Unit Overview - The aim of this unit is to provide the learner with a knowledge and understanding of the basic principles of soil health, and biodynamic principles and practices of soil fertility building. The aim is also to enable the learner to develop the capacity for the management of soil for crop production.
1.1 Identify the basic components of soil
1.2 Discuss how the process of soil formation is influenced by different factors
2.1 Discuss the quality of the soil on your holding
2.2 Suggest measures for improvement of soil on your holding
1. Describe and proportionate the basic elements / components that make up the average soil.
Soil is a complex mixture of minerals (45%) organic matter (5%) and empty space (50%) which can be composed of water and air in different proportions. There are also micro-organisms in soils. They are found in very high numbers but they make up less than 1% of the volume.
2. Describe the geological origin of sand silt and clay soils
All soils are the result of a combination of weathering of the parent geology and the addition of decaying organic matter over time. Silt is a grainy material whose origin is quartz and feldspar. It is formed by both chemical and mechanical weathering. Mechanical weathering might be through frost shattering or abrasion with other materials. Silt is also known as 'stone dust'
Clay soils are made up of millions of clay particles that are tightly packed together, when exposed to water the particles swell up and stick to each other (cohesion.) Silica is the primary mineral that erodes and changes chemically to produce clay.
Sandy soils are composed of a high proportion of sand (85%) of sand particles by mass. Sand is defined by its particle size which is coarser than silt. The mineral composition of sand is silica and calcium carbonate.
3. Describe how the process of soil formation takes place and include the influence of the type of rock, climate, topography, plant and animal organisms and time.
Soils develop because of the weathering of materials on the Earth's surface. This can happen through a chemical process and as a mechanical process (the breakup of rocks) With the addition of water and temperature and time the soil forms through a combination of weathering and also the addition of decaying material from plant and animal life. Algae can help to form soil by producing carbonic acids which causes rock to weather. They also exude sticky substances which help to bind soil particles.
Warm climates are better for the formation of soils, because the chemical reactions involved happen more readily in higher temperatures.
On the Eyam site, the geological bedrock is gritstone. The altitude is 1300ft above sea level. Many pits have been dug across the whole site which reveal that the soil is brown loam with some clay.
4. Demonstrate how to determine soil texture of a given soil in field location and compare with at least 2 other different types of soil.
This was demonstrated during the seminar.
5. Discuss the importance of the soil food web for a healthy soil.
Beneath the soil surface there are an immense number of living organisms. For example, algae, bacteria, fungi, protozoa, nematodes, insects, earthworms. Each of these living organisms has an overall beneficial effect on the soil. Algae produce carbonic acid which aids weathering. They also produce sticky substances which bind the soil. Bacteria digest organic matter and improve soil structure. They also produce by-products that promote plant growth like enzymes, vitamins and hormones. Fungi are multi celled organisms that grow as long strands or threads. They are decomposers, helping soil structure. Mycorrhizal fungi work in harmony with the roots of the plant to bring in certain nutrients and other beneficial elements. Protozoa in the form of Flagellates, Amoebae and Cilliates eat bacteria and are themselves food for earthworms and nematodes. Nematodes are microscopic worms. In their digestion of bacteria and fungi they release nutrients in a plant ready form. Earthworms have been called 'ecosystem engineers' because of their role in aerating the soil.
6. Demonstrate to be able to prepare a soil sample laboratory test your holding, to interpret the test results and to suggest appropriate actions.
Soil PH 5.9
It is most important as it influences the chemical and physiological processes in the soil and the availability of nutrients to the plants. Very high and very low soil pH's will lock up nutrients making them unavailable to the plants. A soil PH of 5.9 is considered medium.
Copper should be present in the soil at >1.5 and <10 ppm. Copper plays many roles in plants but the two most important areas are nitrogen utilization and lignum formation. Copper improves the plants utilization of nitrogen and the formation of proteins
Boron should be present in the soil at >0.8 and <2.00 ppm taken up by plant roots.
Sodium should be kept below <40 ppm. It is not considered a plant nutrient and high levels can cause problems with salinity, soil structure and uptake of other nutrients.
Zinc should be present in the soil at >2 and <20 ppm. Zinc is one of the eight essential micronutrients. It is needed in small amounts but is crucial for plant development and is a common cause of yield reduction.
Calcium (Ca), is an essential plant nutrient. It should be present in the soils at levels of 430-540 ppm.
