Browse on keywords: fertility OR nitrogen fixation
Search results on 06/25/18
690. Bear, F.E.. 1931. Soil management.. J. Wiley, N.Y..
A fairly complete text on soil management - fertility, tillage, organic matter, fertilizers; describes proper plow, moisture content, and depth to improve soil tilth; describes weeds as a potential cover crop; field study in England - free living N fixers input ~44 lb/ac/yr (est.). Azotobacter critical pH = 6.4.
7066. Vandecaveye, S.C. ad S. Anderson. 1934. Longevity of Azotobacter in soils treated with lime and superphosphate.. J. Am. Soc. Agron., 26:353-364.
Few Azotobacter in soils below pH 6.0, according to early studies; need several thousand colonies per gram of dry soil to get appreciable N fixation: liming increased Azotobacter in acid soils; phosphorus addition had no effect; large seasonal fluctuation in Azotobacter; highest numbers in spring and fall. T: Seasonal Azotobacter changes; effect of pH, lime, P.