Submitted to: Trade Journal Publication
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2011
Publication Date: 12/9/2011
Citation: Acosta Martinez, V., Mikha, M.M., Sistani, K.R., Stahlman, F., Benjamin, J.G., Vigil, M.F., Erickson, R. 2011. Multi-location study of soil enzyme activities as affected by different manure types, rates, and tillage application practices. Agriculture. 1(1): 4-21. Interpretive Summary: Significant amounts of manure are produced in the U.S and disposed into agricultural land as a less expensive fertilizer to increase soil nutrients. Thus, it is important to determine continuously the soil enzyme activities in agricultural land under manure as they are sensitive indicators of nutrient cycling and soil organic matter changes. This study evaluated enzyme activities of C (ß-glucosidase, a-galactosidase), C and N (ß-glucosaminidase) and P cycling (phosphomonoesterases) as affected by manure types, rates and tillage application practices for different soils in plots established in 3 states (Colorado, Kentucky and Kansas). Results showed that tillage practices for manure application did not affect the enzyme activities within the first 3 years of this study. The response of the enzyme activities in the 3 different states depended on the manure and soil type. The enzyme activities responded faster in the sandier soil evaluated in Colorado (fine sandy loam) than the soil in Kansas (silt loam) after the 1st year of beef manure applications. Since the 1st year in Kentucky plots, C cycling enzyme activities were almost doubled in dairy and poultry treated soil compared to the none treated soil. However, acid phosphatase activity was higher under the poultry treated soil than in the dairy treated soil while C cycling enzyme activities were similar in soil treated with poultry manure or dairy manure. The three states (studies) showed significant responses in C and P cycling enzyme activities to manure applications within 1-2 years, representing potential benefits in soil nutrient cycling for agro-ecosystems supported with organic fertilizers.
Technical Abstract: A multi-location research effort evaluated enzyme activities key to nutrient cycling such as ß-glucosidase (C cycling), a-galactosidase (C cycling), ß-glucosaminidase (C and N cycling) and phosphomonoesterases (P cycling) in research plots established as follow: (1) two years of beef manure applications to a fine sandy loam at different rates (control: 0, low: 34 kg N ha-1 and high: 96 kg N ha-1) and different tillage practices in Colorado (CO); (2) three years of beef manure applications to a silt loam at different rates (0, low: 67 kg N ha-1 and high: 134 kg N ha-1) in Kansas (KS) and; (3) three years of poultry and dairy manure applications to a silt loam with different tillage practices at the same rate (403 kg N ha-1) in Kentucky (KY). Tillage practices (no-tillage vs. conventional tillage) had no effect on the enzyme activities. Principal Component Analyses (PCA) showed all enzyme activities associated with the high beef manure application rate after the 1st year in CO study at 0-5 cm. By the 2nd year, the low and high beef manure rates differed in the enzyme activities for KS study, but there was no differentiation between the low rate and control in the CO study. At the KY study, PCA plots indicated all enzyme activities were associated to poultry and dairy manure than in the control during the entire study. Acid phosphatase activity was greater in the poultry treated soil compared to dairy or the control; whereas C cycling enzyme activities (ß-glucosaminidase, ß-glucosidase and a-galactosidase) were similar in soil treated with dairy or poultry manure. Soil samples from 5-10 cm did not reveal treatment separation until year 2 for all studies (i.e., only high application rate differed from the other treatments). Our findings with different soils revealed significant responses in C and P cycling enzyme activities to manure applications within 1-2 years, representing potential benefits in ecosystem services (i.e., soil biogeochemical cycling) essential for the future for agro-ecosystems supported with organic fertilizers.