for
optimal growth and yield.
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6. Cont..
Crop Productivity and Yield: Soil fertility
directly influences crop productivity and yield.
Fertile soils support vigorous plant growth,
leading to higher crop yields. Adequate nutrient
availability promotes optimal plant
development, including root growth, leaf
production, flowering, and fruiting. Well-
nourished plants are more resistant to diseases,
pests, and environmental stresses, resulting in
improved crop performance
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7. Cont….
Nutrient Uptake Efficiency: Soil fertility plays a
crucial role in nutrient uptake efficiency. Fertile
soils provide a favorable environment for
nutrient uptake by plant roots. A balanced
supply of nutrients in the soil ensures that
plants can take up essential elements in the right
proportions. This efficient uptake reduces
nutrient losses, minimizes fertilizer waste, and
improves the overall nutrient use efficiency of
agricultural systems.
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8. Cont..
Crop Quality: Soil fertility influences the quality
of agricultural products. Adequate nutrient
availability and a balanced nutrient supply
contribute to the synthesis of essential
compounds in plants, such as proteins,
carbohydrates, vitamins, and secondary
metabolites. These compounds affect the taste,
nutritional value, appearance, and marketability
of crops. Fertile soils can produce crops with
enhanced flavor, color, and nutritional content.
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9. Cont…
Soil Health and Sustainability: Maintaining soil
fertility is essential for soil health and long-term
sustainability. Fertile soils support a diverse and
active soil microbial community, including
beneficial bacteria and fungi. These
microorganisms play vital roles in nutrient
cycling, organic matter decomposition, disease
suppression, and soil structure improvement.
Healthy soils with good fertility are more resistant
to erosion, have improved water-holding capacity,
and exhibit better overall ecosystem function.
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10. Cont…
Environmental Impact: Soil fertility
management is crucial for minimizing negative
environmental impacts. By optimizing nutrient
management practices, farmers can reduce the
risk of nutrient runoff into water bodies, which
can lead to water pollution and eutrophication.
Balanced nutrient applications based on soil
fertility assessments help prevent excessive
fertilizer use and the associated environmental
consequences, such as greenhouse gas emissions
and contamination of groundwater.
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11. Cont..
Sustainable Agriculture: Soil fertility is a
cornerstone of sustainable agriculture. By
maintaining and improving soil fertility, farmers
can reduce their reliance on synthetic fertilizers
and minimize the environmental footprint of
agricultural practices. Sustainable soil fertility
management practices, such as organic farming,
conservation agriculture, and precision nutrient
management, promote long-term soil health,
biodiversity conservation, and ecosystem
resilience.
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12. Cont…
Economic Impact: Soil fertility directly impacts
agricultural profitability. Fertile soils with
optimized nutrient levels can lead to higher crop
yields, improved crop quality, and reduced
production costs. By maximizing productivity
and minimizing input waste, farmers can
enhance their economic returns and ensure the
viability and profitability of their farming
operations.
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13. Factors Influencing Soil
Fertility
Physical Factors
Soil Texture: Soil texture refers to the relative
proportions of sand, silt, and clay particles in the
soil. Sandy soils have larger particles and tend to
have good drainage but lower water and nutrient-
holding capacity. Clay soils have smaller particles
and hold water and nutrients more effectively but
can be poorly drained. Silt soils have intermediate
particle sizes. Soil texture affects the availability of
air and water in the soil, as well as the movement
and retention of nutrients.
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14. Soil Structure: Soil structure refers to the
arrangement of soil particles into aggregates or
clumps. Good soil structure allows for the
formation of pore spaces that facilitate water
infiltration, root penetration, and gas exchange.
It also promotes the movement of roots, soil
organisms, and nutrients. Soil compaction,
caused by factors such as heavy machinery or
excessive tillage, can degrade soil structure and
negatively impact fertility by reducing aeration
and water infiltration.
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15. Chemical Factors:
Soil pH: Soil pH is a measure of the acidity or
alkalinity of the soil. It affects nutrient
availability to plants as it influences the
solubility and chemical reactions of different
nutrients. Each plant species has an optimal pH
range for nutrient uptake. For example, acidic
soils with low pH may limit the availability of
essential nutrients like phosphorus, while
alkaline soils with high pH can lead to nutrient
deficiencies or toxicities. Adjusting soil pH
through practices like liming or acidification can
help optimize nutrient availability.
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16. Soil Organic Matter: Soil organic matter consists
of decomposed plant and animal residues. It
plays a crucial role in soil fertility by improving
soil structure, nutrient-holding capacity, and
water retention. Organic matter serves as a
source of nutrients, energy, and food for soil
organisms. It also enhances the cation exchange
capacity (CEC) of the soil, allowing it to retain
and release essential nutrients for plant uptake.
Increasing organic matter through practices like
adding compost, cover cropping, and reducing
tillage can enhance soil fertility.
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17. Biological Factors
Soil Microorganisms: Soil is teeming with
diverse microorganisms, including bacteria,
fungi, protozoa, and archaea. These
microorganisms play essential roles in soil
fertility. For instance, nitrogen-fixing bacteria
convert atmospheric nitrogen into plant-
available forms, contributing to nitrogen
fertility. Mycorrhizal fungi form symbiotic
relationships with plant roots, improving
nutrient uptake, especially phosphorus. Other
microorganisms decompose organic matter,
releasing nutrients, and participate in nutrient
cycling processes.
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18. Soil Fauna: Soil fauna includes organisms like
earthworms, nematodes, arthropods, and
insects. Earthworms enhance soil fertility by
ingesting soil and organic matter, processing it
through their digestive systems, and excreting
nutrient-rich casts. They also improve soil
structure by creating channels and burrows.
Nematodes, both beneficial and harmful,
influence nutrient cycling and plant health.
Arthropods contribute to organic matter
decomposition and nutrient release
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19. Properties of fertile soil
The ability to supply essential plant nutrients
and water in adequate amounts and proportions
for plant growth and reproduction; and
The absence of toxic substances which may
inhibit plant growth e.g Fe
2+
 which leads to
nutrient toxicity.
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20. The following properties contribute to soil fertility in most
situations:
Sufficient soil depth for adequate root growth
and water retention;
Good internal drainage, allowing sufficient
aeration for optimal root growth (although some
plants, such as rice, tolerate waterlogging);
Topsoil or horizon O is with sufficient soil
organic matter for healthy soil structure and soil
moisture retention;
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21. Cont…
Soil pH in the range 5.5 to 7.0 (suitable for most
plants but some prefer or tolerate more acid or
alkaline conditions);
Adequate concentrations of essential plant
nutrients in plant-available forms;
Presence of a range of microorganisms that
support plant growth.
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22. Fertilization
Fertilization is supplementing the existing soil
with additional, needed nutrients. Fertilizing
wisely increases yield, quality (nitrogen content
and digestibility), and profits.
There are three basic ways to replenish the
nutrients removed from the soil. One way is to
recycle nutrients, mainly by way of animal
waste.
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25. Chapter two :
Soil Properties
and
Classification
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26. Intro….
Soil properties refer to the characteristics and
attributes of soil that can be observed,
measured, and evaluated. These properties play
a crucial role in understanding soil behavior,
fertility, and suitability for various uses. Soil
classification, on the other hand, involves
categorizing soils into distinct groups based on
their properties and characteristics
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27. Intro….
This classification provides a systematic way to
organize and communicate information about
soils. Two fundamental aspects of soil properties
and classification are soil texture, structure, and
porosity, as well as soil horizons and profiles.
Additionally, various soil classification systems,
such as the USDA Soil Taxonomy and Soil
Orders, are used to classify soils on a broader
scale.
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28. Soil Texture
Soil Texture: Soil texture refers to the relative
proportions of sand, silt, and clay particles in the
soil. These particles vary in size, with sand being
the largest, followed by silt, and clay being the
smallest. Soil texture influences various soil
properties. Sandy soils, with their larger
particles, tend to have good drainage but lower
water-holding capacity
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29. Cont….
Clayey soils, with their smaller particles, have
higher water-holding capacity but may
experience poor drainage. Loamy soils, which
are a mixture of sand, silt, and clay, often have
an ideal balance of water retention and
drainage.
