THE IMPORTANCE OF SOIL ECOLOGY IN SUSTAINABLE AGRICULTURE Clive A. Edwards & Norman Q. Arancon The Soil Ecology Laboratory The Ohio State University Columbus, Ohio 1
SUSTAINABLE AGRICULTURE INTEGRATED SYSTEMS OF AGRICULTURAL PRODUCTION WHICH ARE LESS DEPENDENT ON HIGH INPUTS OF ENERGY AND SYNTHETIC CHEMICALS, AND MORE MANAGEMENT INTENSIVE THAN CONVENTIONAL AGRICULTURE. THESE MAINTAIN CROP PRODUCTIVITY, QUALITY AND YIELDS, ARE ECOLOGICALLY SUSTAINABLE, AND PROTECT THE ENVIRONMENT AND NATURAL RESOURCES. 2
SOIL ECOLOGY THE STUDY OF RELATIONSHIPS BETWEEN LIVING ORGANISMS AND THE ENVIRONMENTAL CONDITIONS IN THE SOIL IN WHICH THEY LIVE. 3
THE IMPORTANCE OF SOIL ECOLOGY IN SUSTAINABLE AGRICULTURE THE CONCEPTS OF SUSTAINABLE AGRICULTURE INPUTS INTO SUSTAINABLE AGRICULTURE THE ROLE OF SOIL ECOLOGY AND ITS POTENTIAL INPUTS INTO SUSTAINABLE AGRICULTURAL SYSTEMS A CASE STUDY: THE ROLE OF AGRICULTURAL VERMICOMPOSTING IN SUSTAINABLE AGRICULTURE 4
MAIN INPUTS INTO CONVENTIONAL AGRICULTURAL SYSTEMS INPUTS PRACTICES FERTILITY INORGANIC FERTILIZERS CULTIVATIONS DEEP PLOWING OR NO TILL CROPPING MONOCULTURE OR BICULTURE PEST DISEASE & WEED CONTROL ROTATIONS INSECTICIDES FUNGICIDES HERBICIDES NEMATICIDES 5
MAIN INPUTS INTO SUSTAINABLE AGRICULTURE SYSTEMS INPUT FERTILITY CULTIVATIONS PRACTICES ORGANIC MINIMAL INORGANIC FERTILIZERS- INTEGRATED FERTILIZER MANAGEMENT CONSERVATION TILLAGE OR NO TILL CROPPING ROTATIONS AND/OR CROPPING PATTERNS PEST DISEASE & WEED CONTROL ORGANIC MINIMAL PESTICIDES- INTEGRATED PEST MANAGEMENT 6
INTERACTIONS BETWEEN MAJOR INPUTS INTO AGRICULTURAL SYSTEMS FERTILIZERS CROPPING PATTERNS CULTIVATIONS PESTS DISEASES WEEDS 7
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THE INTEGRATION OF ECOLOGICAL INPUTS INTO SUSTAINABLE AGRICULTURAL SYSTEMS MAXIMUM PROVISION OF NUTRIENTS FROM ORGANIC SOURCES MAINTENANCE OF ECOLOGICAL INTEGRITY IN SOILS THROUGH MINIMUM CULTIVATIONS MAXIMIZATION OF BIODIVERSITY THROUGH: ROTATIONS UNDERSOWING STRIP CROPPING CATCH CROPS MAXIMIZATION OF BIOLOGICAL SUPPRESSION OF PESTS AND PATHOGENS THROUGH: ORGANIC MATTER ALLELOPATHY ENCOURAGEMENT OF PREDATORS AND PARASITES RELEASE OF NATURAL ENEMIES 9
THE ROLE OF SOIL ECOLOGY ORGANIC MATTER BREAKDOWN SOIL-INHABITING INVERTEBRATES SOIL MICROORGANISMS INTERACTIONS BETWEEN INVERTEBRATES AND MICROORGANISMS FOOD WEBS IN SOIL SOIL ECOLOGICAL OUTPUTS FACILITATION OF NUTRIENT RECYCLING 10
NUMBERS AND BIOMASS OF SOIL- INHABITING INVERTEBRATES TYPE OF ORGANISM NO. M -2 KG. HA -1 PROTOZOA 10 9-10 10 20-200 NEMATODA (EELWORMS) 10 6-10 7 10-150 ACARINA (MITES) 10 3-10 5 5-150 COLLEMBOLA (SPRINGTAILS) 10 3-10 5 5-150 EARTHWORMS 10-10 3 100-5,000 OTHERS 10 2-10 4 10-100 11
NUMBERS AND BIOMASS OF SOIL MICROORGANISMS IN SOIL TYPE OF ORGANISM NO. M -2 KG. HA -1 BACTERIA 10 13-10 14 400-5,000 ACTINOMYCETES 10 12-10 13 400-5,000 FUNGI 10 10-10 11 1,000-15,000 ALGAE 10 9-10 10 10-500 12
