A three-year On-Farm research study evaluated Exceed® Superior Legume Inoculant on dry edible bean production. The active ingredient is Rhizobium leguminorsarum biovar phaseoli. The dry inoculant was thoroughly blended with seed in the planter box before planting at a rate of 82.5 oz per 1500 lbs. of seed. The dry edible beans were direct harvested (Fig. 1) each year in September or October. Samples from each plot were analyzed for bean quality parameters. Harvest loss estimates were determined by taking counts in one-square-foot frames randomly chosen in the harvested area. The studies were planted in a replicated and randomized plot design with 4 replications.
Total available N (nitrate nitrogen) in the top 36 inches of soil was 55 lbs., 73 lbs., and 94 lbs. in 2023, 2024, and 2025, respectively. The final year was very nearly 100 lbs. of N, which is the recommendation for top dry edible bean yields by the University of Nebraska. In situations where adequate N is available, the rhizobia inoculants will not perform at optimal levels according to the manufacturer, and a benefit may not be realized.
The data in Table 1 indicate that in 2023 and 2024, with suboptimal N availability in the soil, the inoculant resulted in a significant positive yield and marginal net return increase. In 2025 with N levels near optimal, there was no significant yield or marginal net return advantage when the inoculant was used. In our current times of very high-priced N and concern about excessive N leaching into groundwater, there may be a place for using low-cost Rhizobium inoculants in dry edible bean production.
Growers do not normally use an inoculant with dry edible beans in areas where beans are regularly grown, but if N is significantly lower than the recommended rate, an inoculant might be of value as growers seek to reduce N fertilization on their crops.
The 2025 marginal net return was based on $16.80/bu dry beans, with Exceed® Superior Legume Inoculant at $2.20/ac.
The 2024 marginal net return was based on $24.60/bu dry beans with Exceed® Superior Legume Inoculant at $2.14/ac.
The 2023 marginal net return was based on $22.80/bu dry beans with Exceed® Superior Legume Inoculant at $1.79/ac.
