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

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

Summary

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.

Two field trials were initiated in July 2008 at commercial farms (Khamphout Farm and Benny’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 continuing to be monitored.

At Benny’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 (including 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.

Objectives/Performance Targets

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 Western 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.

Accomplishments/Milestones

Two field demonstration trials at small- (Benny’s Farm in Lanai), and intermediate-scale (Khamphout Farm at Kunia, Oahu) farms were established in 2008. In both trials, prior to cash crop planting, field plots were either planted with sunn hemp (SH) at 40 lb seeds/acre or left fallow (F) with weeds for two to three months. At Khamphout Farm, sunn hemp was planted in July and alternate rows of sunn hemp were tilled in during October. Bitter melon seedlings were then transplanted. We use nematode community analysis as indicators of soil health. Initial soil samples taken right after sunn hemp planting indicated no difference between SH and F plots (Table 1). 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 (Table 1). 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. We are currently monitoring plant growth, nematode population densities and weed coverage.

At Benny’s Farm, sunn hemp was planted in July 2008. Two 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) (Table 2). 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 (including Actinedida, Acaridida, Gamasida) (Table 3). Most of these free-living mites are either saprophagous, or predacious to spider mites.

We were planning to plant Italian parsley and cherry tomato in November, but the farmers were having difficulty to establish their seedlings, followed by severe rainy weather that flooded the field. Thus, planting of Italian parsley have been delayed and we are planning to plant in January 2009.

Milestones

Trial I at Khamphout Farm, Kunia, Oahu, HI
July 2008 – Cover crops planted.
Oct 2008 – Planted bitter melon in strip-till cover cropping system.
Feb 2009 – Terminate bitter melon. Begin row switching for second cash crop.
May 2009 – Terminate second cash crop.

Trial II at Benny’s Farm, Lanai City, Lanai, HI.
July 2008 – Cover crops planted.
Jan 2009 – Plant Italian Parsley, Cherry tomato following cover crop.
March –terminate first cash crop. Begin row switching for second cash crop.
June 2009 – Terminate second cash crop.

Trial III at Aloun Farm (corn demonstration trial)
Feb 2009 – Oct 2009 Two months of sunn hemp cover crops followed by two cycles of corn.

July – Sept 2009 Analyze data, writing reports (for trial I and II) and publications, conducting workshops and survey.

Impacts and Contributions/Outcomes

Farmer participants are convinced that sunn hemp cover cropping prior to their crop planting improves the soil conditions for next planting. Experiments are in progress to demonstrate the benefits of rows switching technique. On Oct 18, 2008, a farmers’ workshop organized by extension specialist, Dr. Sabina Swift, was conducted at Mililani Agricultural Park, Mililani, Oahu. The workshop was targeting at low income immigrant farmers. Twelve farmers attended the workshop. Most of these farmers lease their lands from Mililani Ag. Park and are beginning farmers that are very eager to learn new farming techniques. PI Wang presented “Cover crops for management of above and below ground pests and beneficial organisms in vegetable cropping system.” Extension articles on sunn hemp and marigold were distributed. Seven farmers turn in evaluation forms (the other attendees are spouse of some attendees, thus did not turn in evaluation forms). Five of them are aware of the benefits of cover crop before the workshop. Only one farmer is aware of nematode being a problem in his farm. Six of them plan on using cover crops in their farm after this workshop, but all of them signed up to obtain sunn hemp seeds. All agree that it is important to enhance beneficial organisms in their farms. Six of them agree that using sunn hemp as a cover crop can reduce fertilizer cost.

Collaborators: