Organic Matter Soil Health and Crop Yield Dr Tom Sizmur

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1 Department of Geography and Environmental Science Organic Matter Soil Health and Crop Yield Dr Tom Sizmur University of Reading

2 Structure of talk How organic matter becomes soil organic matter Organic matter as food for earthworms Earthworms reduce soil strength Lower soil strength accelerates crop establishment Organic matter increases crop yield Can we use organic inputs more smartly?

3 Organic matter and soil health Organic inputs Soil organic matter Benefits Manure management Compost and AD Crop residues Cover crops Water and nutrient retention Soil structure Aggregate stability Microbial biomass Infiltration Yield Crop quality Soil erosion Reduced inputs Improved water quality

4 How OM becomes SOM CO 2 Organic Matter (e.g. FYM, crop residues) Soil biology Soil Organic Matter CO 2 Soil biology Modified from RothC: The Rothamsted Carbon Model Kevin Coleman and David Jenkinson 1998 Soil Organic Matter

5 Historical and emerging views of soil carbon cycling MWI Schmidt et al. Nature 478, (2011) doi: /nature10386

6 Organic matter feeds soil biology The vast majority of the organic matter added to soils is metabolised relatively quickly by soil organisms Some of these soil organisms improve the structure of the soil.

7 Minimum tillage experiment Rotation: Spring Barley Winter Oilseed rape Winter Wheat Spring Barley Minimum tillage Farmyard manure and Compost at 0, 2.5 and 3.5 t C ha -1 5 Nitrogen rates (N0 to N4)

8 Earthworm biomass (g m -2 ) Minimum tillage experiment t C/Ha t C/ha 3.5 t C/Ha N0 Compost N0 FYM N3 Compost N3 FYM Earthworm biomass significantly increased by N rate and OM rate

9 3 ecological groups of earthworms Surface dwellers Vertical burrowers Horizontal burrowers Aporrectodea caliginosa

10 You can monitor earthworms

11 Earthworms are ecosystem engineers Improve drainage Reduce soil erosion Promote root growth Accelerate nutrient cycling Aporrectodea caliginosa

12 Earthworms are ecosystem engineers Long before [the plough] existed the land was in fact regularly ploughed and still continues to be thus ploughed by earthworms

13 Soil strength 0-30cm (Kph) Earthworms reduce soil strength R² = No Straw Straw at 5 t ha-1 Straw at 10 t ha-1 Straw at 20 t ha Endogeic earthworm biomass (g m -2 )

14 Good soil structure: Large pores and small aggregates Plant roots need to push aggregates away from them as they grow. They need somewhere to push the soil that they displace Therefore, aggregates should be smaller than the diameter of the plant roots Lots of small (<1 cm diameter) aggregates are better than a few large aggregates/clods

15 Impact of OM on crop yield: Manure incorporation experiment Applications (2.5 t C ha -1 ) Farmyard Manure Compost Anaerobic Digestate Straw Five nitrogen rates (N0-N4) Rotations Wheat Barley Oats Wheat Barley OSR Wheat Barley

16 OSR yield (t/ha) at 90% dry matter Manure incorporation experiment Oilseed rape: Yield Unamended Nitrogen (kg/ha)

17 OSR yield (t/ha) at 90% dry matter Manure incorporation experiment Oilseed rape: Yield Unamended Anaerobic Digestate Compost Farmyard Manure Barley straw Nitrogen (kg/ha)

18 % Oil at 9% Moisture content Manure incorporation experiment Oilseed rape: Oil content Unamended Anaerobic Digestate Compost Farmyard Manure Barley straw Nitrogen (kg/ha)

19 OSR straw yield (t ha -1 ) DM Manure incorporation experiment Oilseed rape: Straw yield Unamended Anaerobic Digestate Compost Farmyard Manure Barley straw Nitrogen (kg ha -1 )

20 Barley grain yield (t/ha) at 85% DM Manure incorporation experiment Barley: Yield Unamended Anaerobic digestate Compost Farmyard Manure Straw Nitrogen (kg/ha)

21 Barley straw yield (t ha -1 ) DM Manure incorporation experiment Barley: Straw yield Unamended Anaerobic Digestate Compost Farmyard Manure Barley straw Nitrogen (kg ha -1 )

22 Grain Yield (t ha -1 ) Grain Yield (t ha -1 ) Sandy soils: Woburn organic manuring experiment Data Fitted Nitrogen (kg ha -1 ) Nitrogen kg ha -1 0 t C/ha 3 t C/ha Potatoes W. Wheat Potatoes Effect size W. Wheat Potatoes Sugar Beet W. Wheat S. Barley Sugar Beet S. Barley W. Wheat Potatoes W. Wheat Sugar Beet S. Barley Sugar beet S. Barley W. Wheat Potatoes W. Wheat W. Wheat S. Barley W. Wheat F. Maize W. Rye S. Barley Potatoes W. Wheat

23 Effect size Sandy soils: Woburn organic manuring experiment Barley Potatoes Sugar Beet Wheat

24 Grains per plant Yield per ear (g) Yield per plant (g) Ears per plant How does OM improve yield? Pot experiment: Wheat OM application rate (gc/kg soil) OM application rate (gc/kg soil) OM application rate (gc/kg soil) OM application rate (gc/kg soil)

25 How can we use OM to improve soil structure and crop yield? Return crop residues Apply manures Reduce tillage Use cover crops/green manures

26 Earthworm biomass (g m -2 ) 50:50 Manure/Straw Mixtures Unidentified Epigeic Anecic Endogeic All plots received 3 tc ha -1 Straw Compost Comp+Straw FYM FYM+Straw AD AD+Straw

27 The Future Effect of substrate diversity on biological diversity, ecosystem services and resilience Perturbation Increased resilience Increased resistance

28 Can we make better use of crop residues? PhD Studentship Starting October 2015

29 Summary Organic matter feeds soil biology Manures increase earthworm populations Earthworms reduce soil strength Lower soil strength promotes root growth and improves access to nutrients and water Better access to nutrients and water increases crop yield and quality You can monitor earthworm populations using the OPAL Earthworm survey guide

30 Acknowledgements Andy Whitmore Chris Watts Andy Gregory Elodie Martin Emilie Parmentier Kevin Wagner Karl Ritz Mark Pawlet Jim Harris Agnese Mancini