Soil Science (Soil and Plant Nutrition) Flashcards
Fundamental materials of which all matter is composed.
Elements
Any substance that cannot be decomposed into simpler substances by ordinary chemical processes.
Elements
A substance that provides nourishment essential for growth and the maintenance of life.
Nutrient
Three criteria for essential nutrients
1.) A deficiency of it makes it impossible for the plant to complete the vegetative or reproductive stage of its life cycle
2.) Such deficiency is specific to the element in question, and can be prevented or corrected only by supplying this element.
3) The element is directly involved in the nutrition of the plant.
Enumerate the beneficial elements
Sodium
Silicon
Cobalt
Beneficial elements are not necessary to a plant life cycle but they can improve the plant’s performances under optimal or stressful conditions.
Beneficial elements can improve plant health at low concentrations but has toxic effects at high concentrations.
Frame work elements
Carbon, Hydrogen, Oxygen
2 classification of mineral elements
Macronutrients and Micronutrients
Macronutrients are further divided into 2:
Primary Nutrients and Secondary Nutrients
Enumerate the Primary nutrients
Nitrogen
Phosphorus
Potassium
Enumerate the secondary nutrients
Calcium
Magnesium
Sulphur
Enumerate the 8 micronutrients
Zinc
Copper
Manganese
Iron
Boron
Molybdenum
Chlorine
Nickel
1% = _______ ppm
10,000
100 ppm = _____%
0.01%
Nitrogen is absorbed by plants in the form of _____ and _______.
NO3 (Nitrate)
NH4 (Ammonium)
Sulfur is absorbed in the form of
SO4(-2) / Sulfate
Phosphorus is absorbed in the form of
H2PO4 and HPO4 / Phosphate
Mobile elements
N, P, K, Mg
Immobile elements
Ca, S, B, Fe, Zn, Cu, Mn
Deficiency of mobile elements occur in the ________ growth, while immobile element deficiency occur in the ____ growth.
Old growth; New Growth
General symptoms of nitrogen deficiency is reduced growth and chlorosis
Phosphorus deficiency symptoms in corn
- Purple or reddish color in older leaves
- Overall stunting that may persist throughout the season
- Lower yield
- Most often occur in young plants
Sulfur deficiency symptoms
- Chlorosis, but on younger leaves first
- Delayed maturity
- Stunting
Nutrient uptake by plants
- Root interception
- Mass flow
- Diffusion
This is the most important form of movement for most cations, especially nutrients like P and K
Diffusion
Sources of Essential Elements in Soil
- Organic matter
- Soil minerals
- Adsorbed nutrients
- Others: rainfall, fertilizer application
This is the major source of nutrients for the plants and is the source that is most easily controlled by man.
Adsorbed nutrients
It is the element that limits plant growth and used by plants in largest quantities.
Nitrogen
The source for all nitrogen (70%)
Atmosphere
- Component of al proteins, enzymes, and chlorophyll
- Regulates the use of K, P, etc.
- Has the quickest and most pronounced effect on plants
- Very mobile in nitrate form
Nitrogen
Sources of nitrogen
- Legumes (Rhizobium)
- Plant residue (C/N ratio)
- Animal residue
- Rain (oxide forms of N made by lightning are brought to the soil)
- Industrial wastes
- Fertilizers
It is the conversion of atmospheric N2 to NH3 in cells. It represents a major input of N to many soils.
Nitrogen fixation
The process of converting Soil organic N to NH4.
Ammonification / Mineralization
Process of transforming NH4 to NO3
It is the microbial oxidation of ammonium (NH4) to nitrate (NO3) occurs under aerobic conditions.
Nitrification
Process of transforming NO3 to N2
Denitrification
Plant nitrogen turn into soil organic nitrogen through ______.
Decomposition
Microbial nitrogen will turn into soil organic nitrogen through _____.
Decomposition
Through non-symbiotic N fixation, N2 will turn into _______.
Microbial N
Through symbiotic N-fixation, N2 will turn into ______.
