Reaction mass of ammonium sulphate and potassium sulfate and sodium sulphate

Toxicity to terrestrial plants

Description of key information

With high probability, not harmful to terrestrial plants when introduced in appropriate concentrations.

Additional information

Data on the toxicity of the reaction mass of ammonium sulphate and potassium sulfate and sodium sulphate to terrestrial plants are not available. Therefore the toxicity of single components of the reaction mass is evaluated separately. The assessment of the toxicity to terrestrial plants is based on data for ammonium sulphate and sodium sulphate since no studies on potassium sulfate are available. There are four valid studies investigating the toxicity of ammonium sulphate to terrestrial plants. The effect of ammonium sulphate solution on seed germination was studied for Avena sterilis spp macrocarpa Mo, in a 21 day test (Gonzalez Ponce and Salas, 1989, cited in OECD SIDS 2007). Seeds were wrapped with filter paper which was wetted with ammonium sulphate solutions of 100 to 5000 mg/L. No significant increase in germination was found up to 2500 mg/L, compared with the control. An inhibitory effect was found at 5000 mg/L ammonium sulphate probably caused by a salt effect. The effect of ammonium sulphate addition on the growth of the onion, Allium cepa L., has been studied under laboratory conditions in 4 Canadian soils, in the presence of lime to raise the soil pH to approximately 6.5 (Abbés et al., 1995, cited in OECD SIDS 2007). After 84 days, yield was greatest for 626 mg ammonium sulphate / kg soil. An inhibitory effect was found at 1880 and 2506 mg ammonium sulphate / kg soil, except for the sandy soil where only 2506 mg ammonium sulphate / kg soil was inhibitory. In general such observations could again be explained by salt effects. A study using 14 day old pinto bean plants exposed to 26 mg/m³ ammonium sulphate aerosol for up to 320 hours (ca. 13 days) in an environmental growth chamber showed no changes in plant biomass or leaf area. However, visible foliar injury occurred, and both abaxial and adaxial leaf resistances were decreased from control values (Gmur et al., 1983, cited in OECD SIDS 2007). The ammonium sulphate application rate is stated to be about 2 orders of magnitude above ambient episode concentration. The 6 year effect of ammonium sulphate spread as a solid fertilizer was investigated in a stand of trees (Picea abies, 12 y old at the beginning of the test) (Rosengren-Brinck and Nihlgard, 1995). Spreading at 471 kg ammonium sulphate per ha per year affected resistance to drought, which was evident in a reduction in the flushing of new shoots. The high levels of ammonium sulphate that induce a toxic effect in plants in these studies, indicates that this substance will have little effect on terrestrial plants when used in the recommended quantities.

For sodium sulphate toxicity, three different species were tested with seeds in sand for emergence, survival, root/shoot length, lateral roots, leaf necrosis, fresh weight and photosynthesis (Croser et al., 2001, cited in OECD SIDS 2005). The most sensitive species proved to be Pinus banksiana (Jack pine), with roots being the most sensitive part of the plant as evidenced by the root length and the number of lateral roots being affected at 10mM (1.4 g/L) sodium sulphate.

There are no studies available for potassium sulfate but the results for ammonium sulphate and sodium sulphate are assumed to be conferrable to potassium sulfate.