Project overview
Organic soybean and dry bean are highly susceptible to weed competition and to white mold disease. No-till planting organic soybean at an increased seeding rate into roll-crimped rye cover crop provides good weed control without suppressing the nitrogen-fixing crop, improves soil health over tilled systems, and saves labor.
This project addressed concerns that dense crop stands resulting from high seeding rates might aggravate the incidence and severity of white mold. Experiments were conducted to optimize soybean and dry bean seeding rates, nitrogen (N) inputs, and cover crop management (seeding rate, termination method) for production, weed and disease control, and net economic return for organic soybean and dry bean.
Farmer takeaways
- Organic soybeans planted no-till into roller-crimped rye yield well and suppress weeds.
- Planting soybeans at 215,000 seeds/ac (~140% of standard rate) without supplemental nitrogen gives the highest net economic returns.
- Roller-crimped rye residues suppress white mold disease in organic no-till soybeans and dry beans.
- Seeding rye at 3 bu/ac enhances weed and disease suppression without affecting soybean yield, while dry bean yield is lower after rye at 3 bu/ac than at 1 bu/ac.
Project objectives and approach
Quantify the efficacy of cereal rye mulch on white mold and weed suppression in organic no-till soybean and dry bean
Soybean and black dry bean (cv. ‘Zorro’) were planted in three treatments in replicated randomized field trials in 2018-19 and 2019-20: rye cover crop roller-crimped at anthesis (no-till), rye cover crop plowed in in before stem elongation, and no cover with tillage for weed control. The rye was seeded at 180 lb/ac (3 bu/ac) in August of the preceding year, and rye biomass at time of roller-crimping and rye residue dry weight at time of bean harvest were measured.
Development of S. sclerotiorum structures that form the infective spores and incidence of visible disease on the crop were monitored. Crop stands, weed and crop biomass, and crop yield were recorded, and a partial budget analysis was conducted to assess net economic returns.
Examine the effects of increasing soybean and dry bean seeding rates on white mold and weed suppression
Soybean was planted no-till into roller-crimped rye at four or five seeding rates from 75,000 to 375,000 seeds/ha in replicated trials at two locations: Aurora, NY (no white mold present) and Geneva, NY (white mold present). Supplemental nitrogen (N) was provided at 0, 56, and 112 lb/ac in the form of Chilean sodium nitrate. Weed and crop biomass, disease incidence, crop yield, and net economic return were assessed. The trials were conducted over three growing seasons (2018-21).
Disseminate research findings including refined seed rate recommendations that account for site-specific disease management considerations
Project outcomes and recommendations were disseminated through a demonstration trial on an organic farm, Extension publications, and field days and workshops at the Geneva and Aurora research sites.
Key findings
Rye residues on the soil surface suppressed white mold
Roller-crimped rye consistently reduced the incidence of white mold disease in soybean and dry bean. The higher seeding rate of rye (3 bu/ac vs 1 bu/ac) enhanced disease suppression, and the effect was related to the physical barrier of roller-crimped rye.
Soybean performed well when planted no-till into roller-crimped rye
The higher seeding rate of rye (3 bu/ac) provided greater weed suppression than the lower rate without any reduction in soybean yields. The rye cover crop and its residues after roller-crimping suppressed weeds, in part by tying up N, which did not affect the N-fixing soybean crop. Soybean seeding rates could be increased without incurring greater risk of white mold disease.
Best economic returns were found at 215,000 seeds/ac and no supplemental N
As seeding rates increased from 75,000 to 375,000 seeds/ac, weed biomass decreased and yield increased. Highest seeding rates and zero N resulted in the lowest weed biomass. Supplemental N stimulated weed growth especially annual grasses, and did not affect soybean yield.
Seeding rates of about 215,000 seeds/ac with no applied N gave the best net economic return for organic soybeans, roughly $900 per acre. Eliminating tillage reduced production costs with no sacrifice in yields.
Dry bean showed some yield tradeoff with the high rye seeding rate
Initial results with organic no-till planting of dry beans were generally promising. However, while the 3 bu/ac rye seeding rate reduced weed biomass, it also reduced dry bean seed yield, thus indicating a need for further research to fine-tune cover crop seeding rate and possibly other management factors for this crop.
Resources
Organic No-Till Planted Soybean Production
Read MoreJournal Article - High Seeding Rates and Low Soil Nitrogen Environments Optimize Weed Suppression and Profitability in Organic No-Till Planted Soybean. Menalled et al. 2021. Frontiers in Agronomy.
Read MoreUSDA - Project Report - ORG 2018-51106-28775
Read MoreLocation
New YorkCollaborators
Matthew Ryan, Cornell University
Region
Northeast
Topic
Weed Management, Transitioning to Organic, Cropping Systems, Business and Marketing
Category
Grain and Field Crops
Year Published
2023
