Data-driven allotment: GRI 13.2 - Climate adaptation and resilience
Introduction
This is one of a series of posts about one of my favourite topics - my allotment! And more importantly, how green it really is, using a selection of topics from GRI Standard 13: Agriculture, Aquaculture and Fishing Sectors.
I am a big believer in learning by doing, so when the Global Reporting Initiative released its standard for the agriculture, aquaculture and fishing sectors in 2022, I thought the best way of getting to grips with it was to try to apply it to my allotment. As I’m sure you can imagine if you’ve ever reported under the GRI standards, this was a challenging task. Firstly, quite a few of the topics simply aren’t applicable (or ‘not material’ as the Standard itself puts it), For example, I don’t keep livestock on the allotment so I don’t have anything to say about 13.11 - Animal health and welfare. Others I can address, but only indirectly, so whilst I don’t use pesticides, I can think about 13.6 - Pesticides use through the lens of ‘organic’ alternatives to conventional pesticides. You can find a complete list of the standard’s topics and which ones I have decided are immaterial or of limited applicability here.
Perhaps unsurprisingly, given my interest in horticulture and food systems, I am also interested in the ‘business’ side of the allotment - i.e. doing a very basic cost/benefit analysis. As I worked through the topics, it also became clear that this information was relevant to topics like 13.3 - Food security and 13.21 - Living income and living wage. Ultimately, I’ve ended up recording both environmental and financial data, some gathered myself and some from reliable sources like the Met Office and the Soil Association. The different types and sources of data are summarised here.
Whilst I have made every effort to be as thorough as I can be about this process, it’s important to remember that this is just an intellectual exercise for me, and I make no claim to the sort of scientific rigour that large food-producing businesses have to put into their reporting.
On to the interesting bit…
This month’s focus is GRI 13.2 Climate adaptation and resilience. To be honest, I wasn’t sure whether to try and cover this topic. It is, I would say, one of the hardest issues to address directly as an individual, decidedly small-scale crop producer. To an extent, I think the adaptations I can realistically make are covered by previous posts on economising water use and expanding the genetic diversity of the crops I grow. I have also mentioned previously about saving seeds wherever possible – this is partly a financial consideration, of course, but it does represent a very slow sort of adaptation as well, in that saving from plants that thrived in my growing conditions does theoretically mean selecting the genetic lines that are the best-adapted to those conditions.
The Standard does recommend reporting on financial implications and other risks and opportunities due to climate change. This is quite an interesting question, but one that’s hard to explore based on the data I collect and the way I collect it. I could think about increasing the proportion of higher-value crops in my mix – for example, my biggest ‘earners’ in 2023 were the cherry tomatoes, rhubarb and runner beans. Of these, the rhubarb is probably the one that I could increase the amount of without generating lots of extra maintenance work. But then, could you live off rhubarb alone? Probably not, so this would mean compromising on the food security aspect of the Standard. Reducing the diversity of my crops is not only counter to a healthy (and interesting!) diet, but also to the need for biodiversity. It would also be a gamble, as rhubarbs are generally quite thirsty plants, so growing more of them would increase the water requirements – a resource that may be in short supply before too much longer.
I’m fortunate enough to be charged a flat rate for the water on the plot, though for a real farm, the price of water would be a major consideration. Increasing the organic matter of the soil, particularly using manure, can help retain water in the soil during dry spells, but it’s a lot of labour, and sourcing that much organic material would be challenging – and expensive – for me as someone without access to livestock. There are some swaps that can be made to reduce water requirements – for example, chards are generally more drought-tolerant than lettuces, so if you want to produce leafy crops, that might be one viable swap. Water can also be concentrated during fruiting time, when plants are the most prone to a sudden lack of water.
The Standard recommends that reporting should “Describe the climate change-related scenarios used for identifying the risks and opportunities posed by climate change.” Now, I am not a climate scientist or modeller, so I speak from a non-expert position, but as I understand it, there is still some uncertainty around what exactly the effects on weather patterns of these changes will be, especially at a local level – climate change is as much a problem of destabilisation as it is one of increasing temperatures. However, the UK Met Office has helpfully produced a really easy-to-understand guide to the potential impacts. Alongside a longer growing season (potentially quite a good thing), they predict:
Warmer and wetter winters
Hotter and drier summers
More frequent and intense weather extremes
Having picked this as my most likely scenario, it seems like the logical thing to do is go through each of these outcomes and see what impact this might have on the way I grow.
Warmer and wetter winters
On the face of it, this might almost sound like a good thing. I don’t tend to grow crops over winter any more, instead focusing on green manures to help replenish the soil. Theoretically, a warmer winter should make it easier to overwinter certain crops, like leeks and cabbages. Of course, the varieties of these generally available as seeds in this country have generally been selected for hardiness in harsher winters already, but every little helps, right?
Well, there are downsides. For one thing, some plants need a cold-triggered dormancy period before they will crop the following year. I don’t tend to grow these – even garlic I tend to leave in the polytunnel over winter. But it could potentially disrupt the growth patterns of some of my fruit bushes. Deciduous bushes, like my blueberries, drop their leaves during the winter, then wait for warming temperatures before starting to leaf again in the new year (around about now, as it happens). If winters get too warm, they might be tricked into budding too early and then losing all their growth in the spring frosts that will inevitably come. This isn’t normally deadly for the plants, but it does mean wasted energy. It can also interfere with fruiting – strawberry blossoms that are touched by any frost won’t actually produce any fruit, for example.
