ZIMSEC O Level Geography Notes:Agriculture:Farm Inputs: Land size, Soil and Slope
- Size of the land is significant in farming because where land is short and farming land is small, traditional farmers have to practice intensive subsistence farming.
- Subsistence farming is the growing of crops mainly for home consumption with very little or no surplus for sale.
- Under modern systems, small farm sizes lead to activities like market gardening, horticulture and silviculture.
- Silviculture is the growing and cultivation of trees.
- Agriculture occurs on land and therefore without this input the activity ceases.
- Where land is plentiful and farms are large, then commercial farming plantation agriculture, shifting cultivation and normadism may be undertaken.
- The soil characteristics are the most important.
- These include: i. Porosity (is a measure of how much of a rock/soil is open space). This space can be between soil grains or within cracks or cavities of the rock.
- ii. Permeability (is a measure of the ease with which a fluid (water in this case) can move through a porous rock or soil),
- iii. Structure (soil structure, refers to the arrangement of soil and how it separates into units called soil aggregates. An aggregate possesses solids and pore space),
- iv. Tilth (Soil tilth is its physical condition, especially in relation to its suitability for planting or growing a crop)
- v. Water retention capacity (is the maximum amount of water that a given soil can hold)
- vi. pH value (determines acidity or alkalinity of the soil) and humus content
- Sandy soils are good for root crops and legumes such as groundnuts and potatoes.
- Loams are excellent for maize and tobacco.
- Clay soils are good for cotton, sugar cane and wheat.
- Acidic soils require application of lime fertilisers as inputs to neutralize the acidity of the soils.
- Alkaline soils need acidic fertilisers.
- Crops like tea naturally need acidic soils whilst soils with a tendency to waterlog must be used for crops like rice, otherwise draining through ditches must be done to successfully grow other crops.
- This is crucial as it determines the drainage of the soil as well as utilization of machinery.
- On steep slopes the gradient is naturally high, it may be necessary to form ridges or terraces in-order to reduce the erosion of the soils and retain water long enough for it to penetrate to the plants roots.
- This factor has led to the sub-division of crops into lowland crops for example maize, wheat and tobacco and hillside crops such as tea and coffee.
- Machinery can work without problems on slopes of up to 11°, although the optimum 12° to 5°.
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