AGR 2320 Lecture Notes - Lecture 30: Buffer Solution, Denitrification, Urease
21 Nov 2016
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Agr 2320 lecture 30 nitrogen (cont"d) and phosphorous. Nitrate n is converted biochemically by mainly heterotrophic bacteria to n2o or n2 gas. As oxygen becomes increasingly limited, other species must function as electron acceptors. Only few species in soils can fill this role: n5+ + 5e- = n2, mn4+ + 2e- = mn2, fe3+ + e- = fe+2, s+6 +8e- = s2- No3 no2 no n2o n2 low oxygen environments (wet soil) Requires both nitrate and organic material to occur. End product related to the time with low oxygen. Pka at 9. 1: when amount of ammonia and ammonium are the same. As ph increases: ammonia increases, ammonium decreases. Co(nh2)2 + 2h2o (urease as catalyst) (nh4)2co3 + h+ 2nh4 + hco3. When apply urea based fertilizers, apply below the soil: ammonia loss is 0 when covered with soil. Urea application: high ph soils, low buffer capacity soils, not incorporated, hot, dry. From manure: storage transfer, application in field.
