Soil pH Flashcards
What is the optimum pH for plants on mineral soils?
6.5
What is the optimum pH for plants on organic soils?
5.8
What does raising soil pH do?
Makes the soil more alkaline
What does lowering the soil pH do?
Makes the soil more acidic
What does limestone do to the soil?
Limestone reacts with acid to neutralise it. Thus the presence of lime in the soil will serve to raise soil pH, loss of lime will lower the pH
How do soils become more acidic over time?
Leaching, cropping, nitrogen fertilisers
How do you measure pH by observing the site?
Soil type(sand is acidic, clays are neutral), indicator species(pines like acid and hazel likes alkaline), rainfall( lots of rain is acidic cos of leaching), rock type (chalk is alkaline and sandstone is acidic) and site history
What are calcicoles?
Alkaline loving plants
What are calcifuges?
Acid loving plants
Why is soil pH important?
Choice of plant species, nutrient solubility, plant health (nutrients deficiency), soil organisms, the formation of an iron pan, some pests and diseases
How is soil sampling done?
Examine the site, test the topsoil, ignore any odd areas, take samples in a w shape, take 25 samples, mix all 25 samples together
How is pH tested?
Hold tube with broad rim at top, insert lower bung, add 2.5cm of soil, add 1.5cm barium sulphate, distilled water to lower mark, indicator to upper mark, insert upper bung, gently invert tube to mix, allow to settle, compare colour with chart
How is pH increased by accident?
Builders rubble and mortar, watering with hard water and dust from roads
How do you increase the pH?
Lime
How is soil pH lowered?
Flowers of sulphur, acidic fertilisers, oak leaf mould, pine leaf mould, composted bark and moss peat
How is pH lowered by accident?
Repeated use of acidic fertilisers, leaching or excessive irrigation with soft water and nitrogen oxides from car exhausts and pollution with sulphur dioxide which gives acid rain
