The Retention and Reactions of Anhydrous Ammonia on Different Soil Types
1958
McDowell, L. L. | Smith, G. E.
Soil texture had a pronounced effect on ammonia movement and retention. The greatest movement of ammonia occurred in the sand and silt loam soils; and the least movement in the clay. The loss of ammonia from the airdry, acid sandy soil at a 6-inch depth of application was 44 times the loss from the calcareous clay soil receiving ammonia at comparable moisture and depth. The retentive capacity of a soil for ammonia increased greatly as the texture became heavier. The loss of ammonia from the air-dry, calcareous clay soil was negligible even at the 3-inch depth of application. A considerable portion of the nitrogen applied as anhydrous ammonia was lost to the atmosphere or was fixed in some form making it non-extractable by the chemical analysis used. The amount of ammonia fixed increased with the greater clay content of the soil. The presence of high concentrations of ammonia in a localized area resulted in the partial breakdown of the soil organic matter. As a result of nitrification and the subsequent increase in hydrogen-ion concentration this condition was no longer observed at the end of 4 weeks of incubation. Ammonia losses were reduced considerably when the application was changed from 40-inch to 16-inch spacings and the rate applied per acre was maintained a constant.
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