major respects similar to those of the Upper Mississippi 

 Valley hills and stretches of moderate gradient; fertile soils 

 intermixed with rocks, pebbles, gravel, sand, and clay; and 

 streams winding among the hills and over the gently sloping 

 areas. 



French farming is noted for its efficiency. It is based on 

 the principle of working with Nature; of adapting the crops 

 to the land, rather than attempting to adapt the land to 

 crops, and of utilization of all factors of soil and water 

 physical, chemical, and biological. With respect to some of 

 these factors neighboring farmers cooperate, as in the use of 

 waters. As is indicated in figure 46, the Upper Rhone 

 Valley is dotted with ponds, most of them man-made. The 

 location of these ponds is shifted from year to year, in accord- 

 ance with each farmer's rotation of "land farming" with 

 "water farming", based on cooperative arrangements re- 

 specting the use of waters. 



These temporary ponds may vary from a few acres to six 

 or seven hundred acres. The most satisfactory location is a 

 slightly depressed, typical grain field. This area can if 

 necessary be surrounded by an earth dike to insure the size 

 and depth needed to capture and retain the usual run-off. 

 The depth, which varies with the danger from ice, the local 

 rate of evaporation, and with the amount of rainfall or stream 

 water which may be expected to replace the evaporation, is 

 usually not less than 4 feet. 



The rotation of use of such a site, variable to meet market 

 and other conditions, is generally as follows: 1 or 2 years of 

 water crop (fish and fowl) alternating with 1 year of grain 

 (wheat or barley). Each crop prepares and improves the 

 soil for the next. This treatment may in places and on 

 occasion be supplemented by small quantities of lime and 

 potash (wood ashes) or phosphate (rock or acid) and nitrates 

 (protein waste from house and barn) to correct accidental 

 deficiencies. 



The biological principle involved is that the stubble of 

 grain, the cellulose material and dead leaves and twigs when 

 under water are attacked and eaten by fungi, notably bac- 



66 



