Describe the cultivation of spring barley or main-crop potatoes under the following headings: (i) Soil requirements (ii) Rotation (iii) Weed control (iv) Yield (tonnes per hectare) - Leaving Cert Agricultural Science - Question 5 - 2009

Barley should ideally follow a continuous sowing cycle with a diverse rotation plan. A crop rotation scheme, such as a one-year interval with a last crop before barley, is effective for potatoes as it limits disease and pest buildup.

For barley, effective weed control can be achieved through herbicide application. In potato cultivation, techniques such as stale-seedbed practices, deep ploughing, and shading off leaves through cultivation are used to minimize weed interference. Regular mechanical weeding such as scuffling and hoeing can also be beneficial.

The expected yield for barley typically ranges between 5 to 7 tonnes per hectare, while for potatoes, the yields can reach significantly higher values, often between 30 to 40 tonnes per hectare.

Placement of fertiliser involves placing it in bands near the seed line, ensuring that the nutrients are available to plants as they germinate.

Broadcasting refers to spreading fertiliser evenly over the soil surface, which is then incorporated into the soil to promote nutrient uptake by crops.

Top-dressing involves applying fertiliser to an established crop to enhance growth and yield potential.

An example of placement would be when sowing potatoes. Broadcasting is suitable for a newly established grassland crop.

A suitable compound fertiliser for floury tubers is one that contains a balanced mix of Nitrogen, Phosphorus, and Potassium, such as 7-6-17 or 10-10-20.

Three causes of low dry matter in potato tubers include excessive nitrogen application, which can lead to too much foliage and insufficient tuber development; lack of potassium, which is crucial for tuber quality; and any factor limiting sunlight, which affects photosynthesis and overall tuber growth.