Question

Define expanded cell theory.

Answer 1

Explanation:

(vi) Short periods of crop occupancy alternate with long periods of fallowing. When the yields can no longer support the community because of soil exhaustion or the invasion of weeds and shrubs, the fields are abandoned and fresh areas cleared. ‘Field rotation’ rather than ‘crop rotation’ is practised.

(vii) This form of ‘migratory agriculture’ still supports many of the aboriginal tribes of the tropical rain forest, despite the efforts made by the local govern­ments to resettle them. The exhaustion of soil nutrients, deterioration of the lightly constructed bamboo houses, and attack by insect-pests, diseases or wild animals are some of the major reasons that make migration a necessity.

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A more advanced form of subsistence farming is ‘sedentary subsistence agriculture’ in tropical lowlands, where the fallowed fields are frequently reused and the community stays permanently in one spot. Crop rotation is also practised in some places and greater attention is given to the land and the crops sown.

Methods of tillage are more intensive, though crude hand implements are often still used and there is a greater employment of manpower in the fields. This type of economy is capable of sustaining a relatively larger population on a permanent basis.

Many more animals are kept, including buffaloes, swine and horses, and animals are used for drought purposes on the farm as well as to supply milk or meat. Crops are sown in the cool season and grown throughout the rainy period to be harvested in the dry season.

Many sedentary farmers in Central America and South-East Asia also find jobs on plantations and return to their homes periodi­cally with thei256765-+ yi