QUANTIFICATION OF FRESH CATTLE DUNG AND FERTILIZER NUTRIENT EQUIVALENCE UNDER CHANGING CATTLE POPULATION: A TEMPORAL STUDY IN THANJAVUR DISTRICT, TAMIL NADU

Abstract

In India's agricultural economy, cattle dung is a vital yet underexploited renewable resource, playing a key role in nutrient recycling, renewable energy generation, reducing greenhouse gases, and boosting soil fertility. This research utilizes livestock census data from 2007, 2012, and 2019, which recorded cattle populations of 446,750, 387,008, and 350,527, in Thanjavur District respectively. Fresh dung output was calculated for different herd categories: adults, making up 60% of the population with an average daily dung production of 22.5 kg; heifers, comprising 25% with 12.5 kg per day; and calves, accounting for 15% with 6 kg per day. Adult cattle consistently produced the majority of the total average daily fresh dung. This production dropped from 7,829.31 tonnes in 2007 to 6,782.32 tonnes in 2012, and further to 6,142.98 tonnes in 2019. This approximately 21.5% reduction over the period aligns with national and regional trends showing a decline in native animal populations and increased mechanization. The Farmyard Manure (FYM) examined has a typical nutrient composition of 0.5% Nitrogen (5 kg per tonne), 0.2% Phosphorus pentoxide (2 kg per tonne), and 0.5% Potassium oxide (5 kg per tonne). Based on 2019 production levels, this translates to an annual supply of about 11,200 tonnes of Nitrogen, 4,480 tonnes of P₂O₅, and 11,200 tonnes of K₂O, derived from daily data. The fertilizer equivalence per tonne of FYM is roughly 10.9 kg of urea (46% N), 12.5 kg of Single Super Phosphate (16% P₂O₅), and 8.3 kg of Muriate of Potash (60% K₂O). This substitution could potentially lead to annual savings of over 24,000 tonnes of urea-equivalent and corresponding amounts of phosphorus and potassium fertilizers in the study area. These savings help lower input costs, reduce dependency on imports, and decrease emissions linked to synthetic fertilizer production. Effective management techniques, such as aerobic composting or anaerobic digestion in biogas plants, can cut methane (CH₄) emissions by 50-90% compared to unmanaged dung piles. These methods also generate renewable energy and nutrient-rich digestate. The use of farmyard manure (FYM) significantly improves soil health by raising soil organic carbon (SOC) levels by 0.1-0.5% annually with regular application (5-10 t/ha). This practice enhances soil structure, water retention, microbial diversity, and long-term productivity, thus counteracting the degradation caused by intensive chemical fertilizer use. These varied benefits underscore the importance of integrated nutrient management (INM) strategies. The study suggests policy actions to improve collection and processing systems and raise awareness to boost environmental and economic benefits as livestock patterns change. Better dung use aids climate-smart farming, the circular bioeconomy, and sustainable rural growth in India.