Soybean Inoculant Types and Rates Evaluated under Dry and Irrigated Field Conditions

Abstract

Effects of high soil temperature and low soil moisture for 7 days following planting were utilized in evaluating inoculant types and inoculating rates with soybeans (Glycine max (L.) Merr.) grown in a soil free of Rhizobium japonicum in Puerto Rico. Granular soil inoculant applied at 10 times the standard application rate provided significantly more tap root and total number of nodules than all other treatments. This increase was observed in sampling at 32 and 98 days after planting under both dry and irrigated conditions. The total of all inoculating types applied at 10 times the rate provided a significant increase in number of tap root nodules, total number of nodules and nodule dry weight per plant only at 32 days when compared with the total for application at the standard rate. Sampling at both 32 and 98 days indicated a significant increase in number of tap root nodules, total number of nodules and nodule dry weight per plant with irrigation when compared to the dry section.