Can we use water more wisely for gardens?

With climate change making warm weather and drought conditions more likely, sustainable water use is becoming ever more important. Heat warms soils and when it does rain evaporation is increased.

Sustainable water use is about balancing the use of water with the availability of water sources, while reducing the need to take water from the environment. One way of utilising water in a domestic garden would involve collecting rainwater during the wetter months, with one of the simplest ways being to install a water butt to utilise runoff from roofs and sheds, then using the water collected efficiently with the aim of minimising the amount of waste water. 

Using grey water can be used as a sustainable short term water source during extremely dry spells. Because of pollutants such as soaps and detergents in these water sources, long term use can negatively affect plants' health and it should not be used on edibles or potted plants. Bath water typically contains the least pollutants compared to dishwater or washing machine water. Grey water should be used immediately because of colonisation of harmful bacteria from food or skin particles typically found in these sources.

Retaining water within soils can be achieved in a number of ways. Keeping the height of a lawn to approximately 10cm during hot weather reduces ground temperatures and subsequently evaporation. It also reduces plant stress allowing the grass to develop a deeper root system. 

Mulching is another effective way of retaining water within the soil while also reducing water logging during heavy rainfall. Mulching reduces evaporation from the soil while also suppressing water thirsty weeds. The mulching material is less important, as long as a sufficient layer is used, although biodegradable materials also have the added benefit of slowly releasing nutrients to the soil. Mulching should be applied to bare soil when the surface is warm and moist, ideally in the autumn. This locks in water and prevents water thirsty winter weeds from establishing.

For potted plants larger containers are much better at retaining water. For smaller gardens where larger containers may not be viable you can add water absorbent granules to retain water. Plastic free biodegradable granules are just as effective and widely available.

When establishing new plants it is important to follow the water requirements. These are often stated on the labels or can easily be looked up online. Watering plants too frequently, especially during establishment, encourages shallower root systems and will hinder the plants resilience to drought conditions in the future. Not being watered too frequently encourages plants to establish deeper roots and become more self-sufficient.

If watering is necessary, timing is important. Watering during dawn and dusk when the air is cooler will reduce evaporation and allow the water to penetrate the soil. Watering should target the roots of the plant and you should avoid watering dry tolerant plants. 

Landscaping techniques and choice of plants are just as important as efficient water use. Creating hydrozones within the garden involves grouping plants with similar water requirements in different areas. This allows you to target watering to plants that need it and not overwater plants that don't need as much. Creating an arid zone with drought tolerant plants is a great place to start. Strategically planting taller shrubs to cast shade over water thirsty plants in the evening can reduce soil evaporation.

For more information on some local initiatives and creating a water wise garden here are some useful links.

RHS Waterwise Garden: Sustain Your Garden Through Drought and Flood by Tom Massey

Tom Massey - The water wise garden 

https://www.watersencam.co.uk/

Cambridge University Botanic Garden - Dry Garden, Visit our Dry Garden for water-wise planting and drought-tolerant planting inspiration

RHS sustainable water use

Deep time walk resumed

Last weekend (Sunday 31 May) Arthur (my husband) and I resumed the Deep Time Walk we started back in February. The weather was very warm but we were prepared with light clothing and hats so we were reasonably comfortable. We joined the walk where we left off before at ‘Crofters’ on Lammas land with a snack for lunch. 

Celebrating the last universal common ancestor (4.2 billion years ago).

For the Deep Time Walk 1 metre represents 1 million years. 

The idea behind the Deep Time Walk  is a walk through time with each metre representing a million years, so Earth’s history (4.6 billion years) is represented by 4.6 km. We stop at ‘earth stations’ where (when) there were significant events, either geological or biological such as ‘the great dying’ or the first plants. It is more usual to consider history compressed in time. E.g. the history of the universe (13.8 billion years) compressed into a year as in Carl Sagan’s Cosmic Calendar ) Home sapiens appeared only about 300,000 years ago so this is either about 11 minutes or 6.5 cm. Personally I find the 6.5 cm [300000 /4.6e9) * 1000 (to metres) * 100 ( to cm)] more relatable and the walk with other people is fun because you can get other viewpoints on related issues such as climate change, net zero and how we can adapt. It feels more like a community project and less like a personal problem. Amongst other things we talked about the impact of doing things as a community rather than as an individual.

The Boring Billion 

I learned that there is a period in the Earth’s history called the ‘Boring Billion’ which is about 1 billion years when there were no major climate events, tectonic plate movements or extinctions. However the walk was by no means boring. 

Human impacts positive and negative 

One thing we learn from history is that our behaviour can have huge impacts. The invention of agriculture was massively influential – not only enabling population increase but also modifying climate by removing trees. This has had serious consequences – mostly bad, but we now have examples of practical regeneration projects at community scale where water is captured, and land rehabilitated from desert to agriculture as shown in this video. 

