Evaluation and implementation of nitrogen fixing species in hedgerow intercropping in Marianas
Adaptability of selected nitrogen fixing trees was studied in three agricultural soils in Guam. Both leaf biomass and seed production varies with plant species and appears to be influenced by soil type. Educational video and pamphlets on plant management of nitrogen fixing trees (NFTs) are being produced for distribution to the local community.
1. Develop protocol for seed propagation of leguminous hedgerow plants and produce a propagation guidebook.
2. Examine biomass production of leguminous hedgerow plants grown in different soil regimes on Guam.
3. Examine seed production of leguminous hedgerow plants grown in different soil regimes on Guam.
4. Examine susceptibility of leguminous hedgerow plants to arthropod, nematode, disease problems.
5. Produce educational publications of plant management of nitrogen fixing trees (NFTs).
Objective 1: Develop protocol for seed propagation of leguminous hedgerow plants and produce a propagation guidebook.
Pamphlets for six nitrogen fixing plants with plant propagation procedures are being created. They are Gliricidia sepium, Desmodium rensonii, Leucaena leucocephala cv. K636, Calliandra calothyrsus, Sesbania sesban cv. Nubica, and Cajanus cajan. Faculty members of College of Agriculture and Life Sciences, University of Guam and personnel of USDA Natural Resources Conservation Services, Pacific Basin, are reviewing the publications. An example of a pamphlet is attached to this report as Appendix 1.
Objective 2: Examine biomass production of leguminous hedgerow plants grown in different soil regimes on Guam.
The monthly biomass production of eight NFTs in three soil regimes on Guam was recorded for one year from November 2000 to October 2001. The plants in the study included Gliricidia sepium, Desmodium rensonii, Leucaena leucocephala cv. K636, Calliandra calothyrsus, Sesbania sesban cv. Nubica, Cajanus cajan, Acacia angustissuma, and Flemingia macrophylla. The study showed that L. leucocephala cv. K636 was able to out yield in alkaline soils at two locations, while in acidic soil F. macrophylla and G. sepium produced greater biomass than the other leguminous trees. The result will be published in the proceedings of Sustainable Agriculture in the Pacific and Asian Regions.
Objective 3: Examine seed production of leguminous hedgerow plants grown in different soil regimes on Guam.
Monthly observation of seed production was summarized. Generally seed production of NFTs reflected the soil’s fertility, and plant’s adaptability to a particular soil type. Desmodium rensonii and Flemingia macrophylla produced numerous seeds regardless of seasons at all three locales. In contrast, Leucaena leucocephala and Sesbania sesban produced more seeds in alkaline soils of Barrigada and Yigo than in acid soils of Ija. Acacia angustissima and Cajanus cajan had good seed production in Barrigada while in Yigo and Ija there were no or very few seeds produced. At all locations Calliandra calothyrsus produced very few seeds and only one flower and pod of Gliricidia sepium was observed only at Barrigada.
Objective 4: Examine susceptibility of leguminous hedgerow plants to arthropod, nematode, and disease problems.
The main troublesome pests on leguminous hedgerow plants were arthropods such as mealybugs (Ferrisia virgata?), Chinese rose beetle (Adoretus sinicus), and longhorn beetle (Prosplus branchii).
No serious foliage, stem and floral diseases were observed on all NFTS at all locations. None of NFTs in Yigo were affected by the root-knot nematode (Meloidogyne spp), although the soil at the Yigo Experiment Station is known to be infested by the pathogen.
Objective 5: Produce educational publications on plant management of nitrogen fixing trees (NFTs).
A 10-min video production of plant management of NFTs is being produced. Script (Appendix 2) was drafted and a producer of video was contracted. We anticipate that the video production will complete in January 2003. Duplicates of the video will be distributed to middle and high schools and organizations where agricultural/environmental science is studied.
Impacts and Contributions/Outcomes
We will generate two products from this project. First, data from the comparison study of nitrogen fixing trees at different soil regimes have revealed each species’ adaptability to various soil environment. The results were summarized and disseminated as an oral presentation at an international conference and as a written report in the proceedings. As a local publication, a factsheet was distributed to community.
The second product created was educational materials as “pamphlet” and “video.” We will distribute them to secondary schools and through Guam Cooperative Extension Service to show the various benefits of NFTs in our agricultural practices.