Plant Nitrogen
NH4 and NO3 will turn into Microbial N through ____.
Immobilization
NH4 and NO4 will turn into Plant N through ________.
N Uptake
It is the incorporation of N to microbial bodies
Immobilization
The conversion of mineral N (nitrate and ammonium) to the organic form.
Immobilization
Reduction of NO3 to N2, NO, and N2O
Denitrification
__________ is carried out by facultative anaerobic bacteria and requires wet, anaerobic, reducing condition.
Denitrification
Excess nitrite will cause
- decreasing biodiversity
- favoring new species invasion
- production of toxins
_________ is the loss of nitrogen as gaseous ammonia (NH3)
Volatilization
Phosphorus is important because:
1. Component of
a) DNA and RNA
b) ADP and ATP
2. Role in plant maturation
- flowering, fruiting, root development, straw strength
Only N and K (sometimes CA) are taken up in larger amounts by the plant
Phosphorus is required for nitrogen fixation to take place. The microbes in the system require that some P be present.
The main P-uptake mechanism is _________.
Diffusion
Plants take up P from soil water. Because only small amounts of P are found in the soil water at any one time, the P must be constantly replenished.
It is the formation of “fixed” or unavailable P compounds
P fixation
Solution P
- inorganic forms of P such as PO4, HPO4, and H2PO4
- and soluble forms of P
P in P-containing minerals turn into solution P because of __________.
Weathering
Plant uptake Solution P
P fixed to soil minerals turn into solution p by sorption / desorption and vice versa.
Solution P will turn into Microbial biomass through _________.
Immobilization
P in Plant and animal residues turn into __________ through immobilization.
Microbial biomass
P in Plant and animal residues turn into organic p through ________.
Decomposition
The status of the soil with respect to the amount and availability to plants the elements necessary for growth.
Soil Fertility
Capability of a soil for producing plants under a specified system of management.
Soil Productivity
Methods of assessing soil fertility status
- Biological Test
- Evaluation of Nutrient Deficiency Symptoms
- Plant Tissue Analysis
- Soil Analysis
This involves the planting of the crop in the soil being evaluated.
Biological test
The Biological test is done by either
Pot experiment and Field Fertilizer experiment
The soil will be considered fertile if the performance of the test plants is comparable or better than optimum growth and yield expected of the variety used / planted.
Biological Test
Advantages:
1. Provides definitive indication of whether the soil can support the growth of the crop/plant or not.
- Allows evaluation of appropriateness of other factors.
Biological test disadvantages
- Time-consuming
- Expensive
- By the time you do the actual wide-scale growing of the crop, the fertility status may already have changed.
Five general types of nutrient deficiency symptoms
- Chlorosis
- Necrosis
- Stunting
- Abnormal coloration
- Lack of new growth or terminal growth
Common visual symptoms
- Chlorosis
- Interveinal chlorosis
- Necrosis or firing
- Abnormal coloration
- Lack of terminal growth
The sampling and analysis of plant parts for certain essential elements.
Plant Tissue Analysis
Any organic or inorganic material of natural or synthetic origin added to the soil to supply certain nutrients essential to the growth of the plants.
Fertilizers
It is the application of liming material to raise the pH level of an acidic soil.
Lime Application
The process by which the land surface is worn away by the action of wind, water, ice, and gravity.
Soil Erosion
The processes of soil erosion
- Detachment of sediments from the soil mass.
- Transportation primarily by flowing water or wind.
- Deposition of sediment
Universal Soil-Loss Equation
A = R x K x LS x P x C
The capacity of the rain to produce soil erosion.
Erosivity
The susceptibility of the soil to be eroded.
Erodibility
Factors of erosivity
Rainfall and Energy
Factors of Erodibility
Physical characteristics and Management (Land Management and Crop Management)
The detachment and movement of soil or rock by water, wind, ice, or gravity.
Erosion
Two types of soil erosion
Natural erosion and accelerated erosion.
Natural erosion is the wearing away of Earth’s surface by water, ice, or other natural agents under natural environmental conditions.
