arash aminei

Glauconite is a micaceous mineral that could be source of potassium. The aim of this study was evaluation of the effects of glauconitic sandstone and potential of iron relase and toxicity in case of using as a potassium fertilizer for canola plants. The plants cultivation experiments were carried out in growth chamber in sand culture with completely randomized design as factorial. The first factor was potassium with three levels including Hoagland nutrient solution, Hoagland nutrient solution lack of potassium and Hoagland nutrient solution lack of potassium accompanied with glauconitic sand stone powders. The second factor was pH of culture medium contained 6 and 7.5. The results indicated that potassium deficiency in Hoagland nutrient solution without potassium treatment caused severe reduction in growth traits, contents of K+, soluble protein, starch and chlorophylls and increased total amino acids in canola plants. Application of glauconitic sand stone powders could release potassium in solution medium as plants treated with Hoagland without + glauconite did not indicated significant differences in fresh and dry mass and potassium content with Hoagland-treated ones. Iron content was higher in roots of Hoagland without potassium + glauconite treated canola plants compared treatments, however, pH reduction from 7.5 to 6 did not increase iron content in this treatment. The reduction of pH of nutrient medium imposed significant decrease of soluble protein, starch and chlorophyll contents that lead to growth retardation of canola plants. The results indicated that glauconitic sandstone has certain potential to release potassium. Iresspective pH of nutrient solution, no toxicity symptom was observed in canola plants following glauconite application.

Potassium is the fourth most abundant element in the earth's crust that plays important roles in enzymes activity, protein synthesis and photosynthesis. Glauconite is a hydro- silicate of iron and potassium. Most of the fertilizers including potassium are imported in our country and finding demotic sources for potassium fertilizers is very important. Glauconite is a micaceous mineral containing K, Fe and Mg, as well as Al and Si. In classification of sedimentary stones, the glauconitic sandstone is classified in green sanstone. The aim of this study was evaluation of K release and the potential use of glauconitic sandstone powder as a potassium fertilizer for wheat and canola plants.
The glauconitic sandstone was collected from around Sozesh village in Maraveh, Golestan Province, Iran. The sandstones were finely ground and passed through a sieve of mesh number 20 and 120. The amount of potassium released from these powders (mesh 20 and 120) were accumlatively identified in distilled water, HCl and and H2SO4 during 6 days. In addition, in order to find the best method for maximum potassium release, different treatments including calcium carbonate – autoclave, furnace – NaOH- autoclave, NaCl- furnace – HCl, HCl- autoclave, H2SO4- autoclave and CaCl2- furnace were utilized. The potential use of this sandstone as a potassium fertilizer was assayed through cultivation of wheat and canola plants in soils treated with 75 and 150 g glauconitic sandstone powder per kg soil.
XRay fluorescence analysis indicated that the glauconitic sandstone consisted of 2.24% potassium oxide along with magnesium, phosphorus, zinc and other essential elements, releasing only 0.13 percent of its potassium during 6 days in water. Study of the potassium release using several treatments indicated that the NaCl -furnace - HCl and H2SO4 –autoclave treatments could release the highest amount of K from the stone that was about 7%. Soil application of glauconitic sandstone for wheat and canola indicated the highest fresh and dry weight of wheat were observed by application of 75 g glauconit per kg soil and use of higher amunts (150 g per kg soil) cuased frsh and dry weight to be reduced. Roots and shoots fresh and dry weight were higher in canola plants supplied with 150 g glauconitic sandstone per kg soil, compared to control.
The results indicated that glauconitic sand stone have the ability to release potassium and may compensate potassium deficiency in soils for wheat and canola. Further field experiments are necessary for the results to be confirmed and determination of glauconitic sandstone use-rates.