Source: LINCOLN UNIVERSITY submitted to
SOILLESS SUBSTRATE EVALUATION AND NUTRIENT MANAGEMENT IN SUSTAINABLE SMALL-SCALE HYDROPONIC PRODUCTION FOR LIMITED RESOURCE GROWERS IN MISSOURI
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0220457
Grant No.
(N/A)
Project No.
MOX-HYDROPONICS-5
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2009
Project End Date
Sep 30, 2013
Grant Year
(N/A)
Project Director
Egilla, JO.
Recipient Organization
LINCOLN UNIVERSITY
(N/A)
JEFFERSON CITY,MO 65101
Performing Department
Agriculture
Non Technical Summary
PROJECT RATIONALE: Environmental concern and increased scrutiny of non-point sources of pollution, has forced the agronomic and horticultural industries to reconsider fertilization and irrigation practices. The small-scale hydroponic industry in Missouri and the NCR require different approaches to best management practice (BMP) development to ensure its viability through sustainable methods of food and flower crops production. The formulation and use of plant mineral nutrients are interrelated and complex, and pose the greatest challenge to the small-scale hydroponic growers. Currently, information about nutrient management in hydroponic production systems is limited. Low yield, poor quality crop, high water and reagent costs, and factors that limit the success of a hydroponic production is often linked to improper nutrient formulations, and the mismanagement of the nutrient solution. Better plant nutrient management involve the selection of appropriate fertilizer formulations for specific crops and crop types, and the supply of optimum rather than excess or deficient nutrient concentrations in hydroponic culture systems. Continuous discharge of nutrient solution leachates from non-nutrient recirculating hydroponic systems may exceed the requirement of nearby crops or grassland even where such nutrients are recycled to field crop. Similarly, repeated dumping of nutrient rich fertilizer solutions from recirculating NFT hydroponic systems on such sites can subsequently overwhelm the capacity of the microecosystem to assimilate the nutrients. Long-term enrichment of surface and groundwater with NO3- and P can contribute to environmental contamination with negative impacts on species diversity and survival in habitats near hydroponic operations. A great deal of the nutrient management strategies developed for extensive field vegetable production systems have limited practical application in hydroponic systems because they do not account for the dynamic relationship between plant nutrient uptake and assimilation in the controlled growing environment of greenhouses. The present research project will examine novel strategies for more precise nutrient management designed for cost effective technologies accessible to small-scale limited resource growers. OUTCOMES/IMPACT: 1) Small-scale limited resource hydroponic growers will be educated on site-specific nutrient management techniques that improve the productivity of their hydroponic production system in an environmentally friendly manner (reduced nutrient losses, increased market quality yield and total output). 2) Cost saving from reduced inorganic fertilizer input, and higher yield of market quality produce will increase profitability and the incomes of small-scale hydroponic producers. 3) Research Technicians and LU students will continue to acquire research skills in hydroponic production, plant biology and environmental stewardship. 4) The hydroponic research program will continue to showcase environmentally sustainable methods of food production to K-12 and Community College students in Missouri.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2051430102040%
2051440102030%
2051461102010%
2051499102020%
Goals / Objectives