Acceleration erosion is the erosion that is much more rapid than normal, natural, geological erosion.
Human and domestic animal intervention can cause accelerated erosion.
Okay! 👍
Two steps of accelerated erosion
- Detachment
- Transportation
Power of Raindrops
1. It detaches soil - force of falling water.
2. Beatings tend to destroy granulation at surface
3. Crusting leads to more runoff
Types of Water Erosion
- Splash Erosion
- Sheet Erosion
- Rill and Gully Erosion
- Stream Bank Erosion
An erosion that is caused by the force of raindrops falling on bare or sparsely vegetated surfaces. The particles are detached by the force of falling raindrops. The soil rises into the air and maybe moved by gravity or wind or water down-slope.
Splash erosion
Soil particles are easily transported in a thin layer or sheet by flowing water.
Sheet erosion
Type of erosion where if the sheet runoff is allowed to concentrate and gain velocity or energy, it will cut rills and gullies as it detaches more soil particles.
Rill and Gully Erosion
Erosion that occurs along the banks of streams. Increased erosion occurs when level of runoff is increased to the river or stream.
Stream Bank Erosion
Factors affecting soil erosion
- Rainfall
- Soil erodibility
a) Soil Texture
b) Soil Structure - Vegetative cover
- Relief
- Human activities
Highly permeable soils are less prone to erosion by water since they are able to absorb water effectively.
Permeable soils also favor root proliferation and encourage vegetation to grow.
Forms of wind erosion
Detrusion and Abrasion
It is the wearing away of rocks and soil projections by fine particles carried in suspension. This forms large rocks carved into grotesque shapes in deserts.
Detrusion
A form of wind erosion that takes place close to the ground where the moving particles are larger and bouncing along over the surface.
Abrasion.
Erosion by wind is also known as
soil blowing
In erosion by wind, the materials are carried away by:
- Extrusion
- Efflution
- Efflusion
Extrusion is the rolling away of large particles
Efflution is the removal of very fine particles
Efflusion is where particles of intermediate size move off downwind into bouncing action called saltation.
Two types of impacts of erosion.
On-site impacts and Off-site impacts.
Soils that commonly have dark organic surface layer and mineral layers underlain by permafrost
Gelisols
Soils that have organic surface horizons
Histosols
- Has a “spodic” horizon
- Light colored acidic soils found in coniferous forests.
- Soils of cool humid regions as in northeast United States
Spodosols
Soils derived from volcanic materials.
Andisol
- Highly weathered tropical soils.
- Has subsurface horizon low in weatherable minerals but high in aluminosilicate clays
Oxisols
Kind of soil in Salcedo, Samar
Oxisol
Soils that are high is swelling clays. When they are dry, large deep cracks form that surface soils falls into, mixing the soil.
Vertisol
Arid soils, often alkaline with salted horizons
Aridisols
Highly weathered soils of warm climates, low base, often leached, acid, and infertile.
Ultisol
The most widespread soil in the Philippines
Ultisols
Soils with “mollic” horizon
Soils that have dark, thick, good structure, high base A horizon.
Mollisols
Forest soils of cool moist climates, light colored, slightly to moderately acid with illuvial layer high in silicate clays.
Alfisols
Young soils, with only those horizons that form quickly.
Inceptisols
Very young soils in new parent materials or where alluvial deposition or erosion limits profile development (slopes)
Entisols
Typical catena in young tropical islands (Philippines and Indonesia)
Andisol - Ultisols - Inceptisols
12 Soil Orders
Gelisol — el
Histisol — ist
Spodosol — od
Andisol — and
Oxisol — ox
Vertisol — ert
Aridisol — id
Ultisol —ult
Mollisol — oll
Alfisol — alf
Inceptisol — ept
Entisol —ent
The Soils of the Philippines
- A book by Carating, Galanta, and Bacatio (2014)
Soil Series of the Philippines
a) Soils of the Lowlands - 104
b) Soils of the Uplands - 89
c) Soils of Hills and Mountains - 91
