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Evaluating vermicompost and rendered meat products as local media components in vegetable seedling production

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Item Summary

Title: Evaluating vermicompost and rendered meat products as local media components in vegetable seedling production
Authors: Gurr, Ian Bernard
Keywords: Vermicompost
Issue Date: Dec 2011
Publisher: [Honolulu] : [University of Hawaii at Manoa], [December 2011]
Abstract: Vermicompost, coconut coir, and thermophilic compost based growing media, with and without amendment with tankage were evaluated as alternatives to peat for organic vegetable transplant production. Treatments evaluated over the course of 4 greenhouse and 1 field trial using eggplant (Solanum melongena var. esculentum) 'Purple Long' and pak choi (Brassica rapa var. chinensis) 'Bonsai' seedlings were: peat:perlite (9:1 v/v) = (P); P amended with 0.7 grams CaCO₃ per liter of medium = (PAM); coconut coir = (C); thermophilic compost = (TC); vermicompost = (VC); P, PAM, C with weekly applications of soluble N-P-K (19-19-19) synthetic fertilizer = (PS), (PAMS), (CS); P:VC, PAM:VC, C:VC, TC:VC at rates of (75:25, 50:50 and 25:75 v/v); P, PAM, C, TC, P:TC (50:50 v/v), TC:VC (50:50 v/v) amended with tankage at rates of 5, 10, 12, 15, 20, 25 grams per liter of medium; P with weekly applications of soluble organic fertilizer comprised of fish emulsion N-P-K (5-1-1) and seaweed extract N-P-K (0.10-0.10-1.5) = (PO). The physical and chemical properties of media were determined and the effect of treatment on seedling shoot tissue nutrient content and seedling shoot growth were evaluated. A field trial was conducted to determine if the media used in greenhouse pak choi seedling production affected crop yield.
The total pore space, water holding capacity and air-filled porosity of the peat and vermicompost used in our study were not significantly different from each other. The pH, EC, nutrient content and C/N ratio of vermicompost was more ideal for seedling growth that that of peat and amendment of peat with vermicompost improved growing media chemical properties. Amending peat, coconut coir and thermophilic compost with vermicompost increased seedling shoot tissue nitrogen content and seedling shoot dry weight, with the greatest shoot dry weights obtained from 100 % vermicompost. Media amendment with tankage up to a rate of 15 g/l of medium also increased 6 week old eggplant seedling shoot tissue nitrogen content and shoot dry weight. Amendment with tankage at 20 and 25 g/l of medium resulted in excessive tissue nitrogen content of 6 week old eggplant seedling and a decrease in shoot dry weight. The effect of transplant seedling quality (tissue nutrient content and shoot dry weight) on crop yield was evaluated in a field trial of pak choi. All treatments received identical field fertilization of 'Sustane ®' N-P-K (4-6-4) turkey manure based organic fertilizer (Sustane Natural Fertilizers, Inc., Cannon Falls, Minnesota) at the rate of 1250 lbs fertilizer/acre or 50 lbs N/acre. At harvest, mature plants in all treatments had shoot tissue macro-and micronutrients contents that were not significantly different from each other, and plant tissue nitrogen, phosphorus and potassium contents for all treatments were within or above sufficiency ranges, yet mature plants from seedlings produced in media amended with vermicompost or with tankage up to rates of 15 g/l of medium, had significantly greater shoot dry weights than plants from seedlings produced in unamended peat.
Vermicompost, along with coconut coir and thermophilic composts are growing media which should be better utilized as alternatives to peat. They are more sustainably produced, and often locally available. Use of up to 100 % vermicompost as a substitute for peat, or the amendment of peat, coconut coir or thermophilic compost based growing media with tankage at rates between 8 and 16 grams/liter of medium can improve seedling tissue nutrient content, seedling shoot dry weight, and crop yield.
At present, there are limitations to the use of these growing media and amendments. In many areas, vermicompost is produced in limited amounts and is relatively expensive compared to peat and other growing media. In Hawaiʻi, thermophilic compost and tankage are both locally produced from the waste products of other industies and are relatively inexpensive as sources of growing medium and nutrients, but thermophilic composts can vary in physical, chemical and biological properties, depending upon feedstock, source and even from batch to batch. Tankage quality and consistency can also vary from batch to batch depending upon feedstock. Also, much of the nitrogen contained in tankage is in organic form and plant availability will depend upon nitrogen mineralization rates which are dependant upon media microbial population, C/N ratio, moisture content and temperature.
Research investigating thermophilic compost maturity and tankage nitrogen mineralization rates and nitrate and ammonium content changes are needed if these locally produced materials are to be better utilized in producing quality vegetable seedling media.
Description: M.S. University of Hawaii at Manoa 2011.
Includes bibliographical references.
Appears in Collections:M.S. - Tropical Plant and Soil Sciences

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