Carbon and nitrogen dynamics in soil amended with different sources of organic manures
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Date
2023-07
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CCSHAU, Hisar
Abstract
An experiment on “Carbon and nitrogen dynamics in soil amended with different sources of
organic manures” was carried out at Department of Soil Science, CCS HAU, Hisar. Organic manures
selected for this purpose were pressmud, vermicompost, poultry manure, FYM, mustard oil cake, and
inorganic fertilizer (urea). The various parameters were studied at different time intervals from 0, 7, 15,
30, 60 and 90 days in a three-month incubation study. The carbon mineralization was found to increase
with proceeding incubation time, reaching its peak at 90 days. The mean value of CO2 evolution
irrespective of incubation days was found highest (94.69 mg CO2/100g soil) in poultry manure
amended soil (T4). During mineralization, very labile fraction of carbon decreased from 0.182% at zero
day to 0.096% at 30th day, and then increased to 0.117% at 90th day. The labile carbon fraction
increase throughout the incubation period. While less labile and recalcitrant carbon fraction showed a
decreasing trend from 0.284% - 0.064% and 0.097% - 0.033%, respectively. Among the various
treatments, highest active pool of carbon was found in FYM amended soil. The ammonical-N content
showed an increasing trend initially and then decreased, while the nitrate - N content and total mineral-
N increased significantly throughout the incubation period, however, the rate of N mineralization was
found highest between 0 to 7 days. Among different treatments, total mineral N content at 90 days was
highest in T6 followed by T7. During the incubation period, the organic nitrogen fractions, THN,
hydrolysable ammonia-N, amino acid - N, amino sugar - N, HUN showed a declining trend, whereas
an increasing trend was observed in the NHN fraction which is due to conversion of passive pool
fractions to active pool and thus ultimately in to mineral nitrogen. The initial THN, amino sugar - N
and amino acid - N fraction was found highest in T7 (MOC amended treatment), while hydrolysable
ammonia - N, HUN and NHN was found highest in T6 (urea amended treatment).