SOIL INVERTEBRATES IMPORTANT IN ORGANIC MATTER BREAKDOWN EARTHWORMS -OLIGOCHAETES MILLIPEDES -DIPLOPODA WOODLICE -ISOPODA MITES -ACARINA INSECTS -INSECTA SPRINGTAILS -COLLEMBOLA TERMITES -ISOPTERA ANTS -HYMENOPTERA BEETLES -COLEOPTERA FLY LARVAE -DIPTERA CATERPILLARS -COLEOPTERA 13
SOIL INVERTEBRATES THAT CAN BE CROP PESTS NEMATODES -NEMATODA POT WORMS -ENCHYTRAEIDAE GARDEN CENTIPEDES -SYMPHYLA MILLIPEDES -DIPLOPODA MOLLUSCS -GASTROPODA SLUGS SNAILS MITES -ACARINA SPRINGTAILS -COLLEMBOLA INSECTS -INSECTA ANTS -HYMENOPTERA TERMITES -ISOPODA BEETLES -COLEOPTERA FLY LARVAE -DIPTERA CATERPILLARS -LEPIDOPTERA THRIPS -THYSANOPTERA 14
SOIL INVERTEBRATES THAT CAN BE PREDATORS OR PARASITES OF PESTS NEMATODES -NEMATODA CENTIPEDES -CHILOPODA MITES -ACARINA (GAMASIDAE) SPIDERS -ARANEAE SCORPIONS -SCORPIONIDA PSEUDOSCORPIONS -PSEUDOSCORPIONES INSECTS -INSECTA BEETLES -COLEOPTERA TERMITES (SOLDIERS) -ISOPTERA FLIES -DIPTERA WASPS -HYMENOPTERA 15
FUNCTIONS OF SOIL- INHABITING INVERTEBRATES ORGANIC MATTER DECOMPOSERS PESTS PREDATORS OF PESTS PROTOZOA --------- -------- NEMATODES NEMATODES NEMATODES ENCHYTRAEIDAE ENCHYTRAEIDAE -------- SYMPHYLA SYMPHYLA SYMPHYLA WOODLICE --------- --------- MILLIPEDES MILLIPEDES ---------- ------------- --------- CENTIPEDES MOLLUSCS MOLLUSCS --------- EARTHWORMS EARTHWORMS --------- MITES MITES MITES COLLEMBOLA COLLEMBOLA --------- INSECTS INSECTS INSECTS 16
EFFECTS OF SOIL ORGANISMS ON CROP PRODUCTIVITY BREAKDOWN OF ORGANIC MATTER RELEASE OF NUTRIENTS IN AVAILABLE FORM PHYSICAL SOIL TURNOVER: ESPECIALLY IMPORTANT UNDER NO TILL IMPROVED SOIL AERATION BETTER DRAINAGE INCREASED WATER-HOLDING CAPACITY PEST AND DISEASE SUPPRESSION 17
A CASE STUDY: THE ROLE OF VERMICOMPOSTING IN SUSTAINABLE AGRICULTURE EARTHWORMS PRINCIPLES OF VERMICOMPOSTING METHODS OF VERMICOMPOSTING EFFECTS ON CROP GROWTH GERMINATION AND YIELDS EFFECTS ON PLANT PATHOGENS EFFECTS ON PLANT PARASITIC NEMATODES EFFECTS ON ARTHROPOD PESTS ECONOMICS 18
EARTHWORMS Earthworms are segmented invertebrates that inhabit soils and organic waste. They are hermaphrodite and usually reproduce by mating, each partner fertilizing the other. After mating they retract their bodies through the saddle or clitellum and pass it over their heads. Each cocoon contains one or more eggs and can survive adverse conditions, hatching when environmental conditions are favorable. They take one to eight months to become sexually mature and continue to reproduce at regular intervals. They require moisture and aerobic conditions for survival and reproduction. 19
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BREAKDOWN OF POTATO WASTES BEFORE AFTER 7 DAYS 21
VERMICOMPOSTS Vermicomposts are organic materials, broken down by interactions between earthworms and microorganisms, in a mesophilic process (up to 25 o C), to produce fully-stabilized organic soil amendments with low C:N ratios. They have a high and diverse microbial and enzymatic activity, fine particulate structure, good moisture-holding capacity, and contain nutrients such as N,K, P, Ca and Mg in forms readily taken up by plants. They contain plant growth hormones and humic acids which act as plant growth regulators. 22
