(a) List four factors that affect the type of soil formed at a place (2 marks)
(b) State: (i) two agricultural uses of land
(ii)a two non-agricultural uses of land. (4 marks)
(c) Sate two functions and two deficiency symptoms of each of the following nutrients in crops: (i) nitrogen; potassium. (8 marks)
(d) Mention two ways in which soil structure Is important in agriculture. (2 marks)
Explanation
(a) Factors that affect type of soil formed at a place: (i) Parent material. (ii) Climate (iii) Topography/relief (iv) Time (v) Biotic factors (vegetation, living organisms, human influence).
(b) Agricultural and non-agricultural uses of land: (i) Agricultural uses of land: Crop production. Pasture establishment. Forestry. Wildlife and game reserve. Fisheries. Animal/ livestock production, Bee keeping, snail farming
(ii) Non-agricultural uses of land: Housing, transport network, Mining, industry, Social infrastructure (schools, markets, stadia, hospitals, etc)
(c) Functions and Deficiency Symptoms of nutrients in crops:
Nitrogen: Functions:
-Promotes vigorous vegetative growth of crops.
-It is responsible for the green colouration of leaves which is important for photosynthesis.
-It is a constituent of plant protein.
-Promotes good root, stem and leaf formation at the expense of fruit and tuber formation.
-It regulates the utilization of potassium and phosphorus by crops.
-It increases the succulence in leafy and fruit vegetables.
-Promotes synthesis of plant enzymes and auxins.
Deficiency symptoms:
(i) Stunted growth. (ii) Restricted root formation. (iii) Leaves turn yellow/yellowish green because of lack of chlorophyll/older leaves turn yellow. (iv) Premature leaf-drop. (v) Stems of crops are weakened especially in cereals. (vi) Premature flowering and fruiting of crops.
(ii) Potassium:
Functions:
– Potassium is an important constituent of plant tissues.
-Aids synthesis of carbohydrate.
– Activates various plant enzyme reactions.
– Promotes development of young plants.
– Necessary for neutralization of organic acids in plants.
– It is associated with stomata movement, hence influences water relationship within the plant.
– Helps in nitrate uptake from the soil.
– Essential for tuber formation.
– Essential for root growth.
-Aids in disease resistance.
– Provides resistance against lodging in plants.
– Neutralises organic acids in plants.
Deficiency symptoms: (i) Premature loss of leaves. (ii) Brown colour at margin of leaves. (iii) Weak stem development/susceptible to lodging. (iv) Delayed growth. (v) Mottling, curling and spotting of leaves. (vi) Results in stunted plants with short internodes.
(d) Ways in which soil structure is important in agriculture:
(i) Determines the number of pores in soil/aeration.
(ii) Determines water-holding capacity of soil.
(iii) Determines ease at which roots penetrate the soil.
(iv) Influences the extent of soil erosion.
(v) Determines the survival of micro-organisms.
(vi) Influences Cation Exchange Capacity (CEC).
(vii) Affects the performance of agricultural operations such as tillage, irrigation.
(viii) Supports the growth of crops.
(ix) Improves water percolation and infiltration.
(x) It influences fertility of the soil.
(xi) Promotes germination of seed.