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I have Volume VI of The Gardener's Assistant with Editor William Watson. Published by The Gresham Publishing Company Limited in 1925 with the following Description from The Oxfam Shop concerning its The Gardener's Assistant (Six Volume Set, 1925):-

"The Gardener's Assistant of 1859 (Chiswick Sept 1859) was by Robert Thompson in a single volume of 774 pages. A new and enlarged edition was issued in 1875. The William Watson edition was "New and entirely remodelled" and first issued in 1900. Subsequently in 1925 William Watson published The Assistant in his own name. As Fredrick Keeble stated in his preface "this work an enduring memorial of his (Watson's) greatness as a gardener. It is right, therefore, that this book should be known by his name. It is true that Thompson laid the foundation of it: but it is no less true that Watson has re-built it, incorporating with skilled hands the new knowledge with the old, and adding ornament in the form of coloured illustrations with arguments not only of beauty, but also usefulness of the work: Therefore over the portals of this treasury of horticulture, his name is inscribed"."

This is a precis of its Soils and Manures chapter in Volume VI with my comments in blue:-

Formation of the soil and its properties.
Soils are formed by the decomposition of rocks, under the influence of air, rain, sun, frost, and the lower plants. In most instances the products of decomposition are partly washed away into streams and creeks, and thence carried into the rivers and into the sea. It is just these, the soluble and the more pulverized parts, which contain most of the available plant food. As the current of the rivers becomes slower, a great deal of the suspended matter sinks to the bottom: first the larger stones and pebbles, then sand and fine clay. Streams and rivers in towns are usually constricted by walls and the flow simply increases through them removing even more material to the sea in 2023.
The matter held in solution in the waters of the rivers, and so deposited, is taken up by the soils with which they come into contact. In this way the valleys receive a large part of the plant food which is formed by the decomposition of the rocks at higher levels.
A part, however, of the dissolved and suspended matter is discharged with the river-water into the sea. The sea often deposits the material thus obtained in the form of sand and clay, the latter forming a soil of superior fertility in 1925. Unfortunately in 2023, England deposits, annually, millions of tons of human sewage, animal sewage, chemical pollutants and microplastics into all its rivers as shown on the Table Waste of Time on the Welcome Page. This makes a toxic mixture authorized by the UK local and main governments to harm the creatures in the sea and the humans who frequent the beaches in England, France, Portugal and Holland or eat the fish / crustaceans from that sea or the English rivers polluting those seas.
The soils obtained from rocks alone, without any admixture of vegetable matter, are not fertile. In order that they may become so, the products of plant growth must be mingled with them. When plants grow on a soil they deposit in their dead leaves and stems the organic matter which they have formed by means of their green leaves. The substance formed by the decomposition of this organic matter is called humus. To this substance the black colour of garden soils is due. In England, since the 1950's householder's have weeded their gardens and left the soil bare. So the humus cannot be replaced. When I do it, I remove the top growth and roots of each weed. When I have cleared an area for that day, I put down a 3 inch (7.5cm) depth of Spent Mushroom Compost. On my next fortnightly day, I check that area for any growth that I do not want; and hoe the mulch if necessary. That mulch will feed the plants in that area, stop the ground from drying out from the sun/wind and reduce maintenance time. When I cut the lawn at the end of the day, I had put the thin prunings on it and the rotary mower slices them into pieces as it does the lawn grass. I use that on top of that mulch to a depth of 0.5 inches (1cm) to give further food - no thicker otherwise the initial fortnight of oxidised decomposition would become too hot. Compost bins in tiny modern gardens in England would be totally useless, so that is why I no longer use them, since I would not produce the necessary amount of prunings to fill a 3 metre x 3 metre x 3 metre compost bin in 1 day. Humus is an organic substance that can be destroyed by fire.
Many of the most important properties of the soil are partly, or almost entirely, due to humus. Vegetation, however, deposits nitrogen compounds as a part of the humus. These compounds are not contained in rocks, but without them no soil can be fertile. By the decomposition of the organic matter of vegetation and of the humus other substances are formed, particularly carbonic acid, that help to decompose the original rocks. Plant roots also, by means of their acidity, actively take part in the decomposition of rocks. At the same time they effectively prevent losses of plant food by surface drainage.

