Using invasive Eurasian milfoil as an organic soil amendment: Effect on tomato yield

View the project final report

• 2014 annual report

Commodities

• Vegetables: tomatoes

Practices

• Crop Production: organic fertilizers
• Production Systems: organic agriculture
• Soil Management: organic matter, soil analysis
• Sustainable Communities: sustainability measures

We are interested in studying the effectiveness of invasive Eurasian Milfoil (EM) as an organic soil amendment because its removal improves water quality and is essential to aquatic environmental stewardship in our area. At the same time, its application may improve soil health on small farms in our region by adding valuable organic matter to the soil and possibly delivering important nutrients. In order to assess the value of EM as an organic soil amendment, we propose a series of experiments that will compare yields and foliar nutrient tests between crops treated with various amounts of dried EM to control plantings. The project may reveal that EM is an effective, local, and low cost organic soil amendment, in which case farmers in the Northeast will benefit economically, environmentally, and have the opportunity to increase the sustainability of their operations. We will share our results to other farmer in the region through the dissemination of a detailed fact sheet through our local extension offices, presentations at local colleges, and at a regional vegetables grower meeting.

Background

Organic fertilizers, when used properly and in place of synthetic fertilizers, can reduce environmental and health risks in agriculture, prevent agricultural pollution, improve crop yields, and protect natural resources. Nutrients in organic fertilizers are contained in complex molecules that are not as easily lost to leaching with the first rain. One of the challenges of organic fertilizers is their relatively high cost , which can be especially prohibitive for small farms. Also, a barrier to sustainability is introduced when farmers face the need to purchase fertilizers that are from far away.

To address these challenges, we propose to test the effectiveness of Eurasian Milfoil (Myriophyllum spicatum) as a local and affordable organic fertilizer/soil amendment. Eurasian Milfoil (EM) is an invasive aquatic species that consistently out-competes native vegetation and quickly spreads to form dense mats on lake bottoms that degrade water quality and interfere with water recreation. By harvesting this environmental threat and using it as an organic soil amendment, we will be turning a big environmental negative into a positive, as EM is not viable on land. Aquatic Invasive Management, LLC is a locally owned and operated business that removes EM from lakes in the North Eastern United States. Owners Andrew Lewis and Tommy Thomson have offered to provide a large supply of the milfoil that they harvest from area lakes to Fledging Crow Vegetables, LLC for use in these experiments.

We already know that dried EM boasts high calcium levels and a carbon to nitrogen ratio of 15:1, and provides a good deal of organic matter into the soil , but we would also like to know if dried Eurasian Milfoil can increase yield of tomatoes. In addition, we will perform foliar tests to determine if nutrient levels are higher in the tomato plants grown with EM amendment compared with the control, the untreated tomato plants. If EM is found to increase yields, it will be beneficial to vegetable producers throughout the region. In addition, we propose that composted or dried EM may be a valuable agricultural product. The processing of wet EM into conveniently packaged dried or composted EM may be an employment opportunity in agricultural communities. This study will be crucial for informing future efforts to turn EM into a product that will benefit our local economy.

The objectives of this study of Eurasian Milfoil as a soil amendment are to:

(1) determine the effect of EM amendment as a soil fertility management practice by measuring yield of tomatoes with and without the amendment;
(2) use foliar nutrient tests to determine whether plant nutrient levels increase with the application of EM.
(3) assess the economic feasibility of EM amendment for sustainable agriculture by completing a cost-benefit analysis.

To address the question of EM’s effect on crop production (objective 1),we will divide our tomato greenhouses into sixteen 20'x 5' plots. We will assign one of the following treatments to each plot:

1.) Low-dose EM treatment, 10 lbs per 100 ft2
2.) Medium-dose EM treatment, 15 lbs per 100 ft2
3.) High-dose EM treatment, 20 lbs per 100 ft2
4.) Control treatment, no EM

Each treatment will be applied to four replications, for a total of 16 experimental plots. Each of the 20 foot sections of our greenhouses will be randomly assigned to one of the three EM amendment treatments or the control group. Foliar nutrient tests will be performed on plants in each replication of the tomato experiments (objective 2). In addition, we will do a pre-treatment soil test and a post-treatment soil test. These tests will be performed by our technical advisor, and will follow appropriate protocol. The cost benefit analysis (objective 3) will be completed using a calculation of labor costs used to dry and compost the EM. Throughout the project duration, we will keep records of the man hours spent to process the EM, as well as the diesel cost to have EM delivered. These records will help us determine if EM amendment is truly an economically feasible option for farmers in the Northeast.