Net nitrogen mineralization in typical paddy soils of the Taihu Region of China under aerobic conditions: Dynamics and model fitting

Abstract

An efficient nitrogen fertilizer recommendation for plant production depends on the amount of N supplied by the soils. A study to investigate the characteristics of net N mineralization in typical paddy soils in an important rice production area of China was conducted on aerobic soils for 147 d of incubation at 25°C. Results showed that the organic nitrogen mineralized ranged from 40 to 360 mg N kg-1 or from 2.92 to 14.17% of total N. In a partial correlation analysis, the N mineralized was only correlated with total N and alkaline hydrolyzable N. Principal component analysis indicated two types of soil physical and chemical properties, each with different influence on N mineralization. Four models: (1) an effective cumulated temperature model (Temperature model), (2) a one-component, first-order exponential model (One-pool model), (3) a two-component, first-order exponential model (Two-pool model), and (4) a two-component, mixed first- and zero-order exponential model (Special model) were fitted to the measured amounts of N mineralized over time using a non-linear regression procedure. All models gave good fits. Model parameters were compared and correlated with the soil basic properties and nitrogen availability indices. All results showed that the Special model performed a better prediction of net nitrogen mineralization in paddy soils under non-flooded conditions than the other models investigated. Key words: Seasonally flooded soil, aerobic net N mineralization, simulation modeling, nitrogen availability indices