Soil Genesis and Development, Lesson 6 - Global Soil Resources and Distribution

 Soil Resilience

The ability of the land to revert to a near original production level after it is degraded, as by mismanagement. Land with low soil resilience is permanently damaged by degradation.

 Soil Performance

The ability of the land to produce (as measured by yield of grain, or biomass) under moderate levels of inputs in the form of conservation technology, fertilizers, pest and disease control. Land with low soil performance is generally not suitable for agriculture.

 Land Area Quality Distribution

 
  Land Quality Class 1

This is prime land.  Soils are highly productive, with few management-related constraints.  Soil temperature and moisture conditions are ideal for annual crops.  Risk for sustainable crop production is generally less than 20%.

 Land Quality Classes 2 and 3

These soils have few problems for sustainable production.  Their productivity is generally very high; however, care must be taken to reduce potential degradation.  Risk for sustainable crop production is generally 20-40%, but risks can be reduced with good conservation practices.

 Land Quality Classes 4, 5 and 6

These soils are not suited for grain crop production without important inputs of conservation management.  In fact, no grain production must be contemplated in the absence of a good conservation plan.  Lack of plant nutrients is a major constraint.  Soil degradation must be continuously monitored.  Productivity is not high.  Risk for sustainable grain crop production is 40-60%.

 Land Quality Class 7

These soils are definitely not suitable for low-input crop production.  Their low resilience makes them easily prone to degradation.  They should be retained as natural forests or range.  Risk for sustainable grain crop production is 60-80%.

 Land Quality Classes 8 and 9

These soils belong to very fragile ecosystems or are very uneconomical to use for crop production.  They should be retained in their natural state.  Risk for sustainable crop production is greater than 80%.