by Sally Morgan
Our small hugelkultur bed has a base of logs and branches, which were then covered with woodchip and a thick layer of compost.
Compost teas
A compost ‘tea’ is another source of nutrients and can be used as a boost for cropping plants. It also helps to beat disease-causing organisms by adding beneficial ones. It is made by adding some good bacteria-rich compost or some vermicompost (worm compost – see below) to a container of water for a couple of days, and the resultant liquid is used as a foliar spray. Some users claim that a compost tea can boost yield by 10-20 per cent.
To make a tea you will need a large container, such as a 20-litre bucket (approx. 4 gallons / 5 US gallons), an aquarium pump, tubing, air stones, a long stick for stirring, molasses, a source of microorganisms such as a good compost, and something to strain the tea, such as old tights or a pillowcase. Aeration is key, as the organisms will quickly use up the oxygen and the liquid will become anaero bic. If you are using tap water, let it stand for a day or so to get rid of the chlorine. Half-fill your container with your compost and connect the air stones to the tubing and pump, making sure they extend to the bottom of the bucket. Then, add your water so that it comes to 10cm (4") below the rim of the container. Start the pump and aerate the liquid. After 10 minutes, add about 2 tablespoons of molasses and stir. This will feed the bacteria and boost their growth. Leave to bubble for 2 to 3 days, stirring vigorously a couple of times each day to stir up the compost. Don’t leave for any longer without feeding again. Turn off the pump, allow the compost to settle and strain the liquid to another container. You must use the tea straight away, while it is full of beneficial microorganisms, and don’t waste the solids. They can be mixed into soil or popped back on to the compost heap.
A bacteria-rich compost tea is claimed to be effective as a foliar spray to combat many diseases, especially those carried by airborne spores that land on leaves, such as mildews and blight. But don’t spray compost tea directly on to leaf crops that are to be harvested within 2 to 3 weeks, as there could potentially be harmful bacteria in the liquid. Compost tea can be applied to seedlings at the two-leaf stage to reduce disease such as damping off, and then again at 2 months to give them protection from other diseases and pests.
Wormeries
Kitchen waste cannot be fed to your animals, because of the risk of transmitting disease, but much of it can be either popped on your compost heap or fed to worms. A wormery is simply the name for a colony of worms living in a container and feeding on organic matter. Their activity converts the kitchen waste – such as vegetable peelings and rotten fruit, bread and cooked food such as pasta – into a fine compost, while the water content of the fruit and vegetable matter is released and can be collected as a nutrient-rich liquid to be used as a plant feed.
These worms can be kept in any one of a range of different types of container, from an old plastic dustbin or water butt to a purpose-made multilayered system with a sump for collecting the liquid waste. A wormery needs to be kept in a sheltered place, out of direct sunlight, where the temperatures will be constant: for example, a garage, a shed, under a lean-to or in a shady spot on the plot.
Compost worms are different from earthworms, which prefer soil. Of the several types of worm found in compost, those used in wormeries are usually tiger worms, also known as brandlings (Eisenia fetida). When setting up a wormery from new, you can order a supply of worms to get the whole process started. If you have a multi-layered system, you place some old compost or coir as bedding on the bottom layer and add the worms. Water it a little, so it is moist but not wet. Then add the kitchen waste, starting with a thin layer. Then, at weekly intervals, add more food, small amounts at a time and preferably shredded, as this is easier for the worms to manage. Don’t keep on adding food if the worms are not coping with it – a thick layer of rotting food will only create a stench and attract flies.
Tiger worms, also known as brandling worms.
Composting worms tackle most foods, but you should avoid citrus peel, spicy foods, onions, milk products, fats and oils, and any meat or fish, as well as tough materials like nuts or woody stems, as these will be avoided by the worms. To prevent too much liquid coming off, add about 20-30 per cent brown waste such as shredded newspaper, cardboard or even wood shavings. Once one layer is full, add another layer on top. The worms will move up as they search for a fresh supply of food, leaving a fine compost behind. A liquid will start to collect after about 10 to 12 weeks, which needs to be drained off regularly. You can use this as a liquid feed, diluted with water to a ratio of 1:10, as it is very concentrated. The vermicompost that the worms produce is really good for making compost teas (see page 55).
This wormery consists of several layers. The kitchen waste is added to the top layer, where the tiger worms are to be found. When a layer is full, a new one is added on top.
Comfrey
Comfrey is a must on any plot. This attractive plant, a relative of borage, is known as a ‘bioaccumulator’ because its roots grow deep into the subsoil and draw up nutrients. The result is leaves with a particularly high nutrient content, especially NPK. Analysis shows the leaves to be about 17 per cent nitrogen and to contain two to three times more potassium than farmyard manure. These nutrients are released when the leaves decompose. Not surprisingly, comfrey has many uses, in particular in the form of a concentrate feed for plants. But take care – if you grow the wild form of comfrey it will set seed everywhere, and its deep roots make it a devil to remove. Instead, buy the sterile variety ‘Bocking 14'. It establishes quickly, and you can cut it back to ground level several times during the summer months. All it needs by way of care is a bit of mulching or compost to replenish nitrogen in the soil around its roots. It can be propagated by root cuttings.
