Prolonged periods of drought and then sudden downpours of rain are becoming increasingly common weather patterns around the globe. Where there used to be a more consistent and steady flow of the changing seasons, we are now experiencing more extremes on both ends of the scale.
Extremes in weather cause challenges for all ecosystems. Plants and animals are having to get used to drought conditions, then sudden flood conditions as well as fluctuations in temperature. On our farms, going from drought to rains can cause havoc to our soils with heavy rains unable to percolate into the parched ground resulting in soil erosion, crop damage and flash flooding.
A Professor from the University of Reading in the UK demonstrated how water soaks into the ground in different conditions. It really shows how ‘heatwave’ drought conditions seriously affect how the water gets into the ground. If water cannot penetrate the soil it will result in more overland flow which can lead to flooding especially if the rains are heavy.
Unfortunately, with climate change, these extreme conditions are going to become more common so we will have to adapt our farming practices to make the most efficient use of the water when it comes.
Why does soil lose its water holding capacity?
Soil retains water by holding it in its pores – the number and size of pores is dependent on the soil type. For example, water is held more tightly in the fine particles of a clay soil or within organic matter, whereas sandy soils have coarse particles that water runs through more readily.
When we experience drought conditions, even a soil with good water retention properties struggles. As the soil dries out the pores in the soil shrink and it can become compressed and cracked.
Ideally the rain we would receive after a dry period would be slow and steady, gradually dampening the soil and increasing its water holding capacity. However, due to extreme heat it is common to experience thunderstorms and heavy rain following drought – the worst combination.
Sudden rainfall will likely run-off over the surface of the soil (especially on sloped land) or divert down the cracks in the soil leaving large areas of soil without water.
Things you can do to increase the water holding capacity of your land
There are a few things you can do on your plot when rain is imminent, add organic mulch around your plants such as grass cuttings, compost or woodchip. This will help to trap water around the base of your plants and give it some time to percolate into the soil. The more water you can get into the soil, the better it will be at retaining further rainfall.
If you have open patches of ground with grass or similar crops on them you can gently spike the earth to create more holes in the ground for water to run into rather than running over the surface.
Dig furrows around your plants or rows of crops to catch water instead of it running off straight away – do be careful not to damage the roots of your plants in the process as they are already in stress.
Get some seeds into the ground ready to be watered in by the coming rainfall, this will save you having to water them in – plants like lettuce or spinach are great for this as they are fairly fast growing and prefer the cool weather after rain.
Preparing for drought in future years
The best way to improve the water retention of your soil in coming years is to increase the organic matter in your soil and the soil diversity. Plant a range of crops and avoid a monoculture. Also plan to rotate your crops around your farm each year. We have some more specific tips on how to get the most out of your soil on our blog here.
Where possible don’t leave ground bare, look into planting cover crops that can help to shade your soil, retain water and provide nutrients for the land while it is not under food crop. This also helps your soil to not become compacted by people or animals walking on it – anything you can do to reduce soil compaction will help with reducing surface runoff.
You can also plant specific ground cover plants around your vegetables such as clovers, these have the same effect of helping to improve soil structure and water retention, but also help to reduce evaporation when there is at least some rain. Leaf cover also helps keep soil cool – most vegetables like to grow in soils at 20-25 degrees celsius, but dark compost soils can quickly retain heat and reach temperatures of double this. Plant roots and soil microbes alike struggle to survive in this environment.
Other things to do to make the most of rainfall
Everyone growing produce should be collecting rainwater to store as reserves for dry periods. During a drought is a great time to make sure that these are in good condition, that gutters leading to waterbutts or tanks are clear and there are no blockages stopping water from reaching your storage areas. If you have impermeable pathways on your land you can also look into diverting runoff from these into the ground or a downhill storage area.
Look for other containers that can be placed outside to capture rainwater, fill your watering cans with water from your storage tanks to ensure that you can capture as much as possible in them when the rain falls.
Irrigation from harvested rainwater
Once you have a good collection of rainwater on your farm you will be better prepared to get through future droughts. Tips for irrigating effectively are much like making the most of the rain. You want to make sure that you are irrigating slowly and gently to the as close to the base of your plants as possible. This will ensure that the water you are adding to the land does not simply run off taking soil and nutrients with it.
Futurepump solar irrigation pumps have been designed to work with drip and low-pressure sprinkler systems to provide a steady supply of water to your crops without flooding the land. You can check out our range of pumps at shop.futurepump.com