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CONCEPT – CHEMICALISATION OF AGRICULTURE
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- The first scientist : German scientist Justus Freiherr von Liebig (1803 – 1873) devised the modern laboratory-oriented teaching method, and is called the "father of the fertilizer industry". He emphasized on nitrogen and trace minerals as essential plant nutrients.
- Law of the minimum : He explained how plant growth relied on the scarcest nutrient resource, rather than the total amount of resources available. A plant's development is limited by the one essential mineral that is in the relatively shortest supply. This concept of limitation can be visualized as "Liebig's barrel". This is a qualitative version of the principles used for determining the application of fertilizer in modern agriculture.
- Chemistry applied to agriculture : By the 1840s, Liebig applied theoretical knowledge from organic chemistry to real-world problems of food availability. He promoted the idea that chemistry could revolutionize agricultural practice, increasing yields and lowering costs. He discussed chemical transformations within living systems, both plant and animal, outlining a theoretical approach to agricultural chemistry. His awareness of both synthesis and degradation led him to become an early advocate of conservation, promoting ideas such as the recycling of sewage.
- Nutrients and minerals : In his theory of mineral nutrients, he identified the chemical elements of nitrogen (N), phosphorus (P), and potassium (K) as essential to plant growth. He reported that plants acquire carbon (C) and hydrogen (H) from the atmosphere and from water (H2O). In addition to emphasizing the importance of minerals in the soil, he argued that plants feed on nitrogen compounds derived from the air. This assertion was a source of contention for many years, and turned out to be true for legumes, but not for other plants. The Zero Budget Natural Farming prponents criticise Liebig and call him "Lie Big".
- Fertilizers : A fertilizer (fertiliser) is any material of natural or synthetic origin (other than liming materials - calcium or magnesium-rich) that is applied to soil or to plant tissues to supply one or more plant nutrients essential to the growth of plants. We can have both natural and artificial fertilizers.
- What fertilizers do : They enhance plant growth, the goal being met in two ways, the traditional (additives that provide nutrients) and artificial (some fertilizers enhance the effectiveness of the soil by modifying its water retention and aeration).
- Macronutrients and Micronutrients :
- The three main macro nutrients are - (a) Nitrogen (N): leaf growth, (b) Phosphorus (P): Development of roots, flowers, seeds, fruit, and (c) Potassium (K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting.
- Three secondary macronutrients are : calcium (Ca), magnesium (Mg), and sulfur (S)
- Main micronutrients are : copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B). Of occasional significance are silicon (Si), cobalt (Co), and vanadium (V).
- What is soil : Soil is a living, highly complex and dynamic ecosystem that harbours and supports the rich diversity of micro and macro flora which in turn influences its properties. It primarily consists of inorganic mineral nutrients and organic matter along with huge numbers of living forms and maintains a balance between physical, chemical and biological factors. Soil is the basis of agriculture and thus the universal food production. Apart from its most widely known role as a medium for plant growth soil performs many other vital functions such as mediating the exchange of gases, flow of energy, nutrients and water, detoxifi cation of pollutants etc. Hence, management of soil health is crucial for ensuring sustainable agricultural productions and maintenance of soil biodiversity including microbial diversity.
- Types of fertilizers : Fertilizers can be classified according to whether they provide a single nutrient (K, P, or N), and are named "straight fertilizers." We also have "Multinutrient fertilizers" ("complex fertilizers") providing two or more nutrients, for example N and P. Fertilizers are also sometimes classified as inorganic versus organic. Inorganic fertilizers exclude carbon-containing materials except ureas. Organic fertilizers are usually (recycled) plant- or animal-derived matter. Inorganic are sometimes called synthetic fertilizers since various chemical treatments are required for their manufacture. The controversies on chemical agriculture centre around these inorganic fertilizers.
- Organic fertilizers : These are fertilizers with an organic origin that arederived from living or formerly living materials. They can also describe commercially available and frequently packaged products that strive to follow the expectations and restrictions adopted by “organic agriculture” and "environmentally friendly" gardening — related systems of food and plant production that significantly limit or strictly avoid the use of synthetic fertilizers and pesticides. The “organic fertilizer” products typically contain both some organic materials as well as acceptable additives such as nutritive rock powders, ground sea shells (crab, oyster, etc.), other prepared products such as seed meal or kelp, and cultivated microorganisms and derivatives.
- Soil health management : It is crucial for ensuring sustainable agricultural productions and maintenance of biodiversity. Fertilizers and pesticides are a necessary evil for industrial agriculture. They do have adverse effects on environment and human health, and also on microbial properties of soil.
- Soil microflora is a key component of agricultural ecosystems that not only plays a significant role in the basic soil processes but is also actively involved in enhancing soil fertility and crop productivity.
- Microbial activity in soil has a strong impact on its physical properties and at the same time it is also instrumental in pursuing eco-friendly practices like bioremediation and biocontrol of phytopathogens inagricultural soils.
- Soil microorganisms have thus been accepted as the bioindicators of soil health and activity.
- Fertilizers and pesticides tend to have long persistence in the soil so they are bound to affect the soil micoflora thereby disturbing soil health.
- Science versus the Rest : In the 21st century, criticism of Green Revolution (set of technologies used from 1960s to boost yields) has become stronger. Newer methods are being proposed to replace chemical agriculture that Green Revolution used. None of the new methods are rigorously proven in the scientific way. Time will tell whether 'chemical agriculture' will be able to adapt and evolve to being 'less harmful but scientifically proven' or will be replaced by some new method.
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