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 can be cultivated in rotation with various crops and is very tolerant of continuous sowing. For potatoes, a 1-year interval from the last crop before planting is recommended. Proper rotation helps in disease control and soil fertility management.

For spring barley, pre-emergence and post-emergence herbicides are used. In potatoes, strategies include using seedbed preparation to prevent weed emergence, as well as mechanical removal through practices like hilling or hoeing, complemented by herbicides at specific growth stages.

The average yield for spring barley typically ranges from 5 to 7 tonnes per hectare, while for main-crop potatoes, it is around 30 to 40 tonnes per hectare depending on soil health and cultivation practices.

Placement refers to the method of applying fertiliser in a band close to the seed where it can be directly taken up by the plant roots, optimizing nutrient use efficiency.

Broadcasting involves scattering fertiliser evenly across the field surface and then incorporating it into the soil. This method is often used for establishing crops, as it prevents nutrient runoff and ensures wider availability.

Top-dressing is the application of fertiliser on top of a growing crop. This practice helps to support plants during critical growth stages with additional nutrients.

An example of a crop situation for broadcasting would be during the establishment of a cereal crop, where the fertiliser is spread over the soil before planting.

A suitable compound fertiliser for the production of floury tubers would be one with a balanced NPK ratio, such as 7-6-17 or 10-10-20, as these ratios provide adequate nitrogen, phosphorous, and potassium.

Three causes of low dry matter in potato tubers include:

1. Excess nitrogen application, which delays maturity and tuber development.
2. Insufficient sunlight leading to poor photosynthesis.
3. Inadequate levels of potassium in the soil, which are necessary for proper tuber development.