Effect of phosphate fertilisation, straw incorporation, insecticide application and inoculation with cyanobacteria on rice productivity

SUMMARY We studied the effect of phosphorus fertilisation, straw incorporation, insecticide application [trichlorfon (dimethyl 2,2,2-trichloro-1-hydroxyethyl phosphonate)] and inoculation with indigenous N2-fixing heterocystous cyanobacteria on the abundance of heterocystous cyanobacteria in soil, nitrogen fixation and grain yield in Spanish rice fields. None of the treatments increased significantly these parameters, although we observed some recurrent tendencies such as the increase of inoculated heterocystous cyanobacteria abundance in the inoculated and not fertilized plots, or the increase in nitrogenase activity in plots with straw incorporated. However, these moderate effects have not significantly benefit rice productivity.