Organic matter 9.1
Organic matter is key to soil fertility, and a 'bank account' to the intelligent farmer. Most productive agricultural soils have an OM% of 3-6%. Organic matter is made up of four main components:-
Once considered a secondary nutrient sulfur is now considered an essential macro-nutrient. Sulfur should be available in the soil at 12-25 ppm. Below this plants show signs of sulfur deficiency
Texture classification: Clay loam
Many tests have been carried out on the soils at Eyam. I have conducted most of them, including surface samples and depth samples in a wide range of fields. The samples chosen were tested by NRM laboratories. The process of collecting samples involved using a stainless steel auger, inserted into the ground and pushed down to around a depth of around 15cm. When withdrawn from the soil, the resulting material is tipped into a container. Test samples are taken in a 'W' pattern across the area. Each sample is added to the container. Where possible vegetation / grass / roots are removed. The contents of the container are mixed together and combined to find a good 'average' sample across a whole field.
7. Compare the structural (and growing) qualities / characteristics of sandy, silty, clay, and peaty soils with the help of the following criteria: Use brief descriptions.
Sandy: loses water quickly
Silt: good drainage easily farmed
Clay: poor drainage retains water
Peat: retains water well and mixed into sandy soils for this capability
2. Erosiveness for wind and water
Sandy: easily blown off the surfac
Silt: erodes less easily because of water retention but can erode when dry
Clay: erodes less easily because of density
Peat : erodes less easily because of water retention. Can wash off moorland when acidity preventes plants from taking hold and consolidating the structure eg Peak District
3. Availability of nutrients
Sandy: nutrient deficient
Silt: reasonable nutrients
Clay: low as organic content is poor
Peat: very high
4.Root penetration –up to 40 cm-and development
Clay: poor depending on clay content
Peat: good depending on proportion
5. Retention of organic matter/ humus
6. Leaching of nutrients
Silt: low if consolidated with a green manure crop
Clay: few nutrients in the first place
Peat: can literally be washed off the land when not covered.
7. Availability of nutrients
Peat : very good
8. Ease of cultivations ‘earliness’-seasonal temperatures
Silt: easy but may develop 'crust'
Clay: difficult if clay content high can develop 'crust' Slow to warm up due to clay and water content.
9.Natural aggregate formation up to 40 cm
Clay: Yes and bigger
Peat: Not likely
14. Likelihood of compaction
Sandy: not likely
Clay: very likely
Peat : likely
8. Describe at least 5 naturally occurring plants and their relationship as an indicator for certain soil conditions.
In the environment of Eyam we have elevated levels of lead in the soil. Certain plants can tolerate high levels of heavy metals in the soils. These plants are called 'Metallophytes' Examples that are found in the local area are the Derbyshire Leadwort and Alpine Pennycress. Wild flowers such as wild orchids have also been spotted on the land at the site.
9. Describe at least 5 different symptoms on cultivated plants that indicate a likely nutrient deficiency.
A nitrogen deficiency would be indicated by yellow spindly plants or yellow leaves.
A potassium deficiency would be shown by browning of the leaf edges, poor flowering or fruiting.
A phosphorus deficiency would be demonstrated by slow growth and dull yellow foliage.
A magnesium deficiency would be shown by early leaf fall and yellowing between the leaf veins.
A molybdenum deficiency can be demonstrated in long twisted leaves which are elongated.
10. Describe the role of silica, clay and lime processes in the context of the soil as indicated in the Agriculture course by R. Steiner.
Silica 'organises heat and light forces' (p74 Biodynamic Gardening) It allows plants to develop a strong connection between heat and light which is why it is sprayed at sunrise. It also helps to give crops the perfect shape. Dennis Klocek says that 'as a plant matures the silica forces tend to collect in the part of the plant that is approaching flowering and fruiting'
Clay is a 'balancing agent in the mineral realm' Dennis Klockek. Clay works to aid the solubility of silica and lime into each other. These are earthly forces since clay, humus, manure and such materials promote vigor.
11. Reflect on the working of and the balance between those processes on your holding
Plants at Eyam grew healthily without disease. The imported topsoil mix and proportions of ingredients (see below) was an important balance. Biodynamic sprays were also key to the development of the soil. See building fertility section.
12. Discuss the quality of your soil on the holding and suggest measures for improvement.
At Eyam we grow in raised beds in imported topsoil. We fill the beds with three ingredients mixed in different proportions according to the crops that we intend to grow. These ingredients are:
• General purpose top soil with low fertility but reasonable structure
• High nutrient mix of manure and bark fines called JPR Gold. This is an organic soil improver with nutrients and also the ability to improve soil structure.
• Biodynamic compost made on the holding.
In combination we have found this to be a successful combination for vegetable growing and as long as the correct mix of these ingredients is obtained then the crop quality will be good.
