Soil And Plant Relationship SS 43 LEC 2024-2025 PDF

UNIT 2 SOIL AND PLANT RELATIONSHIP SS 43 LEC 2024-2025 2.1 Essential Elements and their functions NUTRIENTS IN SOIL  NUTRIENTS IN SOIL Soil is a major source of nutrients needed by plants for growth. The three main nutrien...

UNIT 2 SOIL AND PLANT RELATIONSHIP SS 43 LEC 2024-2025 2.1 Essential Elements and their functions NUTRIENTS IN SOIL  NUTRIENTS IN SOIL Soil is a major source of nutrients needed by plants for growth. The three main nutrients in soils are nitrogen (N), phosphorus (P) and potassium (K).  NUTRIENTS IN SOIL is a key element in plant growth. Among all the essential nutrients, Nitrogen is required by plants in the largest quantity and is important for soil fertility and soil quality (Reeves, 1997).  NUTRIENTS IN SOIL is mainly derived from the weathering of minerals in parent rock material. It is usually the second most limiting nutrient for terrestrial primary production (Cordell et al., 2009).  NUTRIENTS IN SOIL is a constituent of enzymes and acts as a regulator of drought tolerance and water use (M. Wang et al., 2013).  FORMS OF NUTRIENTS IN THE SOIL Calcium Calcium is absorbed from the soil without spending energy. In the plant, it moves to different plants through the xylem, along with water. From the soil, it is absorbed in the form of calcium ions.  FORMS OF NUTRIENTS IN THE SOIL Magnesium Magnesium is absorbed as the Mg2+ ion and is mobile in plants, moving from the older to the younger leaves. It leaches from the soil like calcium and potassium. Magnesium is the central atom amid four nitrogen atoms in the chlorophyll molecule, so it is involved in photosynthesis.  FORMS OF NUTRIENTS IN THE SOIL Sulfur Most of the sulfur in soils is found soil in organic matter sulfur is converted to the sulfate form (SO4-2) which is readily available to plants. The process is affected by the C/S ratio, temperature and moisture.  THE ROLE OF ELEMENTS IN PLANT NUTRITION Magnesium(Mg)  An important component of chlorophyll pigment.  Activates the enzymes of respiration, protein synthesis and photosynthesis. It helps in joining the two subunits of ribosomes.  It is also involved in the synthesis of DNA and RNA. Molybdenum (Mo)  Required for nitrogen fixation in leguminous plants.  Molybdenum ions are part of enzyme nitrogenase and nitrate reductase which are involved in nitrogen fixation.  THE ROLE OF ELEMENTS IN PLANT NUTRITION Zinc (Zn)  This element is absorbed from soil in the form of zinc ions  Zinc is required for the synthesis of growth hormone indole acetic acid (IAA).  It also controls the absorption of phosphorus.  Zinc is a component of several types of enzymes especially carboxylases. Chlorine (Cl)  It plays an important role in carbohydrate metabolism and in balancing anion-cation concentration in the cell.  It is helpful in the photolysis of water leading to the evolution of oxygen.  THE ROLE OF ELEMENTS IN PLANT NUTRITION Copper (Cu)  It is absorbed from soil by roots in the form of divalent cupric ions  Copper acts as an electron carrier in oxidation-reduction reactions.  A component of plastocyanin and cytochrome oxidase which acts as an electron carrier in photosynthesis. Nickel (Ni)  It is an essential part of the enzyme urease. It is probably helpful in the transportation of nitrogenous compounds.  Neither a component of any biochemical compound nor its function and deficiency are properly understood.  RELEASE PROCESSES Nutrient absorption and utilization is not a simplistic process. There are essentially two phases. First, the nutrient must reach the root surface. Then, it must move into cells of the plant. Nutrients must get to the plant root to be absorbed by the large number of root hairs. Root hairs live in association with a diverse group of fungi called mycorrhizae which aid the movement of a nutrient from outside to inside of the root itself.  Factors affecting availability of nutrients  Soil reaction- Soil reaction is the status of pH of soil. Soil reaction is an indication of the acidity or basicity of soil.  CEC- High CEC means that soil is more fertile. Low CEC means that fewer nutrients can be held by the soil, implying a need for more frequent nutrient additions. Soils with low CEC become acidic very quickly (for example sandy soils) and would need liming more frequently than soils with high CEC.  AEC- Anions in soil are adsorbed to positive charges of clay minerals and organic matter. Important anions in soil are. (H2PO4– HPO4=, CI–, SO4=, NO3–, MoO4=). Anion exchange is much greater in soils high in 1: 1 type clay minerals and those containing hydrous oxides of iron and aluminum then that of soils containing high amounts of 2: 1 type of clay minerals.  