Tied-Ridging: Great Concept, But Rare Implementation – A Review of Knowledge and Risk Reduction Options

Publikations-Art

Kongressbeitrag

Autoren

Germer, J., Asch, F., Schaffert, A.

Erscheinungsjahr

2015

Veröffentlicht in

Management of land use systems for enhanced food security: conflicts, controversies and resolutions

Verlag

Cuvillier Verlag , Göttingen

Seite (von - bis)

104

Tagungsname

Tropentag 2015

Tagungsort

Berlin

Water deficit is the main factor limiting crop production in rainfed farming systemsunder arid and semi-arid environments. In these environments uni- and bimodal rain-fall regimes prevail, while annual total precipitation is low, erratic and highly variablebetween years. In addition, high intensity rainfall events lead to significant run-offwater and soil losses from slopingfields. To avoid these losses tied-ridging has beendeveloped as a soil and water conservation technique. The technique consists of es-tablishing contour furrows with cross-ties, creating mini-basins. Water collected inthe basins overflow the cross-ties when rainfall is heavy and follow the furrows thatare built at a slight angle to the contour.Tied-ridging has been shown capable of reducing run-off by more than 75 %, soilloss up to 95 % and to improving greatly soil water availability and consequentlyincreasing yields up to over 50 %. Reduced surface run-off and higher infiltration hasbeen proved not only to increase plant available soil water, but also to significantlycontribute to groundwater recharge. The effects of tied-ridging on soil water, yield andgroundwater recharge are, however, highly variable in space andtime. This variabilityin combination with thefixed additional investment for ridging might be the principalreason for the limited implementation so far.Results from over 100 articles published on tied-ridging research are structured andexamined to assess whether it is possible to tailor multi-factorial threshold values,for precipitation, slope, soil type, crop, tied-ridge dimensions, that are required toallow a significant positive impact of tied-ridging. Furthermore, the published data areanalysed for their suitability to describe functions that can be integrated into currentwater and crop growth models. Integration of tied-ridging as an management optioninto these models could serve farmers, extension workers and researchers to predictthe impact of tied-riding. This could eventually reduce the risk of investment loss,promote implementation and ultimately improve food security. Remaining knowledgegaps identified are translated into into specific research questions.