1. Cultivation and soil water
Neil Barry

2. Cultivation techniques
Single digging – used for previously cultivated soil with good structure.
Double digging – for uncultivated soil or to improve clay soils or those with cultivation pan, poor drainage etc.
Rotavation – for larger areas. Safety considerations – PPE, maintenance, correct operation.

3. Benefits and limitations - digging
Improves the structure of the soil – allows access for water and air
Disturbs natural structure of the soil and may harm beneficial organisms
Exposes pests to predators and the weather. Allows clay clods to be frosted.
Can damage soil structure if the texture and wetness of the soil are not taken into account.
Breaks up cultivation pans and improves drainage.
Brings dormant weed seeds to the surface where light will stimulate germination
Incorporates organic matter and buries crop residues and weeds
Leaves a bare surface which may lead to leaching or capping

4. Benefits and Limitations - Rotavation
Less hard work than manual digging
Expensive to buy or hire, safety considerations.
Makes larger areas more manageable
Can produce a very ‘fluffy’ tilth with large air pockets – will need raking and possibly firming before planting
Provides a good tilth in a short period of time
Will not effectively break up hard or stone pan and may cause a cultivation pan by smearing wet clay soils.
Has most of the benefits of single digging.
Not ideal for incorporating organic matter

5. No Dig Systems Benefits Limitations
Less work than traditional digging approaches to soil management
Will not remedy soil structure problems like hard pan or poor drainage
Does not damage soil structure where this is already good
Large amounts of organic matter are required
Weed seeds are not brought to the surface
Some risk of long term soil acidification – which reduces beneficial organisms
Soil organisms are not disturbed
Pests may build up in the soil as the larvae are not exposed by winter digging

6. How Water is lost from the soil

7. What water is available to plants?

8. Saturation Point, Field Capacity and Permanent Wilting Point

9. Available Water Content
The amount of water that a soil holds between the point at which Field Capacity is reached and Permanent Wilting Point.
The total of the capillary water remaining in the soil at any time.
The water that plants can use.

10. Drainage
Symptoms of poor drainage – standing water; gleys; indicator plant species; surface run off.
Cures – double digging; incorporate coarse organic matter; install tile drains or sub-soiling (clay soils) on large areas.

11. Water retention and irrigation
Irrigate to restore Field Capacity – so add enough to do so when needed rather than water little and often.
Mulches and timing of irrigation can reduce evaporation. Water at the roots – not on the leaves and bare soil.
Organic matter acts like a sponge and creates aggregates with both meso and macro pores.

12. Oes cwestinau gyda chi?
Neil Barry