Save our Arable Soils
Runoff from UK, washing away 3 mil tonnes of our vital, irreplaceable resource called soil.
The dark brown peaty runoff from hilly rough grazing and moorland (Grades 3- 5) in West needs attention. Where does the silt and peat come from - farm - or grouse land?
The bigger loss from our best lands (Grades 1&2) - is the lighter soil from flat/arable land in the East to North Sea and Channel.
About 2 million hectares (out of total 9m of agric. land) are at risk in mainly arable land of soil erosion According to Environment Agency " There are insufficient data on the health of our soils. Investment is needed in soil monitoring. In England and Wales over 2 million hectares of soil are at risk of erosion and intensive agriculture has caused arable soils to lose about 40 to 60% of their organic carbon. "We currently lack sufficient data to know just how badly our soil has been affected" says Government's 25 yr Environment Plan p43.
Wet weather increasing runoff, esp. on arable land "The amount of soil washed off arable fields – and the associated environmental clean-up costs - showed a twenty-fold increase on average. "
Using this data (from Ecological Economics): "The annual erosion in England and Wales was calculated to be approximately 2.9 Mt a−1 which compares with the 2.2 Mt a−1 estimate given by the Environment Agency (2004). The majority of this erosion was associated with silts and sands, especially on arable and horticultural land, where mean per hectare erosion rates were also highest."
Soil degradation overall was calculated in 2010 to cost £1.2bn every year, mainly linked to loss of organic content of soils (47% of total), compaction (39%) and erosion (12%). How on earth do you put a price to our most valuable resource? We cannot go into the sea collect the silt, sand, clay and peat particles, bacteria, fungi, worms and small soil animals and put them back together.
In the “State of the Environment report (PDF), published June 2109, the EA warns that compaction and the loss of organic carbon are “serious threats to soil health”. The UK has lost 84% of its fertile topsoil since 1850, with the erosion continuing at a rate of 1cm to 3cm a year, according The Committee on Climate Change (CCC) report (2015). " “The most fertile topsoils in the east of England – where 25% of our potatoes and 30% of our vegetables are grown – could be lost within a generation,” said Lord Krebs". The point Krebs makes is that this is our best soils that we are talking about - Grade 1 & 2 land.
Erosion is a concern, as spelt out by Krebs introducing the new CCC progress Report. “The Committee’s evaluation of the UK National Adaptation Programme concludes that urgent action is needed with “farming in some of the most productive parts of the country is at risk within a generation, and higher temperatures pose risks to health that are not being properly addressed. Food Erosion is a major threat to food supply within and within a generation unprofitable says Lord Krebbs Chair of Adaption group of CCC. The rate of loss is much the same as it has been for some time – 1-3 cm/year in East England, but the reasons and evidence for erosion need researching according to Cranfield.
IPPC shows problem with farming is based round oil not soil (Full Report). "Soil erosion from agricultural fields is estimated to be currently 10 to 20 times (no tillage) to more than 100 times (conventional tillage) higher than the soil formation rate." This says that soil erosion is particularly bad in ploughed fields 100X rate of soil formation, while 'no till" isnt quite so bad at 10-20 X to fast.
7 ways to flood proof and improve drainage. "Arable growers need to follow a seven-point plan to improve their soil structure especially if, as expected, new farm support payments will depend on healthy soils. Prof Dungait adds that soil organic matter creates and stabilises soils aggregates, while air spaces are very important in soils to help root and soil biology, aid nutrient update and prevent water logging."
Adam in the BBC radio soap 'The Archers' is worried that soil after their flood is being eroded too easily and reckoning that David Archers’ fields are looking better and wants to know why. It is a good question and we should be investing much more research into this. With Agriculture Bill (May 2020) there was talk about farmers being rewarded more (via ELMS) for looking after soils - but as yet no clear signals - we will need soil health indicators. (More below)
Carbon
There was a paper a few years back Nature by P.Bellamy et al, UK soils have lost 12-15% carbon of their total carbon. They used the National Soils Inventory which has been in operation since the early 1960's. the implication was that this may be due to global warming.
But the finding of Bellamy was NOT confirmed by Countryside Survey Executive (Summary & Chap 2). It did not find any decrease in most soil of the ten habitats – like woodland, bracken, fen & pasture. However there were significant losses from arable soils - those growing crops and weeds.
That 'arable' land (Crops and weeds) is land which is usually (or used to be) ploughed. There was a statistically significant decrease in soil carbon over that last ten years - and last 30 years. The authors clearly did not think global warming was the cause – with only one habitat with reduced carbon. The report spelled out their concerns as being to 'management practices.:
Where is the discussion about this? Apart from Adam. Our cropping land has lost 17% of its carbon in last 30 years. That sounds serious to me. This is across 15 million acres – about 1/34 of Britain’s land. So I did the calculations, and if this loss translated to carbon dioxide emissions, then that would represent a contribution of about 1% of all UKs' contributions. (See addenda for calculations)
Soil Animals
And guess where there are the lowest numbers of soil invertebrates? According to Countryside Survey (Chap 8); arable (ie cropped ) land has half the number of soil invertebrates as pasture. In turn pasture has about half of woodland soils. Their results were hampered by poor extraction techniques* that resulted in a seeming reduction of oribatid mites of nearly 50% in ten years. Arable land is not good for them, but not quite that bad. They have been around for around 350 million years ago so it is hard to see how we could have treated soils that badly.
