(a) (i) Name one type of soil pan - Leaving Cert Agricultural Science - Question 2 - 2011

The plough pan forms through continuous tillage, where ploughing occurs at the same depth repeatedly. This process compacts the soil, causing oxidation of the soil layers as it becomes hard and impervious, typically from layer A to B.

One major problem is that it creates a hard, impervious layer that restricts root penetration, limiting drainage and poor germination growth.

The plough pan can be removed through deep ploughing, ensuring that ploughing does not occur at the same depth in successive years, along with techniques such as subsoiling.

Gleyisation is the process influenced by high rainfall and low-lying areas where waterlogged soil reacts with air to create acidic conditions. This process is significant for soil development as it slows down bacterial activity and decomposition, leading to distinctive color variations in the soil profile, primarily blue-gray or gray.

When collecting soil samples, it's essential to check field color differences and to avoid potential contamination sources, such as hedges and gateways. Samples should be collected from several depths (7.5-15 cm) and in various sites to ensure a representative sample is obtained, taking into account the local soil history and topography.

To investigate nitrogen presence, take a soil sample and place it in a flask containing distilled water. Shake the mixture and filter it. Use diphenylamine solution to test for nitrates; a blue color indicates the presence of nitrogen. Conduct a reference check against a color chart to quantify the nitrogen level.