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30. Soil Structure:
Soil Structure: Soil structure refers to the
arrangement of soil particles into aggregates or
clumps. Soil aggregates are formed by the
binding together of individual particles. Well-
structured soils have well-formed aggregates,
which create spaces or pores between them.
These pores allow for the movement of air,
water, and roots through the soil
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31. Cont…
Good soil structure promotes aeration, root
penetration, and water infiltration, enhancing
plant growth and nutrient availability. Poorly
structured soils may have compacted particles
or dispersed aggregates, limiting root growth
and water movement.
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32. Soil Porosity
Soil Porosity: Soil porosity refers to the volume
of pore spaces or voids in the soil. These spaces
can be filled with air or water. Soil porosity is
influenced by soil texture, structure, and the
presence of organic matter. Macropores are
larger voids that allow for the movement of air
and water.
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33. Cont.>
They facilitate root growth, drainage, and the
exchange of gases. Micropores are smaller voids
that hold water tightly and are important for
water retention. A balance of macropores and
micropores is crucial for healthy soil
functioning, as it allows for both water
availability and drainage.
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34. Soil horizons and profiles
Soil horizons and profiles refer to the different
layers or horizons that make up the soil and
their arrangement in a vertical sequence. Each
horizon has distinct characteristics and plays a
crucial role in soil formation and fertility.
The maximum number of soil horizons can vary
depending on factors such as climate, parent
material, and time. In a mature soil profile, the
maximum number of horizons commonly
recognized is six. These horizons, listed from top
to bottom, are:
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35. O Horizon
(Organic Horizon): The O horizon is primarily
composed of organic matter, including
decomposed plant residues, leaf litter, and
humus. It is typically found in forests and areas
with abundant vegetation. The thickness of the
O horizon varies depending on factors such as
climate and vegetation type
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36. Characteristics of the O
Horizon:
Organic Matter: The O Horizon is rich in organic
matter, including dead plant material, leaves,
twigs, branches, and other organic debris. This
organic matter undergoes decomposition,
resulting in the formation of humus, which is a
dark, partially decomposed organic material.
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37. Cont…
Dark Color: The O Horizon is usually dark
brown or black in color due to the presence of
humus. The dark color is an indication of the
high organic content.
High Nutrient Content: The O Horizon is a
reservoir of nutrients. As organic matter
decomposes, essential nutrients such as
nitrogen, phosphorus, potassium, and
micronutrients are released into the soil, making
them available for plant uptake
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38. Functions of the O Horizon:
Nutrient Cycling: The organic matter in the O
Horizon plays a vital role in nutrient cycling
within the ecosystem. As it decomposes,
nutrients are released and become available for
plant uptake. This helps to maintain soil fertility
and supports the growth of vegetation.
Water Retention: The O Horizon has a high
water-holding capacity due to its organic
composition. It can absorb and retain moisture,
reducing surface runoff and promoting
infiltration into the deeper soil layers.
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39. Soil Structure Improvement: The presence of
organic matter in the O Horizon improves soil
structure by enhancing aggregation and
formation of soil aggregates. This improves the
soil's ability to hold water, resist erosion, and
provide a favorable environment for root
growth.
Organic Matter Accumulation: The O Horizon
acts as a reservoir for organic matter. As
vegetation and organic debris accumulate on the
soil surface, they contribute to the formation of
the O Horizon. Over time, the accumulation of
organic matter can lead to the development of
thicker O horizons.
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40. Management Considerations:
The O Horizon is sensitive to management
practices and can be influenced by human
activities such as deforestation, agriculture, and
land development. Clearing vegetation and
improper land management practices can lead
to the loss of the O Horizon, resulting in soil
erosion, reduced fertility, and decreased water-
holding capacity.
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41. Cont….
Conservation practices such as mulching,
composting, and minimizing soil disturbance
can help maintain and enhance the O Horizon.
These practices promote the accumulation of
organic matter, improve soil health, and
contribute to sustainable land management.