GOALS: The goal of this project is to develop specific cultural practices with practical application in managing plant mineral nutrition in small-scale hydroponic production of herbs and vegetables for limited resource growers in Missouri. The goal is to sustain the high yield and quality potential of hydroponic culture of crop plants, while minimizing its negative impact on the environment. Specifically, we will develop methodologies that significantly reduce the enrichment of surface water resources, and drainage systems to ground water from run-off and discharge of excess plant mineral nutrients (fertilizer) from hydroponic production greenhouses. OBJECTIVES: The objectives of this project are: 1)Evaluate selected organic and inorganic soilless substrates for increased yield of vegetables and herbs (Pepper, Tomato, Collards, Kale, Swiss chard, Mustard, Kohl-rabbi and Basil), and plant nutrient use-efficiency in non-nutrient recirculating/ "aggregate" hydroponic system. 2)Calibrate chlorophyll measurements to predict optimal nitrogen concentration in recirculating nutrient solution for the culture of the selected vegetables and herbs above in NFT hydroponic system with either the CM 1000 or the SPAD-502 Chlorophyll meter (SCM). OUTPUT: The database developed from this research allows the establishment of guidelines to improve nutrient use-efficiency, and mineral nutrient management in both nutrient recirculating and non-recirculating commercial hydroponic systems.
Project Methods
RESEARCH METHODS: The following approach will be adopted to achieve the above objectives. In the first study with open (non-recirculating) hydroponic system, soilless hydroponic substrates from both organic and inorganic sources will be evaluated for their 1) mineral nutrient retention capacity, and 2) ability to facilitate nutrient uptake by plant roots, while reducing the amount of mineral nutrients loss from the flow-through nutrient solution. Plant tissue mineral nutrient concentration and marketable yield of vegetables and herbs grown with selected soilless substrates will be compared to determine the most effective substrate for achieving the goal of high productivity and minimum environmental contamination. The selected organic substrates to be evaluated include (Coconut fiber [Coco coir], Sphagnum moss, Peat moss, Composted pinebark and Fafard Organic Mix), and inorganic soilless substrates (Rockwool, Perlite + Vermiculite mix, Expanded Clay). Selected vegetables and herbs for this study will include (Pepper, Tomato, Collards, Kale, Swiss chard, Mustard, Kohl-rabbi and Basil), and plant nutrient use-efficiency in non-nutrient recirculating/ "aggregate" hydroponic system. The second study with Nutrient Film Technique (NFT) hydroponic system will calibrate chlorophyll measurements to predict optimal nitrogen concentration in recirculating nutrient solution for the culture of the vegetables and herbs with either the CM 1000 or the SPAD-502 Chlorophyll meter (SCM). DATA ANALYSIS: "PROC UNIVARIATE" in SAS will be employed to compute the probability that the response variables (leachate N, P and K concentration, leaf nutrient content and crop yield) are distributed normally. Equality of the variances will be determined by Welch's test for variance-homogeneity, and differences between treatments by analysis of variance (ANOVA), using the General Linear Model [GLM]) in SAS (SAS Institute Inc., 2003). Means will be separated by Tukey's Studentized Range (HSD) Test. These data will be used to assess the potential for 1) significant savings in fertilizer input cost to small-scale hydroponic production enterprises, and 2) considerable reduction in nitrate (NO3-) and phosphorus (P) losses into drainage systems and surface water resources. Expected project outcome from the data analysis is increased productivity as well as long-term viability and sustainability of the small-scale hydroponic industry in Missouri, and the North Central Region of the U.S. PROJECT EVALUATION: Stakeholder input and peer review will be sort at the beginning and during the conduct of the various experiments listed under objectives 1 to 2. A project evaluation advisory committee will be formed. The advisory committee members will include faculty from University of Missouri, Lincoln University-Small Farm Program, and Cooperative Extension faculty, Missouri Department of Agriculture staff, and a Regional USDA/ARS Scientist, as well as hydroponic growers.

