Soil Biology; Laboratory Manual (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: PRACTICE 7. NITRITATION. OXIDATION OF AMMONIA TO NITRITE BY NITROSOMONAS. Influence Exerted By Carbonates, Ignited Soil, Soluble Organic Matter, And Aeration. (This experiment also illustrates denitnfication.) Place 25 cc. of the salt solution for nitrite formation (page 95) in each of 12 one-liter Erlenmeyer flasks (ratio of depth to diameter 1: 20-22). Make the following additions: 1 and 2, nothing. 3 and 4, 1 gram ground limestone or dolomite. 5 and 6, 1 gram magnesium carbonate. 7 and 8, 50 grams ignited soil. 9 and 10, 50 grams ignited soil + 1 gram limestone or dolomite. 11 and 12, 0.5 gram dextrose + 1 gram limestone or dolomite. Some students will perform this practice using 100 cc. flasks (ratio, depth to diameter, 1: 3), plugging tightly with cotton. Plug the flasks loosely and sterilize in the autoclave at 12 pounds pressure for 15 minutes. When cool, add with a sterile graduated pipette the required amount of a standard solution of ammonium' sulfate, carbonate, or nitrate, to give 10 milligrams of nitrogen per flask. Inoculate each with 1 gram of fresh soil obtained preferably from some continuous soil or crop experiment. Place flasks in the 30 or the room-temperature incubatoras indicated by instructor. At the end of 2, 3, and 4 weeks test all for nitrite by the method outlined on page 116. Show each test to the instructor. The quantitative determination will be made upon advice of the instructor. Determine the nitrite in 1-10 inclusive by the permanganate method (see page 113). Group Soil Type Blank on Method.. .mgs. N. 1 cc. N/10 KMnO4 mgs. N. No.Treat- mentN/10 KMnO4 takencc.N/10 NaS203 titratedcc.Equiv- alent N/10 KMn04MfPer cent of initial nitrogen changed Qualitativetests ----- / ---?- . ...