Improving and extending the superhero status of the sunn hemp to other growers in need of help

Project Overview

Project Type: Research and Education
Funds awarded in 2007: $10,000.00
Projected End Date: 12/31/2009
Region: Western
State: Hawaii
Principal Investigator:
Dr. Cerruti R. R. Hooks
University of Maryland
Dr. Koon-Hui Wang
University of Hawaii

Annual Reports


  • Agronomic: corn
  • Vegetables: eggplant


  • Crop Production: cover crops, double cropping, multiple cropping, organic fertilizers, strip tillage
  • Education and Training: demonstration, extension, on-farm/ranch research
  • Farm Business Management: whole farm planning
  • Pest Management: cultural control, mulches - living
  • Production Systems: general crop production
  • Soil Management: green manures
  • Sustainable Communities: employment opportunities

    Proposal abstract:

    The overall goal of the proposed project is to 1) enhance the sustainability of using sunn hemp cover crop, and 2) further advance the benefits of sunn hemp for suppressing nematode pests and enhancing beneficial soil microorganisms (free-living nematodes and soil microarthropods) demonstrated previously. To achieve these objectives, sunn hemp (SH) was planted for three months and compared to a fallow (F) with weeds treatments. Subsequently, alternate rows of sunn hemp were stripped-tilled. Then, cash crops will be planted over the strip-tilled rows. The remaining sunn hemp rows will be cut and residues left on the soil surface as organic mulch. The novelty of this project is the follow up of sunn hemp cover cropping system after the first cycle of cash crop. After the initial crop has been harvested, cash crop rows and organic mulch rows will be switched. Nematode community analysis was used to analyze soil health conditions. Currently, two field trials were initiated in July 2008 at commercial farms (Khamphout Farm and Bennie’s Farm). At Khamphout Farm, initial soil samples taken right after sunn hemp planting indicated no differences between sunn hemp (SH) and fallow (F) plots. However, at 2 months after sunn hemp cover cropping (prior to incorporation into soil), SH had lower (P < 0.10) numbers of plant-parasitic nematodes (mainly root-knot nematodes), but no difference was detected for the abundance of different group of free-living nematodes (bacteria-feeders, fungal feeders, omnivores, and predators). However, SH had higher (P < 0.01) structure index than the F control. Structure index is a nematode community index that put emphasis on abundance and weight of omnivorous and predatory nematodes, indicating the soil is less disturbed. Further nematode community analysis, plant growth, nematode population densities and weed coverage are continued to be monitored. At Bennie’s Farm, 2 months after sunn hemp planting, nematode community analysis showed that SH had lower (P < 0.05) percentage of plant-parasitic nematodes, higher (P < 0.05) numbers and percentage of bacteria feeding nematodes, and lower channel index (indicating the soil is undergoing bacteria decomposition rather than fungal decomposition). All of these indices indicated that SH sustained a soil environment enriched with nutrient that favor bacteria decomposition and suppressed plant-parasitic nematodes that would be damaging to the subsequent cash crop. However, nematode diversity was lower in SH plot as compared to F treatment, this could be due to a nematode community temporary dominated by bacteria feeding nematodes. We are continuing to monitor nematode population densities. In addition, we also monitored soil microarthropods using Burlesee funnels. Data collected at 2 months after sunn hemp planting had higher number of free-living mites (include Actinedida, Acaridida, Gamasida). Most of these free-living mites are either saprophagous, or predacious to spider mites. Farmer participants are convinced that sunn hemp cover cropping prior to their crop planting improves the soil conditions to next planting. Experiments are in progress to demonstrate the benefits of rows switching technique. Thus, no-cost extension period is requested.

    Project objectives from proposal:

    1. The overall goal of the proposed project is to 1) enhance the sustainability of using sunn hemp cover crop, and 2) further advance the benefits of sunn hemp well beyond those producers reached during our 2006-2007 W-SARE project “A superhero without a cape: using the cover crop sunn hemp to feed the soil, suppress nematodes, and smother weeds.” Our specific research objectives are to:1.Demonstrate and disseminate how sunn hemp can be utilized to reduce nematode, weed, and insect pests and improve soil and plant nutrient status during multiple crop plantings. 2.Show and disseminate how sunn hemp can be used to increase crop productivity and marketable yields during multiple crop plantings. 3.Deliver an integrated, sustainable, and economically viable sunn hemp cropping system to educators and growers with diverse agricultural needs.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.