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Soil Acidity from Long‐term Use of Nitrogen Fertilizer and Its Relationship to Recovery of the Nitrogen
Author(s) -
Jolley Von D.,
Pierre W. H.
Publication year - 1977
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/sssaj1977.03615995004100020040x
Subject(s) - nitrogen , chemistry , nitrate , nitrification , fertilizer , soil ph , zea mays , denitrification , a value , absorption (acoustics) , environmental chemistry , agronomy , soil science , soil water , environmental science , organic chemistry , biology , physics , acoustics
Two N‐rate experiments in which corn ( Zea mays L.) had been grown continuously for 15 and 17 years were used: (i) to study quantitatively the amounts of acidity that had been developed at different levels of N fertilization and (ii) to determine to what extent the acidity produced can be explained and predicted from the amounts of N recovered in the crops and in the soil as NO 3 ‐N and organic N. The measured acidity was compared with the acidity calculated from N recovery, and both were expressed as percentages of the theoretical (potential) acidity developed from nitrification. No significant increases in acidity were found in either soil below a depth of 30 cm. With amounts of applied N that produced near‐maximum yields, soil nitrate accumulation was small, and the measured acidity (CaCO 3 requirement) was < 30% of the theoretical or potential. When excessive amounts of N were applied, however, relatively large amounts of NO 3 ‐N were found in the profile, and nearly 50% of the theoretical acidity was developed. The calculated CaCO 3 requirements from N recovery at near‐maximum yields tended to be smaller than that measured in the soil. This difference in the Galva soil profile was accounted for in part by a decrease in acidity between 30 and 45 cm, probably caused by nitrate absorption and by denitrification in these layers. With excessive N applications, the CaCO 3 requirements calculated from N recovery were in very close agreement to that measured, averaging 48% and 47% of the theoretical, respectively. Because the acidity calculated from N recovery essentially accounted for the acidity actually found and because the corresponding N recovery was only 68% (Table 6), the 32% of the N unaccounted for evidently was lost without an equivalent amount of base. Thus, the deficit in the acidity found provides corroborative evidence to the N‐recovery data that a substantial amount of the N applied in fertilizer was lost from the soils without an equivalent amount of base. Under the conditions of these experiments, this loss probably was through denitrification.