Leaving Certificate Agricultural Science Cultivation & Seed Bed Preparation H. Jones, St. Columba’s College

Introduction For any crop, either tillage or grassland, a suitable seedbed must be prepared. The soil provides the crop with support, water, air, nutrients and heat. Sub-ploughing, ploughing and cultivation are a major key to the success of the crop. The other major influence is fertiliser application.

Sub - Ploughing On heavy or poorly structured soils, it may be necessary to loosen the soil to a greater depth than achieved by ploughing alone. This is done to improve drainage and root penetration. One of the major causes of this problem is the formation of a plough pan. This is a layer of compacted soil created by the repeated ploughing of the same area of soil.

Sub – Ploughing 2 The weight of the wheels of the tractor and plough pressure cause this. This can also happen after a crop of sugar beet, where the machinery to harvest the beet creates a compacted layer. Sub-soilers are commonly used to alleviate the problem. They consist of one or more vertical tines, which have replaceable feet or shares. For more than one tine, a high powered tractor is required.

The Sub Plough

Carrying out Sub - Ploughing Subsoiling should be carried out on dry soil. Ploughed at a depth of 40 – 50cm Each tine should be no more than 1-2 metres apart.

Ploughing The plough is used to turn over a layer of soil in preparation for further cultivation and sowing. Ploughs can turn from one to eight furrows or furrow slices at a time. The functions of each of the parts of a plough are shown below:

Parts of the Plough The Beam – A single horizontal bar to which the plough units are attached. The Rear Wheel – Attached to the rear of the beam and controls the depth of the plough. The Leg – Links the beam and each plough unit.

Parts of the Plough The Disc Coulter – makes a vertical incision in the soil, cutting the side of the furrow. The Share – Makes a horizontal incision, cutting the bottom of the furrow. The Mouldboard – Lifts and turns the furrow.

Parts of the Plough The Landside – Aligns the plough by pressing against the unploughed ground. The Skim Coulter – Cuts a small slice off the edge of the furrow and throws it away into the previous furrow bottom. This stops the previous crop from growing between the furrows.

Methods of Ploughing When ploughing using a regular plough, furrows are thrown to the right. When ploughing a large field, this results in wasted time (IDLE TIME), fuel and labour. This time can be reduced by ploughing “in lands”. This involves dividing the field into small areas and ploughing these separately.

Methods of Ploughing Both methods of ploughing result in the formation of ridges – empty areas. This problem can be alleviates by the use of reversible ploughs. A reversible plough consists of two sets of plough units, one of which is idle while the other ploughs

The Reversible Plough One unit throws furrows to the right, and the other throws them to the left. This reduces idle time and leaves no ridges. This makes cultivation much easier. However, reversible ploughs are very expensive and only contractors usually buy them.

Autumn vs Spring Ploughing Autumn ploughing is considered more effective than spring ploughing. This is because land ploughed in autumn leaves the soil exposed to wetting and drying and to the freeze-thaw phenomenon. This leaves the surface of the soil more broken up and easier to cultivate in the spring.

Autumn vs Spring Ploughing Seedbeds are more easily prepared, soil conditions are better and sowing dates are earlier. Autumn ploughing is almost essential on clay and silty – loam soils, especially if they are be used for growing sugar beet or potatoes. BUT! A new European Directive (The Nitrates Directive) means that Autumn ploughing is rarely if ever practiced anymore in Europe!

Cultivators and Harrows Between ploughing and sowing, cultivation operations provide: A suitable seedbed for seed germination and plant establishment A suitable soil environment for subsequent growth. The ideal seedbed for cereals and most crops is as follows:

Soil Depth Soil Conditions 0-5 cm Fine, compact – to provide good contact between seed and soil water. 5-10 cm Moderate soil conditions – allow good root development. 10-25 cm Coarse soil conditions – allow anchorage and root development for mature plant. Note: Over cultivated soil conditions lead to poor aeration and poor root development.

Cultivation Machinery Heavy- Duty Cultivator These machines simply consist of a frame with a series of tines, which stir and break up the soil. They range in strength, size and weight depending on the purpose. There are three different types of tines available. Rigid Spring Loaded Spring Tines

Cultivation Machinery 2 Harrows Harrows are lighter than cultivators, and are generally used for seedbed preparation. There are three main types of harrows. Tined harrows – seed bed preparation Disc harrows – seed bed preparation in grass Chained Harrows – very light seedbed prep.

Cultivation Machinery 3 One Run Harrows One run harrows can be used on sandy / loam soils to create a seedbed in one operation after ploughing They contain three basic components: Levelling bar – Breaks up clods Spring Tines – Create fine particles Soil Crumbler – Creates final seedbed and compacts the soil.

Cultivation Machinery Power harrows These consist of two reciprocating tined bars, which break up clods of soil. A crumbler may also be fitted behind the power harrow.

Cultivation Machinery 4 Rotavator (Rotary Cultivator) A Rotavator consists of a rotating bar with L – shaped blades. The bar is powered by the tractor, and can run at speeds of 90 – 240 rpm. The blades “bite” into the soil and throw it against a metal hood, breaking up clods. The Rotavator is a very powerful machine and can produce a seedbed in one run. It is however very expensive and has a very small working width. It can also cause some soil structure damage, so it must be very carefully controlled.

Cultivation Machinery 5 Rollers Rollers are used to remove clods and to produce a smooth soil surface. They may be used before sowing or after sowing to compact the soil and improve seed germination levels. There are two kinds – Cambridge (or Ridged) and Smooth. The level of compaction can be controlled in two ways: The weight inside the roller. The speed of movement.