Soil Health and Organic Matter The Role of Soil Biology in Soil Function, Nutrient Cycling, and Pests and Diseases

Dr. Simon Jeffery 19th November 2015 Agenda

• What is soil health?

• What is the role of soil organic matter?

• What is the role of soil biology in soil function? What is Soil Health?

• Often also referred to as soil quality • Defined as “the capacity of the soil to function to sustain life: A healthy soil can be used productively without adversely affecting its future productivity” - Cornell University (USA) • “Soil health is the capacity of soil to function as a living system, with ecosystem and land use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health” – FAO (2008) What is Soil Organic Matter?

• Includes all plant and animal resides at various stages of decomposition • Dead plant and animal material • Manure • Substances synthesised and excreted by soil organisms • Root exudates What is the Role of Soil Organic Matter in Soil?

• Serves as a reservoir of nutrients for crops • Retains moisture • Increases aggregation and aggregate stability • Reduces compaction and surface crusting • Increases water infiltration • Serves as the fuel for the soil biota! Why are Soil Microbes Important?

• Nutrient cycles • Vital for soil fertility! • Organic matter decomposition (Carbon cycle) • Disease • Causing • Prevention • Biotechnology • Antibiotics • Soil remediation Aboveground Foodweb Belowground Foodweb Who lives in the Soil? The Soil as a Habitat

5 cm 5 mm 0.5 m

Image: K. Ritz The Scale of Soil Life Nematodes

Image courtesy of K. Ritz Nematodes – Plant Pests

Root-knot nematodes (Meloidogyne sp.) cause galls on tubers and roots. Plants are stunted and often off- colour

Image credit – Nischwitz (2012) and Agroscope Nematodes – Natural Enemies

• Entomopathogenic nematodes

Steinernema sp.

- Image credit H. van Megan Nematodes – Natural Enemies Pest Pest Key Efficacious Common name Scientific name Crop(s) targeted Nematodes Artichoke plume moth Platyptilia carduidactyla Artichoke Sc Armyworms Lepidoptera: Noctuidae Vegetables Sc, Sf, Sr Banana moth Opogona sachari Ornamentals Hb, Sc Banana root borer Cosmopolites sordidus Banana Sc, Sf, Sg Sphenophorus spp. Billbug Turf Hb,Sc (Coleoptera: Curculionidae) Black cutworm Agrotis ipsilon Turf, vegetables Sc Black vine weevil Otiorhynchus sulcatus Berries, ornamentals Hb, Hd, Hm, Hmeg, Sc, Sg Synanthedon spp. and other Borers Fruit trees & ornamentals Hb, Sc, Sf sesiids Cat flea Ctenocephalides felis Home yard, turf Sc Pachnaeus spp. (Coleoptera: Citrus root weevil Citrus, ornamentals Sr, Hb Curculionidae Codling moth Cydia pomonella Pome fruit Sc, Sf Corn earworm Helicoverpa zea Vegetables Sc, Sf, Sr Corn rootworm Diabrotica spp. Vegetables Hb, Sc Cranberry girdler Chrysoteuchia topiaria Cranberries Sc Crane fly Diptera: Tipulidae Turf Sc Hb=Heterorhabditis bacteriophora, Hd = H. downesi, Hi = H. indica, Hm= H. marelata, Hmeg = H. megidis, Hz = H. zealandica, Sc=Steinernema carpocapsae, Sf=S. feltiae, Sg=S. glaseri, Sk = S. kushidai, Sr=S. riobrave, Sscap=S. scapterisci, Ss = S. scarabaei. Nematoes – Natural Enemies Continued Pest Pest Key Efficacious Common name Scientific name Crop(s) targeted Nematodes Diaprepes root weevil Diaprepes abbreviatus Citrus, ornamentals Hb, Sr Fungus gnats Diptera: Sciaridae Mushrooms, greenhouse Sf, Hb Grape root borer Vitacea polistiformis Grapes Hz, Hb Iris borer Macronoctua onusta Iris Hb, Sc Large pine weevil Hylobius albietis Forest plantings Hd, Sc Liriomyza spp. (Diptera: Leafminers Vegetables, ornamentals Sc, Sf Agromyzidae) Mole crickets Scapteriscus spp. Turf Sc, Sr, Scap Navel orangeworm Amyelois transitella Nut and fruit trees Sc Plum curculio Conotrachelus nenuphar Fruit trees Sr Scarab grubs** Coleoptera: Scarabaeidae Turf, ornamentals Hb, Sc, Sg, Ss, Hz Shore flies Scatella spp. Ornamentals Sc, Sf Strawberry root weevil Otiorhynchus ovatus Berries Hm Small hive beetle Aethina tumida Bee hives Yes (Hi, Sr) Sweetpotato weevil Cylas formicarius Sweet potato Hb, Sc, Sf

Hb=Heterorhabditis bacteriophora, Hd = H. downesi, Hi = H. indica, Hm= H. marelata, Hmeg = H. megidis, Hz = H. zealandica, Sc=Steinernema carpocapsae, Sf=S. feltiae, Sg=S. glaseri, Sk = S. kushidai, Sr=S. riobrave, Sscap=S. scapterisci, Ss = S. scarabaei. Acari (mites) Predatory mite – Natural enemies

Phytoseiulus persimilis – image credit Talbot (2008) Acari - Parasites

Deer tick (Ixodes scapularis) Lone star tick (Amblyomma americanum) – carries Lyme Disease (and others) – can cause Alpha-gal allergy Protozoa

Image courtesy of K. Ritz Protozoa

Euglypha sp. Difflugia lucida Grossglockneria acuta

Credit: W. Foissner Fungi

Amanita muscari, Hygrocybe punicea, Calvatia gigantean, Pilobilus sp.

Image credits: K Ritz and L. Deacon Fungi - Hyphal

Filamentous – grow as belowground networks called hyphae

Image credit: K. Ritz Mycorrhiza Mycorrhizae

• Symbiotic relationship between a fungus (or fungi) and plant roots • Plant provides photosynthetically produced C compounds (e.g. sugars) • Fungus increases water and nutrient uptake by plant Carnivorous Fungi

Drechslerra anchonia

Image credit: G. Barron and N. Allin The Largest Organism on Earth

• Armillaria bulbosa is common in hardwood forests in America • One individual covered an area in Oregon of more than 890 hectares! Bacteria Bacteria in the Soil Bacteria in the Soil Soil Bacteria • Drive soil process on a global scale • Responsible for some diseases in plants, animals and humans • BUT the vast majority work to our benefit we would not be here without soil bacteria! • Extremely numerous and diverse in soils • Still lots of unknowns • <1% of soil bacteria can be grown in the laboratory Soil Function and Ecosystem Services Soil Based Ecosystem Services

From Haygarth and Ritz 2009 The Nitrogen Cycle Ecological Functions Disease Suppression

Source: Mitchell et al. 2002 The Value of Soil Based Ecosystem Services

From Pimentel et al. 1997 Resistance and Resilience Resistance and Resilience

• Resistance = how strongly a community can resist a stress without being negatively affected • Resilience = how quickly a community can recover after being negatively affected

• “Functional redundancy” is the one of the most often quoted mechanisms underlying these factors Functional Redundancy Thank you for your attention