Windrow composting is an effective treatment method for livestock manure. However, few

studies have investigated the detailed relationship between the composting process and

surface water quality impacts on surrounding areas. This study conducted a compost nutrient

balance analysis (CNBA) of composting materials under natural field conditions using livestock

manure samples collected at a research windrow composting site in central Iowa, USA. The

research site included a fly ash composting pad surface and vegetative filter strip (VFS) buffer

plots. Surface runoff and pollutant transport data that included sediment (solids), nitrogen

(N), and phosphorus (P) nutrient concentrations and losses also were collected and analyzed.

The CNBA results indicated that all composting properties and materials mostly followed the

general compost biodegradation-related trends throughout spring (early) and summer (late)

60-day composting periods. However, the results also showed that while an average of 34%

P was lost due to the composting process, only an average of 0.3% P was lost to runoff from

the no-VFS buffer (control) plots during the composting periods. Published research indicates

significantly lower P losses from control plot runoff may be attributed to the chemical and

physical conversion effects of the P-sorbent fly ash pad surface material. Consequently, further

research should be conducted that considers the use of fly ash or other P-sorbent pad surface

materials in the construction of new windrow composting sites and the upgrading of existing

composting facilities.

Webber, David, et al. "Compost Nutrient Balance Analysis Results and Water Quality Implications from a Demonstration Livestock Manure Windrow Composting Site." Compost Science & Utilization (2025): 1-11.