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42. A Horizon (Topsoil):
The A horizon is often referred to as the topsoil
and is crucial for plant growth. It is rich in
organic matter, minerals, and nutrients. The
texture of the A horizon can vary, ranging from
sandy to clayey, depending on the parent
material and weathering processes. This horizon
is where most plant roots are concentrated.
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43. Characteristics of the A
Horizon:
Organic Matter: The A Horizon contains varying
amounts of organic matter derived from the
decomposition of plant residues, roots, and
other organic materials. The amount of organic
matter in the A Horizon can vary depending on
factors such as vegetation type, climate, and
management practices
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44. Cont….
Mineral Particles: The A Horizon is composed
of mineral particles, including sand, silt, and
clay. The proportions of these particles
determine the soil texture, which influences
factors such as water-holding capacity, drainage,
and nutrient availability.
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45. Dark Color: The A Horizon is often darker in
color compared to the lower horizons due to the
presence of organic matter. The dark color
indicates a higher concentration of humus,
which contributes to soil fertility.
Nutrient Richness: The A Horizon is rich in
essential nutrients necessary for plant growth,
such as nitrogen (N), phosphorus (P), potassium
(K), and various micronutrients. These nutrients
are derived from organic matter decomposition,
weathering of minerals, and biological activity
within the soil.
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46. Twelve Soil Orders
The USDA Soil Taxonomy recognizes twelve
different soil orders, each representing a distinct
set of soil properties and formation processes.
Alfisols: These soils are characterized by a
relatively high clay content, a medium to high
fertility level, and a well-developed horizon
sequence. They are often associated with
deciduous forests and are found in temperate
regions.
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47. Andisols:
Andisols are volcanic ash-derived soils that have
unique properties due to their mineral
composition. They are typically young, fertile,
and have good water-holding capacity. Andisols
are often found in volcanic regions.
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48. Aridisols:
Aridisols are desert soils characterized by
limited rainfall and low organic matter content.
They have minimal leaching and may
accumulate salts and minerals due to
evaporation. Aridisols are commonly found in
arid and semiarid regions.
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49. Entisols:
Entisols are soils with little or no horizon
development. They are usually young, often
found in areas with recent geological processes
or where deposition and erosion are dominant.
Entisols are widespread and found in various
climates.
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50. Gelisols:
Gelisols are soils that are permanently or
seasonally frozen for significant periods. They
are typically found in cold regions, such as
tundra or permafrost areas, and are
characterized by the presence of gel-like
materials.
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51. Histosols:
Histosols are organic soils that have a high
organic matter content and are commonly
known as peat or muck soils. They form in
wetland environments where the accumulation
of undecomposed plant material exceeds
decomposition.
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52. Inceptisols:
Inceptisols are soils that exhibit some degree of
horizon development but have not fully
developed distinct horizons. They are typically
young and found in a wide range of
environments.
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53. Mollisols:
Mollisols are fertile grassland soils with a high
organic matter content. They have a dark color,
deep profile, and excellent agricultural
productivity. Mollisols are commonly found in
temperate and prairie regions.
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54. Oxisols:
Oxisols are highly weathered soils found in
tropical and subtropical regions. They are
characterized by a significant accumulation of
iron and aluminum oxides, low fertility, and a
lack of distinct horizons.
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55. Spodosols:
Spodosols are soils found in cool, humid regions.
They have a distinctive horizon sequence with
an accumulation of organic matter and iron and
aluminum oxides in the subsurface. Spodosols
are often associated with coniferous forests.
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56. Ultisols:
Ultisols are highly weathered soils found
primarily in warm and humid climates. They
have a clay-enriched subsurface horizon and are
typically acidic. Ultisols are commonly
associated with forests.
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57. Chapter 4: soil nutrients
Plants, like all other living things, need food for their
growth and development. Plants require 16 essential
elements. Carbon, hydrogen, and oxygen are derived
from the atmosphere and soil water. The remaining 13
essential elements (nitrogen, phosphorus, potassium,
calcium, magnesium, sulfur, iron, zinc, manganese,
copper, boron, molybdenum, and chlorine) are
supplied either from soil minerals and soil organic
matter or by organic or inorganic fertilizers.
