104 



cult ire which c.iii use the soil j)ermanently where annual cro])s ruin it 

 <^juickly because the plow prepares the land for erosion. 



'I'he speed of soil destruction, with its erosion after plowing, is 

 particularly noticeable with the great American crops, cotton, corn and 

 tobacco, which re(|uire clean cultivation. Many orchards are also 

 ctiltiv lied lor the double |)ur})ose of keepino; down rival plants and 

 preserving moisture, but we pay high in soil loss for the nioisturt; that 

 we get by that nieius on hilly lauds. The plow is one of the greatest 

 cneuiics of tlu' future. As a matter of fact we have already de- 

 stroyed enough laiul in the United States to support many mil- 

 lions of people; and therefore the tree is the more im)iortant because 

 it permits an agriculture that will keep the soil iiulefiuitely, and in 

 permanent production, without plowing. 



I li i\c accideutlv discovered a. better wav of conserving; moisture 

 than by plowing, aiul I ha\c found it going on in widely scattered 

 places and in widely different climates. 



Primitive ])eoples in many ]iarts of the world have long since 

 obtained thi- advantage of cultivation, maiidy increasing the available 

 moisture for the tree or plant, without cultivation of the soil and the 

 loss which follows "the washing of cultivated soils. As an example 

 I cite the Indians of Arizona, who have grown corn crops for cen- 

 turies in a country with but from six to fifteen inches of rain. They 

 do tliis bv pi '.uting in little patches at the mouth of a gully where at 

 tlic time of rain the flood water is led away into furrows and depres- 

 sions so that it thoroughly soaks the ground in which the corn is 

 planti'd. 



My attention was first called to this practice by observing a good 

 patch of barley in the edge of the Sahara in Southern Tunis, where 

 the gulley flow resulting from a winter rain had spread itself out fan- 

 like and soaked the triangular alluvial area of sand, which bore a 

 tine crop of barley in the inddst of the desert. 



I'or centuries the olive growers of parts of Tunis have led gulley 

 water to the olive trees where it was retained, in areas that resembled 

 a tennis eourl. with a 1 'J inch l)auk of dirt around it and two or three 

 olive trees within this area thus watered by impounding. 



A practice somewhat similar to this is shown in F. H. King's 

 classic book on Chinese agriculture, "Farmers of Forty Centuries;" 

 ])ut the most extreme case tint has come to my .-ittention is furnished 

 bv the Berber tribe of the Matmatas, of Tunis. These people live 