Progress 10/01/09 to 09/30/13

Outputs
Target Audience: Targeted audiences include: (1) limited resource small-scale hydroponic industry, (2) greenhouse producers of vegetables, herbs and species for local farmers markets, grocery stores and restaurants, (3) hydroponics and aquaponics producers of vegetables, herbs and spices, (4) amateur horticulturists, part-time farmers and persons with interest in hydroponic food or flower crop production enterprises, (5) master gardeners, agricultural extension specialists and trainers, (6) K-12 and community college students and teachers, (7) undergraduate and graduate students in missouri and midwester U.S. Changes/Problems: Project Modifications in October 2011 Objectives: 1.1. Evaluate selected organic and inorganic soilless substrates for increased productivity, and plant nutrient use-efficiency in an open (non-recirculating) “aggregate” hydroponic system. Modification: Evaluate selected inorganic soilless seed propagation substrates for increased productivity, and plant nutrient use-efficiency in recirculating hydroponic systems. 1.2. Assess the effects of the soilless substrates in objective 1.1, on plant mineral nutrient uptake, and yield of selected vegetable crops in an “aggregate” (Dutch pot) hydroponic system. Modification: Assess the effects of the soilless substrates in objective 1.1, on plant mineral nutrient uptake, and yield of selected vegetable crops in non-recirculating Nutrient Film Technique (NFT) hydroponic system. Reason for modifications to 1.1 and 1.2.: The non-recirculating (Dutch pot) Fertilizer Feeder system was not purchased/ installed. 1.3. Compare plant mineral nutrient uptake and market yield of selected vegetable crops in “aggregate” (Dutch pot) versus liquid (NFT) hydroponic systems. Modification: Dropped. Reason: The non-recirculating (Dutch pot) Fertilizer Feeder system was not purchased/ installed. 2.0. Develop science-based protocols for efficient and cost effective nutrient management in commercial NFT, and “aggregate” (Dutch pot) hydroponic system. Modification: Develop science-based protocols for efficient and cost effective nutrient management in commercial NFT hydroponic system. 3.0. Compare the operating cost of a double-layered polycarbonate glazed greenhouse with that of a double-walled polyethylene glazed greenhouse. Modification: Dropped. Reason: The double-layer polyethylene glazing of the second greenhouse was replaced with polycarbonate glazing. What opportunities for training and professional development has the project provided? One Research Technician with Lincoln University Cooperative Research Programs Department received professional development training by attaining greater proficiency in commercial hydroponic technology research through direct one-on-one work with the project director. Training involved (1) experimental design, data collection and experimental crops management through daily recording of nutrient solution chemistry (pH, EC, nitrate and potassium concentration) with portable meters, as well as water loss through evapotranspiration, and implementing the required adjustments. (2) experimental crop harvesting procedure, processing of plant tissue after harvesting, and preparation for laboratory analysis to determine elemental content. Over the duration of this project, four Lincoln University students on work-study were similarly trained in various aspects of hydroponics production, greenhouse research methods, and data collection. This training improves the students’ knowledge of agriculture, biology and environmental science, while assisting research in the hydroponic project. How have the results been disseminated to communities of interest? Outputs from this project were shared with stakeholders (hydroponics and aquaponics farmers, master gardeners) during multiple onsite tour presentations, horticulture/aquaculture extension specialists, Missouri Department of Agriculture extension aquaculture trainer, amateur horticulturists and hobbyists in Missouri and the Midwestern U.S. Annual onsite presentations and tours were conducted for over 200 K-12 school students from neighboring schools in Cole County, Missouri during the summers of 2011 to 2013 to educate them about controlled environment agriculture technology, energy and water conservation, nutrient management and environmental stewardship. One workshop presentation by the project director to aquaponics and aquaculture farmers at the 2013 annual meeting of the Missouri Aquaculture Association. In addition, findings from this project were disseminated through four abstracted presentations at national annual conferences of the American Society of Horticulture [ASHS] in 2010 (Palm Desert, California), 2011 (Waikoloa, Hawaii), 2012 (Miami, Florida), 2013 (Palm Desert, California), as well as two Association of Research Directors (ARD) symposia in 2011 (Atlanta, Georgia), 2013 (Jacksonville, Florida). Manuscripts are being prepared and/or reviewed for submission to the journals HortTechnology, HortScience, Journal of Plant Nutrition, Plant & Soil. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The goals and objectives stated above were modified in the revised project of October 2011, because equipment required to accomplish objectives 1 and 2 were not installed by the supporting institution (see project revision, October, 2011). Accomplishments under the revised project are listed below. (1) Protocols were developed to assess the efficiency of two approaches to nutrient management in commercial NFT hydroponic system. The two approaches to nutrient solution management (SMGMT; (nutrient solution renewal [RNWL], and nutrient solution replenishment [RPLN]) were evaluated for their effect on marketable and biological yield of the test crops. (2) Experiments were completed to assess the (a) marketable yield response of selected vegetable crops to two most commonly used seed propagation substrates (SBSTR; slabs of rockwool and Oasis™ cubes seed propagation substrates); and (b) hydroponic nutrient solution concentration (NCONC) effects on the uptake of plant elements, and yield of selected vegetable crops in commercial NFT hydroponic culture. Two concentrations of Steiner’s nutrient solution (full- and half strength), and two commercial fertilizer formulations were examined. The leafy-green vegetables used as model crops in the experiments were (1) Arugula (Eruca vesicaria var sativa ‘Astro’); (2) collards (Brassica oleracea ‘Champion’); (3) four cultivars of lettuce (Lactuca sativa cvs. Paris Island Cos, Black Seeded Simpson, Concept, Nevada), and (4) Swiss chard (Beta vulgaris L. ‘Lucullus’).

