Retention Patterns and Effectiveness of Anhydrous Ammonia Applied with an Undercutting Blade
1971
Swart, C. L. | Murphy, L. S. | Swallow, C. W.
Retention of and distribution patterns of anhydrous ammonia applied with an undercutting blade were investigated on soils of varying cation exchange capacities (CEC). Rates of ammonia ranged from 56 to 224 kg N/ ha; spacings between points of ammonia release ranged from 15 to 102 cm. Application depths were 5 and 10 cm. Applying 224 kg N/ha on a silt loam soil resulted in no measurable loss at any depth or spacing. Shallow (5-cm) applications resulted in some ammonia loss on a low CEC soil; 224 kg N/ha applied 10 cm deep also resulted in ammonia loss when dispersed with 102-cm spacings. A 15-cm spacing, however, reduced the loss to less than 1%. Soil texture and depth of application did not appreciably alter the distribution patterns hut affected ammonia losses. Distinct distribution patterns resulted from each release-point spacing. Ammonia distribution patterns were commonly oval around each release point. Lateral movement was directly proportional to application rate, while vertical movement was limited to less than 5 cm. A second phase of the study involved preplant field applications of ammonia for wheat (Triticum aestivum L.). Effects of N rate and spacing of release points on plant N absorption, wheat yield, test weight, and protein content of the grain were recorded for five Kansas locations. Plant N concentration correlated positively with soil inorganic N in samples collected 7 mouths after NH₃ application. Variations in NH₃ release-point spacings produced marked differences in growth, particularly in the spring. The 15-cm and 41-cm release-point spacings generally produced more uniform plant growth, which resulted in higher yields than the 102-cm spacing; however, the differences were not significant at the 5% level.
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