Cropland

Authors: Eleni Briassoulis, Constantinos Kosmas

Editor's note: 6Sept12. Add Google map of cropland study sites and part of table from study site landing page and study site names.

Croplands occupy 11 percent (1.5 billion ha) of the total world terrestrial land area. In the Mediterranean region, they cover 120.1 million hectares, and in China 125-145 million hectares. Croplands are mostly encountered in lowland and hilly areas but also on steep terrains (terraced land).

Various types of cropland are commonly distinguished based on the dominant vegetation cover type (annual crops, perennial crops, trees and shrubs) and the cropping system as shown in the following Table.

 

Major land use Vegetation cover type (group) Cropping system
Agriculture Annual field cropping Shifting cultivation
Fallow system cultivation
Ley system cultivation
Rainfed arable cultivation
Irrigated cultivation
Wet rice cultivation
Perennial field cropping Non-irrigated
Irrigated
Tree and shrub cropping Non-irrigated  tree crop cultivation
Irrigated tree crop cultivation
Non-irrigated shrub crop cultivation
Irrigated shrub crop cultivation

Source: Engelen and Wen, 1995

Cropland systems, or agro-ecosystems, provide important ecosystem services such as food, forage, bio-energy and pharmaceuticals, regulation of soil and water quality, carbon sequestration, support for biodiversity and cultural services. Agro-ecosystems rely on ecosystem services provided by natural systems such as pollination, maintenance of soil structure and fertility, nutrient and water cycling and biological pest control. Inappropriate land management practices in croplands may impair these ecosystem services and produce significant disservices such as nutrient runoff, loss of wildlife habitat, sedimentation of waterways, greenhouse gas emissions and pesticide poisoning of human and other species.

Cropland worldwide is facing various LEDD issues that are driven by the demand for: (a) increasing food and biomass production for the growing world population; (b) adaptation to climate change; (c) expansion of urban areas; (d) tourism development and (e) over-exploitation of land resources. These lead to various degradation processes and LEDD problems such as soil erosion, soil compaction, soil salinisation, soil contamination, organic matter decline, land desertification, soil sealing, and loss of biodiversity, especially soil biodiversity.

Responses to LEDD in cropland vary with the spatial level on which they occur as well as on the general and specific mode of production in a particular cropland region. Those responses may have either positive or negative effects depending on the biophysical and the human context. Positive responses may be generally considered the various conservation practices, such as conservation tillage (no-tillage or minimum tillage), crop rotations for maintaining or improving soil fertility or for reducing soil erosion, organic farming, soil, water and biodiversity protection policies, etc. Positive responses differ from one to another as regards their efficiency as well as farmer expectations on their timing, cost and returns. Some responses, such as conservation tillage, may be profitable in the short term due to reduced labor or/and machinery costs, but others may become profitable only in the medium (contour farming) or in the long term (land terracing).

Negative responses can be generally considered management practices such as burning of plant residues, deep plowing the soil perpendicular to the contour lines, intensification of agriculture, expansion of agriculture in natural areas, land abandonment, policies that induce intensification or impairment of land resources, etc.

Land use change, planned or spontaneous, figures as an important response to LEDD whose effects depend on the type of change; for example, conversion of agricultural land into urban settlements or tourism development usually produces unwanted environmental impacts. On the other hand, afforestation and reforestation usually produce beneficial environmental impacts.

To better understand the responses to LEDD in cropland, to develop methods and techniques for their assessment and to provide land management and policy support for alleviating the pertinent LEDD issues, LEDDRA develops the »Theory of responses, offers »Response assessment methodologies, analyzes the »Policy context and provides applications in selected study sites in »Messara Valley (Crete), »Alento River Basin (Italy), »Zhang Jiachong (China), »Canyoles River Basin (Spain) and »Western Andévalo (Spain).

Locations of the LEDDRA cropland study sites

The main findings of this analysis are presented in the »Synthesis section.


References

  • Engelen, V.W.P., and Wen, T.T., 1995. Global and National Soils and Terrain Digital Databases (SOTER), Procedures Manual. International Soil Reference and Information Centre-ISRIC, Wageningen, Holland.
2014-11-28 10:48:37