Oribatids are the most important group of animals on the planet – according to E.O Wilson (regarded as one of most significant evolutionary biologists and 'socio-biologists'). In 1 minute Interview by Roger Highfield New Scientist Vol 203 Issue 2722 19 Aug 2009 p23, he said:
“Saving Earth’s biodiversity will take nothing less than an IPCC for species…We are not making the headway we should be in preventing the destruction of ecosystems and species…Most Americans have only the vaguest notion about any of that, even though they can talk intelligently about climate change. Yet when it comes to the living world they are in danger of losing something they scarcely understand. What are they missing? People see nature as trees, plants and vertebrates. Yet the world is run by little creatures most people have not heard of; 99 per cent of Earth’s organisms are extremely small. For example, some of the most abundant and crucial land animals are the tiny oribatid mites, which are the size of a pinhead and look like a cross between a turtle and a spider. They are a linchpin organism of the environment, but 20 years ago when I set out to identify them no one had heard of them. Back then there were just two people in the US able to identify them. Fortunately one agreed to work with me. Yet we still don’t know what the vast majority of oribatids do.”* Oribatids are hard to extract from soil samples as they curl up in a ball when conditions get dry/too warm. As this is the basis for Tullgren funnel extractions, they have only to be slightly changed to alter the rate of extraction.
Where has all the carbon gone from the soil?
Likely candidates..
1. Ploughing?
Certainly, whenever you plough, carbon dioxide is released. Details. That is why 'no-tillage' systems are popular in organic systems. A law - Environmental Impact Assessment (Agriculture)(England)(2) Regulations 2006 - was introduced to control ploughing up pastures. So why has there been a significant decrease in carbon over the last 20 or so years (we could do with more recent samples as the last were ten years ago). Has there been an increase in ploughing or deeper ploughing in more conventional arable systems??
So I asked some farmworker friends who are out in these fields all day. They said:
“with minimum tillage and strip till the decrease in ploughing has been immense, many farmers have sold their ploughs, those that do still plough only do so rotationally or behind grass.” With blackgrass coming some may move back to ploughing.
“ploughing has probably become less frequent in recent years. We run a plough based system for both cereals and forage maize establishment but many others locally are using either non inversion or direct drilling. Non inversion involves surface cultivation often combined with deeper sub soil loosening. Typically at least 1 pass to create a stale seed bed which is then sprayed to kill volunteers/weeds before drilling. (Glyphosate or other total herbicide?)
Direct drilling typically involves no surface cultivation and seed is planted straight into the previous years stubble. From the technical press it is clear that ploughing is seen as both slower and more expensive by many farmers. The trend towards larger and larger arable units together with a predominance of winter established crops has reduced ploughing, although grass weed pressure and spray resistance has meant that some are returning to ploughing as part of a rotation. But overall it is hard to see how poughing is the problem.
2. Herbicides?
Is is quite possible even likely, that the use of weedkillers (herbicides) - as part of the no-till regime - may be a major part of the problem. Quite simply, killing off weeds - i.e. plants, kills of the herbage that would otherwise go back to the soil for the soil animals to work on - and hold the carbon. Each plant killed is a small carbon capture and storage unit lost. See Digging up the Dirt'
3. Yields?
So what is it? With bigger and bigger yields, lots more food taken off the land, and less left behind? Has anybody measured this?
Adam in 'The Archers' is planting a herbal ley - to replenish the soil. He is now suggesting lambing at the normal time, so that the ewes and lambs rely on pasture, rather than lambed early and fed on concentrates. It will also mean that lost of the carbon from the grass will go back into the soil. Now Adam has to put his money where his mouth is, and invest in the future project.
Hopefully soon, rather than just talking about about worms, he will look at look at all the little creatures – no more than specks, and how they do all the chemical work of keeping roots healthy and breaking down debris. The soil animals we look at in this site make up about the same weight as worms in terms of biomass, it's just that there are a lot more of them as they are so small. They also move carbon around more. I could almost hear Adam saying ‘we’ll send some clods from each farm to Harper Adams – one of the few HE Farm & Food Colleges. They could see whether there is any difference in the little bugs’.
4. Mixed farms
Since the early 1990s, many farmers did away with mixed farming, encouraged by EU funds. Instead of having farms producing both crops and animals, with the animals often put on to fallow land (after harvest) to eat stubble and fertilise land. England used to be a patchwork of mixed farms, but now most farms in England are either pasture or arable. The moves causing carbon loss would fit the stats and timing, but there is no evidence as the effects were not examined.