The spring growth of comfrey can be cut and will soon regrow.
Comfrey tea and liquid feed
For a plant feed, pull off some comfrey leaves and stuff them into a large plastic bottle that has had the bottom cut off. Remove the cap and turn the bottle upside down over another container. As the leaves rot, a very smelly black liquid oozes out into the container. Alternatively, fill a bucket with shredded leaves, pack down and add a weight (do not add water). After a short time, the black liquid will be found at the bottom of the bucket. This liquid has been found to be as effective as ready-made plant feeds. As it is very concentrated, dilute with water by 1:20 before using.
To make a comfrey tea, shred some leaves, place them in a bucket or plastic dustbin and add water. Leave it for a few weeks. The leaves rot, creating a smelly dark liquid which can be drawn off and also used as a plant feed. To replenish, simply add a bit more water and fresh leaves to the bucket, and you will have a constant supply of nutrients for your plants. You can also use the liquid as a foliar spray, and this is believed to help plants resist mildew. It helps to add a drop of detergent for a foliar spray, as this helps the tea stick to the leaves. You can even spray your apple trees with it, to help reduce the incidence of disease.
Often a lack of nitrogen slows down the breakdown process in a compost heap, and this can be overcome by adding an activator. Comfrey leaves make a pretty good compost activator, as they rot down quickly, releasing lots of nitrogen. When you have a plentiful supply of leaves you can use them as a thick mulch around plants such as tomatoes, where the potassium will be of benefit, or put them in a sack and allow them to rot down to form a leafmould, as you would fallen tree leaves in autumn. The leaves can also be used to line a bean trench, where they will rot down and release their nutrients.
Comfrey is also great for animals, as the leaves are about 25 per cent protein (much higher than that found in alfalfa or soya) and also low in fibre, making it suitable for feeding to chickens and pigs. Don’t feed it fresh, as the animals will not like the prickly leaves; instead, let the leaves wilt for a few days or so first. You can also dry it and use it in poultry feed as a nutritional supplement.
More options for liquid feeds
Green manures
A green manure is a ground cover of mostly fast-growing plants, which is sown after a main crop has been harvested. The plants protect the soil and smother weeds. The green manure is either turned into the soil before the next crop is sown, so it can be broken down by soil decomposers, or it’s chopped up and left on the surface to rot down, creating a mulch layer. Either way, a green manure helps to improve water retention and prevent the loss of nutrients by leaching, especially in the case of nitrogen and in particular on lighter soils, and it helps drainage on heavy clays. It also adds some nutrients and improves soil structure too, by adding bulk.
Green manures are cheap and easy to establish, and there are a number of plants that are suitable for the purpose. The choice depends on the time of year and whether the requirement is for protecting the soil, building fertility or both.
Nitrogen-fixing vetches are a good choice for overwintering.
Phacelia sets seed readily if it’s allowed to flower.
Some green manures, such as fenugreek, crimson clover and Persian clover, germinate and create a thick cover in a few months. They are used as a break in the crop rotation and, being nitrogen fixers (see below), they will boost nitrogen levels. Others, such ryegrass, phacelia and buckwheat, can be sown in autumn and left in the ground until the spring. These overwintered green manures are valuable in giving protection from nutrient loss, but they do not boost soil nitrogen significantly, even if they are nitrogen fixers, as the winter temperatures are too low for nitrogen fixation to take place (a minimum of 8°C/46°F is needed). Some green manures, for example lucerne (also called alfalfa) and chicory, have deep roots, so sowing these plants helps to extract nutrients from deep in the soil and to further improve the soil structure, especially on compacted soils.
One of the best ways of boosting soil nitrogen and improving soil structure at the same time is to grow a green manure of nitrogen-fixing legumes such as clover, vetch or lucerne. Legumes are a family of plants with small nodules on their roots which are filled with N-fixing bacteria: the bacteria take nitrogen from the air and convert it to nitrates that the plant can use. It’s a mutual relationship, as the bacteria get sugars from the plant while the plant gains nitrogen. Fast-growing legumes, such as crimson and Persian clover, tend to be used in summer, when the temperatures are warm.
Clover grows quickly and also fixes nitrogen.
Crop rotations
A crop rotation, as the name suggests, is the practice of moving crops from one area to another each year, so they are not grown in the same soil for 2 years running. This helps to prevent the build-up of pests and disease. Crop rotation can also help to control weeds, maintain soil organic matter and ensure that enough nutrients are available to the different crops each year.
