Biochar Amendment to Enhance Tomato and Melon Productivity and Protect Against Phytophthora Root Rot Disease

View the project final report

• 2015 annual report
• 2016 annual report

Commodities

• Fruits: melons
• Vegetables: tomatoes

Practices

• Crop Production: organic fertilizers
• Education and Training: demonstration, extension, on-farm/ranch research, participatory research, workshop
• Natural Resources/Environment: carbon sequestration
• Pest Management: cultural control, prevention
• Production Systems: organic agriculture
• Soil Management: soil chemistry

Fresh vegetables are important commodities in Utah; 6,560 harvested acres were produced on approximately 700 farms and valued at $16 million in 2007 (National Agriculture Statistics Service). Most of these operations are small farms (less than 15 acres) growing high value crops, including sweet corn, melons and squash, and many are new farms. Approximately 1,300 new farms began operation in Utah from 2004 to 2010, while the area of land in production declined by approximately 500,000 acres (Hilton, J. 2011). The number and capacity of these small specialized farms will continue to increase due to the high demand for locally produced fresh produce and benefits of greater and more stable income for growers. Over 90% of Utah’s population is concentrated on 1.1% of the land; therefore, small-scale farms must operate under increasing constraints on water availability and soil and water contamination from pesticide run-off. Most small-scale farmers are keen to use sustainable agricultural practices and are environmentally-conscious; however, they need more information about sustainable practices relevant to their production situations. In a 2010 survey of commercial vegetable producers in Utah (252 responses), managing irrigation and nutrition for crops grown in arid and alkaline soils were among the most pressing need. Growers also identified concern regarding losses due to diseases, in particular soil-borne pathogens such as Phytophthora root rot. This project will work with Utah producers to test whether a novel soil amendment called biochar can contribute to sustainable production by improving soil water-holding capacity, crop yield and disease resistance in tomato and melon, two important crops in the state. Biochar is a carbon-rich material similar to charcoal, produced by heating plant biomass through slow pyrolysis in a closed system, under a limited supply of oxygen. It may be used as an alternative fuel, or it may be applied to the soil to sequester carbon, where it can require from 4 to over 100 years to degrade. This property of Biochar makes it a desirable amendment because it does not need to be applied every year. The use of soil-applied biochar in agricultural crops has gained interest in recent years because it has been shown to sig­nificantly improve soil tilth, nutri­ent retention and availability to plants, water holding capacity, and soil aggregate stabil­ity (Glaser et al., 2002). Reported increases in crop yields with biochar amendment may be attributed to increase in nutrient availability (Khodadad 2010). Biochar application can stimulate plant resistance to soil borne diseases through promotion of mycorrhizal fungi and soil microbial populations (Steiner 2009). Biochar has little nutrient value on its own and is not a replacement for fertilizer. The positive attributes of biochar are seen primarily when biochar is moistened and mixed with an organic amendment or fertilizer. Effects of biochar have varied among soil types, biochar production practices and application rates. Few studies have evaluated biochar in arid and alkaline soils (Spokas et al, 2012). To gain a better understanding of the utility of biochar amendments for Utah agriculture, we propose to work with producers to investigate soil-applied biochar in two vegetable production systems through a series of experiments. We will focus on biochar products recycled from Utah tree fruit orchards. In the first year (2014) we will conduct a small-scale trial at the USU Botanical Center in Kaysville, UT to determine the optimal rate of biochar application to be used in years two and three on all cooperating sites. The biochar will be produced by a mobile pyrolysis unit built through a collaboration between the Utah Biomass Resources Group (UBRG) and a private firm. We will then test biochar application on three cooperator producer farms. Our findings on how biochar amendments affected yields of tomato and melon, soil moisture retention, cost-benefit economics and root rot disease prevention will be disseminated through field days, demonstrations, oral presentations, how-to videos and fact sheets. Three vegetable producers are interested in participating in this project. Pettingill Farms in Box Elder County is a 130-acre, diverse, conventionally managed farm that grows fruits and vegetables. Zoe’s Garden in Davis County is a 20-acre, diverse, organically managed farm. Day Farms in Layton is a 90-acre, diverse, conventionally managed vegetable farm. Two Utah County fruit producers have agreed to provide fruit tree wood to produce biochar for the project: William McMullin, McMullin Orchard, and Phil Rowley, Southridge Farms. These orchardists have expressed interest in manufacturing biochar as a sustainable practice for recycling farm biomass wastes. Recent reports on the benefits of biochar have stimulated interest among growers; however, it is difficult to piece together results from variable studies. Intermountain growers need locally-relevant information to help them evaluate whether biochar could be a viable option for their industry. Biochar production and use does extend beyond agriculture, as a part of a larger sustainable system promoting waste management, fossil fuel energy alternatives and carbon sequestration. Thus, adoption of biochar by commercial growers as a soil improvement technique could promote the growth of green energy technology and job creation in Utah. Study findings will be relevant to other locations, particularly in the Intermountain West, with similar soils and growing conditions.

Project duration: May 2014 – February 2017

The primary goals of this project are to engage vegetable producers in testing the effects of biochar amendments on plant and soil health and educating the vegetable industry on the project’s findings.

1)      Evaluate soil application rates of fruit wood-prepared biochar for field-grown tomatoes and melons and establish parameters for subsequent trials.

May – August 2014: Two tons of biochar will be prepared by burning fruit wood from our cooperating orchardists in a pyrolyzer assisted by the Utah Biomass Resources Group. Before use, the product will be analyzed for properties that may influence soil and plant health, including cation exchange, pH, ash and carbon content. The biochar will be used in a replicated trial testing five rates (recommended in the literature) at the Utah State University Kaysville Experimental Farm to determine which rate results in the greatest benefit to both melons and tomatoes.

2)      Collaborating with producers, we will evaluate how biochar amendment at the identified optimal rate influences water holding capacity, crop yield and overall plant health of tomato and melon.

June – August 2015 and June – August 2016: Biochar will be applied at the identified rate and replicated at four sites both years: the Kaysville Farm, plus three commercial farms. There will be three treatments at each site for both crops: biochar plus compost, compost alone and untreated. Compost will be tested for nutrients and applied at a rate comparable to a standard fertilizer application for production. We will collect data on soil moisture, nutrient content and quality; plant foliar and root dry weight; total crop yield;and plant health to assess the effect of biochar amendment on tomato and melon production and health.

3)      Determine whether the addition of the biochar product applied at the determined rate prevents or reduces susceptibility to the root rot disease caused by the organism Phytophthora.

June – August 2015 and June – August 2016: In replicated pot trials conducted at the Kaysville Farm over two seasons, tomatoes and melons will be exposed to Phytophthora, with and without biochar. Measurements listed in Objective 2 will be collected, as well as microscopic root examinations and a lab assay (ELISA) of root segments.

4)      Determine whether the use of soil-applied biochar could provide economic benefits to Utah’s vegetable growers.

October – December 2016: The project partners will analyze economic data involved with using biochar on a farm, including material and application costs, root rot disease prevention and benefits to marketable yield.

5)      In collaboration with project producers, prepare and deliver educational programming for other growers and the general public on all aspects of biochar as a soil amendment for vegetable production.