Ivydene Gardens Soil: Soil Formation - What is Soil Texture?

Soil Texture

The proportion of sand, silt and clay is referred to as its texture as shown in the diagram below.

The gaps between the soil particles are called ‘soil pores’. These soil pores are used to provide the plants with water, air and nutrients dissolved in the water. The soil pores for sand (like the big gaps in a jumbled pile of bricks) are large and clay (like the small gaps in a loose pile of cement) pores are small.

 

Addition of Humus, Sand and Stone to improve the structure of Clay Soil

The Soil - The most important element to consider, when starting a planting plan, is the soil. Soil provides anchorage for plant roots and holds the water/nutrients that are necessary for maintaining life.It is made up of the following elements:-

  • ROCK PARTICLES - All soils except peat are mineral soils formed from rock particles. They have been ground out of the rocks on the planet's surface by the relentless action of rain, wind and frost. The size and shape of the particles vary according to the parent rock and the weather action, so that different types of soil are formed: clay, silt, sand and chalk. Each type of soil has different qualities of aeration, drainage and nutrient holding capacity.
  • HUMUS - The product of decayed and decaying plants and animals; humus or 'organic matter' is the magic ingredient which gives fertility to the soil. Humus improves the structure of the soil, making it dark brown and crumbly. It holds moisture without impeding drainage and is home to a wide range of bacteria and other micro-organisms that help the gardener by breaking down organic matter to release nutrients. Earthworms thrive in humus-rich soils, and their movement through the soil aids drainage and aeration. The proportion of humus to mineral particles varies in different soils. It can be added to poor soil in the form of well rotted manure, compost or leaf mould.

 

  • WATER - Entering the soil by precipitation (rain and snowfall), by absorption upwards from the water table underground and by seepage from rivers, lakes and ponds. Water is lost from the soil through natural drainage, through evaporation and through plants taking it up through their roots. Plants need access to water for the food-making process of photosynthesis.
  • AIR - Plants breathe through their roots, using the air trapped between the particles of rock and humus. Without air, soil becomes waterlogged suffocating most plant roots. The living organisms in the soil, on which plants depend, also need air.

ACID and ALKALINE SOIL - Soil with a high lime or chalk content is alkaline. When lime is not present, it is neutral or acid. Peat is acid. Acidity and alkalinity is measured in terms of the soil's pH level.

Neutral or nearly neutral (6.5-7.5) soils are ideal for most plants. At this pH level, nutrients are readily available. Some plants prefer alkaline soil and a few will only thrive in acid soils

 

The Soil Textural Triangle

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Types of Soil

  • CLAY SOIL - Slow to dry out after rain. A lump squeezed in the hand feels dense, sticky and pliable like the clay used in pottery. Clay soils arte known as 'heavy' soils. Clay can be acid, neutral or alkaline.
  • SANDY SOIL - Dries out quickly. Disintegrates when handled. Sandy soils are 'light'. Nutrients and lime are washed away, so sandy soils tend to be acid.
  • PEATY SOIL - Holds water like a sponge. Usually acid and not very fertile.
  • CHALKY SOIL - Drains rapidly washing nutrients away. Very alkaline; the white parent rock is often close to the surface.
  • LIMESTONE SOIL - Drains rapidly. Numerous stones are present, from tiny ones to large rocks. Alkaline pH, but less so than chalk.
  • PERFECT GARDEN SOIL - The best all-purpose soil is known as loam, It is a balanced mixture of clay and sand with plenty of humus and is nearly neutral (The interaction between clay domains, organic matter, silt and sand particles diagram shows how quartz grains - sand - are joined together by clay, organic matter and bacteria). Soils are usually described in terms of their relationship to this ideal, for instance sandy loam, clay loam, silty loam.

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The climate in the South of England is temperate, with up to 20" of rainfall and a minimum temperature of 20-30 degrees Fahrenheit, and so require draught tolerant frost hardy plants.

A 150mm deep mulch of mixed peat, sharp washed sand and horticultural grit was applied on top of a heavy clay soil to improve its structure, and stop the plants therein from drowning, at £10 a square metre. The mix was:

  • 4 cubic metres of Peat (to provide the Organic Polymers/Organic Matter and Carbon.)
  • 2 cubic metres of Sharp Washed Sand (to provide the sand for the production of microaggregates)
  • 2 cubic metres of Horticultural Grit (to provide larger particles for aggregation)
  • 25kg of Garden Lime (to provide Calcium for the plants and allow clay minerals to bond together to form domains. Once clay minerals are stacked together to form domains, they can then bond with organic matter to form microaggregates)
  • 25 kg of Sulphate of Iron (to provide Iron to act as a trace element and to create soil colloid for buffering chemical nutrients in the soil for later use by plants)
  • 25Kg of Sulphate of Potash ( to provide fertilizer for the plants)

The following was then sent to me:-

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and the following was sent to me in October 2004:-

An unsuccessful planting scheme had left bare areas of garden as plants failed to survive winter in the waterlogged clay soil. The loss of numerous plants and the cost of replacing them had left us disheartened. It was evident that remedial action was need in the form of a mixture of gravel, sand and peat to create an organic loam. Approximately six inches was added in April and left to settle and do its job. By July there was a noticeable difference in the quality of the soil and the plants. Shrubs with sparse, mottled leaves were looking glossy and robust, overall growth had increased (including the weeds!) and the soil was holding its moisture well. But the biggest difference came in the confidence it gave us to transform the garden. The borders used to be a no-go area between May and September as the clay baked and cracked, but the new soil was easy to handle and weeds could be successfully removed. We realised that there are no quick fixes - the key to a healthy garden is rich, nutritous soil. Once our plants began to thrive we were optimistic that, with good advice, we could create a garden to be proud of.