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1) Give the characteristics of salt affected soils and state factors responsible for its formation.
Characteristics of salt affected Soil
Soil Type pH Ece(dsm)-1 SAR ESP
Saline Soil 8.5 >4 <13 < 15
Saline Alkali Soil 8.5 >4 > 13 > 15
Alkali Soil >8.5 <4 >13 > 15
Degraded Alkali Soil >8.5 <4 > 13 > 15
Formation of salt affected Soil
1. Arid and semiarid region
2. Poor drainage
3. High water table
4. Over flow of sea water over land
5. Introduction of irrigation water
6. Salts blown by wind
7. Saline Nature of parent rock maerial
8. Excessive use of basic fertilizers
9. Humid and semi humid region
2) Define problematic soil and give its classification
Problematic Soil: These soils need proper reclamation and management measures for their economical use in crop production.
First set has problem in physical characteristics and includes highly eroded soils, ravine land, soil on steeply sloping lands, highly permeable coarse textured soil, slowly permeable heavy texture soils, crusting soil and red chalka soils
The second set includes all the soils which have problem in their chemical characteristics. Acid, saline, saline-alkali soil and alkali soil constitute this set.
Classification of problematic soils refers to the categorization of soils that have specific issues or limitations that affect their use and productivity. These soils may have characteristics such as high acidity, high salinity, poor drainage, low fertility, or high erosion potential. The classification of problematic soils helps in identifying the specific issues and potential management strategies to improve their quality and productivity.
There are different methods and criteria used for the classification of problematic soils, depending on the specific purpose or context. Some common classifications include:
1. Soil Chemical Properties: This classification focuses on the chemical properties of the soil, such as pH, electrical conductivity, cation exchange capacity, and nutrient content. It helps in identifying soils with high salinity, acidity, or nutrient deficiencies.
2. Soil Physical Properties: This classification considers the physical properties of the soil, such as texture, structure, compaction, and water-holding capacity. It helps in identifying soils with poor drainage, low water infiltration rates, or high erosion potential.
3. Soil Biological Properties: This classification assesses the biological properties of the soil, such as microbial activity, organic matter content, and nutrient cycling processes. It helps in identifying soils with low organic matter content or poor nutrient cycling capabilities.
4. Soil Erosion Potential: This classification focuses on the erosion potential of the soil, considering factors such as slope gradient, vegetation cover, and soil erodibility. It helps in identifying soils prone to erosion and implementing erosion control measures.
The classification of problematic soils is crucial for land management and agriculture planning. It provides a basis for implementing appropriate soil management practices, such as soil amendment, drainage improvement, erosion control, and nutrient management. By understanding the specific issues and limitations of problematic soils, sustainable land use practices can be implemented to improve soil quality and productivity.
3) What is wasteland? Give its classification with suitable example
Wasteland:
It is general term which includes any type of land, irrespective of its ownership. which is producing less than 20% of its optimum biological productivity. It is also defined as the land which is degraded and is presently lying unutilized except a current fallow due to different constraints.
Culturable Wasteland: Lands which are capable of have the potential of development vegetative cover. They include undulating upland, sloppy land, Shifting cultivation areas, sand dunes ravines lands, Water logged land, salt affected land, degraded forest land and pasture and non forest plantation land and mining industrial wasteland. Unculturable wasteland: Lands which cannot develop vegetative cover and include barren rocky areas and stip slopes and snow covered areas.
1. Physical Criteria: This classification is based on physical characteristics such as soil type, topography, drainage, and vegetation cover. It helps in identifying different types of wasteland, such as sandy wasteland, rocky wasteland, marshy wasteland, etc.
2. Ecological Criteria: This classification focuses on the ecological functions and potential of the wasteland. It considers factors such as biodiversity, habitat suitability, and ecological connectivity. It helps in identifying areas that have the potential for ecological restoration or conservation.
