Cover crops, the story so far and future thoughts - Steve Corbett - South Region iFarm & Tech Centre Manager - Agrii
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Cover crops, the story so far and future thoughts Steve Corbett – South Region iFarm & Tech Centre Manager
Catch/Cover Crop and Cultivation Strategies Trial
In a Blackgrass Situation
(Stow Longa) 2015/2020
Plot plan 2015 - 2020
2019-20 2018-19 2017-18 2016-17 2015-16 2014-15
12m
Phacelia Phacelia Phacelia
@ 5kg/ha + Mustard @ 12 kg/ha + Mustard @ 12 kg/ha + Mustard "Mega Mix"
@ 10Kg/ha @ 12kg/ha @ 12kg/ha
12m
White mustard White Mustard White Mustard White Mustard White Mustard White Mustard
24m
@ 10Kg/ha @ 10kg/ha @ 10kg/ha @ 10kg/ha @ 10kg/ha @ 10kg/ha
Phacelia Phacelia Phacelia Phacelia Phacelia Phacelia
24m
@ 10kg/ha @ 10 kg/ha @ 10 kg/ha @ 10 kg/ha @ 10 kg/ha @ 10 kg/ha
Black Oat and Radish
Black Oat and Radish Black Oat and Radish Black Oat and Radish Black Oat and Radish Black Oat and Vetch
24m
@ 20kg/ha
@ 25 kg/ha @ 25 kg/ha @ 25 kg/ha @ 25 kg/ha @ 25 kg/ha
Oil Radish (Adios) @ 20 kg/ha
Oil Radish Oil Radish (Adios)
24m
Oil Radish (Adios) @ 20 kg/ha Oil Radish (Adios) @ 20 kg/ha Oil Radish (Adios) @ 18 kg/ha
@ 20Kg/ha @ 20 kg/ha Oil Radish (Adios) @ 20 kg/ha
Straw Rake DD
12m
Straw Rake DD
DD DD Straw Rake DD Straw Rake DD
12m
Subsoil + Karat Plough
12m
Karat (Deep) Karat (Deep) Ribbed Roller DD Flatter Roller DD
Deep Deep
12m
Subsoil + Karat Karat (Shallow) Plough Ribbed Roller DD
Shallow Subsoil +
24m
Plough Plough Min-til Shallow Plough
Karat (Shallow)
Plough
Straw Rake (direct drill) photo 4/11/2014
Compaction obvious and very easily
smeared
Phacelia (photo 4/11/2014)
• Very good system of lateral roots produced
creating a good crumb structure, within top 10cm
• Lacks the ability to break through any
compaction below 10cm.
Black Oat and Vetch (photo 4/11/2014)
• Very good crumb structure established,
combination of both lateral and deep roots from
the two different species present.
• Breaks through compaction well.
Lemken Karat combination used for cover crop establishment
And now with 6 years data, across 618 plots
drilled, assessed and harvested
+ How did the cultivations and catch/cover options perform in gross
margin when averaged across all of the crops over the years……?
And now with 6 years data, across 618 plots
drilled, assessed and harvested
+ The best of cultivations (6 years mainly plough-based) averaged £620 per year
+ The worst cover crop (Oil Radish) averaged £389 per year
A reduction of 37% gross margin
+ However, this is in a blackgrass situation and whilst we are struggling to see the
absolute value whilst using cover crops to combat blackgrass, are we alone….?Added value fallows: the use of customised cover cropping approaches within integrated grass weed management (NIAB/Rothamsted)
And now with 6 years data, across 618 plots
drilled, assessed and harvested
+ Mustard or phacelia averaging around £70 - 80 per hectare lower, is
this a cost worth paying for ‘sustainability’……?2019/2020 Catch/Cover Crop and Cultivations Trial (Stow Longa) + Organic matter build-up after six years?
% organic matter
Maybe….?!Organic matter % Stow (Airfield)
Black oats +
Av of Cults Direct drill Mustard Phacelia Oil radish Oil radish
2018 4.5 4.9 5.4 4.4 4.9
Sampling issues in 2020?
2019 4.2 4.2 4.4 5.1 4.8 4.8
2020 3.8 3.3 4.0 4.4 3.5 4.3
Range 0.7 1.6 0.4? 1.0 1.3 0.6Something ‘measurable’ which is important
Soil Health – Solvita test as an indicator… (11/11/2019)
Karat Deep one Straw rake Back Oat +
Plough pass Direct Drill Radish Phacelia Guidelines
pH 8.0 8.0 8.0 7.9 7.9 6.5
Organic Matter (DUMAS) (%) 3.9 3.7 3.3 4.3 4.4 3
Organic Carbon (%) 2.3 (59%) 2.2 (59%) 1.9 (57%) 2.5 (58%) 2.6 (59%)
C:N Ratio 9.9 10.2 10.7 10.0 10.2 10
C.E.C 26.6 22.6 24.3 27.9 24.3 15
Texture Class Sandy Silt Loam Silty Clay Loam Silty Clay Loam Clay Loam Clay Loam
Phosphorus (ppm) 7 9 10 9 10 16
Potassium (ppm) 212 197 233 239 225 121
Magnesium (ppm) 65 65 77 91 81 50
Calcium (ppm) 6065 5160 5495 6269 5480 1600
Sulphur (ppm) 12 11 4 4 5 10
Sodium (ppm) 31 35 47 50 49 90
Boron (ppm) 3.1 2.69 2.92 3.26 3.15 1.6
Copper (ppm) 6.0 5.6 6.2 6.5 5.9 4.1
Iron (ppm) 203 272 342 233 213 50
Manganese (ppm) 38 65 62 53 52 100
Molybdenum (ppm) 0.25 0.23 0.25 0.26 0.25 0.2
Zinc (ppm) 3.4 4.2 4.9 5.7 5.3 4.1
Black Oat +
Plough Karat Direct Drill Radish Phacelia
Micro Biomass (mg/kg) 932 1152 1328 1438 1834
Potentially Mineralisable
Nitrogen (kgN/ha) 28 33 37 43 54Measuring the soil microbiome and its impact on plant health, future developments + Soil samples were taken from the different cultivation cover crop plots and sent to CEH who carried out DNA sequencing to identify bacterial, fungal and other eukaryote species present and populations + To assess the impact of change caused by cultivation and cover crop the relative populations were plotted out against change in organic matter content of the soil on to a “Non metric dimensional scattergram” + A number of known plant beneficial and pathogen microbes were tagged to see how they had changed with cultivation practice and cover cropping
“Altogether, our micro-biologists identified an
Molecular analyses impressive 62,000 different bacteria,
Graphs are - XY Non Metric dimensional scattergram 2000 different fungi and 4000 different
Contours – are % Organic matter eukaryotes in the Stow Longa microbiome,”
reported Professor Pywell - CEH
Bacteria (16S rRNA gene) Fungi (ITS region) Eukaryotes (18S rRNA gene)
Large difference between “control” and “cover crop” treatments, irrespective of marker gene.
