THE POTENTIAL OF GOAT MANURE AS A HYDROPONIC NUTRIENT ALTERNATIVE FOR TOMATO PRODUCTION IN NAMIBIA A DISSERTATION SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN AGRICULTURE (CROP SCIENCE) OF THE UNIVERSITY OF NAMIBIA BY EDGAR MOWA (200134728) APRIL 2018 Main supervisor: Professor Levi Shadeya-Mudogo Akundabweni (University of Namibia) Co-supervisors: Professor Percy Chimwamurombe (Namibia University of Science & Technology) Dr. Effiom Oku (United Nations University, Ghana) ABSTRACT Hydroponics is a cultivation method of growing plants in water. It is a technology suitable for farming that is under artificially controlled environments but can be adapted to situations where land is a constraint. In Namibia this is a potential method for vegetable cultivation. Hydroponics vegetable production has been demonstrated successfully using a balanced conventional nutrient solution, globally, and therefore, an evaluation of its suitability in Namibia using goat manure solution as a source of organic hydroponic nutrients. An alternative hydroponics nutrient solution has been sought after but often failed due to nitrogen in organic sources being predominantly organic, a form plants cannot access. The study had two stages, the first being a laboratory experiment aimed at formulating a Goat Manure Derived Hydroponic Nutrient Solution (GMDHNS). This involved the determination of source of microorganisms, concentration of microorganisms and amount of goat manure for optimal generation of nitrates from goat manure. Variables measured included nitrate levels generated and levels of other nutrients. The second stage was a field experiment which tested the GMDHNS effect on tomato performance and quality. Variables measured included, plant height, stem diameter, nutrient use efficiency, plant biomass, number of flowers, number of fruits, yield, total soluble solids, and lycopene content. Commercial Hydroponic Nutrient Solution and tap water were used as controls. Locally sourced microorganisms significantly (P< 0.05) transformed organic nitrogen in goat manure into plant available nitrates reaching levels of 198mg/L hence was the basis of the organic hydroponic nutrient solution. Tomato vegetative growth (height, stem diameter and leaves) were significantly (P< 0.05) improved by the formulated GMDHNS compared to growing tomatoes in Tap Water (TW) where no fertiliser was added and that GMDHNS was comparable to using Commercial Hydroponic Nutrient Solution (CHNS) in terms of plant growth. Plant reproduction (flower and fruits) were also significantly (P< 0.05) influenced by the formulated GMDHNS more than by the TW treatment even though yield from GMDHNS was less than that from the CHNS. The quality (lycopene, Total Soluble Solids, fruit size and weight) of fruits produced from plants in the GMDHNS was significantly (P< 0.05) more than that in fruits from the CHNS. Thus, based on the results from this study, it can be concluded that a hydroponic nutrient solution can be formulated from goat manure. Furthermore, it can i be concluded that the locally formulated hydroponic nutrient solution enhances quality, growth and reproductive performance of tomato, even though it may still need further optimization. Follow-up studies to the present study should be done to further optimise GMDHNS and that artefactual should also follow for practical uptake of these findings. PUBLICATIONS 1. Mowa, E., Akundabweni, L., Chimwamurombe, P., Oku, E., & Mupambwa, H. A. (2017). The influence of organic manure formulated from goat manure on growth and yield of tomato (Lycopersicum esculentum). African Journal of Agricultural Research, 12 (41), 3061-3067. 2. Mowa, E., Akundabweni, L., Chimwamurombe, P., & Liswaniso, G. (2018). Analysis of nitrifying microbial community for organic hydroponics. African Journal of Agricultural Research, 12 (1), 1-8. 3. Mowa, E., Akundabweni, L., Chimwamurombe, P., Oku, E. IN PRESS. Formulation of an organic hydroponic nutrient solution using nitrifying microorganisms. International Science & Technology Journal of Namibia. ii TABLE OF CONTENTS ABSTRACT .................................................................................................................. i PUBLICATIONS ......................................................................................................... ii TABLE OF CONTENTS ............................................................................................ iii LIST OF FIGURES ................................................................................................... vii LIST OF TABLES ...................................................................................................... ix ACKNOWLEDGEMENTS ....................................................................................... xii DEDICATIONS ........................................................................................................ xiv DECLARATIONS ..................................................................................................... xv CHAPTER 1: INTRODUCTION ................................................................................ 1 1.1 Rationale for organic hydroponic nutrient solution formulation and efficacy on tomato crop.......................................................................................................... 1 1.2 Research Hypotheses ..................................................................................... 3 1.3 Objectives ...................................................................................................... 3 1.4 Significance ................................................................................................... 4 1.5 Limitations of the study ................................................................................. 4 1.6 Conceptual framework to this study .............................................................. 5 REFERENCES ......................................................................................................... 9 CHAPTER 2: LITERATURE REVIEW ................................................................... 11 2.1 Review of farming systems .............................................................................. 11 2.2 Review of hydroponics and plant performance ............................................... 13 2.2.1 Definition and uses .................................................................................... 13 2.2.2 Applications and effects of hydroponics in vegetable cultivation ............ 13 2.2.3 Nutrient use efficiency and plant biomass ................................................ 19 2.3 Review of hydroponic nutrient solution formulations ..................................... 23 2.3.1 Nutrient solution formulation .................................................................... 23 2.3.2 Nitrifying microorganisms ........................................................................ 26 2.3.3 Goat manure as source of plant required nutrients ................................... 