3.1 Describe the fertitility cycle on the holding including the use of Biodynamic measures
3.2 Describe the role of silica, clay, and lime processes.
3.3 Demonstrate how to care for biodynamic plant and or animal composts
3.4 Discuss improvements for biodynamic soil fertility building on the holding
13. Describe the short term and long term fertility building actions on your holding including the use of BD preparations, green manures, wood chips, leaf mould, liquid manures.
BD Preparations are important in building the soil fertility. We spray Horn Manure (500) in Spring and Horn Silica in the Autumn. The former (500) helps with:
• Soil structure
• Stimulating microbial activity
• Regulating acidity
• Stimulating root growth
• Helping with germination
• Breaking up compacted soils
Fertility building in soil can involve long term and short term measures. At Eyam we grow in imported topsoil and we add organic matter to improve the quality. Introducing well rotted manure mixed with bark fines is one such measure. This improves both the structure and the health of the soil. Introducing our own biodynamic compost to the soil also helps with the structure and the general fertility. Beds are never intentionally left empty as bare soil can be subject to the leaching out of nutrients. Bare soil is also a lost opportunity. Green manures cans be planted and these will later be dug into the beds, for example adding vital nitrogen. Further important measures would include crop rotation to balance out the nutrients in the soil over time. For example nitrogen fixers such as green beans might be grown in a bed the year before a crop that requires additional nitrogen.
14. Discuss how you would improve the short and long term fertility building measures
Use of green manures is the principle way I would improve the fertility of the soil. Preventing compaction is a key aspect. The presence of pockets of air within soil is absolutely essential for its health, including water retention and the prevention of leaching of nutrients.
15. Demonstrate how to build a compost heap using animal and/or plant residues including the application of the preparations.
A compost heap should be built on the soil, so that worms are able to access it. The pile needs to be big to generate the correct heat required. Compost needs to be the right balance of carbon rich materials such as straw and soft green materials such as grass clippings. Manure from farm animals can also be added. There are also 6 six preparations to add to the compost heap, Yarrow 502, Chamomile 503, Nettle 504, Oak bark 505, Dandelion 506 and Valerian 507.
16. Demonstrate how to care for compost heaps.
There needs to be a balance of air (provided by turning the heap) water and warmth. If too dry the pile can be watered, if too wet the composition of the compost can be altered with additional dry materials such as straw. If there is an incorrect mixture of ingredients things can go wrong. For example to many nitrogenous grass clippings will produce a very slimy heap. This could be countered by adding additional dry materials like straw during turnings. Many people advocate the covering of the heap with a breathable but waterproof compost fabric. This can prevent the heap getting too wet or too dry.
17. Demonstrate different application methods of composts.
Biodynamic compost introduces powerful fertility into the soil. Different cropping areas require different amounts of compost. Sprouts may require one wheelbarrow for a 10msq area, onions only half. Some crops benefit from less fertility. For example carrots will split if there is too much fertility and therefore little or no compost is needed. On the other hand, greedy plants such as pumpkins can be literally grown straight on the heap as they require high fertility levels. Sifted compost can be used for seed raising but it is important that this is treated with care, as too much fertility can cause seeds to become etiolated and stems may collapse.
4.1 Demonstrate the appropriate use of tools, machinery and implements for soil cultivations
18. Discuss the pros and cons of dig / plough and no dig/minimum or zero till techniques in relation to soil structure and fertility building including the use of natural and artificial mulching materials.
The no dig approach is a positive step towards maintaining the health of the soil food web. There is a very close symbiotic relationship between the roots of the plant and the soil that those roots sit in. That is the connections between the plant and the soil are so profound that they might almost be described as one organism. This has been demonstrated by experiments. The Mycorrhizal fungi work in harmony with the roots of the plant to bring in certain nutrients and other beneficial elements. As time proceeds the soil builds up its network of fungi so that in well established woodland there can be a fantastic network of connections where trees may even use the soil food web to pass nutrients amongst other trees in the local area. There may be some advantages to digging, such as improving the soil structure in compacted soils, introducing air pockets where oxygen and water can penetrate the soil more effectively. It may also be necessary to dig deeper where soil needs the introduction of compost in an attempt to improve heavy clay soils for example.
The obvious benefit of mulching materials is they can be used to deprive light from weeds which may grow up and compete with the crop you are wishing to grow. They may also contribute nutrients to the soil as the mulch rots down. Woodchips are a good natural mulch whereas landscape fabric can be used as an artificial alternative.
19. Demonstrate to be able to manage soil cultivations for crop production on your holding, including the appropriate use of tools, machinery and implements.
The horticulture area demonstrates these processes. It was first developed in April 2019 and continues to crop productively.
© Brantwood Specialist School
Created by Jim Hildyard