Enhancing and preserving carbon storage in soil using organic amendments. Dr Ruben Sakrabani 18 June 2015

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1 Enhancing and preserving carbon storage in soil using organic amendments Dr Ruben Sakrabani 18 June 2015

2 Outline of presentation Introduction Carbon cycle & dynamics in soil Types of organic amendments Options for enhancing and preserving soil carbon in soil Challenges Conclusions

3 Introduction Many modern agricultural soils are significantly degraded 1 Increased requirements for food Increase in Inorganic Fertilisers Reduction in Nutrient Retention Population 2 Increases Higher Crop Productivity Reduction in SOM 1. Gilroy et al., (2008). Could soil degradation contribute to farmland bird declines? Links between soil penetrability and the abundance of yellow wagtails Motacilla flava in arable fields. Biological Conservation 141, UN (2004). World Population To Report by Department of Economic and Social Affairs James Ulyett (2010)

4 Reasons to enhance or preserve organic carbon in agricultural soils : organic C influences on many soil properties and functions that affect both agricultural production & the roles that soils play in the wider environment Ecosystem Services soils are a significant stock of C within the global C budget (1500 Pg C in soils compared to 760 Pg C in the atmosphere) EU Commission has identified decline in organic C as a threat to soils in Europe

5 Definitions Total C = organic C + inorganic C Organic carbon mostly present in SOM Inorganic carbon carbonates and bicarbonate Black carbon graphitic microstructure, black particulate due to incomplete combustion of fossil fuels; found everywhere and major component of charcoal and soot; very stable C storage refers to how much C is already stored within the different C pools C sequestration refers to the quantity of C that is gained or lost each year

6 The Carbon Cycle (Source : Bashkin V. 2002)

7 Soil Carbon Cycle

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9 Compost or plant residues vs. biochar Compost and other organic material in soils is valuable but mineralises (converts to CO 2 ) in just a few years Biochar will remain essentially unchanged for hundreds or even thousands of years carbon sequestration really is possible Tofield, UEA (2009)

10 Soil C modelling multi compartments models not possible to input bulk SOC into models complex SOC turnover several SOC fractions fast, intermediate, slow popular models are : - CENTURY 5 (Colorado State University, USA) - ROTH C (Rothamsted Research, UK)

11 Effects of ley on productivity Nutritional effects extra N residues in soil by legumes Soil structure effects related to in change in OM Soil-borne pest and disease break crop to reduce eelworms, eyespot etc. The table is a modified version of a table in the book Soil Management by B. Davies, D Eagle & B.Finney 1993, Soil Management p. 93, Farming Press Ipswich.

12 Modelling C from biowaste

13 Soil C dynamics OC does not increase or decrease at a linear rate in response to a change in management, but moves from one equilibrium level to another over a period of years f (soil type, climate, cropping system, organic matter inputs and a range of management factors) and is a balance between rates of organic inputs and decomposition. if land management or land use is reversed, C accumulated will be lost quicker than it was accumulated

14 National Soil Inventory 5,692 samples between organic carbon, ph, extractable heavy metals & nutrients mineral particle-size properties taken from 15 cm deep topsoil samples taken at 5 km grid intersect points across E & W

15 Distribution of original SOC in E & W ( )

16 Decline in soil carbon?

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19 SOC increases with addition of organic amendments (E&W)

20 Soil organic matter field (grass)

21 EU Long Term Field Experiments (biosolids) Woburn Market Garden (UK) Ultuna Continuous Soil Organic Matter Experiment (Sweden) ADAS Historic Sites (UK) Luddington/Lee Valley Gleadthorpe/Rosemaund 1982/1991 Braunschweig (Germany) Askov (Denmark) Pamplona (Spain) ADAS Long-Term Experimental Sites (UK)

22 Soil organic carbon trends - EU Long Term Field Experiments (biosolids)

23 Long term soil organic carbon trends Italy, India, China, Diacono & Montemurro (2010). Agron. Sustain. Dev. 30 (2010)

24 Challenges in utilising organic amendments to control SOC Availability of organic amendments close to landbank transportation cost, topography Heterogeneity of organic amendments how much is available to meet crop requirements Quality of organic amendments PAS 100/PAS 110/Quality Protocols for compost, AD : contaminants (physical and chemical) Regulations NVZ, Safe Sludge Matrix, Biosolids Assurance Scheme; limited landbank e.g. P in biosolids Perception of end users retail sector, specialist markets

25 Conclusions Organic amendments can increase soil carbon stock but it depends on frequency of application, quality, soil and climatic conditions Organic amendments provide not only C but also other nutrients - fertility Build up of soil carbon can influence carbon flux links to climate change Soil carbon enhancement in not continuous and is not stored indefinitely reaches new equilibrium and actions must be in place to preserve this There are challenges transport, perception, contaminant, quality, regulations that needs to be managed