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Effective production and usage of liquid organic fertiliser 

02 Jan 2022

By Sudeepa Lakshan  Fertiliser application is essential for maximizing yield in crop cultivation. With the harvest of a crop, nutrients taken up from the soil are removed. Therefore, when continuing crop cultivation in a field, plant nutrients need to be added externally. Nutrients are supplied through fertilisers. There are different types of fertilisers and organic liquid fertiliser is one such category. Organic liquid fertilisers are formulated with materials of biological origin to exist in liquid form. For the effective use of organic liquid fertilisers there are several factors that need to be considered starting from the production to application.  There are different types of liquid organic fertilisers (e.g. digested organic materials, compost tea, vermi-wash and biofertilisers). In all types, regulating microbial activity is very important.  Discarded fruits and vegetables, fish waste, leaves such as gliricidia, banana stems and peels, seaweeds, and any organic material can be used in organic liquid fertiliser manufacturing. These materials are mixed with water and digested to produce organic liquid fertilisers. The digestion is facilitated by adding a mixture of known microorganisms or adding small amounts of fertile soil or compost. When microorganisms are not introduced externally the digestion process takes a long time.  There are two main digestion methods by which organic liquid fertilisers can be produced: aerobic digestion and anaerobic fermentation. When produced under aerobic conditions, organic liquid fertilisers can be made relatively quickly and the nutrient content is relatively high. Also the release of toxins and toxic gases as by-products is minimised. However, to maintain aerobic conditions the mixture must be constantly stirred (aerated) during the digestion of the organic materials. Thus, the production of organic liquid fertiliser using this method consumes energy. Therefore, the cost of fertiliser produced using this method is high. Hence, small-scale organic liquid fertiliser manufacturers often use anaerobic fermentation approach.  The organic liquid fertiliser called “compost tea” is made by brewing compost in water with or without aeration (aerobic or anaerobic conditions, respectively). The organic liquid fertiliser known as vermi-wash is a liquid extraction separated from the vermicompost. It usually has a higher nutritional value than compost tea. It is challenging to produce vermiwash in large quantities and it is more suitable to produce at home-garden scale.  Biofertilisers are formulations containing live microorganisms. For some biofertilisers liquid based medium is used as a carrier material.  Regardless of the type of organic liquid fertiliser produced, it is imperative to stop or suppress the microbial activity in the organic liquid fertiliser before packing them into bottles. Otherwise, the microbes in the mixture will continue to function and release gases due to metabolic processes. These gases will build up inside the containers increasing the pressure and the containers could explode. This explains why bottles of organic liquid fertiliser are exploding these days.  Several methods are being used to kill or remove the microorganisms before packaging of organic liquid fertilisers except biofertilisers. Such methods include filtering, adding acids, centrifuging, and heating. When filtering is practiced the filters should be fine enough to separate microbial cells from the liquid and otherwise it is not effective at stopping microbial activity.  Organic liquid fertilisers other than bio-fertilisers can be sprayed on to the leaves of crops. Here it is mandatory to dilute with water to the ratio indicated on the package by the manufacturer. Otherwise, the leaves may burn. However, organic liquid fertilisers sprayed on to the leaves cannot satisfy the total nutrient requirement of the crop. Therefore, organic liquid fertilisers are used as supplementary nutrient sources together with solid fertilisers (synthetic chemical or organic) in crop production.  Organic liquid fertilisers are easier to apply to subsistence commercial home gardens than to large-scale commercial agricultural lands. This is due to the fact that these can usually be prepared at a household level. Another reason is that it is easier to take precautionary measures against large animals (such as cats and dogs) and insects such as flies that are attracted by the smell of organic liquid fertilisers when practiced at a small scale compared to commercial-scale agriculture. It is important to note that the application of organic liquid fertiliser alone as a major nutrient application is not sufficient to achieve maximum yield of a crop.  It is also important to follow hygienic practices when applying organic liquid fertilisers. These fluids may produce highly toxic substances such as phenol, cyanide, and cyanuric acid. It is also highly toxic to inhale the gases emitted from these containers, especially from those subjected to anaerobic fermentation. The gases emitted by these, such as hydrogen sulphide, are several times more toxic than hydrogen cyanide.  Various problems have been reported related to organic liquid fertiliser products due to improper quality control, non-application of subject knowledge, and high profit motive. Low quality fertilisers can lead to crop failure, explosion of manure containers, poisoning of human and soil-friendly organisms, and destruction of crops by dogs. Therefore, careless use of organic liquid fertilisers and the application of those that have been prepared without following standards and are of poor quality would result in side effects damaging the health and the environment at large.  The production of organic liquid fertiliser by aerobic digestion is a solution to some problems. Then the probability of producing toxic gases is also low. Also, most microorganisms that are pathogenic to plants are anaerobic, and maintaining an aerobic environment prevents anaerobic organisms from dominating the mixture. Therefore, the application of fertilisers produced with aerobic digestion also reduces the risk of spreading diseases to the crop. Standards are currently being developed for organic liquid fertilisers and biofertilisers. At the same time standard operational procedures should be developed for industrial-scale production of organic liquid fertilisers. There is an urgent need to expedite these. In parallel, awareness about organic liquid fertilisers should be increased among the farming community and prospective manufacturers. Organic liquid fertiliser production can be easily linked with the circulation of resources in par with concepts of circular-economy. Policy environment should be developed to facilitate this. Organic liquid fertiliser can be standardised and used as a supplementary nutrient source to increase crop productivity in the journey towards eco-friendly sustainable agricultural systems.  (The writer is an undergraduate of the Faculty of Agriculture at the University of Peradeniya. The article is based on a discussion with Dr. Warshi Dandeniya from the Department of Soil Science at the Faculty of Agriculture, University Of Peradeniya)   

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Discover Kapruka, the leading online shopping platform in Sri Lanka, where you can conveniently send Gifts and Flowers to your loved ones for any event. Explore a wide range of popular Shopping Categories on Kapruka, including Toys, Groceries, Electronics, Birthday Cakes, Fruits, Chocolates, Automobile, Mother and Baby Products, Clothing, and Fashion. Additionally, Kapruka offers unique online services like Money Remittance, Astrology, Medicine Delivery, and access to over 700 Top Brands. Also If you’re interested in selling with Kapruka, Partner Central by Kapruka is the best solution to start with. Moreover, through Kapruka Global Shop, you can also enjoy the convenience of purchasing products from renowned platforms like Amazon and eBay and have them delivered to Sri Lanka.Send love straight to their heart this Valentine's with our thoughtful gifts!


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