3. Productivity Criteria: This classification assesses the potential productivity of the wasteland for various land uses, such as agriculture, forestry, or horticulture. It considers factors such as soil fertility, water availability, and climatic conditions. It helps in identifying areas that can be reclaimed for productive purposes.
4) What are Soil Quality and Soil Health? State soil quality indicators.
Soil quality- The capacity of specific kinds of soil, function within natural or managed ecosystem boundaries to sustain plant and animal productivity maintain or enhance water and air quality and support human health and habitation. Changes in the capacity of soil to function are reflected in soil properties that changes in response to management or climate
Soil Health - Soil Health is defined as the continued capacity of soil to function as a vital living system by recognizing that it contains biological elements that are key to ecosystem function within land use boundaries.
Indicator
Chemical indicators - Electrical Conductivity, Soil Nitrate, Soil Reaction (pH)
Physical indicators- Aggregate Stability, Available Water Capacity, Bulk Density, Infiltration and Soil Structure.
Biological indicators - Particulate Organic Matter, Potentially Mineralizable Nitrogen, Respiration, Soil Enzymes and Total Organic Carbon.
5) What is calcareous soil? Explain its effects on plant growth.
Calcareous Soil
Soil containing sufficient free CaCO3 and/or MgCO, in varying proportion throughout the soil profile.
Effect on plant growth-
1. When it accumulates in the subsoil or in lower profile, it tends to form hardpan by cementing the soil particles. The hardpan is impermeable and is often the cause of water logging.
2. Reduces some plant nutrient because of high Ph and presence of free calcium and magnesium carbonate. It is often responsible for lime induced chlorosis of number of crops.
3. A high level of calcium exerts a depressing effect on absorption or uptake of nutrients like potassium and Magnesium by the plant and thus upsets its balanced nutrition.
6) What are Acid and Acid Sulphate Soils? Describe in short its formation and management.
Acid Soils - A soil having dominance of hydrogen (H) and aluminium (Al) relative to hydroxyl (OH) ions is called as acid soil. Acid Soil is a base unsaturated soil which gives the soil to a pH lower than 7.0
Formation (sources) of acid soils.
1. Carbon dioxide
2. Acid forming fertilizers
3. Acid parent material and sulphur
4. Plant roots and Humus
5. Leaching due to heavy rainfall
6. Acid rains
7. Removal of bases by crops
8. Hydroxides
Management of acid Soils
Lime Requirement- is defined as the amount of liming material that must be added to raise the soil pH to some prescribed value.
Influence of liming material on soil properties in relation to plant nutrition
Direct Effect:
1. Toxicity of al and Mn and reduced uptake and Mg
2. Removal of hydrogen ion
Indirect Effect
1. Phosphorous availability
2. Micronutrient availability
3. Nitrification
4. Nitrogen fixation
5. Soil physical condition
6. Diseases
7. Efficiency of fertilizers.
Acid Sulphate Soils - Soil with sufficient sulphides (FeS2 and others) to become strongly
acidic (pH < 3) when drained and aerated enough for cultivation are termed acid sulphate
soils, also called as cat clays.
Formation of Acid sulphate soils
Management of Acid sulphate soils
Keeping the area flooded, Controlling water table and Liming and leaching.
7) Explain in detail land capability classification.
On the basis of the soil survey maps and reports, a land capability classification has been developed in which every acre of land is classified according to its capabilities and limitations. There are eight capability classes, which are numbered from I to VIII. Those lands, which have the maximum capabilities and the least limitations, are placed in class 1, whereas those lands, which have the maximum limitations and the least capabilities, are placed in class VIII. The Capability classification consists of three categories
Capability classes- Class I to Class IV encompasses land suitable for cultivation, unit class V to Class VIII includes land unsuitable for cultivation but suitable for permanent vegetation.
Capability subclasses: These are based on kinds of dominant limitation such as wetness or excess water (w), climate (c), soil (s) and erosion (e).
