PAPERCRAFT SOIL HEALTH AND ORGANIC MATTER: ROLES OF THE BIOLOGICAL ENGINE OF THE EARTH

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1 PAPERCRAFT SOIL HEALTH AND ORGANIC MATTER: ROLES OF THE BIOLOGICAL ENGINE OF THE EARTH Soils alive: the biological basis of soil health OUTLINE Introduction context What is soil? Soil biota Soil functions (roles of OM) Mechanisms: soil structure pests & diseases N supply to plants Soil health Soil management PLANETARY MATTERS WHAT IS SOIL? Earth earth The foundation of civilisation Museum of Ontario Googlemaps WHAT IS SOIL? WHAT IS SOIL? A RESOURCE! Minerals Gases A STRUCTURED, POROUS MEDIUM AN ADAPTIVE, DYNAMIC SYSTEM A HABITAT Organic matter Organisms Water Solutes & colloids

2 WHAT IS SOIL? Minerals Gases 5 tonnes per hectare equivalent to 100 sheep Organic matter Organisms Water Handful of arable soil (c. 200g)... approximately 0.5 g of fresh Solutes biomass & (mainly microbial ) colloids grassland 20 times greater = 2000 sheep per hectare SOIL BIODIVERSITY SOIL BIODIVERSITY SIZE # INDIVIDUALS # SPECIES FUNGI µm 100,000,000,000 50,000 m FUNGI 10,000 SOIL BIOMASS PROTOZOA NEMATODES INSECTS ARACHNIDS MOLLUSCS WORMS mm 100,000 10, PROTOZOA NEMATODES INSECTS ARACHNIDS MOLLUSCS WORMS MAMMALS PLANT ROOTS cm m MAMMALS PLANT ROOTS SOIL BIOTA SOIL-BASED ECOSYSTEM GOODS AND SERVICES Supporting Provisioning Regulating Cultural BIOLOGICAL ENGINE OF THE EARTH Cognitive Primary production Gas regulation CO 2, CH 4 NO x, N 2 Climate regulation Nutrient cycling Refugia Biodiversity Soil functions Soil formation Water supply Biomaterials Raw materials Food supply Erosion control Heritage Water storage CNPKS Recreation Water quality Platform Haygarth & Ritz 2009, Land Use Policy 26 S

3 LIFE IN EARTH NEMATODE Dave Walter G. Bradley: uksafari.com 20 µm PROTOZOA - AMOEBA FUNGUS 20 µm 20 µm THE WORKING SOIL ENGINE FOOD WEBS: CARBON PLANT MATERIAL SOIL ORGANIC MATTER THE FUEL OF THE SOIL ENGINE FUNGI PROTOZOA NEMATODES 20 µm INSECTS ARACHNIDS MOLLUSCS WORMS MAMMALS

4 ORGANIC MATTER ROLE OF CARBON POPLAR PLANTATION (2-YEARS OLD) TOTAL C BIOLOGICAL C Carbon is the currency of the soil economy t ha Depth (cm) MICROBE, kg / ha Fungal C Bacterial C Root C Depth (cm) ROOT, kg / ha (adapted from Paul 2007) BIOLOGICAL ENGINE SOIL STRUCTURE Soil structural dynamics Pests and diseases Nutrient cycling Fundamental to soil functioning! Rooting medium Water relations Compaction Erosion Nature of the habitat NEW VIEWS: X-RAY COMPUTED TOMOGRAPHY NEW VIEWS OF THE UNDERWORLD

5 BIOTIC ROLES IN SOIL STRUCTURAL DYNAMICS BIOTIC ROLES IN SOIL STRUCTURAL DYNAMICS DIRECT and INDIRECT EFFECTS MOVING PAINTING GLUING SEWING EATING EARTHWORMS: ECOSYSTEM ENGINEERS EARTHWORM CAST Allolobophora chlorotica (endogeic) Lumbricus terrestris (anecic) Aporrectodea caliginosa (endogeic) Mark Bartlett BIOTIC ROLES IN SOIL STRUCTURAL DYNAMICS DECONSTRUCTION MOVING PAINTING Majority of organic agents of soil structural genesis contain energy GLUING SEWING EATING

6 PHYSICAL PROTECTION MECHANISMS EFFECTS OF SOIL DISTURBANCE aggregate disrupts...exposed organic matter is colonised by microbes Effects of tillage on short-term soil respiration Clay soil (Silsoe) Three tillage regimes none low energy 2 passes with Dyna Drive high energy 4 passes with spiked rotor 6-fold difference in energy input Watts et al. (2000) Watts et al. (2000) Soil & Tillage Res. 53, RESPIRATION RATE Control Low energy tillage High energy tillage SOIL TILLAGE Pivotal role of soil disturbance in reducing soil organic matter concentrations RESPIRATION RATE mg CO 2 m -2 h -1 Days after tillage Priming effect via reduction of physical protection BIOLOGICAL ENGINE PESTILENCE... Soil structural dynamics Pests and diseases Nutrient cycling FUNGI PROTOZOA NEMATODES INSECTS ARACHNIDS MOLLUSCS WORMS MAMMALS PLANT ROOTS

7 BIODIVERSITY and DISEASE ATTENUATION SOIL BIODIVERSITY EFFECTS ON Fusarium oxysporum? Role of monoculture in engendering disease Specific biocontrol agents inoculated biocontrol strategies take-all decline Community-scale interactions role of biodiversity... Fusarium CONCENTRATION log cfu/g INCREASING SOIL BIODIVERSITY Toyota et al. (1996) Soil Biol. Biochem. 28, COMMUNITY STRUCTURE EFFECTS ON PATHOGEN ATTENUATION BIOLOGICAL ENGINE PATHOGEN DEATH RATE Salmonella Dublin Listeria monocytogenes SOIL MICROBIAL COMMUNITY STRUCTURE [PHENOTYPIC PROFILING] Soil structural dynamics Pests and diseases Nutrient cycling Moynihan et al. (2014) Applied Soil Ecol. 89, THE SOIL NITROGEN CYCLE ATMOSPHERIC NITROGEN (MAINLY N 2 ) BIOTIC MECHANISM OF NUTRIENT MINERALISATION FERTILISER Inorg Org DRY / WET DEPOSITION N 2 O FREE SYMBIOTIC N 2 FIXATION NH 4 SOIL ORGANIC N NO SOIL BIOMASS SOIL MINERAL N EXCHANGE SURFACES NH 4 + NO 2 - NO 3 -

8 N MINERALISATION VIA PREDATORS HOW TO MANAGE SOIL BIODIVERSITY? RESPIRATION release of CO 2 C:N RATIO decreases CO 2 PHYSICAL soil structure HETEROGENEITY BEGETS DIVERSITY CHEMICAL organic matter residues C:N RATIO reverts Up to 33 % of bacterial N can be released by predators EXCRETION of NH 4 + SCALE spatial temporal BIOLOGICAL botanical! SOIL HEALTH SOIL HEALTH: THE PIVOTAL FIVE Soil that is constituted and managed in such a way as to be fit for purpose ORGANIC MATTER BIOTA WATER NUTRIENTS STRUCTURE etc. VISUAL SOIL ASSESSMENTS SOIL ARCHITECTURE SOIL S ALIVE! Soil is a living system, founded on an appropriate spatial configuration Appropriate community structures living within such an inner space lead to an effective functioning of the system Organic matter = fuel for the biological engine