Evaluation of potassium thiosulfate as a nitrification inhibitor to reduce nitrous oxide emissions

Authors: CAI, ZEJIANG - Chinese Academy Of Agricultural Sciences; Gao, Suduan; XU, MINGGANG - Chinese Academy Of Agricultural Sciences; HANSON, BRADLEY - University Of California

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2017
Publication Date: 11/10/2017
Citation: Cai, Z., Gao, S., Xu, M., Hanson, B.D. 2017. Evaluation of potassium thiosulfate as a nitrification inhibitor to reduce nitrous oxide emissions. Science of the Total Environment. 618:243–249. https://doi.org/10.1016/j.scitotenv.2017.10.274.
DOI: https://doi.org/10.1016/j.scitotenv.2017.10.274

Interpretive Summary: Reducing nitrous oxide (N2O) emissions from agriculture has significant impact on climate change because agriculture is the largest source for this potent greenhouse gas. This study examined the effects of potassium thiosulfate, a fertilizer for potassium and sulfur, to potentially reduce N2O emissions. Thiosulfate functions as a nitrification inhibitor that inhibits transformation of ammonium to nitrate during which N2O can form. By comparing with commercial inhibitors, potassium thiosulfate was found to reduce N2O emissions significantly and by 50% when application rate increased to 102 mg S/kg soil. The results show that potassium thiosulfate can be equally effective as a commercial inhibitor in reducing N2O emissions. As fertilizer, however, potassium thiosulfate provides nutrients, and can ultimately lead to reduced total chemical input in agronomic systems if it can replace some of the commercial inhibitors for reducing N2O emissions and improving overall nutrient management.

Technical Abstract: Potassium thiosulfate (KTS, K2S2O3) has been shown to function as a nitrification inhibitor, thus has the potential to reduce nitrous oxide (N2O) emissions and play an important role in effective N management. The objective of this research was to determine the effects of KTS on N2O emissions and N transformation processes in comparison with commercial N transformation inhibitors (stabilizers). A laboratory incubation experiment was conducted from urea and ammonium nitrate (UAN) applied at 150 mg N kg-1 in a Hanford sandy loam soil (coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents). Treatments included three rates of KTS (26, 51, and 102 mg S2O32--S kg-1), a urease and nitrification inhibitor (Agrotain® Plus), a nitrification inhibitor (N-Serve® 24), and an untreated control. Nitrous oxide emission, soil pH, and mineral N species were monitored for 35 days. Total N2O emissions were reduced significantly by all KTS treatments and the reduction increased as KTS rate increased. At 102 mg S2O32--S kg-1, KTS reduced N2O emissions by 48% (0.18% of total inorganic N), which was statistically similar to the N-Serve® 24 treatment (60% reduction) although lower than Agrotain® Plus (78% reduction). The KTS resulted in significantly less unaccounted (total N) loss compared to the commercial inhibitors. Using KTS can reduce N2O emissions while providing a fertility benefit, which could reduce total chemical inputs into agronomic systems. Future research needs to determine the effectiveness of thiosulfate for improving overall nutrient management while reducing N2O emissions under field conditions.