A feasible method for organic fertilization of greenhouse tomatoes through drip irrigation

2006 Annual Report for FNE05-556

Project Type: Farmer
Funds awarded in 2005: $3,430.00
Projected End Date: 12/31/2007
Region: Northeast
State: Rhode Island
Project Leader:

A feasible method for organic fertilization of greenhouse tomatoes through drip irrigation


A feasible method for organic fertilization of greenhouse tomatoes through drip irrigation
FNE 05-556
Arthur Mello
81 Stone Church Rd.
Tiverton, RI 02878
(401) 624-6329
[email protected]

The overall goal of our project is to increase our agricultural sustainability by reducing labor costs, increasing farm income, and conserving and protecting soil and water resources. To achieve this goal, we will develop a feasible method of fertilizing our greenhouse tomato crop by applying liquid organic fertilizer through a drip irrigation system. Due to the globular nature of organic fertilizers, they can clog drip irrigation systems. This problem is well-documented by us as well as other growers and agricultural researchers. Through changes to the drip irrigation system and the fertilizer dilution, we will develop a feasible fertilization method, improving our sustainability and that of other growers who adopt our methods.

We are running a vegetable farm full-time in Little Compton, Rhode Island. Currently, we are farming 15 acres, including a 3000-square foot greenhouse. We are in our fourth year of growing organically, and are in the process of obtaining organic certification from USDA through the RI Department of Environmental Management.

Our technical advisor for the project is Thomas Sandham of the Eastern RI Conservation District. Tom is in an advisory role on our soil and water conservation practices. He also reaches a wide network of vegetable farmers in the area, and will be involved in the outreach portion of our project. We have two project collaborators, Dr. Douglas Cox, Floriculture Extension Specialist at the University of Massachusetts, and Dr. Mary Peet, North Carolina State University. Dr. Cox has a lot of experience with greenhouse drip irrigation, as well as agricultural research in general. He assisted with our experimental design, and will be speaking at our proposed grower field day. He has also agreed to write up our results in an extension publication, which reaches many growers in the region. Dr. Peet has done extensive research on organic fertilizers and drip irrigation. She provided valuable guidance during the planning stages of the project.

Tomatoes, grown by us from organic seed, were planted in soilless mix in 3-gallon pots, spaced 18 inches apart in rows in the greenhouse. We used the paired comparison experimental design for our project. The treatments were as follows: (1) 1% dilution fish emulsion applied through the drip system at every watering and (2) 3% dilution fish emulsion applied through the drip system at every other watering. Each treatment included 100 single-plant replicates. Our control was hand application of the fish emulsion fertilizer, with hand watering.

Our first try did not yield the results we expected. We believe this difference was not due to the treatments, but rather to other conditions. Once the plants were set up in the greenhouse for the experiment, we had to wait longer than we expected for the new drip irrigation system to come in before fertilizing the plants. Therefore, the plants went without fertilizer for longer than planned. At the start of the fertilizer treatments, the plants were already showing some signs of stress. Shortly thereafter, we had a fungus problem, which affected the whole greenhouse, including the experimental block. The experimental plants, already stressed, ended up losing several leaves. At this point, about 1 month into the project, we decided to end the experiment and try again at another time.

We will run the experiment again this spring, using the same experimental design and treatments as in the first trial. The plants have already been seeded and will be transplanted as soon as they are ready. As the irrigation equipment is already in place, we do not expect a delay in starting the experimental treatments.

Once the experiment is well underway (by early summer), we will host a field day at our farm for area growers. Growers will tour our greenhouse, hear a summary of the project, and have the opportunity to ask questions and join in discussion with Mr. Sandham, Dr. Cox, and myself. When the project is complete, Mr. Sandham and I will present a short paper detailing the results and grower recommendations at a local grower forum. As mentioned earlier, Dr. Cox will write up our results in an extension publication.

Arthur Mello
February 28, 2006


Thomas Sandham

[email protected]
Techincal Advisor
2490 Main Rd.
Tiverton, RI 02878
Office Phone: 4016247490