Effect of 7-year application of a nitrification inhibitor, dicyandiamide (DCD), on soil microbial biomass, protease and deaminase activities, and the abundance of bacteria and archaea in pasture soils

Abstract

Purpose The nitrification inhibitor dicyandiamide (DCD) has been shown to be highly effective in reducing nitrate (NO 3 − ) leaching and nitrous oxide (N 2 O) emissions when used to treat grazed pasture soils. However, there have been few studies on the possible effects of long-term DCD use on other soil enzyme activities or the abundance of the general soil microbial communities. The objective of this study was to determine possible effects of long-term DCD use on key soil enzyme activities involved in the nitrogen (N) cycle and the abundance of bacteria and archaea in grazed pasture soils. Materials and methods Three field sites used for this study had been treated with DCD for 7 years in field plot experiments. The three pasture soils from three different regions across New Zealand were Pukemutu silt loam in Southland in the southern South Island, Horotiu silt loam in the Waikato in the central North Island and Templeton silt loam in Canterbury in the central South Island. Control and DCDtreated plots were sampled to analyse soil pH, microbial biomass C and N, protease and deaminase activity, and the abundance of bacteria and archaea. Results and discussion The three soils varied significantly in the microbial biomass C (858 to 542 μg C g does not affect other non-target microbial and enzyme activities. The DCD nitrification inhibitor technology, therefore, appears to be an effective mitigation technology for nitrate leaching and nitrous oxide emissions in grazed pasture soils with no adverse impacts on the abundance of bacteria and archaea and key enzyme activities.

A 2-yr field assessment of the effects of chemical and biological nitrification inhibitors on nitrous oxide emissions and nitrogen use efficiency in an intensively managed vegetable cropping system

“…NIs can inhibit nitrification through suppressing the activity of ammonia-oxidizing bacteria or relevant enzymes, effectively delaying the oxidization process that transforms NH 4 + into NO 3 À (Di et al, 2009;Guo et al, 2013). Maintaining a high soil NH 4 + content for a longer time by regulating the rapid conversion of soil N can effectively alleviate NO 3 À accumulation and leaching losses, in addition to reducing N 2 O emissions Fangueiro et al, 2009).…”

The effect of nitrification inhibitors on the nitrous oxide (N2O) release from agricultural soils—a review

“…Guo et al (2013) investigated the effect of long‐term DCD application on microbial biomass, protease and deaminase activities, and the abundance of bacteria and archaea in three pasture soils. Seven years of DCD application did not affect any of the investigated factors.…”

“…Seven years of DCD application did not affect any of the investigated factors. Guo et al (2013) concluded that “the DCD nitrification inhibitor technology, therefore, appears to be an effective mitigation technology for nitrate leaching and nitrous oxide emissions in grazed pasture soils with no adverse impacts on the abundance of bacteria and archaea and key enzyme activities” .…”

Evaluating the ecotoxicity of nitrification inhibitors using terrestrial and aquatic test organisms

“…This also did not show effects even at concentrations of 100 mg L −1 . Guo et al [12] found that after a long-term application of DCD, non-target microbes in the soil were unaffected. Therefore, the authors concluded that DCD only acts specifically on the ammonia oxidation.…”

“…This is a rather high value indicating that Piadin has hardly any toxic effect on the non-target bacterium A. fischeri. Studies testing the effect of other nitrification inhibitors such as DCD and DMPP concluded that these NIs at the recommended application rates do not affect non-target soil bacteria and act specifically on ammonia oxidation [12,36]. As A. fischeri was barely affected, this can be assumed for Piadin as well.…”