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close this bookAmaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions (ECHO; 1996; 397 pages)
View the documentOther ECHO publications
View the documentAbout this book
View the documentAcknowledgements
Open this folder and view contents1: Basics of agricultural development
Open this folder and view contents2: Vegetables and small fruits in the tropics
Open this folder and view contents3: Staple crops
Open this folder and view contents4: Multipurpose trees
Open this folder and view contents5: Farming systems and gardening techniques
Open this folder and view contents6: Soil health and plant nutrition
Open this folder and view contents7: Water resources
Open this folder and view contents8: Plant protection and pest control
Open this folder and view contents9: Domestic animals
Open this folder and view contents10: Food science
Open this folder and view contents11: Human health care
Open this folder and view contents12: Seeds and germplasm
Open this folder and view contents13: Energy and technologies
Open this folder and view contents14: From farm to market
Open this folder and view contents15: Training and missionary resources
Open this folder and view contents16: Oils
Open this folder and view contents17: Above-ground (urban) gardens
View the document18: What is ECHO?
View the documentAdditional ECHO publications
Open this folder and view contentsECHO development notes - issue 52
Open this folder and view contentsECHO development notes: issue 53
close this folder28 additional technical notes about tropical agriculture
View the documentA few alternate seed sources that we commonly use
View the documentAmaranth - grain and vegetable
Open this folder and view contentsArid region farming primer
View the documentCitrus propagation and rootstocks
Open this folder and view contentsCucurbit seeds
close this folderDry farming
View the documentFundamental principles
View the documentRequirements
View the documentI. Increase water absorption
View the documentII. Reducing the loss of soil moisture
View the documentIII. Dry farming practices
View the documentMuscovy ducks for png villages
View the documentFruit crops
View the documentFruit vegetables
View the documentGrain crops
View the documentGround covers and green manures
View the documentGreen manure crops
View the documentIndustrial crops
View the documentThe lablab bean as green manure
View the documentLeafy vegetables
View the documentLeguminous vegetables
View the documentThe moringa tree
View the documentRecipes to learn to eat moringa
View the documentMiscellaneous vegetables
View the documentThe poor man's plow
View the documentPulses (grain legumes)
View the documentRabbit raising in the tropics
View the documentLetter from fremont regier, mennonite central committee, Botswana (and earlier in Zaire)
View the documentRoots and tubers
View the documentSunnhemp as a green manure
View the documentThe sweet potato
View the documentTropical pasture and feed crops
View the documentThe velvet bean as green manure
Open this folder and view contentsPrinciples of agroforestry
Open this folder and view contentsGood nutrition on the small farm
 

II. Reducing the loss of soil moisture

A. REDUCING SOIL EVAPORATION. Water in the soil exists as a continuous film surrounding each grain. As water near the surface evaporates, water is drawn up from below to replace it, thinning the film. When it becomes too thin for plant roots to absorb, wilting occurs.

1. Shelter belts of trees or shrubs reduce wind speeds and cast shadows which can reduce evaporation 10 to 30 percent by itself and also reduce wind erosion.

2. Mulching reduces the surface speeds of wind and reduces soil temperatures.

3. Shallow tilling can create a dirt mulch 2 to 3 inches deep which dries out easily but is discontinuous from the subsurface water, preventing further loss. Tillage must be repeated after each rain to restore the discontinuity. This is most workable where rainfall occurs in a few major rainfalls with relatively long intervals in between.

B. REDUCING TRANSPIRATION. All growing plants extract water form the soil and evaporate it from their leaves and stems in a process known as transpiration.

1. Weeds compete not only for soil nutrients, but water as well and so their control is critical.

2. Selection of crop is significant as well. Dwarf varieties have less surface and so lose less water. Some plants close their stomae when it is hot, reducing their water loss. Others, like corn, curl their leaves during hot afternoon and open them at night, effectively changing their surface area in response to conditions.

3. In dry farming, the number and spacing of plants is reduced so that fewer plants compete for soil moisture. The exception to this occurs when allowances for insect, bird, and rodent loss must be made at planting.

4. Where rainfall is frequently marginal to insufficient, drought "insurance" can be obtained by clear fallowing a sufficient area. An area clear of growing vegetation with a properly maintained stubble and soil mulch can retain 20 to 70 percent of the precipitation received until the next year. Where 5 to 6 acres each year per family have been so set aside in India, the specter of famine due to drought has been eliminated.

5. Post harvest tillage will create stubble and dirt mulches and destroy weeds before the onset of the dry season.

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