Bio fertilizers are organic in nature so they don’t accumulate or magnify in nature hence pose no effect to the environment.
There is an increase use in chemical fertilizers these days, because of increased population we need to grow more and more food crops and thus we need more fertilizers to be applied in the soil. but they are posing a lot of damage to the environment such as eutrophication which can affect the BOD values of water body hence indirectly effecting the ecosystem.
Other effects include bio accumulation and bio magnification for example DDT was banned because of adverse effects and persistency.
Their organic nature also helps in enhancing the physical properties of soil as porosity, water holding capacity and nutrient holding and uptake by plants. Their organic nature makes them prone to temperature, so they are not persistent.
They can be obtained from local resources such as manure, but they have contamination which can be a negative point. These might have seeds of weeds or pathogen in form of bacteria or eggs of a pest that can eventually affect the yield. But they can be manufactured in controlled conditions so that the risks can be eliminated. The best thing about bio fertilizers is that they also include microorganisms to fulfil nutritional needs of plants.
Role of microbes as bio fertilizers
Several microorganisms are used as bio fertilizers one such type is rhizobium that fix nitrogen. It can fix 50-100 kg nitrogen per ha per year. They live in nodules of legume plants which give them food and shelter in repay they provide them nitrogen in uptake able form because nitrogen in air can’t be taken by plants directly. Nitrogen fixation is one of the most important and life supporting phenomenon on the planet Earth and it is very interesting to know that it is carried out by microorganisms. And nitrogen thus fixed can be readily taken up by plants. Similar to this many free living microorganisms fix nitrogen independently inside their bodies which is available to plants after the deaths of these microorganisms.
Microbes also play an important role in decomposition of organic matter added to the soil by mineralizing it thus the nutrients initially locked in that organic matter can be made available to the plants grown in such soils, by the bacteria and other microbes.
Why its use is inevitable
Bio fertilizers are eco-friendly in nature and their use in excess or prolonged use it enhances the fertility of soil substantially. Bio fertilizers are increases crop yield 10-40% by the increase of protein contents, amino acids, N2 fixation and vitamins. It is the admirable way to provide micro nutrients and micro chemicals, source of organic matter and the prevent negative way of chemical fertilizers. Also we cannot solely depends upon chemical fertilizers because of their high cost and toxic effects if they are used for a long time. Bio fertilizers are considered to be a better alternative to chemical fertilizers. Different microbes are also play crucial role in various activities in the ecosystem of soil that make it sustainable for the production of crops.
Role of biofertilizers in photosynthesis
Higher photosynthesis play an important role to promote the growth of plant because 90% of plant biomass that is derived from CO2 consumption through photosynthesis. It was reported that assure tests struggles of Rhizobia increased the surface area of the plant leaves, photosynthetic rate, water utilization efficiency and stomatal conductance, point out that rhizobial inoculation of rice can boost the photosynthetic ability of plant substantially. Water stress carry many reactive oxygen species that can cause damage the photosynthetic equipment of plant. The combination of these bacterial bio fertilizers such as Bacillus lentus, Pseudomonades and A. Brasiliense enhance the antioxidant enzymes also increase the chlorophyll contents of leaves under stress condition. Thus, bio fertilizers can play important role to increase the photosynthetic activity and also play role to grow plant well under stress conditions.
The major microorganisms used as bio fertilizer are
Nitrogen fixing biofertilizer
Nitrogen is the most basic nutrient for the fertility and plant growth. 78% nitrogen is present in atmosphere and not in the usable form for plants. To use this nitrogen convert it in the form of ammonia so that uptake by the plants through biological N2 fixation. In this process the complex enzyme that convert the atmospheric nitrogen into ammonia is known as nitrogenase. N2 fixing organisms are groups as symbiotic and non-symbiotic.
- Symbiotic organisms include Rhizobiaceae that fix nitrogen to the leguminous plants.
- Non symbiotic organisms include endophytic plant and free-living microorganisms such as Cyanobacteria, Azotobacter, Azospirillum etc
Symbiotic rhizobacteria belong to Rhizobiaceae family that fix the nitrogen in leguminous plants. In this process nodules are formed that fix nitrogen to the plant. Non symbiotic rhizobacteria fix nitrogen in the non-leguminous plants that are called diazotrophs which has non-binding interaction with plants.
They are aerobic N2 fixing bacteria in which no nodules are formed which is referred to spirilaceae family. Azospirillum is known for its nitrogen fixing and phytohormone production ability. Azospirillum considered as beneficial bacteria that is used as biofertilizer commercially for several crops, especially for rice and wheat which have economic importance in the whole World. Azopirillum enhance the yield and growth of plant of several agricultural crops in different climatic regions.
They are photoautotrophic non symbiotic free living bacteria. Azotobacter improve the root growth and uptake of plant nutrients substantially. The population of Azotobacter is low in uncultivated soils, generally low in rhizosphere.
Blue-green algae and Azolla
Azolla is the useful source of organic manure and N2 in rice production. Azolla as biofertilizer it easily decomposes in soil and N2 is efficiently available for the rice plants. Azolla is used as biofertilizer in fields preceding to rice cultivation.
Role of biofertilizer in remediation of pesticide effects
Different pesticides are used to control the plant diseases. And their use is an important aspect for modern agriculture and pest management. Sometimes their excessive use can be toxic for environment and a potential threat to plants as well as human beings. Bio remediation is the method to treat the contamination of pesticides and gained specific attention because of its cost effectiveness, Eco friendliness and have a potential removal from the environment. However, nowadays, latest research on pesticides is that degradation of bacteria is coming to maturity as rising option to fight the destroying effects of pesticides so that some microorganisms like Azotobacter, Bacillus, Paenibacillus, Pseudomonas, etc grip the ability to decrease the toxicity.
Additionally strains, Actinomycetes having ability to reduce bio degradation and bio transformation of pesticides. Three major enzymes are involved to degradation of pesticides are: estrases, oxidases and hydrolases. Beside these it can be clear that PGPR carry sustainable way to reduce the contamination of pesticides.
Future perspectives of bio fertilizers
The use of biofertilizers are successfully used in some countries and expected its use will grow in the developing World with the passage of time. However, in future it is expected that bio fertilizers might be used in various strategies, for the development of agricultural lands. Bio fertilizers help to improve the production efficiency of crops Worldwide. However, some issues will require to take attention and resolve the bio fertilizer issues.
- Elaborate the bio fertilizers from laboratory.
- Competitive and effective bio fertilizers should be used for crops.
- It is compulsory to inform farmers and people about the long-term benefits of bio fertilizers that are alternative use of chemical fertilizers. Tell the people about adverse effects of chemical fertilizers.
Bio fertilizers improve the soil status, fertility and provide different growth hormones and phytohormones to the plants. Bio fertilizers play crucial role in the development of agricultural fields and in increasing the production of crops. Also, the usage of bio fertilizers is more beneficial than that of chemical fertilizers.
Chemical fertilizers create environmental stresses and declining the productivity of crops. excessive use of chemical fertilizers and pesticides are not only hazardous for humans as well as adverse effect on ecosystem. Therefore, we should need to adopt the concept of bio fertilizers for modern agriculture. Hence the use of bio fertilizers could be the proper option for the sustainable agriculture.