POTENTIAL INTERACTIONS BETWEEN EARTHWORMS & MICROORGANISMS IN VERMICOMPOSTS Earthworms Mineralization Plant-Available Mineral Nutrients N, P, K, Ca, Mg and Micronutrients Phytohormone-like Plant Growth Regulators Auxins, Cytokinins, Gibberellins Organic Matter Other Plant-Growth Influencing Substances Humic materials Free Enzymes Allelopathic agents Microorganisms Plant Disease and Nematode Suppression 23
PRINCIPLES OF VERMICOMPOSTING Species of organic waste-consuming earthworms such as Eisenia fetida and Eudrilus eugeniae are used Temperature should be maintained at 20-25 0 C Moisture content should be 75% - 90% Organic materials are added to systems in thin layers (2.5-5.0 cm) Earthworms require aerobic conditions and remain in the top 10-15 cm of a system moving up as new organic matter is added to the surface 24
LIFE CYCLE OF EISENIA FETIDA 25
METHODS OF VERMICOMPOSTING METHOD WINDROWS WEDGE SYSTEMS BATCH SYSTEMS DOMESTIC SYSTEMS CONTINUOUS FLOW REACTORS MANUAL AUTOMATED CONTINUOUS FLOW LOCATION OUTDOOR, INDOOR OUTDOOR, INDOOR INDOOR INDOOR INDOOR 26
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FULL-SCALE REACTOR 28
EFFECTS OF VERMICOMPOSTS ON PLANT GROWTH We have demonstrated very considerable increases in rates of germination, growth, flowering and fruiting and yields in crops grown with small substitutions or amendments with vermicomposts. These increases were usually independent of nutrient availability. 29
EFFECTS OF VERMICOMPOSTS ON TOMATO SEEDLING GROWTH 30
tons/ha MARKETABLE YIELDS OF TOMATOES IN THE FIELD 20 Marketable yield of tomato 15 10 5 0 Inorganic Fertilizer Paper Waste 5.0 t/ha Paper Waste 10 t/ha Cow Manure 5.0 t/ha Cow Manure 10 t/ha Food Waste 5.0 t/ha Food Waste 10 t/ha 31
Grams/plant MARKETABLE YIELDS OF STRAWBERRIES Marketable yields of strawberry 3000 2500 2000 1500 1000 Inorganic Fertilizer Food Waste 5.0 t/ha Food Waste 10 t/ha Paper Waste 5.0 t/ha Paper Waste 10 t/ha 32
mg/kg MICROBIAL BIOMASS-N IN TOMATO FIELD EXPERIMENT 25 Microbial biomass N in tomato plots 20 15 10 5 0 Inorganic Fertilizer Paper Waste 5.0 t/ha Paper Waste 10 t/ha Cow Manure 5.0 t/ha Cow Manure 10 t/ha Food Waste 5.0 t/ha Food Waste 10 t/ha 33
EVIDENCE FOR PLANT GROWTH REGULATORS IN VERMICOMPOSTS SMALL SUBSTITUTIONS OF VERMICOMPOSTS INTO GROWTH MEDIA INCREASE PLANT GROWTH INDEPENDENT OF NUTRIENT SUPPLY VERMICOMPOSTS ARE EXTREMELY MICROBIALLY ACTIVE AND MICROORGANISMS PRODUCE PLANT GROWTH HORMONES AQUEOUS EXTRACTS OF VERMICOMPOSTS CAN INCREASE GROWTH INDEPENDENT OF NUTRIENTS BASE EXTRACTS OF HUMATES FROM VERMICOMPOSTS CAN INCREASE PLANT GROWTH INDEPENDENT OF NUTRIENTS GROWTH REGULATORS ADSORBED ONTO HUMATES IN VERMICOMPOSTS PLANT GROWTH PATTERNS E.G. STEM ELONGATION, ROOT GROWTH, FLOWERING PATTERNS ARE OFTEN CHANGED BY VERMICOMPOSTS 34
