soil

One of the first things you should do, when you start an allotment is to find out what soil type you have. This will determine what will grow well, how you work on the land and what must be added for better yields.
There are soil analysis you can have done which are expensive and take weeks for the results to come back or you could do this:

Take a hand full of soil and press it into a ball about half an hour after it has rained:

*If the ball falls apart you have a light sandy soil. This is free draining and easy to work. it warms up quickly in the spring. The one problem is that nutrients can be washed or "leached" away by rain. adding rotted compost or manure will help to bind the soil together. dig in the spring and cover in winter.

*If the ball holds its shape and sticks together, you have a heavy clay soil. this will not drain easily and is hard to work. it is slow to warm up in the spring, becomes water logged and cakes in the heat. But it is full of nutrients and minerals. Dig in plenty of Sharpe sand and organic matter to incorporate air and improve drainage. Dig in the Autumn and let the winter weather help break it down.

*A good soil is some where in between the two above and is called loam. The gardeners dream soil.

Good soil is bursting with microscopic life like fungi, algae, bacteria and worms. if you look after your soil it will look after your plants. healthy soil has a pleasant earthy smell. ideally it should have two to three earth worms in it every spade full. If when you take over an allotment it is covered with stinging nettles, bindweed and dock it is a good sign the soil is fertile. weeds can also tell you the type of soil you have again because different plants like different soils.

Top soil and Sub soil:

Top soil is the first layer of earth you will find it is darker than the rest and is what feeds the plants. About 18" of top soil is needed for soft fruit but most vegetables are happy with 15". Fruit trees need around 24".
Sub soil is lighter in colour and contains very few nutrients but is important for drainage and allowing air to the roots of plants. This area can become an impermeable barrier due to over rotavating. this is know as "hard panning". this can be broken up with a pick axe or fork. and should be done every three years if you use a rotavator.