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Removal of nitrogen and phosphorous in soil
 

Removal of nitrogen and phosphorous in soil

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    Removal of nitrogen and phosphorous in soil Removal of nitrogen and phosphorous in soil Presentation Transcript

    • REMOVAL OF NITROGEN AND PHOSPHOROUS IN SOIL BY VAISHNAVI SUKUMAR
    • NITROGEN Why Nitrogen is important?  Atmosphere is 78% of nitrogen  It is an essential element for all organisms  Major component of amino acids  Fertilizers.  But plants and animals cant get it directly from the atmosphere  So, the cycle begins
    • REMOVAL PROCESSES  Plant uptake  Gaseous loss Ammonia volatilization Immobilization Denitrification • Exchange  Leaching  Runoff and Errosion  Upward movement
    • PLANT UPTAKE • It refers to nitrogen absorption by roots • Once nitrogen is converted into ammonium and nitrate, these can be taken up from soils by plants • Then used in the formation of plant and animal proteins.
    • GASEOUS LOSS Ammonia Volatilization •     Ammonia volatilization is the loss of nitrogen to the atmosphere as ammonia gas Ammonia production and loss is typically associated with urea hydrolysis in soils. In urea hydrolysis, the ph of urea is increased drastically and the proportion of nitrogen in the ammonium form is shifted towards ammonia Ammonia is then released into the atmosphere and no longer available to the plant. Movement of urea into the soil prior to hydrolysis is an effective way to minimize ammonia volatilization.
    • Factors leads to volatilization  Soil pH  Type of fertilizer  Soil Temperature  Soil Moisture  Buffering Capacity:  Crop Residues  Manure
    • IMMOBILIZATION         Immobilization is process that converts inorganic nitrogen to organic nitrogen. It is the reverse reaction of mineralization. occurs when decomposing organic matter contains low amounts of nitrogen. Also occurs if the source of organic matter has a high C:N ratio Microorganisms which need nitrogen to live, scavenge the soil for nitrogen when plant residues contain inadequate amounts of nitrogen. As inorganic ammonium and nitrate are incorporated into the cells of living microorganisms, the total N levels in the soil are reduced When nitrogen is immobilized in the soil, there may be little nitrogen available for crop growth. As a result, plants can suffer from nitrogen deficiency and develop a yellow coloration.
    • Factors leads to immobilization  Soil moisture and temperature  C:N ratio of residue
    • DENTRIFICATION • • • •     It is one source of N loss from the soil. Is the biological process in which nitrate is converted to atmospheric N2 mediated by denitrifying m.organisms. Reduction is accomplished by facultative heterotrophic organisms Denitrifying bacteria's are thiobacillus, paracoccus,micrococcus and pseudomonas Denitrification occurs when oxygen levels are depleted and nitrate becomes the primary oxygen source for microorganisms When bacteria break apart nitrate(NO3-) to gain the oxygen (O2), the nitrate is reduced to nitrous oxide (N2O), and, in turn, nitrogengas (N2). Since nitrogen gas has low water solubility, it escapes into the atmosphere as gas bubbles. Free nitrogen is the major component of air, thus its release does not cause any environmental concern
    • Soil conditions that lead to Denitrification:  Waterlogged soils  Presence of nitrate  Presence of decomposable organic matter  Oxygen  Soil pH  Soil Temperature
    • EXCHANGE  It refers to cation and anion exchange  Such as ammonium, are attracted to soil particles that have a cation exchange capacity.  Ammonium is largely mobile .  Losses of ammonium  Leads to Nitrogen loss
    • LEACHING        When soil becomes excessively wet through rainfall, the soil will reach a point where it cannot hold any more water. This happens because the air spaces between soil particles become filled with water As these air spaces fill, gravity will cause water to move down through the soil profile. As water moves down through the soil, nitrogen can be carried with it. Nitrate is very mobile and easily leaches with water. Heavy rains can cause nitrates to leach downward in the soil below the root zone Once nitrates get into the groundwater, can be toxic to newborns, causing anoxia, methemoglobinemia, or blue-baby disease etc
    • FACTORS LEADS TO LEACHING  High rainfall intensity and distribution  Highly irrigated fields  Coarsely textured soils