There are various rotation systems to choose from, depending on how much space you have and how long-term a rotation you want. They vary from just a couple of years to 8 or more years. Most organic growers opt for as long a cycle as possible, especially when growing onions, and also include a fertility-building crop such as a green manure in their rotations. However, rotations are only a guide and can be tweaked to suit your own needs, so don’t feel that you have to stick to a rigid planting order. It is more important that you have a healthy soil with a rich diversity of soil life than that you slavishly follow a rotation plan. Indeed, some of the latest thinking is that crop rotations are not always essential: those following ‘Natural Agriculture’ systems such as Shumei, for example, will grow the same crops on the land with a no-dig approach for many years.
The main crop groups for a rotation are as follows:
Brassicas: Brussels sprouts, cabbage, cauliflower, kale, kohlrabi, oriental greens, radishes, swedes and turnips
Legumes: beans and peas
Alliums: garlic, leeks, onions, shallots
Potato family: potatoes, tomatoes (also aubergines and peppers, but they suffer from fewer diseases and can be used anywhere in the rotation)
Roots: beetroot, carrots, celeriac, celery, Florence fennel, parsley, parsnips and all other root crops.
When a crop rotation is used, crops that require the same soil treatment are kept together as much as possible, to ensure that they have the best possible growing conditions. This also makes the soil management more straightforward, as it means that over the course of the rotation a whole growing area receives the same treatment. For example, a well-rotted farmyard manure can be added to the soil prior to growing potatoes, leeks, brassicas and marrows, but not on beds designated for carrots, parsnips and beetroot, as the manure tends to be high in magnesium, which can encourage forked roots. It is also linked to white rot in alliums. Lime can be added to the soil before planting if necessary in order to maintain a neutral soil pH, for example added to the brassica beds the autumn before planting to help discourage club root, but it is not spread on potato beds as it can encourage scab. Brassicas are hungry crops, so planting them after a legume crop will mean there should be a good level of nitrogen present in the soil.
Crops such as cucurbits (courgettes, pumpkins, squash, marrows and cucumbers), French and runner beans, peppers, spinach, chard, salads (e.g. endive, lettuce and chicory) and sweetcorn do not suffer from soil-borne diseases, so can be dropped anywhere into the rotation, but it is good practice to avoid growing them too often in the same place.
Crop rotation also helps to suppress weeds, as some plants have dense foliage (courgettes, cabbage and lettuce, for example) and their shade keeps the weeds down. Other crops, such as onion and carrot, are more erect, so do not compete for light. Alternating plants with these different growth habits helps to keep weeds under control over successive years.
Some rotation options
A 4-year rotation is the most common:
Year 1 Potatoes/tomatoes plus squash, preceded by adding manure to the plot
Year 2 Legumes
Year 3 Brassicas, preceded by liming the soil
Year 4 Roots and alliums, followed by manure.
Year 1
Year 2
Year 3
Year 4
Ideally, an equal area is allotted to each group, but in reality there is no point putting aside a large area to grow a particular crop if you don’t like it! Instead, you could keep to the general rotation plan but drop in a larger area of salad leaves or spinach. Also, changes may have to be made mid-season due to failures or problems with the weather. And, should disease crop up – in particular white rot in the allium family – you may need to extend the rotation.
Longer rotations give more balanced soil fertility, a greater gap between crops of the same family, and the opportunity to include green manures to help build fertility.
For example, an 8-year rotation might be:
Year 1 Potatoes
Year 2 Sweetcorn or green manure or mulch
Year 3 Brassicas
Year 4 Legumes
Year 5 Tomatoes
Year 6 Legumes
Year 7 Roots and alliums
Year 8 Squash.
Some crops are perennials and will have a permanent location. Examples include artichokes and asparagus (see Chapter 4, page 75).
Rotations with livestock
Ideally, you should aim to include some of your livestock in the rotation, to boost fertility. This can be achieved on larger plots rather than on small vegetable beds. For example, pigs will turn the soil of a plot, add nutrients in the form of manure, and generally clear the ground. Once the pigs are removed in autumn, any remaining
weeds can be pulled out and the ground can be covered. It is best to use it for hungry crops such as potatoes the following year. After potatoes, the ground can be seeded with a grass mix for chickens. Chickens, too, will add fertility, and they will clear some of the vegetation by scratching the ground. Once the chickens are moved, check the soil pH, as chicken faeces can make the soil acidic, so you may need to add lime. The ground can then be used for crops such as squash, spinach, or even brassicas. Then the ground is cleared and re-seeded with a grass mix, ready for the return of the pigs – giving a 4-year cycle that breaks soilborne disease in crops as well as parasitic disease in pigs and poultry.
This ground has been cleared by pigs. Once they have gone, we rake over the soil as seen here, and cover it for the winter.
Including green manures
Green manures should also be included in your crop rotations. For example, a white-clover cover can be sown under squash or brassicas. The clover will grow slowly during the summer, as it gets shaded by the leafy plants, but will persist. By the end of autumn the white clover will have spread out and created a good winter cover. The following spring, it can be dug in or left in place and the next crop planted into it.