Nature can evolve resilience, given time. 

Life is extraordinarily resilient. For example, our use of fossil fuels has polluted the air with CO2 and acidified the oceans which makes life very difficult for sea creatures with shells as the carbonates that make their shells strong dissolve in acid. However, with selective breeding over time, oysters and other shellfish have evolved protection from the acid (see https://www.stir.ac.uk/news/2019/09/farmed-oysters-able-to-protect-themselves-from-acidification/). The big problem with human induced climate change is that it happens far too fast – even when adaptation is possible.  Slowing it down to the point where nature can adapt fast enough would help enormously. (see https://theconversation.com/cop29-how-fast-is-earth-warming-244093).

Deep Time Walk preview

Yesterday, my husband Arthur (who has been doing a heroic job looking after me through the last year while I have been unwell) and I had a private preview of the Deep Time Walk which is scheduled for 1st March, organised and led by Clara Todd from Water Sensitive Cambridge. We did this partly for Clara to test it out and partly because I was not sure if I could keep up with everyone for the whole walk on the day. In fact we only did half of it – starting with the formation of the Earth (Parker’s Piece) and ending with oxygen-breathing life on Earth, albeit single cell (Lammas Land), in total about 2.3 billion years. That was enough for me, I’m afraid. The framework of the Deep Time walk comes from a team at Schumacher College.

I am writing this to recommend it to you. Perhaps you know it all anyway– but doing it with friends and the opportunity to chat and ask questions (Clara is pleased to take questions and if she does not have the answer maybe someone else will) was fun. Besides which, it is a good excuse for a leisurely walk through our beautiful city.

The walk was designed with 1 metre for 1 million years and we paused at interesting times along the way (Earth Stations) so that Clara could explain what was going on. For example we stopped for

1. Formation of the Earth (4567 million years ago)
2. Formation of the Moon (4450 mya)
3. Ocean Earth (4100 mya)
4. Origin of Life on Earth (3800 mya)
5. First Continents (3100 mya)
6. Oxygenic Photosynthesis (2900 mya)
7. The Great Oxygenation/Snowball Earth (2300 mya) 

Clara has some pictures which are obviously artist’s impressions and not photographs. These and her short explanations are very engaging. 

We took some photos on the day. The weather was fairly dry but it has been very wet recently. We avoided the puddles on Parker's Piece. 

Parker's Piece with Gulls - The weather has been very wet though on the day it was mostly dry; the way was muddy in places but the worst was avoidable. Hopefully by March it will be dryer.

View of the Cam from near Hodson's Folly. It was a grey day but mostly dry.

 I am still not well but Arthur lends me a helping hand when needed.

I thoroughly recommend this walk to you so do sign up for 1st March. 

Why I volunteer for ECCG

I went to an event at Empty Common Community Garden recently and met a lady called Isobelle who has been volunteering there for some weeks. She kindly agreed to answer some questions about her experiences - this is what she said. I hope that if you were thinking about volunteering but not sure, then this will convince you.

When did you first come to the gardens?  My first session in the garden was in late August (24th) this year and I've been every Sunday since. I first came across the garden on a walk last winter, but didn't realise it was a community project in which anyone could join in. I went to a community event by Cambridge Zero earlier in the summer and saw a flyer about the garden there, and then saw the Sunday sessions on the events page on the Transition Cambridge website. 

Reducing the mountain of e-waste

The UK produces about 6 million tonnes of e-waste annually, of which households are responsible for about 400,000 tonnes each year. That's not just phones, laptops, and computers - an ever increasing number of products and appliances now incorporate some electronics, and anything with a plug or battery qualifies as e-waste.

Working with Contractors - update

Depending on what you want to do, retrofitting your house could involve for example changing your heating system or installing solar power. This can be simple or quite complicated, possibly including hiring several contractors, and maybe a project manager too. You may be taking a ‘big bang’ approach or doing it in phases. Selecting competent, reliable contractors that you can trust and maintain a good relationship with is very important. This page is not a step-by-step approach to your retrofit but general advice about how to choose and work with contractors. Much of the advice on this page came from pooled experiences from the Energy Group members and friends.

Improvements in energy efficiency in buildings since 2000

This post is largely based on the article Advances Toward a Net-Zero Global Building Sector in Annual Review of Environment and Resources 2020 [1]. The article is open access so anyone can read it for free. It explores why energy efficiency is important for net zero emissions and charts improvements since 2000 in different regions of the world. It briefly compares the Passivhaus standard with other standards widely used for low energy buildings. The focus is on the UK although much of the evidence comes from elsewhere, primarily Europe.