64 Elementary Principles of Agriculture 



1. Not mulched. (Check or control.) 



2. Surface cultivated one inch deep (soil mulch). 



3. Surface cultivated two inches deep (soil mulch). 



4. Mulch with one inch of coarse gravel. 



5. Mulch with one inch of sawdust. 



6. Mulch with one inch of fine sand. 



7. Mulch with one inch of fine cut straw. 

 Which mulch is most effective? 



Which mulch is most practical under field conditions? 

 What other conditions affect evaporation from the soil? 



96. Soil Moisture Retained by Cultivation. Professor 

 King has investigated the efficiency of surface culti- 

 vation in retaining water in the soil. A piece of fallow 

 ground was divided into plots twelve feet wide, as shown 

 in diagram in Fig. 36. Three were cultivated and two 

 left fallow. The figures in the table show the per cent 

 of water in the soil of each plot, at different depths, at 

 the end of fifty-nine days. The average loss of water 

 from the cultivated plpts was 709.4 tons per acre, while 

 in the non-cultivated plots the loss was 862.3 tons 

 per acre. This makes the mean daily loss of water 

 from the ground not cultivated 3.12 tons per acre 

 greater than was that from the cultivated soil. 



97. "Dry-land Farming." In some sections of the 

 country where the rainfall is so light that the trees and 

 other large plants requiring large amounts of water 

 will not grow, the soil mulch has been found to be an 

 excellent conserver of soil moisture. A crop is grown 

 only every other year. The fields are divided into 

 two parts. One is planted in grain, and the other will 

 be harrowed after each rain, or oftener, to form a mulch. 

 In this way, the water is stored up one season for the 

 next season's crop, and from twenty-five to fifty bushels 

 of grain to the acre are harvested every other year. If 



