Crops require the right soil. Image credit

ZIMSEC O Level Geography Notes:Agriculture:Farm Inputs: Land size, Soil and Slope

Land size

  • 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°.

To access more topics go to the O Level Geography Notes page