The Soil as a Source of Plant Food
The nitrogenous organic matters of ordinary soils are usually inert and inactive for plant life, their oxidation and nitrification, or, in plainer language, their decay, being too slow to subserve the requirements of the multitudinous individuals that make up the various crops of our farms and gardens. Hence the natural soil lef to its own resources is unable to satisfy the demands made upon it. And even with an abundant dressing of farmyard or stable manure, certain soils may still remain unproductive, owing to the non-nitrification of its organic matter. This may be due to sourness and to the lack of available lime or potash.
We get a fairly correct idea of what takes place in a soil in regard to nitrification from an analysis of the drainage water percolating through it. Various soils that had received a copious manuring with about 24 tons of farmyard dung per acre, allowing the following quantities of nitrogen, as nitrates, to drain away. For comparison is also given the amount of nitrogen as nitrates percolating through an unmanured soil:

It is seen that in the dunged soil, the greatest loss of nitrogen occurred during the spring months; this was probably owing to the oxidation of the organic matter that had taken place in the winter, and on the approach of spring, there being no growing crops to assimilate it, this very soluble substance was washed into the drainage.
It may be well to note the whole of the nitrogen that is shown to be lost by drainage from our soils is not all available to ordinary plants, for the reason that many of these only assimilate the spring or early summer-formed nitrates, the principal growth and power of assimilation having ceased by the month of July. Thus we find that the greatest loss occurs from September to December, and the least loss from May to August. Root-crops such as potatoes, beetroot, carrots, onions, turnips, etc., may still get hold of summer-formed nitrates, but the nitrates produced in the autumn and winter are of little use to plants. The reduced volume of combined sewage and rainwater goes to the Treatment Plant. From Page 9 of The Times on Saturday April 1 2023 "About 170,000 truckloads of sludge, a mud-like by-product from sewage treatment works, are spread on fields every autumn as organic fertiliser. But the Environment Agency has told the water industry that the practice could be banned from 2025 in a bid to reduce the amount of nutrient pollution that washes off fields and into waterways. As 87% of sludge is "recycled" to agricultural land each year, the step would close the main route for water firms to dispose of the material" from the Table Waste of Time on the Welcome Page. Since there are no root crops to take this fertiliser during the autumn and winter, this is why the nitrates in it are washed away in the drainage water and this adds to the pollution in the rivers. If this sludge was applied to the farmland 1 month prior to seeding or planting the rootcrops in the spring, then more of the nitrates would be used up by those root-crops instead of polluting our rivers during the autumn and winter with 55.6 lbs of nitrates from the sludge per acre. The spring nitrification alone is, as a rule, quite insufficient for the requirements of the crops then starting into rapid growth, hence the need for and value of increasing quantities of artificially supplied manure.
It is very important for gardeners to bear in mind that the nitrogenous capital of a soil, which represents to a considerable extent its fertility and power of yielding remunerative crops, depends as a rule, on the bulk and composition of the previous plant residues. THE PRESENT CONDITION OF A SOIL IS THUS IN GREAT MEASURE A CONSEQUENCE OF ITS PAST FERTILITY.
In ordinary soils the 4 constituents of sand, lime, clay and organic matter are generally to be found. In regard to potash and phosphoric acid, which must be present in an available form for a soil to be fully fertile, it may be assumed that they are dissolved by the carbonic acid secretions from the plants where the roots are in direct contact with these elements. The 3 chief plant-foods, nitrogen, phosphates, and potash, are all obtained from the soil, but the carbon, which is needed to build up the organic structure of the plant, is obtained from the carbon dioxide of the atmosphere.

