BLE 211: Principles of Agriculture and Forestry. Lecture 2. Agricultural Practices. Crop production systems vary with the crop, time, location and the level of technology of the particular area. In pre-agricultural societies gathering wild plants was the only way to obtain crop products.
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Agricultural Practices • Crop production systems vary with the crop, time, location and the level of technology of the particular area. • In pre-agricultural societies gathering wild plants was the only way to obtain crop products. • The management of natural stands of some useful plant species has continued to play an important role in tropical crop production. • Many practices have also evolved with the evolution of man. They may be: • Extensive on large areas of land or • Intensive in gardens. • Agricultural practices involve the use of choice cultivars and manipulations of soil and other resources to obtain desired yields from plants
Types of Cultivation practices • Shifting cultivation: With increased population, shifting cultivation has been replaced by sedentary occupation and reduced length of fallow period. • Mono-cropping: This is the growing one crop to maturity on a piece of land. Not common in the tropics except in plantations and swamp rice, sugarcane or large-scale maize production. • Mixed-cropping or multiple cropping: It is growing of two or more crops on the same piece of land, simultaneously. Most common of the farming practices in the tropics usually associated with under-developed farm technology. • Crop Rotation: A given combination of crops is grown in a particular sequence on the same piece of land for several years without loss of soil fertility or reduced yields
Types of Mixed cropping • Inter-cropping: Short-term annuals planted through long-term annuals or biennials and harvested before the main crop matures. • Inter-planting: Long-term annual or biennial crops planted through short-term annuals. • Phased Planting: Planting dates are systematically arranged to ensure continuous sequence of growth and harvesting. • Relay Planting: Following one crop with another immediately before harvesting the former crop.
Advantages of Mixed Cropping • Reduces susceptibility to diseases and pests as well as risks of crop failure. • Allows for adaptation of plants to changing soil conditions because of differences in peak demand by associated crops for nutrients and water. • Facilitates vertical and horizontal variations thus allowing cultivation of crops adapted to light and shade. • Permits phased harvesting and even distribution of workload • Provides reasonable soil cover that protects the soil against erosion, while suppressing weed growth. • Provides higher yields that mono-cropping • Adaptable to small-scale hand operated farming
Principles of Crop Rotation • Alternate growing of crops with differential ability to absorb nutrients from the soil or having different depths of rooting system. • Alternating crops susceptible to certain diseases with those that are resistant. • A Planned succession of crops that takes into account any detrimental or beneficial effects of one crop on the following crop. • Alternating soil-exhausting crops with crops that contribute to the improvement of soil fertility. • Alternating crops with peak requirements of labour, water etc.
Agricultural Systems Characteristics • Reducing farm sizes although some large-scale farms are still in existence. • Use of human labour and simple tools. Animal power limited to only a few operations. • Permanent cultivation usually restricted to homestead and to tree crops but with increasing population permanent cultivation especially on flood plains and other productive soil regions is emerging. • Mixed cropping is widespread. There are usually more crops and crop combinations on the homestead farms than on outlying farms. • Cropping is almost entirely dependent on rainfall. Irrigation is mainly practised for the high-value cash crops.
Agricultural Systems Characteristics • Burning is widely used as a means of clearing the land in preparation for planting. • Limited use of manufactured chemical fertilisers due to cost. Soil fertility is maintained through regular fallowing or application of household and animal refuse. • Animals, especially poultry are kept on free range. • Farm animals are fed on fodder while kitchen wastes provide food for a few animals kept in the household. • Extensive animal husbandry relies on continuous movement of livestock in search of forage and water throughout the year. • Low level of capital investment since primary objective of most farmers is subsistence.
Agricultural Systems Characteristics • With the increase in availability of industrial consumer goods, the traditional objective of self-sufficiency in food is gradually giving way to an exchange economy. • In this economy the level of capital investment in farming determines to some extent the level of income and ability of the farmer to acquire consumer goods.
Changes in Agricultural Systems • Shifting cultivation has been considerably modified resulting in more settled land occupation as opposed to constant migration by cultivators. • Nomads continue to move with their animals particularly cattle, sheep, goats and camels, in search of grazing • Intensive production of poultry and pigs is practised. • Dairying as an intensive practice and ranching as an extensive practice are also found in the tropics.
Changes in Agricultural Systems • With the development of large-scale and small-scale irrigation projects, arable farming of cereal, vegetable crops, fruits and flowers has gradually developed. • Large-scale, arable, rain-fed as well as tree-crop plantation has been developed in the more humid areas in response to market demands for industrial and food crops. • Intensive production of vegetables, fruits and flowers has increased tremendously.
Reasons for these Changes • Increase of human population, which impose a greater demand for food and other agricultural products. • Rapid urbanisation attracts labour away from agriculture and encourages intensification. • Technical progress raising the demand for agricultural raw materials and • Changed outlook of farmers from subsistence to commercial production aimed at maximisation of income.
Branches of Agriculture • Animal science: This is concerned with the study of animal breeding and husbandry including aspects of animal health. • Crop Science: The study of crops, their management, harvesting and storage. • Soil Science: The study of the classification survey, conservation and management of the soil for crop and animal production. • Mechanisation - The study of agricultural machinery and tools together with the development of improved implements and methods of managing crops, animals and their products. • Horticulture – This is the study of cultivation of fruits, vegetables and ornamental plants.
Branches of Agriculture • Forestry: Science of forest resources and their management and conservation as well as utilisation of forest and forestry products. • Wildlife and range management - Concerned with the study of wildlife resources in the forest ecosystem. • Fisheries - study of the wildlife resources of aquatic systems. • Agricultural economics - Demand-and-supply relationships in agriculture and the economics of agricultural production including financing, land tenure, marketing of agricultural products, co-operatives, project development and evaluation. • Agricultural extension and Rural Sociology - Development and dissemination of agricultural information; the transfer of technology to farmers and the study of the lifestyles of rural farming populations.