EFFECTS OF VERMICOMPOSTS AND VERMICOMPOST TEAS ON PLANT DISEASES Laboratory Pythium Rhizoctonia Plectosporium Phytophthora Fusarium Field Verticillium Phomopsis Sphaerotheca Uncinula necator 35
Percent Damage SUPPRESSION OF VERTICILLIUM ON STRAWBERRY BY VERMICOMPOSTS 85 80 a 75 ab 70 65 60 b b b 55 50 45 40 Inorganic Fe rtilize rs Food Waste 5t/ha Food Waste 10t/ha Paper Waste 5t/ha Paper Waste 10t/ha 36
Rating SUPPRESSION OF POWDERY MILDEW ON FIELD GRAPES BY VERMICOMPOSTS 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0.0 Inorganic Fert Paper 5t Paper 2.5t Food 5t Food 2.5t 37
38 PLANT PARASITIC NEMATODE POPULATIONS Tomato 0 2 4 6 8 10 12 14 16 Inorganic Ferilizer Paper 20t/ha Paper 10t/ha Food 20t/ha Food 10t/ha Cattle 20t/ha Cattle 10t/ha Compost 20t/ha Strawberry 0 5 10 15 20 25 30 35 Inorganic Fertilizer Paper 5.0t/ha Paper 10t/ha Food 5.0t/ha Food 10t/ha Pepper 0 2 4 6 8 10 12 14 16 Inorganic Ferilizer Paper 20t/ha Paper 10t/ha Food 20t/ha Food 10t/ha Cattle 20t/ha Cattle 10t/ha Compost 20t/ha Grape 0 5 10 15 20 25 30 35 40 Inorganic Fertilizer Paper 10t/ha Paper 5.0t/ha Food 10t/ha Food 5.0t/ha No fertilizer Numbers/ 20 g sample
Number of nematodes per 250 cc soil SUPPRESSION OF MELOIDOGYNE BY FOOD WASTE ON TOMATOES BY VERMICOMPOST Population Density 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 Pre-planting Post-planting Control 5 t/ha 10 t/ha Treatment 39
EFFECTS OF VERMICOMPOSTS ON ARTHROPOD PESTS SUCKING INSECTS APHIDS MEALY BUGS TWO-SPOTTED SPIDER MITES CHEWING INSECTS CABBAGE WHITE CATERPILLARS CUCUMBER BEETLES TOMATO HORNWORMS 40
Number of Aphids EFFECTS OF VERMICOMPOSTS ON DEVELOPMENT OF APHID INFESTATIONS ON CABBAGE 90 80 70 60 50 40 30 20 10 0 Day 3 Day 6 Day 8 Day 10 Day 13 Day 15 Day 17 0 20 40 Percentage Vermicompost 41
Damage Ratings EFFECTS OF VERMICOMPOSTS ON DAMAGE RATINGS OF TWO-SPOTTED SPIDER MITES INFESTATIONS ON EGGPLANTS 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 Day 3 Day 6 Day 8 Day 10 Day 13 Day 15 Day 17 0 0 20 40 Percentage Verm icom post 42
CONCLUSIONS ON ROLE OF VERMICOMPOSTS IN SUSTAINABLE AGRICULTURE Vermicomposts have great potential in horticulture and agriculture crop production due to production of plant growth regulators by the greatly increased microbial populations. These accelerate the germination, growth, flowering and yields of plants independent of nutrient supply. Vermicomposts also have potential, as solids or aqueous vermicompost extracts, in integrated pest management programs, since one application suppresses soil-borne plant pathogens, plant parasitic nematodes as well as numbers and reproduction of arthropod pests such as aphids, beetles and caterpillars. 43
CONCLUSIONS ON THE ROLE OF SOIL ECOLOGY IN SUSTAINABLE AGRICULTURE SUSTAINABLE AGRICULTURE DEPENDS ON INPUTS FROM BIOLOGICAL ORGANISMS INSTEAD OF CHEMICALS. THIS MAKES THE SOIL ECOLOGY PRINCIPLES AND INPUTS TO SUSTAINABLE AGRICULTURAL SYSTEMS A CRITICAL COMPONENT. 44