Cultivation and soil water Neil Barry

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.

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

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

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

How Water is lost from the soil

What water is available to plants?

Saturation Point, Field Capacity and Permanent Wilting Point

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.

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.

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.

Oes cwestinau gyda chi? Neil Barry