Industrial-scale hydrothermal treatment of cattle manure for rapid compost production: compost quality and potato yield

Hydrothermally treated (HT) composting is an advanced method for rapid management of cattle manure. An industrial-scale facility was established to evaluate the quality of HT compost in comparison to farmyard manure (FYM) compost, cow dung compost (used as a control), and five independent batches for replication. The preparation of all the composts was done using cow dung and cattle barn residues (straw and fodder). Cattle manure was hydrothermally treated at 220 °C and 150 psi for 15 min, and a hyperthermophilic phase started early in the HT composting process on day two. The HT compost reached maturity, as indicated by GI ≥110, within 21 days and stabled at 60 days of maturation without phytotoxic effects. At final maturity, HT compost contained 0.86 ± 0.12% total nitrogen, 0.45 ± 0.02% phosphorus, a pH of 7.16 ± 0.15, and a C: N ratio of 15.11 ± 0.82. Pb, Cd, Cr, and Ni levels varied in the process but were all found to be in a safe range for agricultural use. To compare the performance of HT compost (1.0 t ha −1 ) + chemical fertilizer to FYM (15 t ha −1 ) + chemical fertilizer, a field experiment was laid out on potato cultivation. The marketable yield was 13.83 ± 0.20 t ha −1 for the application of HT compost and 11.15 ± 0.10 t ha −1 for FYM. These findings show that HT composting offers a shortened composting time and a scalable solution for managing cattle manure, providing sustainable benefits for cattle farmers, particularly in countries like Bangladesh.