Soil texture- Fine texture, such as clay and silt, ensures the availability of nutrients in the soil. (ii) But coarse texture like sand prevents the availability of nutrients in the soil as coarse texture encourages the leaching of nutrients from the soil.  Factors affecting availability of nutrients  Erosion causes loss of nutrients- Heavy rainfall causes the washing or carrying away of top soil which is rich in plant nutrients  Moisture Content – At optimum moisture content, nutrient supply to plant roots by diffusion and mass flow is enhanced. When soil moisture levels stray to the dry side, lower soil solution creates lower plant available nutrients. When soil moisture levels rise to the high side, it can decrease plant nutrient through leaching, denitrification and volatile sulfur loss to the atmosphere.  Level of organic matter  Soil Air  Soil temperature  NUTRIENTS DEFICIENCY/TOXICITY  Home Service About Us Contact Deficiency: Whenever the supply of an essential Nutrient element becomes limited, plant growth is retarded. Deficiency/Toxicity Learn More  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY o The chlorophyll content of plant leaves is reduced. o Flowering, fruiting, protein, and starch contents are reduced. o Plants often have stunted growth due to reduction in cell division. o Leaves develop a yellow color, which is a condition known as chlorosis.  NUTRIENTS DEFICIENCY/TOXICITY TOXICITY Dark green leaves and foliage Leaf tips may turn down Yellowing on the affected leaves Claw leaves will eventually start turning yellow, getting spots and dying Deficiency Symptoms Home Service About Us Contact  Plants often have stunted growth due to reduction in cell division.  Leaves develop a yellow color, which is a condition known as chlorosis.  Since nitrogen is a mobile nutrient within the plant, nitrogen moves from older growth to new growth when deficient.  As a result, nitrogen deficiencies first appear in older leaves.  Since deficiency symptoms are sometimes difficult to diagnose, the location of the symptom (new or old growth) helps us determine which nutrient, if any, is deficient.  When nitrogen is severely deficient, chlorotic leaves may die and fall off the plant.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Plants are stunted and older leaves often dark dull green in color Stems and leafstalks may turn purple Plant maturity is often delayed Plant will be dwarfed or stunted  NUTRIENTS DEFICIENCY/TOXICITY TOXICITY Interfere with the availability of Copper and Zinc Very rare and usually buffered by pH limitations.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Chlorosis may cause yellowing of leaves Stunted growth TOXICITY Leaf tip and marginal necrosis  NUTRIENTS DEFICIENCY/TOXICITY Deficiency Young leaves and fruit display Yellow brown spots surrounded by a sharp brown outline edge. Blossom end root of tomatoes is a classic case TOXICITY Can compete with Mg and K uptake causing their deficiencies Rarely occurs  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Yellowing between leaf veins, sometimes with reddish brown tints Early leaf fall TOXICITY Rare and not generally exhibited visibly Deficiency Symptoms Home Service About Us Contact  Deficiency symptoms first show up on older leaves since magnesium is a mobile nutrient. Commonly, plants develop interveinal chlorosis. Interveinal chlorosis is a condition in which the plant tissue becomes yellow while the veins remain green. Interveinal tissue in some crops may turn reddish, purplish, and bronze.  If severe, the entire leaf may become chlorotic and eventually die.  In severe cases, symptoms may appear on younger leaves and cause premature leaf  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Yellowing of the entire leaf including veins usually starting with the younger leaves Leaf tips may yellow and curl downward TOXICITY Leaf size will be reduce Overall growth will be stunted Leaves yellowing or scorched at edges Deficiency Symptoms Home Service About Us Contact  A common symptom of sulfur deficiency is uniform chlorosis of leaves. deficiency symptoms may resemble nitrogen deficiencies, except the symptoms first appear on new growth of most crops since sulfur is mostly immobile.  Growth may be stunted, with spindly and thin stems.  Growth rate is retarded and maturity is delayed.  NUTRIENTS DEFICIENCY/TOXICITY TOXICITY Chlorotic leaf tips Leaf necrosis Leaf falling An even plant death  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Other symptoms include rotting and discoloration of fruits and roots Leaves may be thickened, curled, and brittle. The plant may also have stunted growth.  Deficiency symptoms first appear in new growth. Leaves may be thickened, curled, and brittle. Stems may also become cracked.