Periodicity of organic constituents in high input tropical rice soil uri icon


  • A hypothetical linkage of long-term sustainability aspects with periodic fluctuations of certain soil biochemical parameters was investigated for a continuously cropped tropical rice soil. Dynamics in the organic matter phase of the irrigated top soil were monitored in both N-fertilized and N-free control plots of a long-term continuous rice cropping experiment.
  • Microbial biomass and protein-specific respiratory ETS activity in permanently submerged rice soil show basic periodic changes. The input of N-fertilizer expands periodicity onto soil protein pools too. Periodic concentration changes of phenolic compounds that seem to limit respiratory mineralization remained unaffected by nutrient and integrated pest management (IPM). Soil biochemical parameters in the intensively cropped rice soil suggest periodic pool size changes that are presumably governed by soil microbial biomass.
  • Positive correlations between the variability of soil protein concentrations and grain yields suggested an important role of soil protein in adequately fertilized plots. Significant periodicity was noted for microbial biomass, total protein, and soluble phenols in fertilized plots. N-free control plots, on the other hand, lacked periodicity for total protein, but showed it for microbial biomass, soluble phenols, and protein-based respiratory enzyme activities.
  • Top soil (20-cm layer of Andaqueptic Epiaquoll) of an almost permanently submerged rice field with three continuous annual crops at IRRI (Philippines) receiving integrated pest management was sampled at time intervals of 3-4 weeks for more than 3 years, including a period of El Nio. Analyses targeted phospholipid-based soil microbial biomass, total soil protein, soluble phenols, and respiratory electron transport system (ETS) activities involved in non-fermentative mineralization of soil organic matter. Periodic trends were analyzed using spectral and cross spectral analysis.

publication date

  • 2015
  • 2015
  • 2015