Nitrifying Bacteria
We now know that the production of nitrates in the soil is accomplished by the action of 2 organisms (bacteria), each of which performs a distinct stage in the work. By one organism ammonium carbonate is oxidized, and the nitrogen converted into a NITRITE. By the second organism NITRITES are converted into NITRATES. The nitrous organism can oxidize ammonia to NITRITE, but it cannot change a NITRITE into a NITRATE. The nitric organism, oxidizes NITRITES readily, but it cannot oxidize ammonia. Both of these organisms are present in all fertile soils, but the formation of NITRITES is not usually perceived, as they are at once converted into NITRITES.
As a general rule in the absence of the element oxygen, one of the constituents of atmospheric air, certain soil bacteria cause decay, splitting or breaking up the organic matter present with the formation of humus, while in the presence of oxygen other bacteria become the active oxidizing agents.
One essential condition for the active process of oxidation and decomposition is the presence of air; an open porous soil is thus far more exposed to oxidation and nitrification than one in a closely consolidated condition; hence arises the beneficial effect of mixing porous substances, such as peat, charcoal and sand with stiff horticultural moulds. The operation of tillage also tend to promote in the soil oxidation of the organic matter, and assist in its nitrification.
A sufficiency of water is essential for the activity of all living agents; oxidation and decay are thus far more rapid in a moist soil than in a dry one. The constant waterings given to plants in a well-conducted garden provide this condition. It must, however, be remembered that a great excess of water is fatal to oxidation, the admission of air being excluded as soon as the soil is filled with water.
Temperaure is another prime factor in determining the rate of oxidation and nitrification in mould; the activity of all living agents, whether animal or vegetable, being dependent on the occurrence of a favourable degree of heat, and being confined to certain specific ranges of temperature. Oxidation is consequently found to be far more rapid in summer than in winter, and much more energetic in hot climates than in cold; accordingly we find it more active in a conservatory than in an open garden.
The nitrifying organism cannot carry on its work unless it is furnished with some alkaline substance to neutralize the nitric acid formed; and in leaf-moulds rich in humus the nitrification is sometimes rendered difficult by the lack of such a constituent, which may be either lime, magnesia, or potash. In a great many fertile soils the conveyance of calcareous matters by the frequent waterings suffices to keep a sufficient richness in lime; (irrigation water from chalk soils contains lime) but in leaf-moulds containing an excess of organic matter the bases rendered soluble by nitrification get rapidly used up, and the moulds in consequence become overcharged with acidity to the injury of the growing plants. It is needful in such cases to apply some basic material, carbonate of potash being preferred (a constituent of wood ashes), which tends to accelerate the nitrification in an extraordinary manner. In some experiments carried out in May and June 1892, carbonate of potash applied as a manure to leaf-mould was found to increase the nitric acid formed by 9.15% in one case and by 5.14% in another, while the addition of lime raised the nitrifying power scarcely 0.25%. When you have mown using the highest cutting height on your rotary mower the autumn leaves from your trees and ones from under the trees in the verges outside your home, mulch your flower/vegetable beds with them and then spray that mulch with carbonate of potash.

The Soil and Water
Since a certain amount of water is necessary for plant life, it is of great consequence that the soil has the power not only of absorbing moisture from the atmosphere, either in the state of dew, rain, snow, or other aqueous deposits, but of retaining this moisture.
Schubler found that after 72 hours exposure to moist air

• humus had taken up nearly 2.5 times as much water as clay, and
• 40 times more than sand,
• which, under the same circumstances, took up 16 times less than pure clay.

In a second series of experiments he placed weighed quantities of the dried soils in funnels, made them perfectly wet by the gradual addition of water, and then left them to drain. As soon as the water ceased to drop from them, the wet masses were carefully weighed. The difference in weight between the dry and wet soils was taken to represent the amount of water that they would hold after thorough saturation by long-continued rain.
The retentive power of the different soils was then determined by exposing the saturated masses for about 4 hours to a dry atmosphere, having a temperature of 66 degrees Fahrenheint (19 degrees Celsius).
The greater the loss of water experienced under these conditions, the less retentive the soils were shown to be.
The following are some of the results obtained by Shubler:-

These differences are mainly dependent on the mechanical texture or porosity of the soil material. In a soil consisting of solid particles of fairly uniform size, the interspaces are about 40% of the volume, whether the particles are large or small; but if the particles are a mixture of large and small (such as gravel and sand), the volume of the interspaces is much diminished. On the other hand, if the particles themselves are porous, as in the case of chalk, loam, and especially of humus, the volume of the interspaces is much increased. It is this volume of the interspaces which determines the amount of water which a soil will contain when perfectly saturated, or the amount of air which it will contain when dry.
The influence of humus on the capacity of a soil for water is remarkable. The surface soil of the experimental wheat-field at Rothamstead was sampled in January 1869, when saturated with water:-

• the unmanured land contained 32.4 of water per 100 of dry soil;
• the land manured with farmyard manure for 26 years contained 65.8 of water per 100 of soil.