    • RUNOFF AND ERROSION  Runoff and erosion losses may include nitrate, ammonium, and organic nitrogen  when nitrogen fertilizers are applied to soils and rain or irrigation water is applied, the water dissolves and runsoff the surface finally these ions move with it.  Soil erosion moves more nitrogen  When erosional soils are deposited in rivers and lakes, microbial activity will slowly convert nitrogen compounds into soluble forms.
    • UPWARD MOVEMENT  Nitrate can also move upward, especially in semi-arid and arid regions.  Upward movement of nitrate and other soluble ions occurs when evaporation exceeds precipitation, causing water to move upwards.
    • Prevention of Nitrogen Loss  The best way to prevent losses of nitrogen from agricultural lands is through good soil and water management practices  Proper fertilization and control of surface runoff and erosion offer the best methods for preventing nitrogen from getting into streams and lakes
    • PHOSPHOROUS
    • WHAT IS PHOSPHOROUS AND WHY IT IS SO IMPORTANT?       Phosphorus cycle is the movement of phosphorus from the environment to organisms and then back to the environment. Phosphorus is mainly found in water, soil, and rock. Phosphorus is essential for life. ◦ Component of DNA ◦ Building block of our bones and teeth. Unlike the other cycles, phosphorus cannot be found in air in the gaseous state Phosphorus is most commonly found in rock formations and ocean sediments as phosphate salts Phosphate salts that are released from rocks through weathering usually dissolve in soil water and will be absorbed by plants.
    •  Animals absorb phosphates by eating plants or planteating animals.  When animals and plants die, phosphates will return to the soils or oceans again during decomposition.  After that, phosphorus will end up in sediments or rock formations again, remaining there for millions of years. Eventually, phosphorus is released again through weathering and the cycle starts over.
    • REMOVAL OF PHOSPHOROUS FROM SOIL
    • METHODS  Plant uptake • Sorption and Desorption  Precipitation and Dissolution  Mineralization and Immobilization  Leaching  Runoff and Erosion
    • PLANT UPTAKE  Plant roots absorb phosphorus from the soil solution.  Absorb phosphorus in the form of orthophosphate, but can also absorb certain forms of organic phosphorus  Phosphorus moves to the root surface through diffusion.  The presence of mycorrhizal fungi, which develop a symbiotic relationship with plant roots and extend threadlike hyphae into the soil, can enhance the uptake of phosphorus in plant
    • SORPTION AND DESORPTION •  • •  Sorption is the chemical binding of plant available P to soil particles, which makes it unavailable to plants. Soils that have higher iron and/or aluminum contents have the potential to adsorb more P than other soils. P-sorption results in a decrease of plant available phosphorus Desorption is the release of adsorbed P from its bound state into the soil solution Adsorption occurs quickly whereas desorption is usually a slow process.
    • Factors that affect P-sorption  Soil Mineral Type  Amount of clay  pH  Temperature
    • PRECIPITATION AND DISSOLUTION  Phosphorus can become unavailable through precipitation,  Which happens if plant available inorganic P reacts with dissolved iron, aluminum, manganese , or calcium to form phosphate minerals.  Dissolution of phosphate minerals occurs when the mineral dissolves and releases phosphorus
    • Mineralization and Immobilization  Mineralization is the microbial conversion of organic P to H2PO4-or HPO42-, forms of plant available P known as orthophosphates.  Immobilization occurs when these plant available P forms are consumed by microbes, turning the P into organic P forms that are not available to plants.. • During immobilization there is not enough P to sustain both plants and microorganisms; and so, microorganisms scavenge the soil for P  The microbial P will become available over time as the microbes die
    • RUNOFF AND EROSSION  Runoff is a major cause of P loss from farms.  Erosion by wind can carry particles that contain sorbedP to water systems, where phosphorus may later desorb  Sediments containing phosphorus can also contaminate ground and/or surface waters  Phosphorus availability is reduced by the removal of plant material during harvest.
    • LEACHING  Phosphorus leaching can occur if the soil reaches maximum phosphorus holding capacity, especially when P fertilizers are over applied.  Sandy soils are most susceptible to phosphorus leaching  The consequence of phosphorus leaching is the contamination of ground water reserves.
    • THANK YOU