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Occur un newer plants Plants may have chlorosis, stunted growth, and curling of young leaves. Leaf tips and leaf edges may begin to die back. Leaves may develop a dark bluish-green cast.  NUTRIENTS DEFICIENCY/TOXICITY TOXICITY Restrict root growth by burning the root tips Compete with plant uptake of Fe and Mo or Zn Reduce branching and eventually plant die Deficiency Symptoms Home Service About Us Contact  Plants may have chlorosis, stunted growth, and curling of young leaves.  Leaf tips and leaf edges may begin to die back.  Leaves may develop a dark bluish-green cast.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Interveinal chlorosis in younger leaves. TOXICITY Occurs due to a low growing medium pH or from an excessive application of Fe  Home Service About Us Contact Deficiency Symptoms  Deficiency in corn causes interveinal, light striping or a whitish band beginning at the base of the leaf and extending towards the tip.  The margins of the leaf, the midrib area, and the leaf tip usually remain green.  Plants are stunted because internodes are shortened (Rosetting)  Relatively immobile in the plant. Severe zinc deficiency may result in new leaves that are nearly white, an effect termed "white bud“.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY interveinal, light striping or a whitish band beginning at the base of the leaf and extending towards the tip. The margins of the leaf, the midrib area, and the leaf tip usually remain green Plants are stunted because internodes are shortened  NUTRIENTS DEFICIENCY/TOXICITY TOXICITY Growth reduction Leaf chlorosis  Home Service About Us Contact Deficiency Symptoms Interveinal chlorosis in younger leaves. The youngest leaves maybe white, because Fe, like Mg, is involved in chlorophyll production.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY interveinal chlorosis may develop on young leaves, except the chlorosis appears as yellow dots. The plant may have stunted growth. TOXICITY Burning of the tips and margin of older leaves as reddish brown spots across older leaves  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Older growth may become chlorotic The margins of leaves may develop spots of dead leaf tissue.  NUTRIENTS DEFICIENCY/TOXICITY DEFICIENCY Wilting of leaves, especially at leaf margins. Chlorotic blotches with necrotic spots located between the veins or on the margin of the younger leaves. TOXICITY Starts as premature yellow in of leaves then in marginal or tip necrosis of older leaves. Deficiency Symptoms Home Service About Us Contact  Wilting of leaves, especially at leaf margins, is a typical symptom of Cl deficiency, even in water culture, when plants are exposed to full sunlight (Broyer et al., 1954)  Home Service About Us Contact Nutrient Mobility in Plants Macronutrients Symbol Mobile in plant Macronutrients Symbol Mobile in plant PRIMARY INTERMEDIATE/SECONDARY Nitrogen N Mobile Calcium Ca Immobile Somewhat Phosphorous P Somewhat Mobile Magnesium Mg Mobile Potassium K Very Mobile Sulfur S Mobile  Home Service About Us Contact Nutrient Mobility in Plants Micronutrient s Mobile in Symbol plant Micronutrients Mobile in Symbol plant Iron Fe Immobile Zinc Zn Immobile Cobalt Co Immobile Manganese Mn Immobile Chlorine Cl Mobile Molybdenum Mo Immobile Copper Cu Immobile Nickel Ni Mobile  Relationship between soil nutrients supply and plant growth There are soil factors that may affect nutrients availability to plants. These factors should be manage to maintain the fertility of the soil. 1) Cation exchange capacity (CEC) is a measure of the amount of cations (positively charged ions) that can be held by the soil. As the clay content, organic matter content and pH increase, the CEC will also increase. As CEC increases, so does the ability of the soil to hold nutrients. Since much of the plant uptake (and leaching) of nutrients comes from the soil solution, as the CEC increases, the nutrients in solution decrease and become less mobile in the soil. Having optimum levels of cations on the CEC and having low levels of non-nutrient and potentially harmful cations such as Al on the CEC is important for supplying these essential nutrient cations for plant uptake.  Relationship between soil nutrients supply and plant growth 2) Texture is defined as the proportion of sand, silt and clay in the soil. As the clay content increases, so does the CEC, resulting in a greater ability to hold nutrients. Soils with more sand and less clay have lower CECs and cannot hold as many cations. Since sandy soils also have large pore spaces, leaching of nutrients is greater than on a soil with more silt and clay.  