Mung Bean

Mung bean (Vigna radiata) is a fast-growing, warm-season annual legume valued for short-season nitrogen fixation, quick summer canopy, and excellent heat/drought tolerance. Growers choose mung bean to fill hot weather windows (for example, after small-grain harvest), add diversity to cover crop mixes, and contribute legume nitrogen while providing grazeable forage. (USDA–NRCS Iowa 2025 Mung Bean factsheet; Kansas State Univ. Extension eUpdate, 2023)

Benefits of Mung Bean as a Cover Crop

• Erosion Control: As a legume cover, mung bean contributes to the erosion protection associated with legumes; across studies, legume cover crops reduced soil loss by 38–69% compared to no cover crop. In conventionally tilled fields, cover crops (all types) have reduced sediment losses by an average of 20.8 tons per acre per year. Expect moderate erosion protection from mung bean (rated “Fair” by NRCS) relative to high-biomass grasses. (SARE Ecosystem Services—Covering the Soil to Prevent Erosion; USDA–NRCS Iowa 2025 factsheet)
• Weed Suppression: Mung bean establishes quickly but generally produces modest biomass; NRCS rates its weed suppression as “Fair.” A Midwest meta-analysis found about 5 Mg/ha (≈4,460 lb/ac) of cover crop biomass is needed to reduce weed biomass by ~75%, a level mung bean alone may not reach consistently—so pair it with higher-biomass species or increase seeding density for better suppression. (USDA–NRCS Iowa 2025 factsheet; Nichols et al., 2020 meta-analysis)
• Soil Structure Improvement: Mung bean’s legume root system creates pores in the upper profile and can extend deeply; research tracing root profiles found ~70% of mung bean roots in the top 0–20 cm with roots detected down to 120–140 cm, which helps open channels, promote aggregation, and improve trafficability. (Notulae Botanicae Horti Agrobotanici, root distribution study)
• Water Management: Cover crops can improve rainfall infiltration dramatically; syntheses show infiltration increases of more than six-fold in some systems, decreasing runoff and helping store water for subsequent crops. Mung bean’s quick canopy and root channels support these effects, particularly on well-drained soils. (SARE Ecosystem Services—Improve Soil Conditions & Prevent Pollution)
• Disease/Pest Break: Rotating out of corn into a non-host like mung bean disrupts corn rootworm life cycles; crop rotation remains one of the most effective cultural controls for corn rootworm populations (with caveats where rotation-resistant variants occur). (Univ. of Nebraska–Lincoln, Corn Rootworm Education; Iowa State Univ. Corn Rootworm IPM)
• Nitrogen Management: As a legume, mung bean fixes atmospheric N. Field studies of warm-season legumes report mung bean aboveground N contents around 63 kg N/ha (~56 lb N/ac) and biological N fixation near ~26 kg N/ha (~23 lb N/ac) under Mediterranean summer conditions; green-manure trials in Ethiopia measured mung bean N contributions of ~29–39 kg N/ha (~26–35 lb N/ac). Compendia report broader ranges of 26–88 kg N/ha (~23–79 lb N/ac), depending on environment and management. (MDPI Plants 2019 field trial; NCBI/PMC 2024 green manuring study in sugarcane; IntechOpen review (table of legume green manures))
• Biomass Production: In Iowa NRCS evaluations, dry matter production typically ranges from about 500–2,000 lb/ac per season, depending on planting/termination dates and rainfall—enough for moderate soil cover and N contribution, especially in mixes. (USDA–NRCS Iowa 2025 factsheet)

