Efficiency of two nitrification inhibitors (dicyandiamide and 3, 4-dimethypyrazole phosphate) on soil nitrogen transformations and plant productivity: a meta-analysis.

Dicyandiamide (DCD) and 3, 4-dimethypyrazole phosphate (DMPP) are often claimed to be efficient in regulating soil N transformations and influencing plant productivity, but the difference of their performances across field sites is less clear. Here we applied a meta-analysis approach to compare effectiveness of DCD and DMPP across field trials. Our results showed that DCD and DMPP were equally effective in altering soil inorganic N content, dissolve inorganic N (DIN) leaching and nitrous oxide (N2O) emissions. DCD was more effective than DMPP on increasing plant productivity. An increase of crop yield by DMPP was generally only observed in alkaline soil. The cost and benefit analysis (CBA) showed that applying fertilizer N with DCD produced additional revenues of $109.49 ha(-1) yr(-1) for maize farms, equivalent to 6.02% increase in grain revenues. In comparisons, DMPP application produced less monetary benefit of $15.67 ha(-1) yr(-1). Our findings showed that DCD had an advantage of bringing more net monetary benefit over DMPP. But this may be weakened by the higher toxicity of DCD than DMPP especially after continuous DCD application. Alternatively, an option related to net monetary benefit may be achieved through applying DMPP in alkaline soil and reducing the cost of purchasing DMPP products.