Environmental Parameters Affecting the Concentration of Iodine in New Zealand Pasture

Abstract

Iodine (I) is an essential trace element commonly deficient in agricultural systems. Whereas there is much information on I in food crops, there is a lacuna of knowledge on the environmental factors that affect pasture I concentrations. We aimed to identify the most important environmental factors affecting the concentration of I in New Zealand pastures, and the consequences to agricultural systems. Soil and pastoral samples were collected throughout the country and analyzed for I and other elements. The soils contained 1.1 to 86 mg I kg−1, with 0.005 to 1.4 mg kg−1 in the pasture. In 26% of pastures, I concentrations were insufficient for sheep nutrition, whereas 87% contained insufficient I for cattle nutrition. Pasture I concentrations were negatively correlated with the distance from the sea, and the concentration of oxalate‐extractable amorphous Al, Fe, and Si oxides, which immobilize soil I. Soil organic C and clay increased I retention in soil but did not significantly affect pasture I concentrations. Future work should investigate how soil properties affect pasture I uptake in inland areas. Core Ideas 87% of New Zealand pastures contained insufficient iodine for cattle. Pasture I levels are higher close to the sea. Pasture I levels are lower in soil that is high in Fe and Al (oxyhydr)oxides.

Effect of Dietary Seaweed Supplementation in Cows on Milk Macrominerals, Trace Elements and Heavy Metal Concentrations

“…These higher concentrations may be due to the experimental farm being on the banks of the Ölfusá River, a body of water that carries glacial water (commonly rich in I) and at close proximity to the sea (~20 km) [ 78 , 79 ]. Coastal areas have more I in the soil and subsequently produce forage that may also have higher I concentrations [ 80 ]. The potential effect of Icelandic cow genetics may not be excluded as it is known that breed can also be a driver for milk I concentrations [ 75 , 81 ].…”

The Potential of Myrtaceae Species for the Phytomanagement of Treated Municipal Wastewater

“…The site is located about 1 km east of the coast and strong westerly winds are common in this area, increasing sea spray [65]. It has been demonstrated that sea spray can affect pasture Na concentrations up to 50 km inland [66]. Although Na is not an essential element for most terrestrial plants and can be directly toxic, with woody species being most susceptible [67,68], there were no visual signs indicating such toxicity in K. robusta and L. scoparium.…”

Multiple geochemical factors may cause iodine and selenium deficiency in Gilgit-Baltistan, Pakistan

“…Unlike most other elements, weathering of rocks and sediments is not a major source of I for the soil–plant system (Johnson, 2003 ). Only a small proportion of the soil I available to plants is derived directly from rock weathering (Fuge & Johnson, 2015 ; Jensen et al, 2019 ). In contrast, oceans are major reservoirs of I (Fuge & Johnson, 2015 ; Manousou et al, 2019 ; Medrano-Macías et al, 2016 ) and volatilisation from ocean water and movement through the atmosphere plays an essential role in I cycling through the environment and the biosphere (Johnson, 2003 ; Medrano-Macías et al, 2016 ).…”

“…In contrast, oceans are major reservoirs of I (Fuge & Johnson, 2015;Manousou et al, 2019;Medrano-Macías et al, 2016) and volatilisation from ocean water and movement through the atmosphere plays an essential role in I cycling through the environment and the biosphere (Johnson, 2003;Medrano-Macías et al, 2016). Thus, I input from the atmosphere, as dry or wet precipitation, often contributes greatly to soil and plant I (Bowley et al, 2019;Fuge & Johnson, 1986;Jensen et al, 2019;Johnson, 2003). It is recognised that I concentrations are greater in coastal areas compared to inland and mountainous regions located away from coasts (Bowley et al, 2016;Fuge & Johnson, 2015;Humphrey et al, 2018).…”