29 2.4 Review of organic vegetable quality ................................................................ 33 2.5 Review of the tomato plant .............................................................................. 35 2.5.1 Its basic biology ........................................................................................ 35 2.5.2 Tomato importance and uses ..................................................................... 35 2.5.3 Tomato cultivation and growth requirements ........................................... 39 REFERENCES ....................................................................................................... 41 CHAPTER 3: FORMULATION OF AN ORGANIC HYDROPONIC NUTRIENT SOLUTION FROM GOAT MANURE ..................................................................... 59 iii ABSTRACT ........................................................................................................... 59 3.1 INTRODUCTION ........................................................................................... 60 3.1.1 Statement of the Problem .............................................................................. 60 3.1.2 Objective ....................................................................................................... 61 3.1.3 Research hypothesis .................................................................................. 61 3.2 MATERIALS AND METHODS ..................................................................... 61 3.2.1 Study site ................................................................................................... 61 3.2.2 Manure collection and preparation............................................................ 62 3.2.3 Source of microorganisms ........................................................................ 64 3.2.4 Identification of microbes ......................................................................... 65 3.2.5 Concentration of microorganisms ............................................................. 66 3.2.6 Manure for optimal nitrate generation by inoculum ................................. 67 3.2.7 Data analysis ............................................................................................. 68 3.3 RESULTS ........................................................................................................ 69 3.3.1. Levels of nutrients in unprocessed goat manure ...................................... 69 3.3.2. Nitrate levels from three sources of microorganisms .............................. 69 3.3.3 Identification of microbes ......................................................................... 70 3.3.4. Concentration of microorganisms ............................................................ 76 3.3.5. Manure for optimal nitrate generation by inoculum ............................ 77 3.4 DISCUSSION .................................................................................................. 79 3.5 CONCLUSION ................................................................................................ 83 REFERENCES ....................................................................................................... 85 CHAPTER 4: CROP PERFOMANCE RESPONSE TO APPLIED FORMULATED NUTRIENT SOLUTION ........................................................................................... 89 ABSTRACT ........................................................................................................... 89 4.1 INTRODUCTION ........................................................................................... 89 4.1.1 Statement of the Problem .......................................................................... 90 4.1.2 Objective ................................................................................................... 90 4.1.3 Hypothesis ................................................................................................. 90 4.2 MATERIALS AND METHODS ..................................................................... 90 4.2.1 Experimental setup .................................................................................... 90 4.2.2 Vegetative growth ..................................................................................... 92 4.2.3 Reproductive growth ................................................................................. 92 4.2.4. Nutrient Use Efficiency............................................................................ 93 4.2.5 Plant dry biomass ...................................................................................... 93 4.2.6 Statistical analysis ..................................................................................... 94 4.3 RESULTS .................................................................................................... 94 iv 4.3.1 Vegetative growth ..................................................................................... 94 4.3.2 Reproductive growth ................................................................................. 98 4.3.3 Plant biomass .......................................................................................... 103 4.3.4 Nutrient Use Efficiency........................................................................... 103 4.4 DISCUSSION ................................................................................................ 104 4.4.1 Vegetative rresponse of tomato plants to goat manure-derived hydroponic nutrient solution ............................................................................................... 104 4.4.2 Reproductive rresponse of tomato plants to goat manure-derived hydroponic nutrient solution ............................................................................ 105 4.4.3 Nutrient Use Efficiency and plant biomass ............................................. 106 4.5 CONCLUSION ......................................................................................... 109 REFERENCES ..................................................................................................... 110 CHAPTER 5: FRUIT QUALITY DUE TO THE FORMULATED NUTRIENT SOLUTION .............................................................................................................. 113 ABSTRACT ......................................................................................................... 113 KEYWORDS ....................................................................................................... 113 5.1 INTRODUCTION ......................................................................................... 113 5.1.1 Problem statement ................................................................................... 114 5.1.2 Objective ................................................................................................. 114 5.1.3 Research hypothesis ................................................................................ 114 5.2 MATERIALS AND METHODS ................................................................... 