Title: Effects of organic dairy manure amendment on soil phosphatase activities Authors
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 19, 2012
Publication Date: N/A
Technical Abstract: Organic dairy production is increasing in the U.S. due to concerns over environmental, human, and animal health. It is well known that the application of livestock manure to soil can influence enzyme activities involved in nutrient cycling and soil fertility, such as soil phosphatases; however, organic dairy manure (ODM) has different physico-chemical properties than manure from conventional dairies. To investigate the effects of ODM on soil phosphatase activities and plant growth, we conducted a greenhouse study with sudangrass (Sorghum bicolor subsp. drummondii) grown for 16 weeks in soil amended with manures collected from 14 organic dairies. Soil phosphatase [acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE)] activities in pots that received ODM were determined at planting and after 16 weeks of plant growth, and compared to phosphatase activities in pots that received inorganic fertilizer or conventional dairy manure (CDM). Preliminary data analyses revealed that both ODM and CDM increased ACP activity at planting over 2-fold. However, neither manure type had any effect on ALP, and only four ODM samples significantly increased PDE activity. Statistical analysis will continue this summer to evaluate relationships between enzyme activities, plant biomass production, soil test P, and manure physico-chemical properties. This work will provide information on the fertilization value of ODM and key characteristics controlling P availability from ODM.