Abstract
BackgroundUnderstanding the nitrogen (N) mineralization process and applying appropriate model simulation are key factors in evaluating N mineralization. However, there are few studies of the N mineralization characteristics of paddy soils in Mollisols area of Northeast China.Materials and methodsThe soils were sampled from the counties of Qingan and Huachuan, which were located in Mollisols area of Northeast China. The sample soil was incubated under waterlogged at 30°C in a controlled temperature cabinet for 161 days (a 2: 1 water: soil ratio was maintained during incubation). Three models, i.e. the single first-order kinetics model, the double first-order kinetics model and the mixed first-order and zero-order kinetics model were used to simulate the cumulative mineralised N (NH4+-N and TSN) in the laboratory and waterlogged incubation.Principal resultsDuring 161 days of waterlogged incubation, the average cumulative total soluble N (TSN), ammonium N (NH4+-N), and soluble organic N (SON) was 122.2 mg kg-1, 85.9 mg kg-1, and 36.3 mg kg-1, respectively. Cumulative NH4+-N was significantly (P < 0.05) positively correlated with organic carbon (OC), total N (TN), pH, and exchangeable calcium (Ca), and cumulative TSN was significantly (P < 0.05) positively correlated with OC, TN, and exchangeable Ca, but was not significantly (P > 0.05) correlated with C/N ratio, cation exchange capacity (CEC), extractable iron (Fe), clay, and sand. When the cumulative NH4+-N and TSN were simulated, the single first-order kinetics model provided the least accurate simulation. The parameter of the double first-order kinetics model also did not represent the actual data well, but the mixed first-order and zero-order kinetics model provided the most accurate simulation, as demonstrated by the estimated standard error, F statistic values, parameter accuracy, and fitting effect.ConclusionsOverall, the results showed that SON was involved with N mineralization process, and the mixed first-order and zero-order kinetics model accurately simulates the N mineralization process of paddy soil in Mollisols area of Northeast China under waterlogged incubation.
Highlights
Nitrogen (N) mineralization is a foundational step in soil organic N transformation, but it is one of the most important processes in soil N cycling
The results showed that soluble organic N (SON) was involved with N mineralization process, and the mixed first-order and zero-order kinetics model accurately simulates the N mineralization process of paddy soil in Mollisols area of Northeast China under waterlogged incubation
During the N mineralization process, soil organic N is mineralised into inorganic N primarily in the forms of ammonium N (NH4+-N) and nitrate N (NO3−-N), or is transformed into an intermediate transitional fraction as soluble organic N (SON), which is mineralised into inorganic N
Summary
Nitrogen (N) mineralization is a foundational step in soil organic N transformation, but it is one of the most important processes in soil N cycling. More than 50% of N that is absorbed during rice growth is from the soil, regardless of whether or not N fertilizer has been applied [1, 2]. During the N mineralization process, soil organic N is mineralised into inorganic N primarily in the forms of ammonium N (NH4+-N) and nitrate N (NO3−-N), or is transformed into an intermediate transitional fraction as soluble organic N (SON), which is mineralised into inorganic N. Most studies on paddy soil N mineralization have focussed on soluble inorganic N and little attention has been paid to SON in leachates [3,4,5,6]. A more accurate simulation of the N mineralization process in paddy soil is important to guide strategies for the rational application of fertilizer in rice production.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
