Do tropical climatic conditions reduce the effectiveness of nitrification inhibitors? A meta-analysis of studies carried out in Brazil

Nutr Cycl Agroecosyst https://doi.org/10.1007/s10705-023-10266-0 REVIEW ARTICLE Do tropical climatic conditions reduce the effectiveness of nitrification inhibitors? A meta‑analysis of studies carried out in Brazil Pablo Lacerda Ribeiro · Filipe Selau Carlos · Gabriel Barth · Karl H. Mühling Received: 9 September 2022 / Accepted: 19 February 2023 © The Author(s) 2023 Abstract Extensive research has been performed into the effectiveness of nitrification inhibitors (NIs) in preventing N losses; however, tropical agriculture has been underrepresented in recent meta-analyses. Here, we apply a meta-analytic approach using data from 50 articles to identify the impact of NIs (DMPP, DCD, and DCD + NBPT) on crop yield, N2O emissions, soil N H4+ and N O3− concentrations, and NH3 volatilization in subtropical and tropical regions of Brazil. In addition, the survey includes information about location; climate zone; cultivated crops; soil Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/s10705-023-10266-0. P. L. Ribeiro (*) · K. H. Mühling Institute of Plant Nutrition and Soil Science, Kiel University, Hermann‑Rodewald‑Strasse 2, 24118 Kiel, Germany e-mail: K. H. Mühling e-mail: F. S. Carlos Universidade Federal de Pelotas, Campus Capão do Leão, Campus Universitário, S/N, Capão do Leão, Rio Grande do Sul 96160‑000, Brazil e-mail: G. Barth Fundação ABC, Rua Jonas Borges Martins, 1313 Cx. Postal 1003, Castro, Paraná 84165‑250, Brazil e-mail: pH; soil organic carbon; soil texture; experimental method; soil management; irrigation; fertilizer source, rate, and type; and NI type and rate. Overall, the data set showed that NIs increased crop yield and soil NH4+ concentrations by 3 and 60%, respectively, whereas N2O emissions and soil NO3− concentrations were reduced by 62 and 31%, respectively. Ammonia volatilization was not changed by NI application. However, the combination of a NI with a urease inhibitor decreased such losses by 39%. The effectiveness of the NIs was highest in irrigated fields, fine-textured soils, and mineral N sources. Moreover, NI performance in Brazil was found to be similar in tropical and subtropical climates, and was also comparable to values previously reported in meta-analyses, including those conducted in temperate climates. Therefore, NI application is indicated to be an efficient strategy to delay nitrification and mitigate N 2O emissions in tropical agroecosystems. Keywords N2O emissions · NH3 volatilization · DMPP · DCD · Subtropics · Urease inhibitor Introduction Agriculture accounted for 11% of world greenhouse gas (GHG) emissions in 2019, with 10.3% of these emissions being derived from the use of synthetic fertilizers (FAOSTAT 2019a). The application of nitrogen (N)-based fertilizers leads to the production Vol.: (0123456789) 13 Nutr Cycl Agroecosyst of nitrous oxide (N2O), a potent GHG. Furthermore, low nutrient use efficiency may result in ammonia (NH3) volatilization, nitrate leaching (NO3−), and further environmental degradation (i.e., groundwater contamination and indirect N 2O emissions) (Carlos et al. 2022; de Paulo et al. 2021; Simon et al. 2020). Therefore, mitigation measures, such as nitrification inhibitors (NIs), have been developed to reduce NO3− leaching and increase N use efficiency. The oxidation of ammonium (NH4+) to nitrite (NO2−) can be delayed by applying NIs, which act to inhibit ammonia-oxidizing bacteria (AOB) activity (Ruser and Schulz 2015; Hayden et al. 2021). Dicyandiamide (DCD), 3,4-Dimethylpyrazole phosphate (DMPP), and 2-chloro-6-(trichloromethyl) pyridine (Nitrapyrin) are the most widely investigated and commercially utilized NIs (Zerulla et al. 2001; Wolt 2004; Yang et al. 2016). Guo et al. (2022) indicated that DCD and DMPP can reduce N2O emissions by up to 85% and 99%, respectively, under a range of temperature and moisture levels. Conversely, Mazzetto et al. (2015) and Nauer et al. (2018) reported that N2O emissions from cattle urine and urea applications were not reduced by DCD and DMPP, respectively. Such a wide range of different results are commonly found in the literature because NI efficiency relies on numerous factors such as temperature, moisture, pH, texture, organic carbon content, tillage, the choice of NI, and fertilizer types and rates (Ekwunife et al. 2022; Guo et al. 2022). Therefore, researchers have conducted a series of meta-analyses to quantitatively pool the available information about NI efficiency in contrasting environments, agricultural practices and soil conditions, aiming to identify the most important influencing factors and optimize NI use (Abalos et al. 2014; Ekwunife et al. 2022; Linquist et al. 2013; Thapa et al. 2016; Yang et al. 2016). Ekwunife et al. (2022) showed that NIs can reduce N2O over-winter emissions by 23% in temperate regions with soils subjected to freezing–thawing. Abalos et al. (2014) indicated that NIs perform better under conditions that favor high drainage and when high inputs of N fertilizer are applied, increasing crop productivity. Thapa et al. (2016) also found that NIs mitigate N2O release, and this effect was more prominent in neutral, coarse-textured, and irrigated soils, although no effect on crop yield was reported. Considering only field studies, Yang et al. (2016) compiled 81 studies across the globe and observed Vol:. (1234567890) 13 that both DCD and DMPP were similarly effective in regulating N soil transformations and controlling N2O emissions, but DCD showed the best performance in increasing crop yield. However, most of the studies described above were carried out in subtropical and temperate climate zones, and tropical regions are under-represented in this field of research. Nevertheless, tropical agriculture plays an important role in global food production, fertilizer use, and GHG emissions. For instance, Brazil, a country containing subtropical and tropical climates, was the fourth highest consumer and the second greatest importer of N-based fertilizers worldwide in 2019, accounting for 4.5% of N 2O emissions derived from the agricultural use of synthetic fertilizers (FAOSTAT 2019b). The use of NIs could be an important tool for climate change mitigation; however, they are not universally efficient. Correspondingly, we investigated the key factors contributing to increasing or decreasing the efficiency of NIs in Brazilian subtropical and tropical agriculture. We hypothesized that NI performance is weaker under tropical than subtropical and/ or temperate conditions due to the interaction of factors such as warm temperatures and more frequent soil wetting and drying cycles, which may influence NI degradation and stimulate the abundance and activity of AOB (Mazzetto et al. 2015). We utilized a meta-analytic approach to identify the impact of NIs (DMPP, DCD, and DCD + NBPT) on (i) crop yield, (ii) N 2O emissions, (iii) soil N H4+ − and NO3 concentrations, and (i (...truncated)