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Egilla, J. N., R. Ogutu and I. Nyirakabibi. 2013. Tissue Elemental Content and Growth Response of Lettuce to Hydroponic Solution Concentration Varied with Cultivar. HortScience 48(9):S315. (Abstr.) Jonathan Egilla, Rose Ogutu and Isabelle Nyirakabibi. 2013. Comparative leaf growth and yield response of collards to nutrient solution withholding or concentration increase during NFT hydroponic culture. Program Abstr. #566, p. 251). 17th Biennial Research Symposium of the ARD, Jacksonville, Florida, April 6-10, 2013. Egilla, J. N., R. Ogutu and I. Nyirakabibi. 2012. Mineral Nutritional Status and Yield of Swiss chard in Hydroponic Culture as Influenced by Nutrient Solution Management and Seed Propagation Substrate. HortScience 47 (9): S138. (Abstr.) Egilla, J. N., R. Ogutu, and I. Nyirakabibi. 2011. Nutrient Solution Concentration, Management, and Propagation Substrate Affects the Yield of Swiss chard in Hydroponic Culture. (Program Abstr. #O-SP-S-6, p.148). 16th Biennial Research Symposium of the ARD, Atlanta, Georgia, April 9-13, 2011.


Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Despite recent advances in hydroponic technology, information about best approaches to the management of nutrient solution during crop culture is limited. Various methods have been recommended for the control and maintenance of nutrient concentration in re-circulating hydroponic culture for optimum plant growth and quality. All approaches have advantages and disadvantages. (a) Monitoring/measuring the concentration of individual ions in the nutrient solution. With this method, some nutrient ions are rapidly depleted, causing growers to add toxic amounts of nutrients to the solution. Excessive uptake of individual mineral ions can lead to nutrient imbalances and plant growth disorders. Furthermore, determining which elements accumulate or are depleted requires the time consuming and expensive process of laboratory plant analysis. (b) Managing nutrients by mass balance where nutrients are added to the solution depending upon what the plant is required to take up. Commercial application of the mass balance approach requires staff training or automation, which are less affordable options in the small-scale hydroponic production industry. (c) Measurement of electrical conductivity (EC), which estimates total ion concentration in the nutrient solution, but provides no direct information about individual ions. (d) Nutrient solution renewal (RNWL): complete replacement or the original nutrient solution, is adopted as a safeguard against nutrient disorders. The frequency of renewal depends upon the season or growing environment, crop type and stage of growth. Outputs: The effect of two approaches to nutrient solution management (SMGMT) and seed propagation substrate (SBSTR) on leaf mineral nutrient content and yield of Swiss chard (Beta vulgaris L. cv. Lucullus), were evaluated in a commercial standard nutrient film technique (NFT) hydroponic system. Fifteen-day old seedlings were transferred into NFT culture, and grown with a soluble fertilizer solution (15N-2.2P-12K, plus micronutrients) at 200 mg N per liter. The treatments comprised of the two SMGMTs: nutrient replenishment (RPLN) and RNWL, and two seed propagation substrates (Oasis or Rockwool cubes). Nutrient replenishment involves maintenance of the original nutrient solution at constant EC by adding fresh nutrient solution or water when making-up for evapotranspiration. Mean pH and EC (mS/cm) of the re-circulating nutrient solution during the cropping cycle were respectively, 6.2 and 1.78. Mean day/night ambient temperature and relative humidity were 24/9 Celsius and 81/41%, respectively. With RNWL, the original nutrient solution was replaced completely at 41 days after transfer (DAT) into NFT culture, and all treatments were maintained for 20 more days until plant leaves attained market maturity. PARTICIPANTS: The participants on the research project are: the Principal Investigator (Dr. Jonathan Egilla), one Research Technician (Isabelle Nyirakabibi), and two undergraduate Student Research Assistants (SRA's). Isabelle received training on setting-up of experiments, data collection, and use of plant physiology instrumentation in commercial hydroponic research, as well as training and supervision of the SRA's in various aspects of hydroponic research and horticulture practices. TARGET AUDIENCES: Targeted audiences include: (1) the general public, (2) greenhouse producers of vegetables, herbs and spices for local farmers markets, grocery stores and restaurants, (3) professional hydroponic and aquaponics producers of vegetables, herbs and spices, (4) part-time farmers and persons interested in hydroponic food or flower crop production enterprises, (5) Master Gardeners, Agricultural Extension Specialists and Trainers, (6) K-12 and Community College Students and Teachers, undergraduate and graduate students of universities in Missouri. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Outcomes: Laboratory leaf analysis at 61-DAT indicates significant (p=0.05) SMGMT x SBSTR interaction for leaf nitrogen (N) and manganese (Mn), indicating that the effect of SMGMT on leaf N and Mn varied with SBSTR. With RNWL, leaf N was higher in Rockwool than Oasis cubes, whereas with RPLN, N was highest in Oasis (p≤0.05). Except for N (Rockwool > Oasis, p≤0.05), SBSTR had no effect on the leaf content of the other macronutrients with the RNWL method. Compared with Oasis, Rockwool increased leaf phosphorus (P), calcium (Ca) and magnesium (Mg) with RPLN (p≤0.05), but not potassium (K) and sulfur (S). Of the micronutrients leaf iron (Fe) content was higher (p≤0.05) in Rockwool than Oasis with RNWL, but no other micronutrient was affected. With RPLN, Rockwool increased (p≤0.02) the leaf content of all micronutrients over Oasis cube, except for copper (Cu) and molybdenum (Mo). Leaf growth and marketable yield at 61-DAT were closely related to mineral nutrient content. There was significant (p=0.05) SMGMT x SBSTR interaction for leaf fresh- and dry weight (LFW, LDW [g]), but not leaf count (LC) and leaf area (LA [sq. cm]) per plant. However, within SMGMT LC, LFW, LDW and LA were higher in Rockwool than Oasis cube (p≤0.01). These observations indicates that the combination of nutrient solution renewal with Rockwool substrate, provided a better growing condition for optimum mineral nutrition and yield of Swiss chard in NFT hydroponic culture. The positive response of leaf yield to Rockwool is attributed in part to greater mineral nutrient retention in Rockwool, which resulted in enhanced seedling growth during establishment, and later in the cropping cycle than observed in Oasis cube. Impact: These findings contribute to the understanding of nutrient management and substrate selection in nutrient re-circulating hydroponic systems. The information represents a valuable guide to hydroponic vegetable growers in their choice of root support substrate, and nutrient management regime.

