Soils The soil is the powerhouse of the garden. Get this wrong and you might as well give up and go back indoors! In describing soil there are two main definitions, the type of soil and the soil properties. Soil Types Basically soil is split into three types, Acid and alkaline, with neutral soil in between. Soil acidity is measured using the standard chemical analysis method from 0 – 14 with 0 as acid and 14 as alkaline. The numbering is further broken down to 1 decimal point between number, but remember that each point is half (or double) the content of the next point. That is 6.9 is twice as acid as 7.0. However, very little can happen outside the 6 – 8 range for plants. Neutral is at 7 and most plants will thrive happily at this point. Remember that the range between 6.5 and 7.5 is not one point, but ten times double. Acid Soil This is mainly made up of decaying matter, for example a peat bog. The matter as it decays releases chemicals into the soil and this is where the acid balance comes. Acid soils can go as high as 5.5 though not much could tolerate that level. The soil is usually quite dark and has an obvious matter content. The more the matter rots the less acid there is. This is why adding well rotted manure is good for the soil. Alkaline soil This is usually dependent on the type of bedrock in the area you live. Areas with a high limestone content will normally have a more alkaline soil. Remember that if your property is on an old brown field site, you don’t know what the chemical balance is more than a few inches down, oil, industrial waste, building rubble, paint etc. you must look deep, roots will. Soil Properties The main points regarding soil properties can be covered quite quickly. The properties range from ‘free draining’ to ‘heavy clay’ each have a benefit, and each a drawback. Light or free draining soils have the following advantages:- They allow roots to grow easily. Easier to prepare and work with. Warms up quickly in the spring, helping promote earlier growth. Allows air pockets for the roots which are vital to plant growth. They have the following disadvantages:- They allow nutrients to leech away quickly. Dry out quickly in times of dry weather. Heavy clay soils tend to be opposite, but it is important to understand clay soils. Sand particles are thousands of times larger than the particles in clay soil, this means that the electric and chemical bond between clay particles is far stronger than sand and there is less room for air movement. Roots have to fight to survive in these circumstances and problems like waterlogging become critical. Remember that if you dig a hole to plant your new pride and joy from the garden centre in a clay soil, and make that hole only just deep enough to fit the plant rootball, then a bit of rain will cause that plant hole to become a sump into which all the water pools, and it will not drain away quickly. You must make the hole far larger and deeper than the plant needs, adding extra compost or organic matter, to allow for drainage and growth.