115 5.2.1 Fruit weight and size data collection and analysis .................................. 115 5.2.2 Brix value data collection and analysis ................................................... 116 5.2.3 Lycopene data collection and analysis .................................................... 117 5.3.4 Statistical Analysis .................................................................................. 121 5.3 RESULTS ...................................................................................................... 121 5.3.1 Fruit weight and size ............................................................................... 121 5.3.2 Brix values .............................................................................................. 123 5.3.3 Lycopene content .................................................................................... 124 5.4 DISCUSSION ................................................................................................ 127 5.4.1 Weight and size ....................................................................................... 127 5.4.2 Brix values .............................................................................................. 128 5.4.3 Lycopene content .................................................................................... 129 5.5 CONCLUSION .............................................................................................. 131 REFERENCES ..................................................................................................... 132 CHAPTER 6: OVERALL CONCLUSIONS & RECCOMMENDATIONS .......... 134 6.1 CONCLUSIONS ............................................................................................ 134 6.2 RECCOMENDATIONS ................................................................................ 136 v APPENDICES ......................................................................................................... 138 APPENDIX 1 (A): Metagenomic BLAST results for the Garden inoculum source: amoA gene ........................................................................................................... 138 APPENDIX 1 (B): Metagenomic BLAST results for the Compost inoculum source: amoA gene ............................................................................................... 146 APPENDIX 1 (C): Metagenomic BLAST results for the Compost inoculum source: nxrA gene ................................................................................................ 163 APPENDIX 1 (D) Metagenomic BLAST results for the Garden inoculum source: nxrA gene ............................................................................................................. 177 APPENDIX 2: Chromatograms generated from HPLC analysis of different lycopene standard concentrations and lycopene analysis of tomato fruits from Goat Manure Derived Hydroponic Nutrient Solution (GMDHNS) and Commercial Hydroponic Nutrient Solution (CHNS). .............................................................. 195 APPENDIX 3: STATISTICAL ANALYSIS TABLES ....................................... 207 vi LIST OF FIGURES Figure 1: Log-frame based conceptual framework………………………………….8 Figure 2: Map showing study area………………………………………………….62 Figure 3: Mineralization of organic nitrogen into nitrate by the addition of microbial inocula from various sources………………………………………………………..70 Figure 4c & 4g: Relative abundance of the various communities of the total Ammonia-Oxidising Bacteria (AOB)……………………………………………….72 Figures 5c&5g: Relative abundance of the various communities of the total of Nitrite-Oxidising Bacteria (NOB)…………………………………………………...75 Figure 6: Inoculum requirements with SANUMARC compost……………………….76 Figure 7: Optimum amount of organic fertilizer…………………………………....77 Figure 8: Effect on plant height of tomatoes grown in different nutrient solutions……………………………………………………………………………..95 Figure 9: Effect of different nutrient solutions on the number of leaves produced by tomato plants………………………………………………………………………...96 Figure 10: Effect of different nutrient solutions on stem diameter of tomato plants………………………………………………………………………………...97 Figure 11: Average number of flowers produced by tomato plants according to different treatments………………………………………………………………….98 Figure 12: Average number of fruits produced by each tomato plant according to different treatments………………………………………………………………….99 Figure 13: Average yield per tomato plant as influenced by different nutrient solution……………………………………………………………………….…….100 Figure 14: Average weight of a single fruit produced by tomato plants as influenced by nutrient solution………………………………………………………………...101 vii Figure 15: Average number of days it takes for tomato plants to flower under different treatments…………………………………………………………..........102 Figure 16: Average number of days it takes to first harvests from tomato plants grown in different treatments………………………………………………...……103 Figure 17: Chromatogram of lycopene standard solution under chromatographic condition………………………………………………………………………..…120 Figure 18: Average weight of a single fruit produced by tomato plants as influenced by nutrient solutions………………………………………………………………………122 Figure 19: Sizes of tomato fruits produced from CHNS compared with those produced from GMDHNS…………………………………………………………123 Figure 20: four pointed (n=2) calibration curve for lycopene standard showing area vs concentration……………………………………………………………………124 Figure 21: Chromatogram of lycopene in tomatoes from CHNS (a) and GMDHNS (b)…...………………………………………………………………………..…….125 Figure 1: Lycopene concentration levels in tomatoes in the 2 treatments…….....126 viii LIST OF TABLES Table 1: The comparison of goat manure macro nutrient composition with other sources……………………………………………………………………………….29 Table 2: The comparison of goat manure micro nutrient composition with other sources……………………………………………………………………………….30 Table 3: treatments for investigating optimal source of microorganisms mineralising organic nitrogen……………………………………………………………………..65 Table 4: Levels of mineral nutrients in goat manure collected from Utuseb farm………………………………………………………………………………….69 Table 5: Descriptive statistics for source of microorganisms between the 3 treatments…………………………………………………………………………....70 Table 6a: Ammonia Oxidising Bacteria (AOB) species composition from the 2 sources of inoculum and species diversity…………………………………………..71 Table 6b: Nitrite Oxidizing Bacteria (NOB) species composition from the 2 sources of inoculum and species diversity…………………………………………….……..74 Table 7: Descriptive statistics for source of microorganisms between the 3 treatments……………………………………………………………………………76 Table 8: Descriptive statistics for optimum concentration of manure between the 3 treatments……………………………………………………………………………77 Table 9: Levels of mineral nutrients in the formulated organic nutrient solution…..78 Table 10: Implications of mineral nutrients…………………………………………79 Table 11: Treatments for investigating performance of tomatoes…………………..92 Table 12: Descriptive statistics for tomato plant height in the 3 different treatments……………………………………………………………………………95 ix