Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2010
Publication Date: May 24, 2010
Citation: Vaughn, S.F., Deppe, N.A., Berhow, M.A., Evangelista, R.L. 2010. Lesquerella Press Cake as an Organic Fertilizer for Greenhouse Tomatoes. Industrial Crops and Products. 32:164-168. Interpretive Summary: In this research, we found that tomato growth and fruit yield in potting mix supplemented with lesquerella press cake was equal to plants grown with a standard chemical fertilizer or cottonseed meal, a commonly-used organic fertilizer. Lesquerella is an oilseed crop belonging to the mustard family that is being developed as a new crop for arid regions of the southwestern United States. Lesquerella oil is rich in hydroxy fatty acids (HFAs), which are important as industrial raw materials for making polymers such as nylon, resins, waxes, corrosion inhibitors, coatings, lubricating greases, and cosmetics. Currently, most HFAs are obtained from imported castor oil, as little castor is grown domestically. The lesquerella press cake contains levels of nutrients which should make it an excellent organic fertilizer for container-grown plants. Developing this press cake as a fertilizer for organic growers and home gardeners would help to support the initial growing and processing costs associated with a new crop such as lesquerella.
Technical Abstract: Lesquerella press cake is a co-product generated during the processing of the new oilseed crop lesquerella [Lesquerella fendleri (A. Gray) S. Wats.]. Developing commercial uses for the press cake would increase the profitability of growing lesquerella. The press cake contains levels of nutrients which should make it an excellent organic fertilizer for container-grown plants. Tomato (Solanum lycopersici L. 'Red Robin') plants were grown in potting mix supplemented with press cake and cottonseed meal at rates of 0.0, 2.5, 5.0 and 10.0 % (w/w). Both of the amendments had only minor effects on the physical properties (bulk density, total porosity percentage, total solids percentage, pH, EC) of the potting mixes with increasing rates, although there was substantially less shrinkage of media amended with 5 and 10% press cake than with the same rates of cottonseed meal. At rates of 10.0% for press cake and 5.0% for cottonseed meal (which supplied similar substrate nitrogen levels), plant heights, total tomato yield per plant and number of fruit per plant were equal to that of the chemically-fertilized control. There were no differences among treatments for average fruit weight. Chlorophyll content was generally similar among the treatments during the course of the experiments, with a trend towards lower values for the 2.5% rates of press cake and cottonseed meal near the conclusion of the experiments. From these results, it appears that lesquerella press cake may be a useful organic fertilizer for container-grown tomatoes.