Many of the fields used to grow crops in England, have not been fertilised with farmyard manure since the 1950's. I have seen white fields which appear to have lost all their topsoil to become currently just chalk. The treated sludge as fertiliser (45% of the Nitrogen per acre from this fertiliser, then exits the field in the drainage water before the Spring, to cause nutrient pollution in rivers, as shown above) from the privatised water companies may be applied to this chalk in the autumn. The land is left until the spring when crops are sown or inserted for growing in the Spring and Summer. Extra chemical fertiliser may also be applied to make up for its lack and it may have to be irrigated fairly often, since the rain that falls is either evaporated within the next 24 hours or sinks below the roots of the crop. The mineral content of fruit and vegetables in the UK has reduced from 1940 to 2019 - published on 15 October 2021 leading to malnutrition in the UK - "Globally, malnutrition in all its forms is the greatest cause of death and morbidity. In 2017 as many as 11 million deaths annually and 255 million Daily Adjusted Life Years (DALYs) could be attributed to malnutrition, and low intake of whole grains and fruits were important contributors (Murray 2019). Mineral micronutrient malnutrition is widespread but there are insufficient global data to quantify the problem: only anaemia (related to Fe deficiency and other causes) and iodine status are assessed in any detail and the data have not been updated since 2005. Iodine deficiency was estimated at 35% globally (WHO 2004), and the global prevalence of anaemia for the general population was estimated at 25% (WHO 2005). For other essential mineral nutrients, a lack of data means that the full extent of global deficiencies is unknown.
Historical declines in essential minerals in fruit and vegetables (F&V) have been shown in several countries including the UK (Mayer 1997) and USA (Davis et al. 2004). These reductions should act as a wake-up-call for the need to improve food systems to optimise the nutritional value of foods."
Good to know that the government (Department for Environment, Food and Rural Affairs in the United Kingdom is responsible for enironmental protection, food production and standards, agriculture, fisheries and rural communities in the entire United Kingdom) is approving this increasing level of malnutrition through the agricultural production in the UK, and that its food is not as nutritious - and becoming even less so - for both its visitors and its population; than it was before the Second World War.
Percentage change in mineral content of fruits and vegetables in the UK between 1940 and 2019
** is a significant change, * is a lower significant change

Capillary Powers of Soil.
A series of investigations by Zenger show conclusively that the capillary power of soils is greater in proportion as their PORES are finer; but fineness of PORES must not be confounded with fineness of PARTICLES. It is true enough that up to a certain point a soil will have more capillary power in proportion as its PARTICLES are more finely divided; but the moment this limit is passed fineness is disadvantageous for capillarity, since the minute PARTICLES of earth are apt to cohere and cling together so closely that few, if any, open spaces are left between them for the admission of water.
The figures in column 2 of the next table represent the percentage amounts of water that were imbibed by the soils which had been screened to a olerably uniform state of moderate fineness, while in column 3 are given the percentage amounts of water imbibed by the same soils after they had been finely pulverized. It will be noticed that there is but little difference between the third column and the second in the case of soils which are naturally porous.

Wilhelm noticed that a garden loam that naturally imbibed 114 per cent of water could absorb only 62 percent after it had been pulverized.
The power of a soil to hold water tends to retard evaporation from the soil. It appears that plants cannot exhaust the retentive soils so completely of their water as they can the soils which are non-retentive. thus:-

• in a loam capable of holding 52% of capillary water, a Tobacco plant wilted at night when the soil contained 8% of moisture.
• in a mixture of humus and sand competent to absorb 46% of moisture, another Tobacco plant wilted when the moisture had been reduced to 12%;
• and in coarse sand which could hold 21% of moisture, a third plant wilted when the proportion had fallen to 1.5%. Here the Tobacco plant was able to pump the soil almost completely dry.
• In these experiments 44%, 34% and 19% of water respectively were more or less available for the plant.

