Abstract:
An experiment was conducted in the Instructional farm attached to the College of Agriculture, Vellayani during the Kharif season in 1994. The object was to study the effect of different bioinoculants {Azospirillum, Rhizobium, Vesicular arbuscular mycorrhiza (VAM) as well as different levels of nutrients ie control, 25, 50, 75 and 100 percent of the recommended dose of fertilizer and their interaction on increasing the forage production of maize - cowpea intercropping system.
The height of maize plant, number of leaves, and leaf area index were maximum for the treatment, Azospirilllum - maize + Rhizobium - cowpea but the maximum leaf-stem ratio was observed for Azospirillum- maize + VAM - cowpea. In cowpea, all the growth characters were maximum for the treatment, VAM - maize + Rhizobium-cowpea. It was also seen that fertilizer level above 50 percent didn't produce any significant increase in these characters.
In maize, highest root length was observed for Azospirillum - maize + Rhizobium - cowpea treated plants and highest root volume for, Azospirillum - maize + VAM - cowpea
treated plants. Maximum nodulation in cowpea was observed for the treatment, VAM -maize +Rhizobium- cowpea and maximum root length for Azospirillum – maize + VAM – cowpea. Mycorrhizal colonization percentage was found to be higher in the roots of inoculated plants for both crops. All these character were found to be maximum under no fertilizer application.
. Maximum green matter and drymatter yield of maize occurred for the treatment, Azospirillum – maize + VAM - cowpea and for cowpea, the treatment VAM –maize +Rhizobium – cowpea. It was also noted that 50 percent of the recommended dose of fertilizer was enough for producing maximum yield.
The treatment Azospirillum – maize + VAM cowpea produced maximum uptake of nitrogen in maize, phosphorus in cowpea and potassium, calcium and magnesium uptake in both the crops. The treatment VAM –maize + Rhizobium – cowpea produced the maximum uptake of phosphorus in maize and nitrogen in cowpea. The uptake of nutrients do not differ significantly after 50 percent of recommended dose of fertilizer.
In maize, crude protein yield and crude fibre yield were maximum for the treatment, Azospirillum – maize + VAM- cowpea under high levels of fertilizer. In cowpea, the treatment VAM – maize + Rhizobium – cowpea at high levels of fertilizer produced maximum value.
The available nitrogen, phosphorus, potassium, calcium and magnesium status of the soil varied significantly due to the interaction between biofertilizer and chemical fertilizers.
The treatment combination, VAM – maize + Rhizobium – cowpea + 50 percent of the recommended dose registered the highest net profit of Rs.8110.00 and Benefit – cost ratio of 1.502.
The treatment combination, VAM- MAIZE + Rhizobium-cowpea + 50 percent of the recommended dose can be given as the final recommendation in fodder maize-cowpea intercropping system.