Progress 09/01/06 to 08/31/09
Outputs
OUTPUTS: Changes in soil properties and vegetable growth were quantified during the transition from conventional to organic farming on a low-fertility tropical soil. A control (no soil nutrients added), a treatment with 0.50 Mg/ha urea, and two (compost+ chicken manure) treatments providing approximately 140 mg/kg total nitrogen (N) were applied to an Oxisol (Rhodic Haplustox, Wahiawa Series) in a field on Oahu, Hawaii. Chinese cabbage (Brassica rapa, Chinensis group) and eggplant (Solanum melongena) were grown sequentially as test crops. Weeds, especially Guinea grass (Panicum maximum), and leaf insects were problems for crop production if not controlled. Soil quality as measured by hot-water soluble carbon, dehydrogenase activity and cation exchange capacity was increased by compost amendments. Total organic carbon or CO2 respiration rate, however, did not correlate with the soil amendments. Nitrogen nutrition seemed to be the main factor that improved growth and carotenoid content in cabbage. The treatment with urea promoted better growth in the first crop (cabbage), whereas a good-quality compost, made of grass-clippings/tree trimmings, lime and rock phosphate, gave the best growth in the second crop (eggplant), suggesting N mineralization from organic inputs requires time (3-4 months) in field conditions before N became more available to crops. PARTICIPANTS: Ms. Archana Pant, a Ph.D. student in the department of Tropical Plant and Soil Sciences, University of Hawaii. Dr. Ted Radovich, a specialist in sustainable and organic agriculture, in the college of Tropical Agriculture and Human Resources, University of Hawaii. TARGET AUDIENCES: Organic farmers in Hawaii; graduate students in agriculture. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Switching from conventional to organic farming provide opportunities as well as challenges in getting good crop yields and making profits. The challenges that an organic farmer may face include weeds, insects, and plant nutrient requirements. Amending the soil with good-quality composts (characterized by low C/N ratio, high N, P, K and micronutrients) is essential to providing adequate nutrients in organic farming. Synchronization between crop demands and nutrient release from soil amendments is important. On the other hand, soil quality as measured by such parameters as hot-water soluble C, dehydrogenase activity, and cation exchange capacity, would be improved by adding organic amendments, especially to low-fertility soils of the Tropics.
Publications
- Ortiz-Escobar, M.E. and N.V. Hue. 2007. Current developments in organic farming. p. 29-62. In: S. G. Pandalai (ed.) Recent Research Developments in Soil Science , vol. 2 (2007).
- Pant, A.P., T.J.K. Radovich, N.V. Hue, S.T. Talcott, and K.A. Krenek. 2009. Vermicompost extracts influence growth, mineral nutrients, phytonutrients and antioxidant activity in Pak choi (Brassica rapa cv. Bonsai, Chinensis group) grown under vermicompost and chemical fertilizer. J. Sci. Food and Agric. DOI 10.1002/jsfa.3732, vol. 89:2383-2392.
|
Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: Trained a Ph.D. student on organic farming practices. Two greenhouse experiments were completed to evaluate the effects of compost tea on phytonutrient concentration and dry-matter production of Chinese cabbage (Brassica rapa chinensis). The teas were made by three methods: (1) non aerated brewing, (2) aerated brewing, and (3) aerated brewing + microbial enhancing. PARTICIPANTS: PARTICIPANTS: Ms. Archana P. Pants, a Ph.D. student, is working on this project. Dr. Ted Radovich, who is a researcher at the University of Hawaii, specializing on sustainable agriculture, is a collaborator. TARGET AUDIENCES: TARGET AUDIENCES: Exchange information with the Hawaii Organic Farmers Association and the public who are interested in organic farming. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Compost tea, which is a brewed or steeped and filtered solution of compost and water, has gained considerable popularity in use in organic farming. Compost tea-applied crops may have different levels of secondary plant metabolites, such as glucosinolates, carotenoids, and phenolic compounds. In fact, our findings showed that (1) Methods of tea preparation did not affect plant growth or content of phytonutrients, and (2) In contrast, tea applications (both to roots and above-ground) increased dry-matter production and carotenoid content, but decreased phenolic content of 4-week-old cabbage relative to the water control. Thus, the use of compost tea might have important implications to flavor, nutritive and market values of organically grown crops.
Publications
- No publications reported this period
|
Progress 09/01/06 to 08/31/07
Outputs
OUTPUTS: Presented to local organic farmers, organizations, and home-owners advantages and disadvantages of organic farming. Trained a Ph.D. student on organic farming: techniques, requirements, and benefits.
PARTICIPANTS: Ms. Archana P. Pants, a Ph.D. student, is working on this project. She is learning analytical methods on how to extract and measure phyto-nutrients in vegetables. Dr. Ted Radovich, who is a researcher at the University of Hawaii, specializing on sustainable agriculture, is a collaborator.
TARGET AUDIENCES: Exchange information with the Hawaii Organic Farmers Association. People who are interested in organic farming.
Impacts
Organically grown products are believed to be healthier and more nutritious than their conventionally grown counterparts. A few reports have shown that phyto-nutrients are higher in organic vegetables. To verify such findings, we measured the content of lycopene and beta-carotene in Chinese cabbage plants, which were grown under four treatments: unamended control, urea added, compost incorporated, and compost mulched. The soil used was a fertile Mollisol from Waimanalo, Oahu, Hawaii. Our preliminary data showed that lycopene levels in cabbage leaves were slightly higher, though statistically not different, in the treatments with organic inputs than in the others.
Publications
- No publications reported this period
|
|