Community differences could be driven by change in Organic matter.
Tillage regime also likely a factor: “Straw rake” similar to Cover crop treatments.
Any stats needs to take account spatial arrangement of experiment, and ideally would have additional soil parametersReduced tillage Cover Crop
Examples of - no Cover Crop + min tillage
Changes in Plant
Beneficial and pathogen
No Cover Crop/
Karat (shallow)
Microbes found in the
Conventional
natural fallow
Karat (deep)
straw rake +
Black Oat +
Oil radish
Mustard
Phacelia
plough
Radish
Soil samples from Effect on
crop
Stow Longa
Soil Organic Matter
Many of those present are
not known to effect the
Possible beneficial
microorganisms
crops currently being Bradyrhizobium N fixing
grown in the field but were N fixing
Verrucomicrobia
chosen as have been
typed. Takeall
Metarhizium decline
Phytomyxea Club root
Pathogens
Potential
= population Increase Plasmodiophora
cabbage
club root
= population decrease Pythium A & B & C Root rot –
beneficial
subspecie
Pythium D
s?
?
Very early days as yet with many species to look at and also to start understanding the huge number of Interactions and
the how we can best manage our soils to get the soil biome to work with us in producing healthy and nutrient efficient
crops.
This work does show the potential of what could be possible.
In Autumn 2019 the work was expanded with CEH looking at 400 samples across Farms under different cropping, tillage
and organic amendment regimes.Summary of catch/cover crop trials 2015/20
Over the course of this experiment we have Gross margin analysis – do catch/cover crops pay at
drilled, assessed and harvest 618 plots, so Stow Longa?
robust data?! - No
Can we get any control of blackgrass from Any yield increases from using cover crops?
cover crops? - Not reliably at Stow Longa on a heavy land site with blackgrass,
- Yes, possibly but certainly not guaranteed but good results on lighter land without grassweed issues….
Do cover crop species give improvements to
soil structure? Are cover crops really contributing to soil health and can
this help with sustainability going forward?
- Yes if established well, but this does not
- Very good indications that they do deliver soil health longer –
necessarily lead to absolute responses in yield over term, but this is still being measured…
cultivations…
Which species will dry the soil best for late Is there another option in cover cropping which would
autumn and spring drilling? lead to more robust competition in a grassweed situation,
- Phacelia and Mustard amongst others N capture, increase soil structure and health?
- Clover species are being currently investigated as a perennial
How do we best establish the different mixes? option under the Agrii ‘Green Horizons’ initiative
- Good seed/soil contact and drill early!OK what about other soil and types and other
situations?Summer cover crop, Buckwheat, Phacelia, Vetch Banbury near Oxford: Medium / light soil
Strip cultivated and drilled with Buckwheat, Berseem clover in August, ready to drill Sugar Beet into the strip the following spring. Suffolk: Medium soil type
Undersown clover between maize, holding soil structure allowing following wheat crop to be drilled into the clover. Worcestershire: Light / sandy soil
Crimson clover along with buckwheat as an OSR companion Cotswolds: Light brash soil
Companion with OSR to remain as semi permanent cover, first wheat drilled direct into the clover. Lincolnshire: Medium soil
The effect of two years white clover in the previous cereal crops as a companion. Removed in year 3 and planted with OSR, 30 kgs free N ( GAI 2.4 v 1.8 )+++
The effect of two years white clover (left of the yellow line) in the previous cereal crops as a companion. Removed in year 3 and planted OSR, 70 kg free N !! ( GAI 2.77 V 1.10 )
Beans, vetch, linseed, phacelia, radish drilled July into stripped wheat straw. Kent: Light brash soil
Hairy vetch, stubble turnips, radish drilled early August, picture taken December Cover set up ready for grazing with sheep. Kent: Light brash soil
Vetch, Berseem clover, Phacelia drilled early August ready to graze with sheep end November Lincolnshire: Medium/ light soil due to be drilled spring barley February
X
Back to the start point.. What? How? Why? What are you trying to do with a cover crop Which species / when When to sow How to establish When and how to remove Why put more costs into the system Monetary value Carbon value Organic matter Trapping nutrients
Throws Farm Cover Crop Trials Summer 2021 + Summer cover crop species explored + Establishment techniques + Following crop establishment + Nutritional values + Soil organic matter level changes + Carbon footprint discussions + Carbon sequestration
Thank you Any questions? You can find me at steve.corbett@agrii.co.uk
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