Different kinds of plants appear to resemble one another more closely than might have been expected in respect to this power of exhausting soils of their moisture, and the researches of Hellriegel have shown that any soil can supply plants with all the water they need, and as fast as they need it, so long as the moisture within the soil is not reduced below one-third of the whole amount that it can hold. Melcourt Industries Ltd planted a bare field with fruit trees in the spring, mulched half the field with bark mulch, then soaked the soil in the whole field. By August the trees in the mulched area during that hot english summer were fine, whereas the ones in the unmulched area were showing severe moisture loss. Melcourt did absolutely nothing except record the moisture loss each month; between April and August, in that field.

Humus or Vegetable Mould
Humus, in the condition in which it is met with in garden soils, is a mixture of remains of plant and animal residues in the most diverse stages of decay. When roots, leaves, wood, straw or dung, lie upon or in the earth, they absorb moisture and gradually become brown and soft, then blackish-brown and crubly, lastly black and pulverulent, as may be very easily traced in the soil covering the ground in forests.
There are 2 kinds of humus known:-

1. "peaty humus" - this is produced in the absence of air. It is very resistant to decomposition and is of acid character. Peaty mould - Peat - is formed on moorland by the decay of the leaves and roots of Erica tetralix, Erica vagans, and frequently also from Erica cinerea, which flourish there, the soil being held together in such a manner by the roots of the growing plants as to allow of its being cut into square blocks, and so despatched for market. To prepare the material for use, it must be broken up and sifted, removing the larger undecomposed roots which hold the mass together.
2. "mild humus" - mild humus is produced by certain bacteria in presence of air. It is neutral in reaction and undergoes further oxidation comparitively readily.This mould - Leaf-soil - is obtained from the forests, and is the result of the decomposition of the fallen leaves mixed with the earth upon which they rest; that obtained from under the oak trees is considered the best. The peculiar property of this leaf-mould is, that it facilitates drainage and aeration, causing a quick and active plant-growth, with a free development of root.The partial decomposing leaves and roots forming the mould require a free passage of air to allow of the nitrification of the organic matter, and, given this, the roots of the growing plants put into it develop rapidly. But as both the drainage and evaporation from such mould are great, frequent waterings become necessary in actual work. The mould has also a large absorptive power: 100 parts by weight of the mould will take up 190 parts by weight of water.
   The fertility of all classes of soil is closely connected with its powers of retaining plant-food, it has been shown that it has a great absorbent power for potash and phosphoric acid, but that nitrate of soda is retained in a much less degree.
   The following table shows the amount of selected chemicals constituent in 100 parts of the finely sifted leaf-mould obtained in France:-
   

Different Soils employed in Horticulture.
Each year a certain portion of the plant growth dies off - leaves and branches fall, and parts of the roots decay. Some of the organic substances which fall upon the surface of the ground returns again to the atmosphere; but a certain part remains and, added to that which decays underground, becomes as it oxidizes, available for future growth. The atmosphere of the soil, which at first differed but little from that which exists above it, becomes highly charged with carbonic acid, which decomposes the minerals - lime, potash, magnesia - in the soil, and thus, year by year, more and more of the nitrogen collected by each generation of plants become available for the generation that succeeds it. The rest of this subsection shows the benefit of leaving this vegetation on the ground where it falls. You will notice that in forests, where the detritus is left alone that this process works, but being such stupid idiots in Britain we weed an area leaving bare ground where those weeds were, we also remove all the prunings and the grass mowings from the property, and then if we are generous we throw different chemical fertilisers at different plants, which dissolves in the rain and washes through the soil to only provide a few days of some nutrients.

What a waste of time trying to educate people who eat with their mouths and they forget that plants eat with their roots, which are built to eat the plant-food as created by the earthworms, fungi, and other life in the soil round them from the decomposing plant materials, not to have that soil life bypassed by the use of chemicals. Even mainstream agriculture is slowly providing us vegetables and fruit in the UK leading to malnutrition for everyone who eats it as shown above.

