Two new articles were published in issue 32/2019 of the International Scientific Journal Icelandic Agricultural Sciences (www.ias.is).
The first article can be accessed here: https://ias.is/wp-content/uploads/2019/12/IAS-2019-6-Bjorn_Gudmundur_Arngrimur_Thorsteinn_61-74.pdf
The article, Precipitation, drainage and loss of nutrients from peatlands in Hvanneyri, is by Björn Þorsteinsson, Guðmund Hrafn Jóhannesson, Arngrím Thorlacius and Þorstein Guðmundsson.
The article deals with the amount of substances in wastewater from fields in Hvanneyri. The main nutrients and fertilizers, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and sulfur (S), were measured in the wastewater, as well as precipitation and flow. . Highly soluble ammonium, nitrate, and phosphate were also measured.
The results showed that there was a large difference in both the amount and concentration of substances in the effluent between seasons, as there was much more effluent during the winter months and the concentration of substances was also higher than during the growing season. The total leaching of Ca, Mg, K and Na turned out to be rather large, but the leaching of nitrogen components and phosphorus was smaller than might be expected with reference to the fact that this is fertilized arable land on drained bog.
This is the first study of nutrient loss from arable land in a well-defined body of water where the fate of nutrients in ditch effluent can be properly accounted for. This is therefore a very important contribution to the discussion on the loss of substances in agriculture and possible eutrophication in the drainage of fields.
The second article can be accessed here: http://ias.is/wp-content/uploads/2019/12/IAS-2019-7-TMulloy_ICBarrio_KBjornsdottir_ISJonsdottir_DSHik_-75-85.pdf
The article, Fertilizers equalize the short-term effects of sheep grazing in the highlands of Iceland, is by Tara A. Mulloy, Isabel C. Barrio, Katrín Björnsdóttir, Ingibjörg Svala Jónsdóttir and David S. Hik.
The article describes experiments at Þeistareykir and Auðkúluheiði where the effect of sheep grazing on vegetation cover and vegetation mass of vegetation on sparsely vegetated surfaces, by comparing sharp and ungrazed fields that were either treated with fertilizer or not. The study was repeated in two different habitats (mountain kelp and mel) in two areas, inside and outside the volcanic zone. Sheep grazing did not affect the vegetation cover of a sparsely vegetated surface, but in fertile fields on such land, grazing reduced the biomass of plants (mainly grasses). Grazing pressure can increase significantly in fertile areas and counteracts the accumulation of biomass. When using fertilizer to control soil erosion on pastures, the biomass removed by increased grazing must therefore be taken into account.
There is a lot of discussion about the effects of sheep grazing and grazing management on pastures and soil erosion, but knowledge about the effects of grazing and grazing management is lacking. This study is therefore an important contribution that both increases our knowledge and is a relevant contribution to the discussion on grazing issues.
Editorial
IAS