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The post is important under Environment section for Prelims and, Conservation and Sustainable Growth for mains (Environmentally Sustainable Agriculturally Practices, Green Revolution and Second Green Revolution)
Today there is an article in The Hindu titled “Bio-char, compost tea are the new recipe”.
The bold words and sentences are the ones that are important, especially for prelims.
I have given a detailed explanation for each of the key terms.
Kollam, Kerala, is famous for fishing and fishery-related activities; as an agricultural sector, it does not evoke any enthusiasm. (Why?)
- What with the prevailing soil and climatic conditions, which favours leaching and draining of soil nutrients into the Arabian sea and Ashtamudi Lake (Ashtamudi Lake is located in Tamil Nadu. True or False?), the soil has high acidity making it unfit for cultivation of any kind (Why? Because friendly micoorganisms don’t like acidic medium. They like slightly alkaline or basic medium [having a pH greater than 7]).
- Vertical farming: More plants in less space. Highly successful in Israel. Future agriculture will be highly based on vertical farming techniques. (This can make life easier in urban areas where inflationary effects are very high)
- The ooze is enriched before application with bio-fertilisers and friendly microbes, such as azetobacter and azospirilum (explained below)
- He diluted one litre of sea water with 10 litres of fresh water and applied it in the soil and on the foliage, to utilise the 92 micro-nutrients (What are micro nutrients and macronutrients? ) (How can sea water be helpful in agriculture?) available in sea water by spraying this sea water-fresh water mixture once in a month, he claimed that he could produce nutrient rich organic vegetables.
Related Post: ‘Aerobic’ rice cultivation
- Bio-char reduces the acidity of the soil, protects the plants from diseases, promotes growth of friendly microorganisms, and reduces the loss of micro nutrients apart from increasing water retain-ability.
Agricultural Benefits of Compost Tea
- Compost Tea is a Liquid fertilizer for flowers, vegetables and houseplants.
- Compost tea is an aerobic (in the presence of oxygen) water solution that has extracted the microbe population from compost (dead and decaying matter) along with the nutrients.
- In simple terms, it is a concentrated liquid created by a process to increase the numbers of beneficial organisms as an organic approach to plant/soil care.
- Air is sent through the water to keep the water oxygenated, as this favors the beneficial bacteria and fungi over the pathogens.
- At the end of the brewing cycle, what you have is a concentrated liquid full of billions of microorganisms (bacteria, fungi, protozoa, nematodes) that can then be sprayed directly onto the leaf surface.
- The liquid fertilizer occupies the infection sites on the leaf surface and is held there by simple sugars that the plant puts out that work as a glue to keep the beneficial microorganisms thriving and protecting the plant.
Bio char
- Bio char is found in soils around the world as a result of vegetation fires and historic soil management practices.
- Intensive study of bio char-rich dark earths in the Amazon (terra preta), has led to a wider appreciation of bio char’s unique properties as a soil enhancer.
- Bio char is charcoal that is as soil amendment (minor improvement).
- It created using a pyrolysis process (decomposition brought about by high temperatures), heating biomass in a low oxygen environment.
- Once the pyrolysis reaction has begun, it is self-sustaining, requiring no outside energy input.
- Byproducts of the process include syngas (H2 + CO), minor quantities of methane (CH4) (greenhouse gas), organic acids and excess heat.
- Once it is produced, bio char is spread on agricultural fields and incorporated into the top layer of soil.
- The syngas and excess heat can be used directly or employed to produce a variety of biofuels.
Related Post: Clean coal technology
Agricultural Benefits of Bio char
- It increases crop yields, sometimes substantially if the soil is in poor condition.
- It helps to prevent fertilizer runoff and leeching, allowing the use of less fertilizers.
- It retains moisture, helping plants through periods of drought more easily.
- Most importantly, it replenishes exhausted or marginal soils with organic carbon
- It fosters the growth of soil microbes essential for nutrient absorption, particularly mycorrhizal fungi.
- Bio char can increase soil fertility of acidic soils (low pH soils)[pH < 7 = Acidic Soils; pH > 7 = Basic Soils] [The most fertile soils are slightly acidic (pH just below 7)]
- Bio-char reduces the acidity of the soil, protects the plants from diseases, promotes growth of friendly microorganisms, and reduces the loss of micro nutrients apart from increasing water retain-ability.
