Phosphorus distribution and loss in the livestock sector - The case of Thailand

Mass balance analysis of phosphorus (P) flows in livestock activities in Thailand was conducted with the aim to determine quantitatively its current status coupled with recovery and recycling potentials. From the total average P input to the Thai livestock sector of 126,343 t P y−1, over 90% of these quantities come from animal feed, while the remaining is from the import of animal products. After animal feed P is contained mostly in (a) manures (103,114 t P y−1) of which 96% are recycled to cultivation fields, (b) animal products (meat, milk, and eggs) (8120 t P y−1), (c) solid waste and wastewater released from processing plants (1201 t P y−1) and (d) unidentified loss during animal husbandry activities (13,908 t P y−1). Products produced from the livestock sector are delivered to the domestic market (89%) and exported (11%). The manures recycled, however, contribute to only 41% of the country's P fertilizers applied on crop lands. The overall mass balance for Thailand's livestock ecosystem indicates a P utilization efficiency of 88%. Concurrently, the livestock ecosystem exhibits an annual loss of 15,311 t P y−1. The greatest loss of about 39% occurs in layer hen husbandry activities; while, the highest loss per ton product is due to layer duck farming. Based on the findings of this work it is recommended that minimization of P loss, especially from husbandry farms, via maximization of P recycling be the focus of future research. Results should be aimed at reducing P imports needed for food cultivation and curtailing pollution causing eutrophic environments.