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Apparent Recovery of Fertilizer N by Coastal Bermudagrass on a Swelling Clay Soil 1
Author(s) -
Kissel D. E.,
Bartek Larry,
Zatopek L. J.
Publication year - 1979
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1979.00021962007100030002x
Subject(s) - cynodon dactylon , fertilizer , leaching (pedology) , agronomy , soil water , human fertilization , environmental science , forage , sink (geography) , chemistry , biology , soil science , cartography , geography
The apparent recovery of N fertilizer by Coastal bermudagrass [ Cynodon dactylon (L.)] growing on swelling clay soils has usually been quite low (approximately 40 to 50%), possibly due to biological immobilization of large quantities of applied N fertilizer. The objective of this study was to determine if the net immobilization might be reduced after several years of continued fertilization, thereby improving the recovery of N by Coastal bermudagrass. The 6‐year study was set up with variable N rates (NH 4 NO 3 was the N source), some applied only the first 3 years of the study, some applied only the last 3 years and some fertilized throughout the study. Measurements were taken of N removed in forage, soil NO 3 −‐N at the 504 kg N/ha rate, and soil organic N at the end of the study. Immobilization (as determined by the increase in soil organic N) accounted for over 50% of the applied N, about equal to the amount of N going into the harvested portion of the grass. Other potential losses of N such as leaching and denitrification were apparently insignificant. There was no indication of inorganic N accumulation in the later years of the study. However, some improvement in N availability was noted in the last three years of the study on those plots receiving fertilizer throughout the 6‐year study. The results from this study suggest that immobilization of fertilizer N on Coastal bermudagrass pastures would be a substantial sink for applied N fertilizer for an unknown but large number of years. Continuous generous fertilization programs would result in a gradual buildup of soil organic N with a resulting gradual improvement in N recovery by forage.