Few years from now, fertilisers could turn from commodities to knowledge chemicals. Our columnist takes a peek into the world of Nanofertilisers, which promise to bring precision to agriculture by delivering nutrients more effectively and efficiently to plants. Nanotechnology has the potential to cut down fertiliser consumption by few orders of magnitude and transform the industry beyond recognition.
The traditional Independence Day address of our Prime Minister from the ramparts of the Red Fort was unusual this year for many social and environmental pronouncements. Among them was an appeal to the farming community to cut down on the usage of chemical fertilisers by 10-25%. Expressing concern about the deteriorating soil health due to excessive use of chemical fertilisers and pesticides, Prime Minister Modi called for a campaign that will completely eliminate their use. This clarion call will no doubt cast long shadows on the future of the Rs 5000 billion Indian fertiliser industry, which has made a huge contribution to the success of the Green Revolution and subsequent self-reliance in food production.
CSE Rating Report
Curiously, just a fortnight before this momentous appeal, Centre for Science and Environment (CSE) released the environmental rating of the Indian Fertiliser Industry, the 7th industrial sector to be covered by the Green Rating Project (GRP), the country’s only independent, rigorous and credible programme of its kind. The CSE report says that the industry has performed well in curtailing its energy consumption and GHG emissions, but raises several alarms on the environment front. The report is very critical about the poor efficiency of Nitrogen use – a mere 35%. Imbalanced application of nitrogenous fertilisers is leading to widespread soil sickness. The report urges that the Nitrogen use efficiency must double to 70% and recommends that our agricultural practices must shift from the present practice of bulk application of fertilisers to a more precise delivery of essential nutrients. The CSE report also laments that there has been very little product innovation in the fertiliser industry.
Wasteful Practice
Traditionally, fertilisers are applied to crops by either spraying or broadcasting. These are extremely wasteful practices. It has been estimated that 40-70% of Nitrogen, 80-90% of Phosphorous and 50-90% of Potassium content of the applied fertilisers do not reach the targeted area of the plants and are lost to the environment. The net result is a low bioavailability to the plants and increased contamination of soil and groundwater. There are many ways by which the nutrients are lost in the environment, among them – wind drift, surface runoff, leaching, photolytic and microbial degradation and hydrolysis by soil moisture. The poor utilisation of nutrients leads to overuse of fertilisers, which further increases the losses to the environment in a self-destructive cycle.
Nanotechnology
Nanotechnology can be used to affect a slow and controlled release of the nutrients to plants. Nanostructures, due to their high surface area to volume ratio, have a tremendous potential to deliver nutrients to specific target sites. Deploying nanostructures as carriers, nutrients can be released in a slow controlled fashion, thereby significantly improving their uptake efficiency. Surfaces of nanostructures can be modified to hold the nutrients more strongly and help in slow and regulated release. There are several ways in which nutrients can be loaded on to nanostructures. The nutrients maybe absorbed on the nanoparticles or attached by means of ligands. Another technique is to encapsulate the nutrients in a nanoparticulate polymeric shell. The nutrients may also be entrapped in polymeric nanostructures. Alternatively, the nutrients themselves could be synthesised as nanoparticles.Nanofertilisers
Field studies with nanofertilisers have shown very positive results. Mesoporous silica nanoparticles with Urea entrapped inside have yielded a controlled release profile, with a fivefold improvement in the release time compared to conventional fertilisers. Zeolites, with their three-dimensional crystal structure, excellent porosity and large surface area, are the most favoured and extensively used substrates for nanofertilisers. Zeolite nanocomposites carrying nitrogenous and phosphatic fertilisers have enhanced farm productivity with significantly lowered dosages. Higher uptake of Nitrogen by crops has been reported when Urea was applied with nanozeolites.
Micronutrients
Conventional fertilisers do not possess all the nutrients essential for plant growth. With nanotechnology, it is possible to customise fertilisers to deliver special micronutrients on demand, in tiny accurate dosages. Nanofertilisers can be engineered to address a specific nutritional deficiency in plants. Zinc and Copper are among the most commonly required micronutrients that are not provided by conventional fertilisers. Nanoparticles of Titanium Dioxide have been reported to enhance nitrogen fixation and promote photosynthesis. Cerium Oxide nanoparticles are also most sought after for crop improvement and nutritional benefits. Noble material nanoparticles, especially Silver have been found to provide many benefits. In addition to promoting plant growth, nanotechnology can also be used to enhance the nutritional levels of plants for human well-being; a case in point is the Selenium enrichment of plants to satisfy human requirements.
Risks
The risks of nanoparticles to human health and safety are yet to be fully understood. Since the size of nanoparticles is similar to biological molecules like antibodies and proteins, it is suspected that they will easily enter humans and animals through oral, respiratory and intradermal routes and interfere in the functioning of vital organs. The line separating deficiency and toxicity is thin, and the possibility of metallic nutrients accumulating in plants and entering the food-chain cannot be ruled out. Much work needs to be done on the characterisation of nanoparticles. Protocols on their handling and application needs to be established.
Epilogue
The Haber-Bosch process of 1909 for synthesis of Ammonia is regarded by many as the most significant invention of 20th Century for fundamentally altering the Nitrogen Cycle and laying to rest the Malthusian spectre. But hundred years after that epic invention, chemical fertilisers are not being looked upon kindly by many environmentalists. Rampant overuse of fertilisers have degraded large swathes of arable land. Meanwhile as population continues to burgeon, food security is a cause of growing concern. Nanotechnology offers an alternative method of delivering nutrients to plant cells in a more efficient and sustainable manner. Nanofertilisers bring a new level of precision to agriculture and significantly increase farm output while preserving soil health. However, there are health risks that need to be carefully evaluated before we embrace this technology wholeheartedly.
Last year, IFFCO established a laboratory at their Kalol Plant in Gujarat to study nanofertilisers. In March this year, the company announced that the product is expected to be marketed within the next 2 years. The company’s management also made the astonishing claim that 2 grams of the nanofertiliser will be equivalent to 100 kgs of Urea! If and when that happens, the fertiliser industry would be transformed from a commodity business to a knowledge business.
Readers’ responses may be sent to: k.sahasranaman@gmail.com or chemindigest@gmail.com