Organic farms like Riverford Organic Farmers do not use pesticides or artificial chemical fertilisers and so the land increases in fertility through their management, rather than decrease in fertility on farms such as where the topsoil has been washed off leaving bare chalk and everything then has to be grown with chemical fertilisers, pesticides and herbicides.
The following is this week's Guy's News from Riverford Organic Farmers on Monday 14th August 2023:-
'Riverfords first veg boxes, delivered in 1993, were heavy on cabbages, swedes, and chard. It quickly became obvious that to reach beyond the diehard localists, we would need a broader range of fruit and veg, especially in spring and early summer when UK veg is scarce. Over 20 years, we slowly built a group of about 20 growers in Spain, France, and Italy, and I bought a farm in the French Vendee. Today, these farms provide a third of the fruit and veg in your boxes during those difficult months. Trucking (we never air freight) from Europe is a compromise, but by building close, lasting relationships with growers, we are confident that it is socially and environmentally better than the alternatives, with better quality. It is certainly much less carbon intensive than growing in the UK under heated glass.
Over the last 5 years, farming has become steadily higher risk for these growers. In Andalucia, polytunnels were shredded by giant hail. Crops have been destroyed by heat, with lemons cooking on the trees. Freezing winters also kill citrus, and plantations have been lost to wildfires. Everywhere, competition for ever-scarcer water is a growing issue. We recruited growers further north, but Catalonia is now one of the worst affected areas, with restrictions on irrigation that are drastically affecting yield and quality. In Murcia, 40% of water now comes from the sea - but with an energy cost of 3kwh/cubic metre, and issues around marine water intakes and brine discharge, desalination can come with its own environmental costs.
Denying anthropogenic climate change is not an option; we must plan for a changing future. In the Vendee, we lost much of the sweetcorn to drought last year. Having built a new reservoir that doubled our water capacity, the quality and yield this year has been great. We must learn to grow more food from deeper-rooting perennial crops, which can reach water underground; one of our oldest and best growers near Granada is slowly transitioning from garlic, asparagus, and spinach, to deep-rooting, drought-resistant olives. Some crops will need to move north; others will need to be grown under the protection of polytunnels and glass, reducing water usage and giving better control of weather risks. Rather than assuming that we can buy our way to food security in an increasingly fragile global market, we need to plan and invest in the infrastructure that will, at least, reduce the disruption ahead.'

Britain is going to run out of water and there is nothing being done about it - a large % of water is lost by the privatized water companies in its own pipework, another large % of water is lost between their pipework and the stop tap of the customer but these issues are mostly being ignored. The river water that is used to provide the privatised water companies with water to be used to supply its customers is being polluted by a combination of raw human sewage/rainfall onto customers properties as well as microplastics, agricultural fertiliser runnoff and dumped chemicals. When suddenly a large proportion of the UK public has no water, the UK will be stuffed, when you see below as to the current state of the desalination plants in England.
"The UK only has a few desalination plants including in the Isles of Scilly and the Channel Islands. In 2010, a plant was built in Beckton, east London which has the capacity to deliver up to 100M litres of water a day and has been used during dry spells to boost Thames Water’s reservoirs in London.
In 2021, Southern Water scrapped plans to build a £600M desalination plant on the edge of the New Forest in the face of local opposition. The scheme would have used water from the Solent.
After the driest summer in 30 years, Cornwall and other south western regions are still in an official drought. South West Water drought and resilience director David Harris said: "The South West's water resources are under immense and increasing pressure. Our current system relies heavily on rainfall, and climate change has shown us that we need to develop alternative, climate-independent sources of water in Cornwall.
“The South West has 1,376km of coastline, which makes desalination a logical option to explore as part of our additional £45M investment this year in new water resource schemes. We are assessing potential desalination sites in Cornwall as part of this planning.' from article by Ella Jessel on 13 March 2023.

I will leave you to read the rest of this chapter with these subheadings:-

• Soil types and characteristics
• Nitrogen in soils
• Exhaustion of plant-food in soils
• Some reasons for tillage of soils
• Fertility of soils
• Manures
• Organic manures
• Lime and liming
• Nitrogenous manures
• Potash manure
• Phosphatic manure
• Inorganic manures
• The effect of manure

Clay soil will absorb 40% of its volume in water before it turns from a solid to a liquid. This fact can have a serious effect on your house as subsidence.