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58. Cont…
For plants to utilize these nutrients efficiently, light,
heat, and water must be adequately supplied.
Cultural practices and control of diseases and
insects also play important roles in crop
production. Each type of plant is unique and has an
optimum nutrient range as well as a minimum
requirement level. Below this minimum level,
plants start to show nutrient deficiency symptoms.
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59. Excessive nutrient uptake can also cause poor
growth because of toxicity. Therefore, the proper
amount of application and the placement of
nutrients is important. Soil and plant tissue tests
have been developed to assess the nutrient
content of both the soil and plants. By analyzing
this information, plant scientists can determine
the nutrient need of a given plant in a given soil.
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60. Cont…
In addition to the levels of plant-available
nutrients in soils, the soil pH plays an important
role in nutrient availability and elemental
toxicity). This chapter describes the essential
nutrients, the chemical forms in which they are
available to plants, their function in plants,
symptoms of their deficiencies, and
recommended nutrient levels in plant tissues of
selected crops.
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61. Nitrogen
Symbol: N; available to plants as nitrate (NO3 –),
and ammonium (NH4 + ) ions.
Nutrient functions
• N is biologically combined with C, H, O, and S
to create amino acids, which are the building
blocks of proteins. Amino acids are used in
forming protoplasm, the site for cell division and
thus for plant growth and development.
• Since all plant enzymes are made of proteins, N
is needed for all of the enzymatic reactions in a
plant.
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62. • N is a major part of the chlorophyll molecule
and is therefore necessary for photosynthesis.
• N is a necessary component of several vitamins.
• N improves the quality and quantity of dry
matter in leafy vegetables and protein in grain
crops.
Deficiency symptoms
• Stunted growth may occur because of reduction
in cell division.
• Pale green to light yellow color (chlorosis)
appearing first on older leaves, usually starting at
the tips. Depending on the severity of deficiency,
the chlorosis could result in the death and/or
dropping of the older leaves.
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65. Phosphorus
symbol: P; available to plants as orthophosphate
ions (HPO4 2 –, H2 PO4 – ).
Nutrient functions
• In photosynthesis and respiration, P plays a
major role in energy storage and transfer as ADP
and ATP (adenosine di- and triphosphate) and
DPN and TPN (di- and triphosphopyridine
nucleotide).
• P is part of the RNA and DNA structures, which
are the major components of genetic
information.
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66. Cont…
• Seeds have the highest concentration of P in a
mature plant, and P is required in large
quantities in young cells, such as shoots and root
tips, where metabolism is high and cell division
is rapid.
• P aids in root development, flower initiation,
and seed and fruit development.
• P has been shown to reduce disease incidence
in some plants and has been found to improve
the quality of certain crops.
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67. Deficiency symptoms
• Because P is needed in large quantities during
the early stages of cell division, the initial overall
symptom is slow, weak, and stunted growth.
• P is relatively mobile in plants and can be
transferred to sites of new growth, causing
symptoms of dark to blue-green coloration to
appear on older leaves of some plants. Under
severe deficiency, purpling of leaves and stems
may appear.
• Lack of P can cause delayed maturity and poor
seed and fruit development.
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70. Potassium
symbol: K; available to plants as the ion K+
Nutrient functions
• Unlike N and P, K does not form any vital
organic compounds in the plant. However, the
presence of K is vital for plant growth because K
is known to be an enzyme activator that
promotes metabolism.
• K assists in regulating the plant’s use of water
by controlling the opening and closing of leaf
stomates, where water is released to cool the
plant.
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71. Cont…
• In photosynthesis, K has the role of
maintaining the balance of electrical charges at
the site of ATP production.
• K promotes the translocation of photosythates
(sugars) for plant growth or storage in fruits or
roots.
• Through its role assisting ATP production, K is
involved in protein synthesis.
• K has been shown to improve disease
resistance in plants, improve the size of grains
and seeds, and improve the quality of fruits and
vegetables.
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72. Deficiency symptoms
• The most common symptom is chlorosis along
the edges of leaves (leaf margin scorching). This
occurs first in older leaves, because K is very
mobile in the plant.
