Soil Organic Matter and role of nutrients

Organic matter (O.M) consists of partially decayed and partially re-synthesized plant and animal residues. It also contains living and dead microbial cells, microbially synthesized compounds as a result of microbial activity.

Soil Organic Matter and role of nutrients

Wasim Javed and Najam abbas 

Organic matter (O.M) consists of partially decayed and partially re-synthesized plant and animal residues. It also contains living and dead microbial cells, microbially synthesized compounds as a result of microbial activity.

Function of O.M.

1. O.M is main source if different nutrients, Upon decomposition in soil, all plants animals residues release N,P,S and other nutrients essential for plant growth.
2. It improves physical and chemical properties and structure of soil.
3. It improves water holding capacity of soil organic matter can held water 20 times of its weight.
4. It improves aeration and infiltration of soil. It gives dash color to soil and regulate the temperature.
5. It increases the carton exchange capacity (CEC) of soil and soil retains nutrients against reaching.
6. O.M helps in the aggregation of soil particles and structure of soil improved.
7. It is used for the reclamation of saline/saline sodic soils.
8. It is only source of organic carbon in soil so provides energy for microbes.
9. O.M. buffer soil ph in the slightly acid neutral and alkaline ranges.
10. Environmental point of view, O.M helps in degradation of pesticides, petroleum, cyc, heavy metals pollutants. It retains pollutants against reaching and retard pollution of ground water.
11. It provides natural chelates which increased micronutrients availability.

Functions of Nutrients in Plants.

Macronutrients.

For proper plant growth , it need 16 nutrients that include carbon, hydrogen , oxygen, that plant acquire from air, calcium , magnesium and sulpher are considered as secondary element  other can be divided into Macronutrient , that plant need in higher amount and micronutrient those are required in less

amount.

1. NITROGEN.

1..                 N is a constituents of all proteins and enzymes, several metabolic intermediates in                           synthesis and energy transfer and of DNA.

2.   Plants require N for their growth and reproduction.

3.   N is an integral component of chlorophyll.

4.   N promotes the formation of protoplasm.

5.   In all plants, N influences the utilization of P, K and other plant nutrient.

6.   In cereals, N increases the grain size and their protein content.

7.   N promotes vigorous vegetative growth and deep green colour.

2. PHOSPHORUS

1. P plays a vital role in several physiological processes i.e. photosynthesis, respiration, energy transfer and strange, cell division and cell enlargement.
2. High energy P compound are energy currency of plant.
3. P is an important structural component of biochemical compounds like nucleic acid, DNA, RNA, co-enzymes, phosphor proteins, photo lipids and sugar phosphate.
4. P is mainly stored in fruits and seeds so consider essential for seed formation.
5. P is required for greater strength of straw in cereals.
6. It increases disease resistance in crop and improve quality of vegetable and fruits.

3. POTASSIUM.

1. More than so enzymes are in plants which require K for their activity.
2. It provides the osmotic pull which draws water into plant roots.
3. In stomata general cell, high cone of K is present which controls their opening and closing.
4. K is required for production of high energy phosphate compound like AOP, ATP.
5. K involves in CO2 assimilation into sugar and then translocation of these assimilates.
6. It involves in protein, starch synthesis and BNFL Biological N fixation.

4. CALCIUM.

1. It plays an important part in maintaining cell integrity, membrane permeability, pollen germination and growth.
2. It is an essential part of cell wall.
3. It is required for cell elongation and cell division.
4. The role of Ca in cell membrane stability is important in uptake and other metabolic processes.

5. MAGNESIUM.

1. Mg occurs at the centre of the chlorophyll molecule, so essential for photosynthesis.
2. It is important for cell elongation, synthesis of oil in plant.
3. Mg is an activator for many enzymes required in growth processes.

6. SULFUR.

1. S is a constituent of amino acids ( i.e. cysteine cystine and methionine) and is therefore essential for protein synthesis.
2. It participates in some enzymatic reactions and is a component of volatile compounds.

MICRONEUTIRENTS.

I. Zinc (Zn)

6. 1. It is involved in the enzyme activity.
   2. It is involved in protein synthesis and synthesis of auxin (IAA), which regulate plant growth.
   3. It is involved in carbohydrates and Nitrogen metabolism.

II. Iron (Fe)

1. It is involved in Redox reaction in plants.
2. It is component of cytochromes, ferreclosin
3. It is not part of chlosophyll but involves its synthesis
4. It is necessary photosynthesis, respiration and N-fixation.

III.Borox (B)

1. B is involved in sugar transport.
2. It is component of cell wall and increase cell stability.
3. It also influences the permeability of cell membranes and play a role in cell division, elongation and differentiation.
4. It is also required for pollen germination and pollen tube growth

V. Copper (Cu)

1. it is component of cytochrome oxidase and many other oxidase enzyme.
2. Cu participates in protein and carbohydrate metabolism and N2 fixation.
3. It is important for photo synthesis, respiration, fertilization, lignifications.
4. As much as 70% of plant Cu is concentrated in chlorophyll.

VI. Manganese (Ma)

1. It plays a vital role in water splitting and C2 evaluation in photosynthesis or in Hill reaction.
2. It is also involved in recluse reactions.
3. Mn is important in CO2 assimilation and in N metabolism.
4. MN2+  c;an substitute for Mg2+ in phosphorylation.

VII. Malybodenum (Mo)

1. The role of Mo in N assimilation of plants is well known.
2. MO is key to N- fixation as it is the component of nitrate reductase and nitrogenase enzymes which helps in fixing N2 to Ntt3.
3. It is required in the synthesis of ascorbic acid and in physiological availability of Fe within plants.