Geography Give geographical resons.

(i) In countries like Saudi Arabia, Qatar, Oman etc. the soils are not arable so there is need to fulfil their food requirement.
(ii) Hence, countries like Saudi Arabia, Qatar, Oman import food from other countries.

(i) When man realized that the fertile soils along the river beds give higher yields.
(ii) He settled in the valleys and started living there in groups.
(iii) This led to the rise of Indus civilization.

(i) Man started producing greater amount of food crops for the growing population.
(ii) He realized that crop production and prosperity in agriculture depends on the fertility of soil and the optimum availability of water.
Hence, there emerged competition among the people to discover fertile lands & settle there.

(i) Use of organic manures, vermicompost, compost helps maintain the pH balance.
(ii) It also increases the proportion of humus thus retaining the fertility of soil.
(iii) Hence, it is advisable to use organic manures, vermicompost & compost regularly.

(i) Construction of continuous contour trenches (CCTs) at different heights checks the velocity of water running along the slopes.
(ii) This reduces soil erosion.

(i) A layer of soil gets removed due to wind or water which leads to soil erosion.
(ii) Planting trees controls the velocity of the wind, thus reducing the erosion of soil by wind.
(iii) The roots of the plants hold the soil which also prevents soil erosion.