Fertilización fosfatada e inoculación de soja en vertisoles

the symbiosis between rhizobia and soybean [glycine max (l.) merril] provides most of the nitrogen requirements of the crop through a process that also depends on the availability of nutrients, for example phosphorous. the objective of this study was to determine the contribution of p fertilization (0, 18 y 36 kg ha-1) and bradyrhizobium japonicum inoculation on the nodulation and grain yield of soybean crops in vertisols with low soil p availability. in the sites without previous soybean crops, the inoculation promoted a greater nodulation, and shoot dry matter and grain yields above the non-inoculated crops. nodulation and shoot growth increased with increasing available p (psoil + pfertilization) levels up to 12.4 mg kg-1. in the sites rotated with soybean, yields were greater in the inoculated crops. shoot dry matter and grain yields increased with increasing available p levels only under inoculation. in general, the inoculated and fertilized crops showed greater production suggesting the convenience of the combined nutrition of soybean crops for achieving greater grain yields.