Agricultural Science (AS)·Soil · NSSCAS 2.1a
Soil fertility: nutrients, deficiencies & nitrogen fixation
Narrated lesson · press play
A farmer near Tsumeb plants maize on two lands side by side. On the land where she grew cowpeas last year, the maize stands tall and deep green; on the other, it is short and yellow. Same seed, same rain, same sun. Why? The answer is in the nutrients hidden in the soil, and in some very clever bacteria living on legume roots. In this AS lesson we go deeper than NSSCO: the macro- and microelements a plant needs, the hunger signs when each is missing, how to correct them, and how legumes fix nitrogen from the air for free.
What you'll learn in this lesson
By the end you should be able to (NSSCAS Agricultural Science (AS) 2.1a):
- Sort the essential plant nutrients into macroelements (N, P, K, S) and microelements (Mo, Mn, B, Fe)
- Explain the role of each macroelement (N, P, K and S) in plant growth
- Explain the role of each essential microelement (Mo, Mn, B and Fe) in plant growth
- Use nutrient mobility to explain why some deficiencies show on old leaves and some on young leaves
- Describe the specific deficiency symptoms of named macro- and microelements
- Recommend how each named nutrient deficiency might be corrected
- Describe the role of nitrogen-fixing bacteria (Rhizobium) in symbiosis with legumes
- Explain the importance of Biological Nitrogen Fixation (BNF) as an alternative to inorganic nitrogen fertilisers
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