General information
Name of best practice	Enarenado
Geographic distribution (countries)	Spain and Canary Islands
Origin of practice		indigenous/traditional or 100+ yrs old
		traditional, but improved
		recently introduced
		new technology
For what type of land use		livestock/fish farming
		cropping
		ecosystem conservation
Main purpose		water availability
		nutrient availability
		soil conservation
		others (please specify):

 

Type / Description of practice
Short description of practice (if possible with figures/drawings/photo)	Enarenado is practiced in arid areas of Spain and the Canary Islands.  The practice entails placing a layer of sandy soil (10 – 30 cm) over a very clay-rich soil (Fig. 1).  This results in greater soil water retention and better crop performance.  The physical soil principles involved are as follows:  clay soils in unsaturated conditions (hot, arid climates) result in greater water loss due to capillary action and evaporation than sandy soils.  By applying sand to the surface of clayey soils (such as vertisols), the hydraulic conductivity of the soil is reduced and less water escapes via evaporation.  In the Canary Islands, boulders are often placed in wall-like structures above the sandy layer (Fig. 2).  The boulders capture mist and dew which then seeps into the sandy soil layer.  The sandy substrate used in the Canary Islands is of volcanic origin, but in Spain the sandy material used is often derived from sedimentary rocks.
Fig. 1  Enarenado rehabilitation, depicting a vertisol with sandy material on the surface.
Fig. 2.  Enarenado and dew capture soil restoration practices on the Canary Islands.

 

Natural resources prerequisites
Soil	A sandy substrate is required	Relief	Any
Climate	Semi arid to arid i.e. <500 mm rainfall per annum	Vegetation	Any
Other prerequisites		A clayey soil is required for amelioration i.e. the sand is used to increase the soil water holding capacity of the clayey soil.
Time requirements to restore land/water/nutrients		Immediate.
Reference level in this comparison		The untreated clayey soil.

 

Socio-economic factors / prerequisites
Land ownership/tenure		Any
Farm sizes		Any
	Supports shifting cultivation			Supports rangeland management
	Supports sedentary farming			Supports uncontrolled grazing
	Supports livestock production			Supports others (please specify):
	Transhuman system
Usually requires credit:			no		yes
Machine requirements:			no		yes (name what), specify
Labour requirements:			hired or		family labour
Investment phase: - labour to transport sand.			high		moderate		low
Maintenance: - requires replacement every few years.			high		moderate		low
Do quantifications exist? (give data or reference)		no data found to date.
Requires/supports division of labour (gender, age, ethnic group ...).			no		yes (name what), specify
Requires/supports participation of communities (e.g. joint field preparation):		Not really.  Only requires the action of a few individuals. Land tenure is a major constraint, but this technology could be undertaken by government programs and international donor agencies. Also, could be undertaken at a small scale in agricultural fields near villages. To start a small niche is often required to galvanize communities into action.

 

Advantages of the practice
Yields, profit	Increases yield of crops.
Biophysical	Increases water holding capacity of soil.
Labour economic	Provides labour.
Socio-cultural, religious	None
Skill/knowledge requirements	None
Ecological (on-site, off site)	Increases water holding capacity of soil.
Others (please specify)	- -

 

Disadvantages / Constraints of the practice
Yields, profit	None
Biophysical	Alters soil structure, which may affect natural ecosystem components e.g. certain clay soil-adapted plants may no longer thrive on the sandy substrate. Possible negative effects of soil fertility decrease Availability of the substrate is a very limiting factor potentially
Labour economic	None requirement for machinery or a lot of labour
Socio-cultural, religious	None
Skill/knowledge requirements	None targeted soil research required. Time must be allocated to create awareness of how to improve productivity (NB: introduce technology in such a way that people take ownership of the ideas)
Ecological (on-site, off site)	Alters soil structure, which may affect natural ecosystem components e.g. certain clay soil-adapted plants may no longer thrive on the sandy substrate.
Others (please specify)	- -

 

Dissemination
Dissemination		was/is a success
		was/is slow
		still in test stage
If successful for new technologies: Was it so far		“early adoption” (curiosity, testing)
		“verified adoption” (farmers repeat practice still in third year)
If farmers modified initial new practice during adoption process, then how?	Not applicable.  This system has been used for hundreds of years.
Any data/reference on adoption and dissemination (where, how many farmers/ rangers/ herdsmen):	This is a traditional practice in Canary Islands and Spain, probably utilised for more than three hundred years.
If disseminated, then how		Farmer-Farmers		Media
was it done?		Extension service		Research project
		Others (specify)
If via research, was it		Technology Transfer		Participatory On-farm Research
If via research/ extension or others, was it		free or with incentives		without incentives
Name at least 2-3 crucial conditions for successful adoption by farmers
Sandy soil required Clayey substrate required for amelioration (e.g. vertisols). Availability of labour Demonstration plots by extension agents Secured land rights
Who adopted it (describe typical adopters)?	Crop farmers.
In which region(-s)?	Arid Spain and Canary Islands.
Name at least 2-3 important dissemination/adoption constraints/blocker.
Sandy soil not available. Fertilizers to amend sandy soil not available. Female farmers may not want to adopt because it is labour intensive and older farmers also for same reason Perception of risk of impact on soil characteristics and yield
Who did not adopted it (describe typical non-adopters)?	Not known.
In which region(-s)?	Not known.

 

Evaluation
How was its restoration ability evaluated so far?	Unknown.
References, if known:	Unknown.
How could remote sensing/ GIS contribute to monitor restoration success?	GIS could be used to map areas that are underlain by clay soils that could potentially benefit from the application of a sandy substrate.
How could adoption and dissemination be improved?
Undertake experiments to demonstrate the value of the practice in terms of water conservation.
Provide finance for implementation of practice.
Rank three crucial research needs.
1.	Determine the extent of the area in Africa that could benefit from enarenado.
2.	Determine the availability of sandy substrates for enarenado.
3.	Determine the effectiveness of these sandy substrates in terms of improving water availability to crops.
Key literature on the practise (biophysical as well as socio-economic)	Hercowitz, M. 2001. THE LANZEROTE SOCIETY.  PhD thesis. University of Barcelona Fernández-Rodríguez, E.J. 1993. SPECIAL CHARACTERISTICS OF THE "ENARENADO ALMERIENSE" FOR THE DEVELOPMENT OF A SOIL WATER BALANCE SUBROUTINE; A DYNAMIC SIMULATION APPROACH. Acta Hort. (ISHS) 335:553-556 Martinez, P.F. 1993. MODIFIED SOIL CULTURE AND HYDROPONIC TECHNIQUES IN A MEDITERRANEAN CLIMATE. Acta Hort. (ISHS) 323:129-138
Submitted initially by	Anthony Mills, Department of Soil Science, University of Stellenbosch (mills@nbi.ac.za)