Capability units: These are further subdivisions of capability subclasses. A capability includes soils which are sufficiently uniform in their characteristics, potential and limitations and required fairly uniform conservation treatment and management practices.
8) Explain the process of soil compaction and soil crusting.
Soil Compaction
Soil compaction is the process in which soil particles are packed together in a closer state of contact indicated by a change in bulk density, porosity etc.
Changes occurred due to soil compaction
1. Compression of soil solids
2. Compression of liquid and gases
3. Changes in liquid and gas contents in the pore space(both macro and micro pore spaces)
4. Re-arrangement of soil solids
Soil Crusting- It is phenomenon associated with deterioration of soil structure, where then natural soil aggregates break and disperse.
Influence of soil crusting on soil productivity
1. Serious barrier for seedling emergence
2. Crust clogs the surface macro pores and inhibits the rate of infiltration of water in the soil causing run off.
3. Loss of water storage in soil profile and less availability of water to plants
4. Causes interill soil erosion
5. Lack of soil aeration
Control of soil crusting
1. Surface mulch
2. Addition of organic matter
3. Application of soil conditioners i.e. polyionic conditioners like HPAN (Hydrolyzed poly acrylonitrile), VAMA (Vinyl acetate maleic acid copolymer) and non soil conditioner like polyvinyl alcohol (PVA).
4. Application of gypsum, pyrite in sodic soil, lowering of exchangeable sodium percentage minimizes crust formation.
5. A light tillage while the soil is still moist break up the crust before it hardens.
9) State quality parameters of irrigation water. Describe in brief any one of them.
1) Total concentration of soluble salts (EC)
2) Relative proportion of sodium to other cations (SAR)
3) Concentration of boron or other elements that may be toxic
4) Bicarbonates concentration as related to the concentration of calcium + magnesium.
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10) What is meant by bioremediation? Explain it in detail through MPTs.
Bioremediation is the use of living organisms for the recovery/cleaning up of a contaminated medium (soil, sediment, air, water).. Explain it in detail through MPT.
Multipurpose trees are trees that are deliberately grown and managed for more than one output. They may supply food in the form of fruit, nuts, or leaves that can be used as a vegetable; while at the same time supplying firewood, add nitrogen to the soil, or supply some other combination of multiple outputs. "Multipurpose tree" is a term common to agroforestry, particularly when speaking of tropical agroforestry where the tree owner is a subsistence farmer.
When a multipurpose tree is planted, a number of needs and functions can be fulfilled at once. They may be used as a windbreak, while also supplying a staple food for the owner. They may be used as fencepost in a living fence, while also being the main source of firewood for the owner. They may be intercropped into existing fields, to supply nitrogen to the soil, and at the same time serve as a source of both food and firewood.
Common multipurpose trees of the tropics include:
1) Gliricidia sepium - the most common tree used for living fences in Central America, firewood, fodder, fixing nitrogen into the soil.
2) Moringa (Moringa oleifera)- edible leaves, pods and beans, commonly used for animal forage and shade (it does not fix nitrogen as is commonly believed)
3) Coconut palm- used for food, purified water (juice from inside the coconut), roof thatching, firewood, shade.
4) Neem- limited use as insect repellent, antibiotic, adding nitrogen to soil, windbreaks, biomass production for use as mulch, firewood.
11) Explain contribution of Rocks & minerals towards development of saline and sodic soils.
Rocks and minerals play a significant role in the development of saline and sodic soils. Saline and sodic soils are characterized by high levels of soluble salts and sodium, respectively, which can negatively impact agricultural productivity. Here are some ways in which rocks and minerals contribute to the formation of these soil types:
1. Parent Material:
The composition of rocks and minerals in an area serves as the primary source for the elements that make up the soil. Certain types of rocks, such as marine sediments or evaporites, contain high concentrations of salts and sodium. Over time, weathering and erosion of these rocks can release these elements into the soil, leading to the development of saline and sodic soils.