• Because K is needed in photosynthesis and the
synthesis of proteins, plants lacking K will have
slow and stunted growth.
• In some crops, stems are weak and lodging is
common if K is deficient.
• The size of seeds and fruits and the quantity of
their production is reduced.
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75. Calcium
symbol: Ca; available to plants as the ion Ca2+
Nutrient functions
• Ca has a major role in the formation of the cell
wall membrane and its plasticity, affecting
normal cell division by maintaining cell integrity
and membrane permeability.
• Ca is an activator of several enzyme systems in
protein synthesis and carbohydrate transfer.
• Ca combines with anions including organic
acids, sulfates, and phosphates. It acts as a
detoxifying agent by neutralizing organic acids in
plants.
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76. • Ca is essential for seed production in peanuts.
• Ca indirectly assists in improving crop yields by
reducing soil acidity when soils are limed.
Deficiency symptoms
• Ca is not mobile and is not translocated in the
plant, so symptoms first appear on the younger
leaves and leaf tips. The growing tips of roots and
leaves turn brown and die.
• Ca deficiency is not often observed in plants
because secondary effects of high acidity resulting
from soil calcium deficiency usually limit growth,
precluding expressions of Ca
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77. Deficiency of calcium
The symptoms of calcium deficiency often appear in
the new growth or developing fruit. Common signs
include stunted or distorted growth, yellowing or
browning of leaves, necrotic spots or patches on young
leaves, and blossom end rot in fruits (characterized by
dark, sunken, and rotten areas on the blossom end). In
severe cases, plant tissues may become weak and
susceptible to diseases.
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80. Magnesium
symbol: Mg; available to plants as the ion Mg2+
Nutrient functions
• The predominant role of Mg is as a major
constituent of the chlorophyll molecule, and it is
therefore actively involved in photosynthesis.
• Mg is a co-factor in several enzymatic reactions
that activate the phosphorylation processes.
• Mg is required to stabilize ribosome particles and
also helps stabilize the structure of nucleic acids.
• Mg assists the movement of sugars within a
plant.
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81. Deficiency symptoms
• Because Mg is a mobile element and part of the
chlorophyll molecule, the deficiency symptom of
interveinal chlorosis first appears in older leaves.
Leaf tissue between the veins may be yellowish,
bronze, or reddish, while the leaf veins remain
green. Corn leaves appear yellow-striped with
green veins, while crops such as potatoes,
tomatoes, soybeans, and cabbage show orange-
yellow color with green veins.
• In severe cases, symptoms may appear on
younger leaves and cause premature leaf drop.
• Symptoms occur most frequently in acid soils and
soils receiving high amounts of K fertilizer or Ca.
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84. Sulfur
symbol: S; available to plants as the sulfate ion,
SO4 2–
Nutrient functions
• S is essential in forming plant proteins because
it is a constituent of certain amino acids.
• It is actively involved in metabolism of the B
vitaminsbiotin and thiamine and co-enzyme A.
• S aids in seed production, chlorophyll
formation, nodule formation in legumes, and
stabilizing protein structure.
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85. Deficiency symptoms
• Younger leaves are chlorotic with evenly,
lightly colored veins. In some plants (e.g., citrus)
the older leaves may show symptoms first.
However, deficiency is not commonly found in
most plants.
• Growth rate is retarded and maturity is
delayed.
• Plant stems are stiff, thin, and woody.
• Symptoms may be similar to N deficiency and
are most often found in sandy soils that are low
in organic matter and receive moderate to heavy
rainfall.
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88. Boron
Symbol: B. Available to plants as borate, H3 BO3
Nutrient functions
• B is necessary in the synthesis of one of the
bases for RNA formation and in cellular
activities.
• B has been shown to promote root growth.
• B is essential for pollen germination and
growth of the pollen tube.
 • B has been associated with lignin synthesis,
activities of certain enzymes, seed and cell wall
formation, and sugar transport.
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89. Deficiency symptoms
• Generally, B deficiency causes stunted growth, first
showing symptoms on the growing point and younger
leaves. The leaves tend to be thickened and may curl and
become brittle.