Planting and Management Advice

• Seeding Rate (cover-crop use): Drill 15 lb/acre PLS; broadcast 18 lb/acre PLS. If broadcasting without good incorporation/pressing, increase the rate 25–50% to compensate for poorer seed–soil contact. (USDA–NRCS Iowa 2025 factsheet; Mississippi State Univ. Extension—Broadcast Seeding)
• Seeding Depth: 1–2 inches is typical for reliable moisture; in dry seedbeds on non-crusting soils you can go to 3 inches. Plant somewhat shallower than soybean on most soils. (USDA–NRCS Iowa 2025 factsheet; Univ. of Wisconsin Agronomy—Mungbean; Iowa State Univ. Alt. Ag.)
• Soil Type and pH: Best on fertile loams and sandy loams with good internal drainage; avoid heavy, poorly drained clays. Optimal pH is ~6.2–7.2. (Univ. of Wisconsin Agronomy—Mungbean)
• Planting Time (seasonal windows by region):
• Upper Midwest/Great Lakes: As soils warm to ≥59°F, plant from about mid‑May through early August in Iowa; in Wisconsin, the prime window for grain-type plantings is May 15–June 6 (summer cover crops can be established later where frost-free days allow). (USDA–NRCS Iowa 2025 factsheet: minimum germ temp 59°F and mid‑May–early Aug window; Univ. of Wisconsin Agronomy)
• Central Plains: Good option as a short-season summer cover after winter wheat/canola; Kansas experience highlights its heat/drought tolerance and suitability for double-crop windows in June–July. (Kansas State Univ. Extension eUpdate, 2023)
• General rule: Wait until soils reliably exceed 59°F; local NRCS/MCCC tools now provide county-specific seeding dates reflecting updated climate normals. (USDA–NRCS Iowa 2025 factsheet; ISU/MCCC decision tool update, 2025)
• Termination (methods and timing):
• Cold kills: Mung bean’s cold tolerance is ~32°F; hard frosts will terminate stands left into fall in northern regions. (USDA–NRCS Iowa 2025 factsheet)
• Mechanical: Mow/shred at full flower or earlier if needed to prevent seed set; broadleaf legumes are harder to kill by rolling/crimping and often need flowering stage plus multiple passes or a herbicide follow-up. (Southern Cover Crops Council—Termination of broadleaf/legume covers)
• Chemical: Use a labeled burndown; ensure the cover is actively growing. Observe plant-back and product-specific intervals (e.g., 2,4‑D at 1 qt/ac ≥30 days before soybean; 1 pt/ac ≥7 days). Terminate 2–4 weeks before planting if soil moisture is limiting, or 3–4 weeks prior where “green bridge” pests are a concern. (Michigan State Univ. Extension—chemical termination reminders; NC State Extension—termination timing guidance; SARE—Conservation Tillage Systems in the Southeast, termination timing 2–4 weeks)
• Rotational Considerations:
• Excellent non-host break before corn to suppress corn rootworm—rotation is still among the most effective tactics (manage volunteer corn to avoid attracting beetles into the rotation year). Be aware of rotation-resistant variants in parts of the eastern Corn Belt. (Iowa State Univ. Corn Rootworm IPM; Univ. of Nebraska–Lincoln, rotation guidance)
• Avoid placing mung bean immediately before or after soybeans where soybean cyst nematode (SCN) or major soybean diseases are issues: mung bean is a documented SCN host and has shown susceptibility to several key soybean pathogens (e.g., F. virguliforme—SDS; C. sojina—frogeye). Use a grass/monocot crop between legumes in problem fields. (Plant Health Progress—SCN diagnostic guide (host list includes mung bean); Plant Health Progress 2023: screening mungbean against soybean diseases in Iowa)
• Water Requirements and Stress Tolerance: Mung bean is notably tolerant of heat and drought (rated “Very good” for drought and low-fertility tolerance by NRCS) and performs best on well-drained soils; avoid waterlogged, compacted, or heavy clays. Ensure moisture from flowering through pod fill if growing it long enough to maximize biomass. (USDA–NRCS Iowa 2025 factsheet; Univ. of Wisconsin Agronomy—Mungbean; Kansas State Univ. Extension eUpdate, 2023)

Notes to optimize success:

• Inoculate seed with the appropriate Rhizobium for Vigna spp. to ensure strong nodulation and N fixation. (USDA–NRCS Iowa 2025 factsheet)
• Because mung bean’s biomass is moderate, consider mixing with a grass (e.g., millet, sorghum-sudangrass) for stronger weed suppression and erosion control, while still capturing legume N benefits. (Nichols et al., 2020 meta-analysis; SARE Ecosystem Services—Erosion and Infiltration)