Relationship between soil nutrients supply and plant growth 3) Soil structure is defined as the arrangement of soil particles into aggregates. Good soil structure is represented by significant aggregation. This allows for optimal root growth and water and nutrient access for any given soil. Destruction of good structure, by compaction or tillage can result in an increase in runoff since water cannot move as readily down through the soil profile. Under poor drainage conditions, nitrate nitrogen can be lost through denitrification. With excessively drained soils (sandy) leaching losses are more important. Some nutrients like iron and manganese are more soluble under very wet or flooded conditions. Relationship between soil nutrients supply and plant growth 4) Soil moisture is very important for root growth, so adequate moisture will improve uptake of nutrients by diffusion and root interaction. Soil moisture is also important for organic matter decomposition (which releases N, P and S).  Relationship between soil nutrients supply and plant growth 5) Soil pH affects the availability of most nutrients. For example, at low pH and high pH, phosphorus is less available than when the pH is around 6.5. At a low pH it is bound by aluminum and iron and at a high pH is bound by calcium. Many of the micronutrients are also sensitive to pH, being more available in slightly acid soils. At high pH’s, molybdenum can become too available and be toxic to plants. Soil pH is important in N transformations including mineralization of organic materials (biological degradation), nitrification (bacteria responsible for this process are pH sensitive) and N fixation.  Relationship between soil nutrients supply and plant growth 6) Soil temperature affects the plant’s ability to grow and thus affects nutrient uptake. Temperature also controls the mineralization of organic forms of nutrients to mineral forms that plants can take up. Mineralization and thus nutrient availability is reduced or stopped completely at very low and very high soil temperatures.  Leibig`s law of Minimum In the 19th century, the German scientist Justus von Liebig formulated the “Law of the Minimum,” which states that if one of the essential plant nutrients is deficient, plant growth will be poor even when all other essential nutrients are abundant.  Leibig`s law of Minimum The Liebig Law of the Minimum says that crops yields are regulated by the factor in greatest limitation, and yields can be increased only by correction of that limiting factor. When that limitation is overcome, yields are then regulated by the next important limiting factor. Further yield increase will then occur only if that factor is corrected. This process is repeated, with step-wise yield increases, until there are no remaining limiting factors.  Leibig`s law of Minimum Justus von Liebig made great contributions to the science of plant nutrition and soil fertility. As a result of millenia of practical experience of farmers manuring fields to improve fertility, many early chemists thought that the "principle of vegetation", the essential nutrients needed for plant growth, were organic in nature rather than mineral. Liebig essentially debunked the humus theory and made a scientific case for plant requirements for mineral elements from the soil, carbon from CO2 in the air, and H and O2 from water. Liebig thought that plants derived most of their nitrogen content from the air as well, which is somewhat correct for legumes, but not true for other plants. Liebig developed the first mineral fertilizers applied to replenish nutrients removed from soils by crops and clearly saw mineral fertilizers as part of sustainable agricultural practices.  Leibig`s law of Minimum Justus von Liebig (1803-1873) was a German chemist who spent the early part of his accomplished career as a pioneer in organic chemistry. He turned to what is now called biochemistry about 1838, and first published on agricultural chemistry in 1840, and made numerous significant advances and engaged in extensive, fruitful debate with other researchers in the field.  Leibig`s law of Minimum Recent scholarship, beginning in 1950, has discovered the significance of the German agronomist Carl Sprengel (17871859) who conducted pioneering research that could be considered the start of agricultural chemistry, including disproving the humus theory and formulating the Law of the Minimum. His publications on these subjects predated Liebig's 1840 publication and therefore he has precedence for these discoveries. It is uncertain that Liebig was unaware of Sprengel's work, so Liebig may be considered a propagandist and promulgator of these discoveries and, by virtue of his greater reputation, may have been unduly credited for the discoveries themselves. The Association of German Agricultural Experimental Stations regularly acknowledges outstanding service or achievement to agricultural with the Sprengel-Liebig Medal, thereby honoring both scientists THANK YOU Prepared by: , Iantroy