A mixture of clay, sand, humus and bacterium is required to make soil with a good soil structure for your plants.

The rain or your watering can provides the method for transportation of nutrients to the roots of your plants. Soil organisms link this recycling of nutrients from the humus to the plant.

Oxygen, Carbon Dioxide and Nitrogen as gas is used and expired by the roots of plants into a soil which has airspace in it in order for those plants to grow.

Understanding the above provides you with an action plan for you to do with your own soil.

A more in-depth explaination of how soil works:-

"Plants are in Control

Most gardeners think of plants as only taking up nutrients through root systems and feeding the leaves. Few realize that a great deal of energy that results from photosynthesis in the leaves is actually used by plants to produce chemicals they secrete through their roots. These secretions are known as exudates. A good analogy is perspiration, a human's exudate.

Root exudates are in the form of carbohydrates (including sugars) and proteins. Amazingly, their presence wakes up, attracts, and grows specific beneficial bacteria and fungi living in the soil that subsist on these exudates and the cellular material sloughed off as the plant's root tips grow. All this secretion of exudates and sloughing off of cells takes place in the rhizosphere, a zone immediately round the roots, extending out about a tenth of an inch, or a couple of millimetres. The rhizosphere, which can look like a jelly or jam under the electron microscope, contains a constantly changing mix of soil organisms, including bacteria, fungi, nematodes, protozoa, and even larger organisms. All this "life" competes for the exudates in the rhizosphere, or its water or mineral content.

At the bottom of the soil food web are bacteria and fungi, which are attracted to and consume plant root exudates. In turn, they attract and are eaten by bigger microbes, specifically nematodes and protozoa who eat bacteria and fungi (primarily for carbon) to fuel their metabolic functions. Anything they don't need is excreted as wastes, which plant roots are readily able to absorb as nutrients. How convenient that this production of plant nutrients takes place right in the rhizosphere, the site of root-nutrient absorption.

At the centre of any viable soil food web are plants. Plants control the food web for their own benefit, an amazing fact that is too little understood and surely not appreciated by gardeners who are constantly interfereing with Nature's system. Studies indicate that individual plants can control the numbers and the different kinds of fungi and bacteria attracted to the rhizosphere by the exudates they produce.

Soil bacteria and fungi are like small bags of fertilizer, retaining in their bodies nitrogen and other nutrients they gain from root exudates and other organic matter. Carrying on the analogy, soil protozoa and nematodes act as "fertilizer spreaders" by releasng the nutrients locked up in the bacteria and fungi "fertilizer bags". The nematodes and protozoa in the soil come along and eat the bacteria and fungi in the rhizosphere. They digest what they need to survive and excrete excess carbon and other nutrients as waste.

The protozoa and nematodes that feasted on the fungi and bacteria attracted by plant exudates are in turn eaten by arthropods such as insects and spiders. Soil arthropods eat each other and themselves are the food of snakes, birds, moles and other animals. Simply put, the soil is one big fast-food restaurant.

Bacteria are so small they need to stick to things, or they will wash away; to attach themselves they produce a slime, the secondary result of which is that individual soil particles are bound together. Fungal hyphae, too, travel through soil particles, sticking to them and binding them together, thread-like, into aggregates.

Worms, together with insect larvae and moles move through the soil in search of food and protection, creating pathways that allow air and water to enter and leave the soil. The soil food web, then, in addition to providing nutrients to roots in the rhizosphere, also helps create soil structure: the activities of its members bind soil particles together even as they provide for the passage of air and water through the soil.

Without this system, most important nutrients would drain from soil. Instead, they are retained in the bodies of soil life. Here is the gardener's truth: when you apply a chemical fertilizer, a tiny bit hits the rhizosphere, where it is absorbed, but most of it continues to drain through soil until it hits the water table. Not so with the nutrients locked up inside soil organisms, a state known as immobilization; these nutrients are eventully released as wastes, or mineralized. And when the plants themselves die and are allowed to decay in situ, the nutrients they retained are again immobilized in the fungi and bacteria that consume them.