Publications

  • Jonathan N. Egilla. 2012. Yield and leaf elemental concentration of beetroot in response to nutrient solution composition in hydroponic culture. J. Plant Nutr. 35:203-214.
  • Egilla, J. N. R. Ogutu and I. Nyirakabibi 2011. Mineral nutrient stress altered growth and yield of collard leaves in NFT hydroponic culture. HortScience 46(9):S328. (Abstr.)


Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: In order to develop an efficient and cost effective nutrient management program in hydroponic production knowledge of nutrient solution concentration and root substrate are essential. Variable and low yield output, poor quality crop, high fertilizer/reagent costs, and a great deal of factors that limit the success of hydroponic production are often linked to improper nutrient formulations, root substrate selection and poor nutrient solution management during crop culture. Small-scale hydroponic growers commonly utilize soluble commercial fertilizers having variable nutrient composition for crop production. Currently, there is limited research information about appropriate nutrient solution concentrations and their interactions with various cultural practices on crop yield in commercial hydroponic culture. Consistent with one of the objectives of this project, an experiment was conducted to evaluate the influence of nutrient solution concentration and propagation substrate on the growth and yield of Swiss chard in recirculating hydroponic culture. The influence of nutrient solution concentration (NCONC), and propagation substrate (SBSTR) on the growth, and marketable leaf yield of Swiss chard (Beta vulgaris L. cv. Lucullus), were evaluated in a commercial Nutrient Film Technique (NFT) hydroponic system. Two-week old seedlings of Swiss chard cv. Lucullus were transferred into a commercial NFT hydroponic system under controlled environment greenhouse conditions at the second true-leaf stage. The treatments comprised of two propagation substrates (Oasis or Rockwool cubes), and two concentrations of a soluble fertilizer (15N-2.2P-12.5K plus micronutrients), prepared at 150 and 200 mg N/L (C1 and C2, respectively). Mean pH and electrical conductivity (EC; mS/cm) of the circulating nutrient solution during the cropping cycle were respectively, 6.2, and 1.78. Mean max/min ambient temperature and relative humidity (RH) were 24/9 degrees Celsius and 81/41%, respectively. The nutrient solution was renewed at 42 days after transfer (DAT) of seedlings into NFT culture. At 63 DAT, mean per plant leaf count (LC), leaf fresh weight (LFW), leaf dry weight (LDW) and leaf area (LA) were determined. PARTICIPANTS: The participants on the research project at the time of this experiment are: Dr. Jonathan Egilla, (Horticulturist, Principal Investigator), Dr. Rose Ogutu (Horticulturist, Post-doctoral Research Associate), and Isabelle Nyirakabibi (Research Technician). Dr. Rose Ogutu received training on research methods in commercial hydroponic production, and supervision of undergraduate Student Research Assistants. Isabelle Nyirakabibi received training on setting-up of experiments, data collection, use of plant physiology instrumentation in commercial hydroponic research, and supervision of undergraduate Student Research Assistants (SRA's). TARGET AUDIENCES: The targeted audiences include (1) the general public and consumers of hydroponic vegetable crops. (2) Greenhouse producers of vegetables, herbs and spices for local Farmers Markets, grocery stores and restaurants. (3) Manufacturers of Greenhouses and hydroponic equipment, tools and fertilizers. (4) Aquaponic farmers. (5) Part-time farmers and persons interested in food or flower crop production enterprises under protected structures. (6) Master Gardeners, Agricultural Extension Specialists and Trainers. (7) K-12 and Community College Students and Teachers, undergraduate and graduate students of universities in Missouri and Mid-western United States. PROJECT MODIFICATIONS: Project Objectives: 1.0. Evaluate selected organic and inorganic soilless substrates for increased productivity, and plant nutrient use-efficiency in an open (non-recirculating) aggregate hydroponic system. Modification: Evaluate selected inorganic soilless substrates for increased productivity, and plant nutrient use-efficiency in recirculating hydroponic systems. Reason for modification: (1) The anticipated modification to the non-recirculating (Dutch pot) system is yet to be completed. (2) The anticipated installation of a Fertilizer Feeder System has not yet been implemented.

Impacts
At 63 DAT, mean per plant LC, LFW, LDW and LA were significantly (p&#8804;0.01) higher at C2 compared with C1 in Oasis cubes. However, in Rockwool only LFW was significantly (p<0.05) increased at C2. Mean per plant LC, LFW, LDW and LA across SBSTR were respectively, 14%, 64%, 46%, and 54% higher at C2 than C1. Similarly, LFW, LDW and LA were significantly (p&#8804;0.05) higher in Rockwool, regardless of CONC. However, LC was not affected by SBSTR, and NCOC x SBSTR interaction was non-significant (p=0.05). Mean LC, LFW, LDW and LA across NCONC were respectively, 10%, 52%, 54%, and 31% higher in Rockwool than Oasis cubes. These observations suggests that Rockwool substrate provided a better root environment for optimum yield of Swiss chard in NFT culture at both nutrient solution concentrations under the conditions of this experiment. IMPACT: This study demonstrated differences in the yield response of Swiss chard to propagation substrate and nutrient solution concentration during a cropping cycle in Nutrient Film Technique hydroponic system. These findings provides valuable and feasible guide to the small-scale hydroponic grower on decisions regarding the most appropriate propagation substrate and nutrient solution levels for larger leaf vegetable crops like Swiss chard. Optimum crop yield and crop quality are essential for improved profitability in hydroponic production. Over 100 visitors including two prospective hydroponic growers, extension educators and students visited the controlled environment research greenhouses during this period.

Publications

  • Jonathan N. Egilla and Abua Ikem. 2011. Influence of Nutrient Source and Growing Environment on Tissue Elemental Concentration and Yield of Cos Lettuce in Hydroponic Culture. International J. Veg. Science. 17(1): 83-100.