Then there’s the pests and diseases to consider. Warm, wet conditions are ideal for fungi like the Phytophthora infestans that causes potato and tomato blight. The spores of this fungus are dormant in the soil over the winter, waiting for new potatoes and tomato plants to be put in. They may be spurred on by warmer, wetter conditions, to devastating effect, especially if these conditions come when the tubers have just gone in the ground, so are particularly vulnerable.
These are two issues that it’s not really possible to make any adaptations for. I could cover my fruit bushes with fleece when frosts are predicted, but honestly, I don’t have the time to go down to the plot and do that at a moment’s notice. One change I may be able to adapt to, however, is the effects of increased winter rainfall on the soil. The difficulty here is that the soil tends to be more barer over winter, so when the rain strikes, it can cause soil erosion and compaction. This is something I have attempted to adapt to by covering as much of the plot as possible in a green manure over the winter. You can see the effects here:
Notice how there seem to be so many more stones in the uncovered bed – there aren’t actually more stones (the beds are right next to each other and have undergone pretty much exactly the same cultivation methods), it’s just that in the uncovered bed, the rain has compacted and washed the soil off the stones, exposing them.
Hotter and drier summers
This is probably the biggest challenge, however. As I’ve previously noted, East Anglia is one of the driest regions in the country, and we don’t have an unlimited supply of water (contrary to what all the flooded fields I see around might suggest). Again, as previously noted, I have been making some changes to reduce my water consumption, but I thought I would take a moment to review which of my veg are the most sensitive to hotter weather and reduced rainfall:
Vulnerable
Cabbage (plenty of water needed whilst establishing and during head-formation)
Cauliflowers (need water to prevent heads splitting into smaller less-productive florets)
Potatoes (especially during tuber formation – dense foliage can prevent water reaching soil)
Runner beans (need lots of water whilst forming pods, which they do very prolifically – prefer wet cool summers)
French beans (similar issues to runner beans – could perhaps be mitigated by growing dwarf versions that don’t have to support so much vertical growth)
Lettuce (famously need lots of water to prevent bolting – may need to be switched for another leaf crop)
No change
Kale (need water whilst establishing, but generally quite tolerant after that)
Carrots (generally quite drought resistant, though sustained high temperatures can cause bolting)
Chard (as mentioned above, this is a potential alternative to lettuce)
Peas (some water needed whilst establishing and during prolonged dry spells)
Pak choi (do need plenty of water if grown during summer, but I tend to grow them as a late-season crop, when there is generally more rain – this may change if the growing season keeps getting longer)
Mooli (similar to pak choi, I tend to sow these later in the year)
Tomatoes (need consistent watering to prevent the fruit splitting, but I grow these in my polytunnel, so they aren’t generally subject to changes in rainfall anyway, as all their water is applied manually)
Benefit from changes
Garlic (sitting in water once bulbs have formed can cause rotting)
Shallots (similarly, susceptible to rot in damp soil once bulbs formed – watering during late summer can impact storability)
Onions (same as shallots)
So in conclusion, I will need to take care over the brassicas, potatoes and beans. I will also need to think about replacing the lettuce crops, either with another leaf crop like chard, or by switching to a non-heading ‘cut and come again’ variety. Because these are picked gradually, they don’t need to build up and maintain such a mass of water in their leaves at any one time, so they shouldn’t be quite so susceptible to drought. Alternatively, I could just grow some salad leaf shoots on the window sill at home, where the growing medium is not so prone to evaporation. It definitely takes up more space though!
More frequent and intense weather extremes
This is a tricky one to plan for – these sorts of extremes are, by their nature, unpredictable. Rather than trying to plan reactive measures, the best option is probably to try and proactively build resilience into the soil. At one end of the extreme – prolonged dry spells and droughts – hopefully my efforts to increase the organic matter content of my soil will improve its water retention, providing something of a buffer against prolonged periods of no rain. Similarly, I am planning to make use of ollas this year, in an effort to retain water in the ground amongst the crops most vulnerable to drought, like the beans.
As for the heat, there’s not a huge amount I can do. I can try to shade some plants, and some vulnerable plants like the brassicas should benefit from the limited shade provided by the anti-insect netting that covers them. I can also open the various flaps of the polytunnel to allow the air to flow through and hopefully prevent scalding of the tomatoes and various seedlings growing in there. But that’s about it, as far as I know. I can’t grow the sorts of large trees or hedges that would cast more cooling shade, nor can I install a pond to lower the ambient temperature around my plants (both methods being used to cool cities).
And at the opposite end of the extreme – heavy downpours – adding organic content to the soil should also lighten it a little. One of the biggest problems with the heavy soil we have in my area is that it tends to get waterlogged during heavy rain. A higher organic content should help lighten the soil a little and improve the drainage. The effects of this make take several years to be seen, so it’s definitely a long-term project. In addition to covering the ground with green manures during the winter, I am experimenting this year with introducing ground cover around actual crops. For example, I am planning to underplant my brassicas with red clover. This should hopefully help soak up any excess rain, then slowly release it back in the soil. Again, time will tell with this.