Practice exam #3 - QUESTION 6

a) Gleysolic order. Diagnostic horizon: Bg, BCg, Cgk. b) Some advantages of this soil order is that it has a high CEC, which means it can store large amounts of nutrients. It also has a pH that lies within the 6-7 range for optimal plant growth. It also has a 5 cm thick LFH, indicating that there is a good source of organic residues providing nutrients into the soil.

   Some disadvantages of this soil order is its extremely high clay content. This will create very poor drainage conditions in the soil, leading to poor aeration that will inhibit plant growth. Also, the lower horizons have a low Ca:Mg ratio, which is bad for plant growth. The structure of the lower horizons are massive, which also causes extremely poor aeration, and is hard for plant roots to penetrate.

Generally, the top 20 cm of this soil are suitable for plant growth, but below that is extremely unfavourable.

Good start. When answering this type of question (in general) consider clearly separating your advantages from your disadvantages (e.g. two bullet lists)