Formulation and evaluation of organo-mineral fertilizer pellets for soil and plant nutrition in low-carbon soil

Prof. Braj Kishore Singh1, Prof. Johan Perret1, Graduate Student Tanyaradzwa Chinyukwi1

1Earth University, Las Mercedes, Guacimo, Costa Rica

The excessive use of inorganic fertilizers can lead to a decline in soil organic matter content, increased soil acidity, degradation of soil physical properties, nutrient toxicity and increased rate of erosion. Application of organic fertilizer could improve soil’s physical, chemical and biological properties. However, a notable improvement in these properties requires the application of high rate of nutrient rich organic matter with low C:N ratio. Studies were conducted at EARTH University in Costa Rica to optimize the production of organo-mineral pellets (C:N:P:K) from food waste, chicken and cow manures, peat, silicon, and inorganic fertilizers. Carbon rich C:N:P:K were tested for agronomic performance and economic viability. A guideline for the selection of raw materials was developed, an interactive computer program was designed to optimize the formulation of compost and C:N:P:K, a pilot production plant was set up, and tests were conducted to evaluate the effects of C:N:P:K on soil nutrition and crop production. The guideline included tests for compressibility, resistivity, abrasivity, particle size, hygroscopicity, moisture content, and chemical composition. The computer program helped optimize C:N ratio, water content, and compatibility of different ingredients for the production of C:N:P:K. The pilot plant design and operation provided information for scaling up the unit to a full-scale commercial production plant. The pilot plant consisted of modules for composting, sieving, drying, grinding, formulation, pelletizing, final drying, and packaging of C:N:P:K. The pellets were tested in laboratory for their nutrient release curves and in the field to compare their performance with chemical fertilizers containing only N:P:K. The C:N:P:K were more efficient in nutrient release overtime. They had positive effects on soil properties, and had low transportation and handling costs per unit active fertilizer ingredients compared to compost or municipal waste.


K. Singh is a professor of Soil Science & Plant Nutrition at EARTH University in Costa Rica. He obtained M.Sc. from PFU, Moscow in agro-chemistry and Ph.D. from University of Florida in Soil Science. Dr. Singh joined EARTH University in 1990 along with the first cohort of pioneer students. He was one of the lead scientists in MasterCard Foundation’s grant to develop Global Masters in Health & Sustainable Development, one of the principal investigators in the US Department of Energy funded Biofuel Project, one of the principal research scientists in Multinational Project on structure-based drug design for Chagas Disease in partnership with NASA, and coordinator of Lemelson Foundation supported Hub and Spoke model to promote invention, innovation and entrepreneurship at academic institutions and rural communities. In 2017, Dr. Singh was one of the expert witnesses to successfully defend Costa Rican Government in UNICITRAL arbitration in Washington D.C. Professor Singh has been providing training and conducting international workshops in soil and plant nutrition for the past 28 years. He has developed, registered, and introduced in international markets over 25 products to improve soil-plant health, water purification, and public sanitation. Dr. Singh is the co-founder of Green Roots Consultants, a consulting firm dedicated to provide local solutions to global challenges in agriculture production, natural resource management, and human capacity enhancement. He has advised over 65 theses research in soil fertility, plant nutrition & environmental health. Dr. Singh is one of the founding members of EARTHIANOS – a global group of EARTH graduates committed to innovation based social entrepreneurship.


7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia


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