Laserfiche WebLink
• Nu3 N in Soil <br />(ASA Agronony No. 9 Methods of Soil Analysis) <br />Reagents: <br />All water shall be distilled-deionized (d 6 d) <br />1. Calcium Sulfate FS:tracting Solution: Mix 4.Og Calcitan Sulfate (CaSO4.2H70) <br />in 1800 ml d s d H2O and place on magnetic stirrer for about 1 hour. (SZine <br />difficulty may be encrnmtered in dissolving the CaSO since the solution is <br />approaching saturation.) Add 2g AgSO4 and dilute to42 liters. his solution <br />should be stored in a brown bottle in a dark cabinet. <br />2. Phenoldisulfonic Acid: Dissolve 25g pure, white phenol in 150 ml H2SO4 <br />(conc.). Add 75 ml of fuming H2SO4 (15~ 503) and heat over boiling water <br />for 2 hours. Store the resulting solution in an amber glass bottle. <br />3. Calcium Carbonate: Prepare a saturated solution of calcium carbonate (CaCO3) <br />by adding 25g to 1 liter d & d H2O. <br />Homogeneous Mixture: Weigh 7.14 g of Ca (C&i)2 and 17.86 g of MgCO3 and <br />mix on wheel. <br />• 9. Ammonium Hydroxide: Conc. 26 - 308 Sp. Gr. 0.90. <br />5. Standard Nitrate Solution: Dissolve 7.221 g of pure dry FQ1O3 in d b d H2O <br />and dilute to 1 liter ~.n a wlumetric flask for a 1000 ppm NO3 N stock <br />standard. <br />1. Weigh 10 g of soil into a 50 ml caitrifuge tube. <br />2. Pipet 25 ml of extracting solution to each sartg~le and stopper tightly. <br />3. Prepare reagent blank by pipeting 25 ml of extracting solution into a <br />centrifuge tube and stopper. <br />4. Mix each sample on Maxi-Mix. <br />5. Place cm mechanical shaker for 15 minutes. <br />6. Add 0.2 g Ca(OH) and 0.5 g MgCO3 (One #190 scoop of Homogeneous mixture), <br />mix then shake for 10 minutes. <br />7. Centrifuge until clear or pass through #0.45 micron filter paper. <br />• 8. Pipet 10 ml of extractint or suitable aliquot containing 1.0-5.0 ug into <br />a 100 ml beaker. <br />6-66 <br />