Work experience opportunity http://coedenfach.wikifoundry.com/page/Events 1

Courses at Botanic Gardens:

Soils & Growing Media 3

Aims: To develop an understanding of Soils & Growing Media, it’s components & characteristics.

Objectives At the end of this session, you should be able to: State the four components of soils & growing media, Understand the characteristics of the main soil types, Distinguish between soil structure & soil texture, Describe four ways to preserve soil structure, Define soil pH and carry out a pH test. A good understanding of Soil & Growing media characteristics will be of use when looking after plants & soft landscaping & following a few rules will make your life a lot easier.

Soil components 1 Mineral matter – 45% Organic matter – 5% Air – 25% Water – 25%

Soil components 2 Mineral matter – stones, sand, silt and clay, Organic matter – humus, vegetable matter and organisms, Air – in the larger pores, Water – in the smaller pores,

Soil components 3

Soil texture 1 Definition: Proportions of sand, silt and clay particles in a given soil: Three types: Sandy – large particles & pores- gritty, Silty – medium particles & pores- silky, Clay – small particles & pores – sticky.

Soil texture 2 Characteristics of different soil types: Sandy: very good drainage, needs regular watering, loses nutrients, Silty: good drainage, water & nutrient retention, risk of compaction, Clay: very good water & nutrient retention, difficult to cultivate.

Soil texture triangle Reproduced courtesy of Iowa State University

Soil structure 1 Definition: The way in which the particles are combined into larger groupings or aggregates, Formed by chemical, organism and root activity Sandy soils form a poor structure, Silty soil structure can be easily broken down, Clay soils create a strong structure.

Soil structure 2 Can be damaged by: Cultivating when too wet, frozen or very dry, Pedestrian traffic/using heavy machinery, Repeated cultivation to the same depth, Sprinklers leading to surface capping.

How to preserve structure Do not work when wet/frozen/too dry Add organic matter, Minimise compaction, Add sand where traffic unavoidable, Cultivate to different depths, Water with fine spray.

Organic matter Formed from decomposed plant and animal tissue, Broken down by soil organisms, Humus – binds particles so improves soil structure, adds nutrients, improves water retention.

Water & air Adequate quantities of both are essential for healthy growth of most plants, Found in pores between aggregates, Too much water pushes out air, Too little water causes wilting and death.

Soil pH 1 Definition: Measure of how acidic or alkaline a soil is. Dictates which plants will grow successfully, Scale of 1-14, with 7 seen as neutral, Most UK soils range from 4-8, Most plants prefer pH of 6.5.

Soil pH 2 pH influences which nutrients are available in the soil and which need to be added, These can be added as organic or inorganic, in solid or liquid form, pH test can determine what fertilisers are required,

Objectives At the end of this session, you should be able to: State the four components of soils & growing media, Understand the characteristics of the main soil types, Distinguish between soil structure & soil texture, Describe four ways to preserve soil structure, Define soil pH and carry out a pH test. A good understanding of Soil & Growing media characteristics will be of use when looking after plants & soft landscaping & following a few rules will make your life a lot easier.

Oes cwestinau gyda chi? Neil Barry