• In many crops, the symptoms are well defined and crop-
specific, such as:
• peanuts: hollow hearts
• celery: crooked and cracked stem
• beets: black hearts
• papaya: distorted and lumpy fruit
• carnation: splitting of calyx
 
 
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93. Copper
symbol: Cu; available to plants as the ion Cu++
 Nutrient functions
• Cu is essential in several plant enzyme systems
involved in photosynthesis.
• Cu is part of the chloroplast protein
plastocyanin, which forms part of the electron
transport chain.
• Cu may have a role in the synthesis and/or
stability of chlorophyll and other plant
pigments.
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94. Deficiency symptoms)
• Reduced growth, distortion of the younger
leaves, and possible necrosis of the
apicalmeristem.
 • In trees, multiple sprouts occur at growing
points, resulting in a bushy appearance. Young
leaves become bleached, and eventually there is
defoliation and dieback of twigs.
• In forage grasses, young leaf tips and growing
points are affected first. The plant is stunted and
chlorotic.
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96. Chapter : five
Soil PH and
organic
matter
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97. Soil pH
Soil pH refers to the measurement of acidity or
alkalinity of soil. It is a crucial parameter that
affects the availability of nutrients to plants and
the overall health of the soil. The pH scale
ranges from 0 to 14, with 7 being considered
neutral. Values below 7 indicate acidic soil,
while values above 7 indicate alkaline or basic
soil.
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98. The ideal pH range for most plants is slightly
acidic to neutral, between 6 and 7.5. However,
different plants have varying pH preferences.
Some plants, like blueberries, prefer more acidic
soil (pH 4.5 to 5.5), while others, such as certain
types of grass, can tolerate more alkaline
conditions (pH 7.5 to 8.5).
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99. The origin of PH
The term "pH" is an abbreviation for "potential of
hydrogen." It is derived from the French words
"pouvoir hydrogène."
The "p" in pH represents the "potential" or
"power," referring to the measure of the activity or
concentration of hydrogen ions (H+) in a solution.
The "H" represents the chemical symbol for
hydrogen, the lightest and most abundant element
in the universe.
So when you combine "potential" and "hydrogen,"
you get "pH," which is a measure of the
concentration of hydrogen ions in a solution,
indicating its acidity or alkalinity.
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100. Why its important in soil PH
pH plays a crucial role in soil fertility because it
directly influences the availability of essential
nutrients to plants. The pH of the soil affects the
chemical reactions that occur in the soil, which
in turn affect nutrient solubility, microbial
activity, and nutrient uptake by plant roots.
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101. Nutrient availability:
Different nutrients have optimal availability at
specific pH ranges. For example, macronutrients
like nitrogen (N), phosphorus (P), and potassium
(K) are most readily available to plants in
slightly acidic to neutral soils. If the soil pH
deviates too much from the optimal range,
nutrient deficiencies or toxicities can occur,
limiting plant growth and productivity.
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102. Microbial activity:
Soil microorganisms, such as bacteria and fungi,
play a vital role in nutrient cycling and soil
health. Their activity and effectiveness in
breaking down organic matter and releasing
nutrients are strongly influenced by pH. Certain
microorganisms thrive in specific pH ranges, and
their activity can be inhibited or promoted
depending on the soil pH. Balanced pH levels
support a diverse and active microbial
community, facilitating nutrient availability for
plants.
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103. Biological processes:
Many enzymatic and biochemical processes that
occur in the soil are pH-dependent. Enzymes
responsible for nutrient transformations and
organic matter decomposition have specific pH
optima. Deviations from the optimal pH range
can hinder these processes, affecting nutrient
cycling and organic matter breakdown, which
are vital for nutrient availability and soil
fertility.
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104. Crop Soil pH
Alfalfa 6.2 - 7.5
Barley 5.5 - 7.0
Dry bean 6.0 - 7.5
Corn 5.5 - 7.0
Oat 5.5 - 7.0
Pea 6.0 - 7.0
Potato 5.0 - 5.5
Sugar beet 6.5 - 8.0
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105. Ph adjustment
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