problems worse. So, after studying Topic 3, you should be able to discuss how soil impacts plant growth – its texture and structure and how these relate to nutrient uptake. As well as this, you should be able to discuss how the different layers – topsoil, subsoil, and parent rock may influence the soil and therefore plant growth, as well as organic content. You should also be able to relate this knowledge to the consequences of soil erosion and degradation, and discuss how to ameliorate soils and restore nutrient levels. What should you be looking for in terms of crumb structure, porosity, texture, and colour of your soil with a view to growing the widest range of plants? You should also understand that several nutrients cycle including carbon and nitrogen and you should be able to explain how these cycles work. In terms of nutrients, you should understand macronutrients and micronutrients – what they are, what they do, and where plants obtain them. What are the symptoms associated with specific nutrient deficiencies and what can the grower do to restore these? How does soil become degraded and is there anything growers can do to reduce the likelihood of this happening or to restore soil once it has happened? Why do we need to do this? You should be able to link this in with horticultural practices such as mono-crops, using large, heavy machinery regularly, working while the soil is wet, and clay versus sandy soils. How do fertilizers work? Remembering plants generally only take nutrients in if they are in solution, how do we get nutrients to plants? What kinds of fertilizer and how does a grower select these?
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