Progress 10/01/09 to 09/30/10

Outputs
OUTPUTS: Low yield, poor quality crop, high water/reagent costs, and a great deal of factors that limit the success of hydroponic production are often linked to improper nutrient formulations, and management of the nutrient solution during crop culture. Within the small-scale hydroponic industry, methods of nutrient solution management (SMGMT) in circulating hydroponic culture are variable. Currently, research information about the effect of different SMGMT methods and their interactions with plant culture techniques on crop yield is limited. In Nutrient Film Technique (NFT) experiments the seed propagation medium (root substrate) provides root support for the crop plant until harvest. The role of propagation substrate SBSTR on the marketable yield of leafy vegetable crops in hydroponic culture is not well understood. An experiment was conducted to determine the yield response of Swiss chard to two commonly used propagation substrates (Rockwool and Oasis cubes), and two methods of SMGMT (nutrient solution renewal [RNWL] and nutrient solution replenishment [RPLN]). Seedlings of Swiss chard (Beta vulgaris L. cv. Lucullus) at the second true-leaf stage were grown in a commercial NFT hydroponic system until harvest, under controlled environment greenhouse conditions. Mean max/min ambient temperature and relative humidity (RH) were 24/9 oC and 81/41%, respectively. The nutrient solution was either renewed or replenished at 42 days after transfer (DAT) into NFT culture. The crop was grown with a soluble fertilizer (15N-2.2P-12.5K, plus micronutrients); prepared at 200 mg nitrogen (N)/L. Mean pH and EC (mS/cm) of the circulating nutrient solution during the cropping cycle were respectively, 6.2, 1.78 with nutrient RNWL, and 6.4, 1.70 with RPLN. At 63 DAT, mean per plant leaf count (LC), leaf fresh weight (LFW), leaf dry weight (LDW) and leaf area (LA) were determined. PARTICIPANTS: Principal Investigator (Jonathan Egilla), one Post-doctoral Research Associate (Rose Ogutu), one Research Technician (Isabelle Nyirakabibi) and four undergraduate students of Lincoln University of Missouri continue to receive training on hydroponic crop production research methods and plant nutrient management. TARGET AUDIENCES: The targeted audiences include 1) The general public 2) Greenhouse producers of vegetables, herbs and spices for local Farmers Markets, grocery stores and restaurants. 3) Professional hydroponic and aquaponic producers, 4) Hobbyists, part-time farmers and persons interested in food or flower crop production enterprises, Master Gardeners, Agricultural Extension Specialists and Trainers, K-12 and Community College Students and Teachers, undergraduate and graduate students of universities in Missouri. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Nutrient solution management significantly (p &#8804; 0.002) affected mean per plant LC, LFW, LDW and LA. Across SBSTR these growth components were 18%, 82%, 45% and 48% higher with RNWL than RPLN. Similarly, across SMGMT, all four components of leaf yield were significantly (p < 0.05) increased in Rockwool compared with Oasis cube. There was no significant SMGMT x SBSTR interaction for LC, LFW, LDW or LA (p = 0.05). Within SMGMT, only LFW and LA were significantly (p = 0.05) increased by nutrient renewal, LC and LDW were not affected. With nutrient replenishment, all four components of leaf yield were increased in Rockwool compared with Oasis cube. These observations suggest that nutrient solution renewal and Rockwool substrate provided better growing conditions for improved yield of Swiss chard, and that similar yields can be obtained under comparable environmental and culture conditions. About 50 visitors including hydroponic growers, extension educators and students visited the controlled environment greenhouses during this period. IMPACT: This study demonstrated differences in the yield response of Swiss chard to propagation substrate and nutrient management during a cropping cycle in Nutrient Film Technique hydroponic system. These findings provide a valuable guide to the small-scale hydroponic grower when deciding on the most appropriate propagation substrate and nutrient solution management method for leaf vegetable crops like Swiss chard. Optimum crop yield and crop quality are essential for improved profitability in hydroponic production.

Publications

  • Jonathan Egilla and Rose Ogutu. 2010. Yield response of Swiss chard to nutrient solution management and propagation substrate in nutrient recirculating hydroponic culture. Abstr. No. 275, 107th Annual International Conference of the American Society for Horticultural Science. Desert Palm, CA. August 2-5, 2010. Supplement to HortScience 48 (8): 248.
  • Jonathan Egilla, Rose Ogutu and Isabelle Nyirakabibi. 2010. Influence of nutrient solution concentration and propagation substrate on the growth and yield of Swiss chard in recirculating hydroponic culture. Abstr. No. 170, 107th Annual International Conference of the American Society for Horticultural Science. Desert Palm, CA. August 2-5, 2010. Supplement to HortScience 48 (8): 165.