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Acidic Zones from Ammonia Application in Conservation Tillage Systems
Author(s) -
Robbins S. G.,
Voss R. D.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300040044x
Subject(s) - tillage , soil ph , soil acidification , fertilizer , soil horizon , nitrification , cation exchange capacity , environmental science , chemistry , ridge , ammonia , limiting , soil science , soil water , agronomy , nitrogen , geology , biology , mechanical engineering , paleontology , organic chemistry , engineering
Subsurface soil acidity resulting from repeated NH 3 applications in long‐term conservation tillage systems that do not disturb the NH 3 injection zone was studied in six different crop‐fertilizer‐tillage systems by: (i) observation of the size, shape, and distribution of acidic zones in the field by using a pH color indicator method and (ii) intensive quantitative sampling of the upper 25‐ to 30‐cm soil layer with subsequent laboratory analysis for soil pH. Acidic soil zones created by the nitrification of the injected NH 3 were roughly circular with 12‐ to 18‐cm diam. Soil pH of the acidic zones was generally 0.9 to 1.8 pH units lower than that of the surrounding bulk soil. In the ridge till‐plant and ridge slot‐plant systems studied, a distinct highly localized persistent acidic soil zone was detected in each interrow. On the basis of the extent and degree of acidity observed, it is concluded that yield‐limiting problems due to acidification by continuous NH 3 applications are not likely in the ridge management systems studied. In the flat no‐till systems studied, numerous persistent acidic soil zones were observed scattered throughout each interrow. It is concluded that soil acidity problems due to long‐term NH 3 usage potentially could develop in the no‐till systems studied where NH 3 is not injected in the same vicinity each year. Efforts toward localized placement of N by the farm operator could effectively minimize potential problems due to the acidifying effects of NH 3 in conservation tillage systems.