Just as important, every member of the soil food web has its place in the soil community. Each, be it on the surface or subsurface, plays a specific role. Elimination of just one group can drastically alter a soil community. Dung from mammals provides nutrients for beetles in the soil. Kill the mammals, or eliminate their habitat or food source, and you wont have so many beetles. It works in reverse as well. A healthy soil food web won't allow one set of members to get so strong as to destroy the web. If there are too many nematodes and protozoa, the bacteria and fungi on which they prey are in trouble and, ultimately, so are the plants in the area.

And there are other benefits. The nets or webs fungi form around roots act as physical barriers to invasion and protect plants from pathogenic fungi and bacteria. Bacteria coat surfaces so thoroughly, there is no room for others to attach themselves. If something impacts these fungi or bacteria and their numbers drop or disappear, the plant can easily be attacked.

Negative impacts on the soil food web

Chemical fertilizers, pesticides, insecticides, and fungicides affect the soil food web, toxic to some members, warding off others, and changing the environment. Important fungal and bacterial relationships don't form when a plant can get free nutrients. When chemically fed, plants bypass the microbial-assisted method of obtaining nutrients, and microbial populations adjust accordingly. Trouble is, you have to keep adding chemical fertilizers and using "-icides", because the right mix and diversity - the very foundation of the soil food web - has been altered.

It makes sense that once the bacteria, fungi, nematodes and protozoa are gone, other members of the soil food web disappear as well. Earthworms, for example, lacking food and irritated by the synthetic nitrates in soluble nitrogen fertilizers, move out. Since they are major shredders of organic material, their absence is a great loss. Soil structure deteriorates, watering can become problematic, pathogens and pests establish themselves and, worst of all, gardening becomes a lot more work than it needs to be.

If the salt-based chemical fertilizers don't kill portions of the soil food web, rototilling (rotovating) will. This gardening rite of spring breaks up fungal hyphae, decimates worms, and rips and crushes arthropods. It destroys soil structure and eventually saps soil of necessary air. Any chain is only as strong as its weakest link: if there is a gap in the soil food web, the system will break down and stop functioning properly.

Gardening with the soil food web is easy, but you must get the life back in your soils. First, however, you have to know something about the soil in which the soil food web operates; second, you need to know what each of the key members of the food web community does. Both these concerns are taken up in the rest of Part 1" of Teaming with Microbes - The Organic Gardener's Guide to the Soil Food Web by Jeff Lowenfels and Wayne Lewis ISBN-13:978-1-60469-113-9 Published 2010.

This book explains in non-technical language how soil works and how you can improve your garden soil to make it suitable for what you plant and hopefully stop you using chemicals to kill this or that, but use your grass cuttings and prunings to mulch your soil - the leaves fall off the trees, the branches fall on the ground, the animals shit and die on the land in old woodlands and that material is then recycled to provide the nutrients for those same trees, rather than being carefully removed and sent to the dump as most people do in their gardens leaving bare soil.

The following is from "A land of Soil, Milk and Honey" by Bernard Jarman in Star & Furrow Issue 122 January 2015 - Journal of the Biodynamic Association;_

"Soil is created in the first place through the activity of countlesss micro-organisms, earthworms and especially the garden worm (Lumbricus terrestris). This species is noticeably active in the period immediately before and immediately after mid-winter. In December we find it (in the UK) drawing large numbers of autumn leaves down into the soil. Worms consume all kinds of plant material along with sand and mineral substances. In form, they live as a pure digestive tract. The worm casts excreted from their bodies form the basis of a well-structured soil with an increased level of available plant nutrients:-

• 5% more nitrogen,
• 7% more phosphorous and
• 11% more potasium than the surrounding topsoil.

Worms also burrow to great depths and open up the soil for air and water to penetrate, increasing the scope of a fertile soil.

After the earthworm, the most important helper of the biodynamic farmer is undoubetdly

• the cow. A cow's digestive system is designed to make use of roughage such as grass and hay. Cow manure is arguably the most effective and long lasting of all the fertilizing agents at the farmer's disposal and has been found to have a carry over effect of at least 4 years. It is also one of the most balanced and it contains no grass seeds, since they have been completely digested.
• Pig manure is rich in potassium, attractive to earthworms and beneficial on sandy soils.
• Horse manure increases soil activity and stimulates strong healthy growth, but it does contain grass seed and other seeds."