Theory question 103
Soil Fertility and Plant Nutrition(a) Give one function each of the following bacteria in the nitrogen cycle: (i) Rhizobium. (ii) Nitrosomonas. (iii) Pseudomonas. (iv) Nitrobacter.
(b) A farmer discovered that aphids have invaded a cowpea farm. (i) State three effects of aphids on the cowpea plants. (ii) Mention four cultural ways by which the farmer could control aphids on the cowpea farm.
(c)(i) Explain the term forestry. (ii) Name five products that could be obtained from forests.
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(a)(i) Rhizobium: fixes atmospheric nitrogen in root nodules of legumes. (ii) Nitrosomonas: converts ammonium compounds to nitrites. (iii) Pseudomonas: denitrification – converts nitrates to nitrogen gas. (iv) Nitrobacter: converts nitrites to nitrates.
(b)(i) Any three: suck sap, causing wilting and stunting; leaves curl and yellow; transmit viral diseases (cowpea mosaic); honeydew encourages sooty mould; reduced yield.
(ii) Any four: early planting; crop rotation; resistant varieties; clean weeding/field sanitation; removing and burning infested plants; correct spacing; intercropping; encouraging natural enemies.
(c)(i) Forestry is the science and practice of establishing, managing and using forests and their resources.
(ii) Any five: timber; firewood/charcoal; bushmeat; wood pulp/paper; medicinal plants; mushrooms; honey; gums, resins and latex; fruits and nuts; rattan/canes.
One function per bacterium.