Theory question 104
Soil Fertility and Plant Nutrition(a) State three functions of nitrogen in crop plants.
(b) Mention four effects of excess soil nitrogen and three effects of nitrogen deficiency on plants.
(c) Apart from lightning, state three other ways by which nitrogen is added to the soil?
(d) List six soil micro nutrients
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(a) Any three: part of proteins and protoplasm; part of chlorophyll, giving dark green leaves; promotes vegetative (leaf and stem) growth; increases protein content of grain; helps uptake of other nutrients
(b) Excess (any four): too much leafy growth; delays flowering and maturity; weak stems and lodging; lower quality/low grain yield; more disease attack; soft, watery tissues
Deficiency (any three): yellowing (chlorosis) of older leaves; stunted growth; small leaves; early maturity with low yield; thin stems
(c) Any three: fertilizer application (inorganic); organic manure (farmyard manure, compost); symbiotic fixation by Rhizobium in legume nodules; free-living bacteria (Azotobacter, Clostridium) and blue-green algae; decomposition of plant and animal remains
(d) Any six: iron; manganese; zinc; copper; boron; molybdenum; chlorine
Separate excess from deficiency effects.