Soil Cultivation

Introduction By cultivation we mean the preparation of the soil for sowing or planting by digging, rotavating or ploughing. In a domestic garden digging will usually be the method used. In large gardens or small commercial operations a rotavator may be used while in larger commercial operations- a tractor with ploughing and harrowing attachments may be used. rotavator

Pre Cultivation Tasks Clearing unwanted vegetation – This may be just getting rid of weeds or undergrowth, but it could include more major tasks like removing trees. Removing debris or other features not required – the task of getting rid of old bricks; concrete, or other builder's debris. – Other things that may need to be removed are paths, walls, fencing or buildings. Ensuring there is adequate topsoil – This may be a problem with new houses. The builder may have removed or destroyed the topsoil. If this is the case topsoil will need to be purchased. Contouring the site – This could be either flattening an undulating site, or putting undulations in a flat site. – In either case the important thing is to protect the topsoil by removing it, making the changes with the subsoil, and then replacing the topsoil.

Advantages of Cultivation 1. Prepares an uncultivated area for planting. 2. Improves the structure of 'the soil by improving access for air and water. 3. Exposes clods to, the weathering effects of winter. This is still one of the best methods of getting a good structure in a heavy soil. 4. Breaks up pans that may prevent free circulation of water and air. 5. Allows organic matter or fertilisers to be incorporated into the soil. 6. Buries crop remains and weeds. 7. Exposes pests to weather and predators.

Disadvantages of Cultivation 1. Disturbs the natural structure built up by organisms such as earthworms. 2. Can damage the soil structure if done when soil conditions are not suitable, or by using heavy machinery. 3. Dormant seeds may be brought to the surface where they will germinate. 4. Leaving a bare surface may cause erosion or the leaching of nutrients. 5. Moisture may be lost from the soil. 6. Hard work!

When to dig 1. When soil conditions are suitable - not wet or frozen or parched. Ideally the soil should be friable. 2. Dig clay soils in autumn to get the benefit of overwintering to break it down. 3. Light soils can be dug in autumn or spring.

Single digging Single digging entails digging to a depth of 1 spit (30 cm or spade depth). In shallow soils do not bring any of the subsoil up into the topsoil even if it means digging to a depth of less than 1 spit. The normal method of single digging is to dig out the first trench and move the soil close to where the last trench will be. The second trench is then dug and placed into the first trench. This process is repeated until the final trench is filled with the soil from the first trench.

Double digging As its name implies double digging entails digging to a depth of 2 spits. Double dig if: Double dig – The- ground has not been cultivated before – There are pans within the soil profile – The soil is very heavy Even if the topsoil extends to the two spits it is still worth keeping soil from the upper spit on top of the soil from the lower spit since it will be the most fertile. The simplest way to achieve this is to dig the second spit in situ. Organic matter can be incorporated in the second spit as it is dug.

No-dig systems Vegetables can be grown in conditions that require no digging other than the initial cultivation. Double dig the soil for the initial cultivation incorporating plenty of organic matter to provide a reservoir of humus and nutrients. Use narrow beds separated by permanent paths so that all cultivation and harvesting can be done without treading on the beds. If drainage is a problem use the topsoil from the paths to make raised beds. Make the paths wide enough for a wheelbarrow. Keep the ground covered to prevent the structure being damaged by rain and to reduce weeds. This can be done by: – planting close together – intercropping – green manures – mulching

Deep bed? This no-dig system is also called the deep bed system. Advantages 1.The natural structure of the soil is preserved. 2.Soil organisms are not disturbed. 3.Drainage can be improved if raised beds are used. 4.Harvesting can be done in any weather. 5.Weed seeds are not brought to the surface. 6.Less hard work and time is required Disadvantages 1.Pests may build up in the soil. 2.It maybe difficult to maintain levels of organic matter in the soil since it can only be applied as a surface mulch 3.Fertility and structure may be reduced in the long term.