What is to be done?
We know some will just say ‘organic’s is the answer, but there seems a lot more to it than that. And as Adam is considering there are lots of things which can be done. But who is doing the measuring and working out what is most effective?
NB a lot of research in this area is about the impacts of global warming on our agriculture, not the other way about. So for example the Committee on Climate Change’s Report to Parliament June 2015. ‘Meeting our Carbon Budgets Progress Report 2015 Chap 5 mentions methane and nitrous oxides as contributing to global warming. But it doesnt mention carbon loss and possible carbon dioxide increase. In fact in the Headline indicator table for emissions of agriculture, they say CO2 ‘not applicable’. Nevertheless they say to:
“ Strengthen the current voluntary approach to reduce agricultural emissions: the farming industry should develop robust indicators to properly evaluate the GHG Action Plan. Government should consider stronger measures as part of its 2016 review if it cannot assess the effectiveness of the existing scheme.”
The Agriculture Bill/Act of 2020 puts a lot of emphasis on ELMS - Environment Land Management Scheme as part of the future subsidies. This means rewarding farmers for looking after the environment more. The question is how does this affect soils? The Environmental Land Management Policy (ELM) discussion document (DD), confirms "that soil management will feature among the actions contributing to the delivery of public goods – and raises a number of practical questions about how payments will be estimated and allocated as well as more philosophical ones regarding fairness and enforcement". However, much of the publicity for the measures state there will be 'public money for public goods'. IS SOIL A PUBLIC GOOD? Most of us think so. But apparently not, according to DEFRA who consider soil is a 'natural asset from which public goods flow'. So DEFRA do not consider soil is a public good.
Who should be doing what?
Clearly Countryside Survey think that management practices need to be changed. But which ? How? How has DEFRA responded?
Research Clearly we need more research - in the following areas
The start would be to do the research, but we are a bit short of publicly funded land research these days, having lost ¾ of our research stations in last 30 years.
Have we invested any research into these areas
1. Where has the carbon gone?
2. Is any emitted as carbon dioxide? If so how much and how.
3. How going to measure carbon dioxide emission from soil
4. What are the changes over last 30 years that have contributed to this decline
5. trying to portion blame? Soil emitting because of ploughing, not holding carbon as with cover crops, more product going off land, less waste coming back to land.
6. Has anybody worked out how much better for the land and emissions animals are compared to vegetable production? The blame usually goes to animals - should it?
Addenda
Calculating Carbon Loss
Method 1
Using figures from above which are in g C kg−1? (carbon grams per kilogram soil)
1. How many arable acres? 15.3 million acres are arable in UK. (Wiki)
2. How much does 8cm topsoil weigh? One AFS (old furrow 6-7 cm deep) weighs 2,000,000 lbs = 980kgm (Answers)
3. How much lost throughout UK?
45.6g/kg (from Table 2 above) X 980 kgm 44688 goes to 38.0 X980 kg 37240 per acre ie loss of 7448 kg times 15 million acres = ca 112,000 million kg (112 million metric tons or tonnes) carbon lost from arable fields in last 30 years
4. Carbon dioxide (given off from soil) weighs 3.6667 times more than the atomic weight of the carbon lost from the soil. Call that 410 million tonnes of carbon dioxide come off arable soil..
5. So over last 30 years, 410/30 = 13.5 m tonnes /yr contribution
6. Current (2008) UK emissions of carbon dioxide are about 530 million tonnes per year (Forest commission) So 13.5 m tonnes /yr is over 2.5% of total…
This amounts to About 2.25% of ALL our total GHG emissions.
Method 2
Calculating carbon dioxide emitted from soil as a result of loss of carbon based on 0-15cm figures
1.4.3 Bulk density and soil (0-15cm) carbon stock The mean bulk density of soils (0-15cm) in the Arable and Horticulture Broad Habitat in England in 2007 was 1.25 g/cm3 which when combined with soil (0-15cm) carbon concentration gave a soil (0-15cm) carbon stock estimate of approximately 43tC/ha . This was the lowest carbon stock estimate of all Broad Habitats (See Table 2.9 below)
CS Reports 2007 Chapter 3 Enclosed Farmland
Using the earlier figures to get percentage fall. This translates to 51.6 in 1979, and would amount
51.6 – 43 t/ha (8.6) difference & 15 million acres (= 6 m hectares)
= 8.6 X 6070000 = 52mt lost
Or 52 X 3.66 carbon dioxide emitted = 191 mt CO2
Results
That second calculation is about half the first estimate. That would be due to the depth of soil – about twice as deep in second calculation; so the weight involved was twice the first. I went for 8cm in first calculation, because it was the only depth I could get a weight for and because thought that any carbon loss would be mainly from that top 8cm.
We hear nothing about this carbon loss. (True? Or am I just missing something?) Where is the discussion about this when many others are going on about animals causing carbon in the air. When I raise this, I hear that 1/6th of our arable crops go to feeding animals, I point out that means 5/6ths do not.