2. Mineral Weathering:
The weathering process breaks down rocks and minerals into smaller particles, releasing various elements into the soil. In the case of saline and sodic soils, the weathering of certain minerals can contribute to the accumulation of salts and sodium. For example, the weathering of feldspar, a common mineral in many rocks, can release sodium ions into the soil.
3. Groundwater Interaction:
Rocks and minerals can influence the quality of groundwater, which can, in turn, affect the development of saline and sodic soils. Some rocks have high salt content or contain minerals that can dissolve in water and increase its salinity. When groundwater interacts with these rocks, it can become saline or carry high levels of dissolved salts. Over time, this water can percolate into the soil and contribute to salinization.
4. Soil Formation Processes:
The interactions between rocks, minerals, and other soil-forming factors (such as climate, vegetation, and topography) influence the development of saline and sodic soils. For example, in areas with poor drainage, water may accumulate near the surface, leading to the buildup of salts or sodium in the soil. The type of rocks and minerals present in the area can influence the drainage characteristics of the soil and contribute to the formation of saline and sodic conditions.
It is important to note that while rocks and minerals can contribute to the development of saline and sodic soils, human activities such as improper irrigation practices, excessive use of fertilizers, and deforestation can exacerbate these soil problems. Understanding the geological factors that contribute to the formation of saline and sodic soils is crucial for implementing appropriate soil management strategies, such as drainage improvement, soil amendments, and crop selection, to mitigate their negative effects on agriculture.
12) Explain Characteristic features and management of eroded soils.
1. Characteristic Features:
- Loss of topsoil: Eroded soils have a reduced thickness of topsoil, which is typically the most fertile and productive layer.
- Exposed subsoil: The erosion process can expose the subsoil, which may be less fertile and have poorer drainage characteristics.
- Reduced organic matter: Eroded soils often have lower levels of organic matter, as the topsoil, which contains a significant portion of organic material, is lost.
- Poor soil structure: Erosion disrupts the natural soil structure, leading to compacted or crusted soil layers that can impede water infiltration and root growth.
2. Management Strategies:
- Conservation tillage: Implementing conservation tillage practices, such as no-till or reduced tillage, can help minimize soil erosion by leaving crop residues on the soil surface to protect against wind and water erosion.
- Contour farming: Planting crops along the contour lines of the land helps slow down water runoff and promotes water infiltration, reducing the risk of erosion.
- Windbreaks and shelterbelts: Planting trees or establishing windbreaks can help reduce wind erosion by providing a barrier that slows down wind speed and protects the soil surface.
- Cover crops: Planting cover crops during fallow periods or intercropping with main crops can help protect the soil from erosion by covering the ground and reducing exposure to wind and water.
- Terracing: Constructing terraces or contour plowing can help control water runoff on sloping lands by creating level areas that slow down water flow and promote infiltration.
- Soil amendments: Applying organic matter, such as compost or manure, can help improve soil structure, water-holding capacity, and nutrient content in eroded soils.
- Vegetative barriers: Planting grasses or legumes as vegetative barriers on slopes can help stabilize the soil and reduce erosion by intercepting water runoff and reducing its velocity
13) Difference between Soil Quality & Soil Health.
Soil Quality: Soil quality refers to the overall condition of the soil and its ability to perform specific functions. It is a broader term that encompasses various physical, chemical, and biological properties of the soil. Soil quality can be assessed based on factors such as nutrient content, pH level, organic matter content, water-holding capacity, and soil structure. It focuses on the soil's ability to support plant growth and sustain agricultural productivity.
Soil Health: Soil health is a more specific term that emphasizes the biological aspects of soil quality. It refers to the ability of the soil to function as a living ecosystem and support diverse and abundant populations of microorganisms, plants, and animals. Soil health focuses on the interactions between soil organisms and their impact on nutrient cycling, soil structure, water infiltration, and overall soil fertility. A healthy soil is one that has a balanced and active soil food web, with beneficial microorganisms and organisms that contribute to nutrient availability and plant growth.
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