Other Environmental Benefits
- Most carbon in the soil is lost as greenhouse gas (carbon dioxide, CO2) into the atmosphere if natural ecosystems are converted to agricultural land.
- Soils contain 3.3 times more carbon than the atmosphere.
- This makes soils an important source of greenhouse gases but also a potential sink if right management is applied.
- The use of crop residues for bio-energy production reduces the carbon stocks in cropland.
- Further the dedication of cropland to bio-fuel production increases the area of cultivated land and thus carbon loss from soils and vegetation.
- Bio char remains stable for millennia, providing a simple means to sequester carbon emissions.
- If bio char is returned to agricultural land it can increase the soil’s carbon content permanently and would establish a carbon sink for atmospheric CO2.
Leaching
- In agriculture, leaching refers to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation.
- Leaching may also refer to the practice of applying a small amount of excess irrigation where the water has a high salt content to avoid salts from building up in the soil (salinity control).
- Leaching is an environmental concern when it contributes to groundwater contamination.
- As water from rain, flooding, or other sources seeps into the ground, it can dissolve chemicals and carry them into the underground water supply.
- It takes decades to restore a lost forest in evergreen rain forest regions. Why?
- Leaching is particularly important in evergreen rain forests where the top soil is devoid of nutrients due to leaching by surface runoff. It takes decades to restore a lost forest in evergreen rain forest because of poor top soil.
Carbon Sink & Carbon Sequestration
- A carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period.
- The process by which carbon sinks remove carbon dioxide (CO2) from the atmosphere is known as carbon sequestration.
- I will confine this post to Environmentally Sustainable Agricultural practices. I will post detailed articles on Environment concepts later.
Azotobacter
- Azotobacter is a spherical bacteria.
- They are aerobic, free-living soil microbes.
- They play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil.
- Apart from being a model organism, it is used by humans for the production of bio fertilizers, food additives, and some biopolymers.
Azospirillum
- Azospirillum represents the best characterized genus of plant growth-promoting rhizobacteria.
- It is nitrogen-fixing and is found in rhizospheres of several grasses.
Rhizosphere
- The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms.
- Soil which is not part of the rhizosphere is known as bulk soil.
- Protozoa and nematodes that graze on bacteria are also more abundant in the rhizosphere.
- Thus, much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to roots.
Mycorrhizal Fungi and Plants
What are Mycorrhizae?- Mycorrhizae are symbiotic relationships that form between fungi and plants.
- The fungi colonize the root system of a host plant, providing increased water and nutrient absorption capabilities while the plant provides the fungus with carbohydrates formed from photosynthesis.
- Mycorrhizae also offer the host plant increased protection against certain pathogens.
- Fungi are heterotropic organisms, and must absorb their food.
- Fungi also have the ability to easily absorb elements such a phosphorus and nitrogen which are essential for life.
- Plants are autotropic, producing their food in the form of carbohydrates through the process of photosynthesis.
- More than 80% of the species of higher plants have these relationships, and so do many pteridophytes (ferns and their allies – fir, douglas fir, pine, spruce etc.) and some mosses (especially liverworts). They are as common on crop plants (cereals, peas, tomatoes, onions, apples, strawberry, etc) as in wild plant communities
- However, plants often have difficulty obtaining and absorbing many of the essential nutrients needed for life, specifically nitrogen and phosphorus.
Micro-nutrients and Macro-nutrients in soil
- Source: http://soils.wisc.edu/facstaff/barak/soilscience326/macronut.htm
- Macronutrients: N, K, Ca, Mg, P, and S, and
- Micronutrients: Cl, Fe, B, Mn, Zn, Cu, Mo, and Ni
- “Macro” and “micro” nutrient fertilizers refer to the quantity of nutrient needed by plants, not to their importance to plant growth.
- Macronutrients are divided into two classes: primary and secondary.
- The three primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K); all are required in relatively large quantities by plants. The ratio considered ideal stands at 4:2:1. (this was asked in previous prelims)
- The secondary macronutrients, calcium (Ca), magnesium (Mg), and sulfur (S), are required in lesser quantities relative to the primary category.
- Micronutrients are required by plants in far smaller quantities than any macronutrient. Micronutrients required by plants include zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl). Relative to the macronutrients, micronutrients are required in trace quantities.
- The uses of each of these elements for plants will be covered under NCERT Biology
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