High nutrient solution fertilizers derived from local organic inputs for field and greenhouse application in the tropics

View the project final report

• 2014 annual report
• 2015 annual report

Commodities

• Agronomic: corn
• Fruits: melons, papaya
• Vegetables: cabbages, peppers, sweet corn, tomatoes, turnips

Practices

• Crop Production: food product quality/safety
• Education and Training: extension, farmer to farmer, on-farm/ranch research, workshop
• Farm Business Management: budgets/cost and returns
• Natural Resources/Environment: biodiversity
• Production Systems: organic agriculture, transitioning to organic
• Soil Management: soil analysis, nutrient mineralization, soil microbiology, soil chemistry, organic matter, soil physics, soil quality/health
• Sustainable Communities: partnerships, sustainability measures

Replacing imported fertilizers with local resources is the highest research and educational priority identified by stakeholders throughout the Pacific at multiple meetings. While progress is being made in developing recommendations for locally produced solid fertilizers, the need for solution fertilizers derived from local resources has not yet been adequately addressed. This is especially true for growers of long term food crops, such as taro and fruit trees, who need to provide supplemental nutrition throughout the cropping cycle. The production of locally derived nutrient solutions for fertigation will keep local farmers competitive, reduce water-use and loss, and protect the environment by reducing chemical use. Anecdotes from innovative growers and preliminary findings in the lab has shown that locally produced tankage (rendered meat, 9% N) was a good source of soluble nitrogen (NO₃-N and NH₄-N). At lab scale, some treatment effects on nitrogen release from tankage were tested. The preliminary results are promising, although there is a need to evaluate more treatments and increase scale in order to come up with recommendations for local farmers. The goal of this project is to develop capacity among Pacific Island growers to cost effectively produce concentrated nutrient solutions from local materials, accelerating current efforts to reduce grower reliance on imported fertilizers. Lab, greenhouse, and field (including on-farm) trials were conducted to produce high quality liquid organic fertilizer for fertigation purposes. A recipe was developed and its quality was evaluated in a series of field trials (including on farm) to produce vegetable crops and a series of greenhouse trials to improve seedlings quality of vegetable and fruit crops. Workshops/field days and public talks were given to disseminate the project findings. A book chapter and an extension bulletin were produced.

Objective 1: Identifying optimal temperature, time, chemical, and biological factors to maximize mineralization and aqueous extraction of N from tankage.

Activities: Develop and validate procedures to enhance the extracts of nitrate (NO₃-N) and ammonium (NH₄-N) from tankage using factors, such as:

1) Chemical and Biological (Baking soda, vermicompost, molasses, yeast).

2) Covering and aeration (cover/no cover, and aeration/no aeration).

3) Time and temperature (Time intervals 0-48 hours and 20-35^oC).

Objective 2: Developing yield response curves and recommendations to optimize aqueous solution for greenhouse and field applications.

Activities: Develop and validate greenhouse and field application recommendations to local farmers and producers through:

1) Series of greenhouse trials (to test quality of highest nitrogen soluble solution).

2) Series of on-farm trials (to evaluate laboratory and greenhouse trials results).

3) Evaluation of results (Develop greenhouse and field application recommendations).

Objective 3: Disseminating the project findings among local producers, extension agents, and other university professionals, through a series of workshops and field days, extension bulletins, production procedure manual, and other online resources.

Activities include: Transfer the project findings among local farmers and other professionals through:

1) At least three on-farm workshops and field days to be conducted on different Hawaiian Islands (Oahu, Molokai, and Big Island).

2) At least two Extension bulletins and a short manual for solution fertilizer production procedures.

3) At least two scientific peer reviewed publications.

Note: Cost analysis of solution fertilizers production will be conducted throughout all activities.