Combined effect of crop types, microbial inoculants and N fertilizer rates on availability of nitrogen

The present study was done in a pot experiment at Faculty of Agriculture Monsoura University during summer 2007 to study the combined effect of crop types microbial inoculants and N fertilizer rates on availability and uptake of nitrogen at different days after planting DAP. Randomized complete block design with three replicates was performed. The first factor was arranged for 3 crops i.e rice Oryza sativa cv. Sakha 101 tomato Lycopersicon esculentum. mill cv. Super Merry Mand and cowpea Vigna unguiculata L. Walp cv. Karim seeds The second factor Microbial inoculants Non-inoculated - Inoculated with blue green algae with the rice non-inoculated - Inoculated with nitrobin for tomato crop and non-inoculated - inoculated with rhizobium for cowpea crop and the pollinating of the seeds before planting. Finally the third factor was occupied with 3 nitrogen fertilizer rates control half and all recommended dose of N according recommended doses for cultivated crops. The obtained results show as the following Data illustrate that except 35 DAP for dry shoot and 70 and 105 DAP for dry root there are significant differences between average of dry shoots g pot at 70 and 105 DAP and as affected by affected by crop types i.e. rice cowpea and tomato crops inoculations and N rates at different plant growth. Statistical analysis reveal that there are no significant differences between average of N concentration in shoots at 35and 105DAP except 70 DAP meanwhile there are no significant differences between average of N concentrations % in roots at 35 and 70 DAP except at 105 DAP as affected by crop types i.e. rice cowpea and tomato crops inoculations and N rates at different plant growth. Generally the highest mean values of dry shoot roots and yield and N concentration were obtained from all nitrogen dose + inoculated with Rhizobia + cowpea. Meanwhile the lowest mean values of fresh shoots were obtained from untreated with nitrogen + untreated with inoculation + tomato. It is evident that the highest mean values of utilization efficiency % of applied of nitrogen readings were attained due to all nitrogen doses + inoculated with Rhizobia + cowpea: On the other hand the lowest means were obtained from half N doses + untreated with inoculation + rice.