A survey of dairy manure management practices in California

Written (n = 139) and oral (n = 45) surveys were conducted to identify practices for the collection, storage, and use of manure on California dairy farms in Tulare, Fresno, and Madera counties. The purpose of the survey was to develop benchmark data for development and implementation of research and educational programs to improve utilization of manure nutrients and to minimize adverse impacts to ground and surface waters. The 53.2% response rate represented 16.4% of the dairies in the three counties. Mean milking herd size ranged from 381 to 910 cows. Additional dry cows and replacement heifers were present. Producers used a combination of manure collection techniques (75.6%) or a single technique (24.4%). Data did not total 100% because multiple techniques were reported. Liquid wash or flush waters were stored in ponds on 95.9% of the dairies. Settling ponds or basins (39.1%) or mechanical solid separators (14.2%) were used to reduce the solid loading rate in storage ponds. Manure solids were collected by tractors (solid system) or from settling ponds or basins (liquid system). Few producers (4.1%) identified composting as a component of manure handling. Liquid manures were used for year-round irrigation (62.2%), spread as a slurry (9.5%), sold or transported off the farm seasonally irrigated (62.2%). Solid spread on farm land (78.4%), used for bedding (27.0%), sold off the farm (58.1%), removed from the farm (6.8%), or composted (5.4%). Sampling and nutrient analyses of soils and manure solids and liquids were seldom performed. Results from this survey indicate a need for the development of educational programs to improve the management of manure nutrients.