Overcoming adverse effects of chemical fertilizer:

A biofertiliser to revolutionise agro practices

by Dhaneshi Yatawara

Research and Development Minister Patali Champika Ranawaka

Finding the actual picture of the Chronic Kidney Disease in the North Central Province revealed the alarming condition of the Sri Lankan Farming community. The World Health Organisation and the Sri Lankan Government continue to categorise this as "Chronic Kidney Disease of Unknown Etiology". Yet it is proven that the heavy use of chemical fertilisers and pesticides over a very long period of time have created an unending burden on the farmers of the North Central Province.

Many groups of people of the world raised their voice against the heavy use of chemical fertilisers and pesticides in agriculture and many scientists have proved the ill effects of these. Scientists and agriculture experts researched and revealed to the world that there are alternatives. Better alternatives come up as a result of the obvious reasons seen in failing health of people, degraded soil conditions, low harvests etc.

In Sri Lanka the Agriculture Ministry has instructed the National Fertiliser Secretariat to ban the import of Triple Sulphur Phosphate because it contained an excessive amount of cadmium which contaminate water. In September 2013 Government imposed a ban on pesticides Carbaryl, Chlorophyriphos, Carbofuran and Propanil and the weedicide Glyphosate.

Sri Lanka records as theworld's eighth highest user of Chemical Fertilisers and spends over Rs. 50 billion a year on importation of chemical fertilisers, out of which Rs. 40 billion is borne by the government as subsidies.

The Sri Lankan agriculture industry that heavily depended on agro chemicals for several decades, found it difficult to revert to the age old traditional environment friendly agricultural practices. Chemical fertilisers gave fast results than carbonic fertiliser and the soil takes time to get back the rich composition that got destroyed by chemical fertilisers. Yet the farmers saw the harvest levels dropping with more and more use of chemical fertilisers but they had no alternative. They had to increase the amount of fertiliser spending more money yet comparatively low increase in the harvest which eventually lowered their income.

So, at the end of a few decades the agro chemicals started showing the negative impact of its use putting the farmers at a dead end. It is at this juncture a new concept came to the world named as biofertilisers. This was a breakthrough in the science world. As scientists explain, biofertilisers are the type of fertilisers produced using the microorganisms in the soil such as bacteria and fungi. "The earlier biofertilisers were monocultured - which means it is based on a single type of a microorganism like a fungi or a bacteria," said Prof Gamini Senevirathne, Senior Research scientist of the Institute of Fundamental Studies (IFS) in Kandy.

Scientists found that using soil microorganisms to make biofertilisers was more environment friendly and sustainable.

The living part of soil organic matter includes a wide variety of micro-organisms such as bacteria, viruses, fungi, protozoa and algae. It also includes plant roots, insects, earthworms, and few larger animals that spend part of their life in the soil. The living part of the soil is responsible for keeping air and water available, providing plant nutrients, breaking down pollutants and maintaining the soil structure.

Specific Bacteria species like 'Rhizobium, Pseudomonas, Azatobactor, Azospirillum, mycorhiza' helps to improve the soil condition and certain fungi species like 'Mycorrhiza' which form symbiotic associations with plant roots.

In a research lead by Prof. Senevirathne revealed that rather using a single microorganism it is effective to use two types of microorganisms that would work together supporting each other. "In our research we saw that certain bacteria and fungi can form a symbiosis and create their community like a thin film which is called a biofilm," Prof. Senevirathne said.

The bacteria can fix nitrogen from air provide it to the fungus as a raw material for food and the fungus gives the food back to the bacteria. When going deep in to the research examining the proper ties of this microbial community scientists found that this could be successfully used to fix nitrogen in the soil. "And we found that this biofilm secrets several compounds - among those we found plant growth promoting hormones, organic acids which are used to solubalise phosphorous in the soil. And found positive for suppressing pests and pathogens," said Prof. Senevirathne.

"When we added up all these initial findings we realised that this biofilm is suitable to be used as a bio fertiliser," he said.

According to Prof. Senevirathne conventional bio fertilisers are always based on single microorganisms, bacteria or a fungus and at times they have used cocktail but without attachments. "But when the symbiosis occurs there is a great advancement in efficiency of the community," he said.

The IFS team started the research around 2003 and the findings led them to create a biofertiliser lab scale. "When we found the positive factors we started to develop this biofilm in to a bio fertiliser in a test tube or in scientific terms in 'in vitro' conditions," the professor said.

Then the research was published in international science journals. "And then 2005 we started a research collaboration with the Tea Research Institute (TRI) for testing this biofertiliser with tea. by then we were doing tests with other crops as well. Field trials were going on by then," he said.

Accordingly, the TRI scientific officers found that with the use of the biofertiliser that the NPK fertiliser use can be cut down by 50 percent. The IFS still continues the collaboration with the TRI.

Researchers confirm that this biofertiliser does not contain any pathogenic micro-organisms and is also free from Heavy Metals such as Cadmium (Cd), Arsenic (As), Lead (Pb) & Mercury (Hg).

In 2010, a new private company in to chemical industry, Lanka Bio Fertilisers (Pvt) Limited started discussing with us on commercially producing this, Prof Senevirathne said. The public private partnership succeeded further expanding the scope of the research. The product got patented. Today the product is in the market as a fertiliser for tea.

According to Prof. Senevirathne currently the biofertiliser is made suitable for rice and was developed through research done with Rice Research Institute and several individual farmers. The biofertiliser for vegetables is going through its test runs in several home garden projects. All these are in their field runs to examine its effectiveness in different weather conditions.

"In conventional agriculture we have destroyed all micro-organisms. This has deteriorated the soil condition and to farmers this is a problem and they don't see an increase in the harvest compared to the increased amount of chemical fertiliser used. This is a final result in using chemicals fertilisers for a long term," Prof. Senevirathne said. "In short term the bio fertiliser will fix nitrogen secrete plant growth promoting hormones etc. But in long term this biofilm trigger the natural system of the soil. The bio fertiliser increase the diversity of the microbes in the soil as well as animals that are helpful in plant growth as well. by giving that we can improve the condition of the soil, pest and disease suppression, drought tolerance, moisture retention," he said.

How long does this take , according to Prof. Senevirathne this happens very rapidly with the new biofertiliser. Conventional bio fertilisers as mentioned earlier are mono cultures and can cut down up to 25 percent of the NPK fertiliser of a crop. But this new biofertiliser cuts the usage of chemical fertilisers up to 50 percent which is quite enough to impress the growers and farmers providing them with an economical solution.