WATER SUPPLY FOR CROPS. 21 



bushels per acre, while that on the unsiibsoilcd plot gave 

 only 49 bushels per acre. 



Mulching is also a means by which evaporation can be 

 checked and the water supply retained. A mulch produces 

 this effect by shading and protecting the soil from the 

 beating rains, drying winds, and the rays of the sun. 



The rain, beating on the soil, not only compacts it, it 

 washes the fine particles into the non-conducting air spaces, 

 and thus forms line spaces, or active capillary tubes, through 

 which the subsoil water is rapidly conducted to the surface ; 

 this process goes on with great vigor of action Avhen the sur- 

 face of the earth is hot under the sun of long summer days, 

 and fast exhausts the water in the subsoil. Any non-con- 

 ducting material which shades the ground without allowing 

 a circulation of air between it and the soil, will serve as a 

 good mulch, and keep the soil loose, cool and moist. Dry 

 haj', leaves, saw-dust, chip dirt, boards, dry sand, or even 

 loose, dry soil, are all good mulches. That mulching does 

 serve to retain the moisture, is evident to any one who has 

 tried it, and noticed the increased freshness and vigor of 

 mulched plants during dry weather. 



Prof. Sanborn, by experiments at the Missouri Agricul- 

 tural College ( Bulletin No. 4) , found, after a continued drought 

 of four weeks, that samples of soil taken six inches deep, 

 from heavily mulched ground, contained 10,5 per cent, of 

 moisture, while samples taken at the same time, from un- 

 mulched ground, contained only 5.62 per cent, of moisture, 

 and that the mulched soil was very much cooler, and yielded 

 a better crop than the unmulched. 



In experiments on fodder-corn, I have found that either 

 an effective mulch of meadow hay, or pieces of old boards, 

 or a similar condition ' produced by frequent tillage, had 

 about the same effect, the dry surface caused by the tillage 

 acting as a mulch. That a layer of loose soil obtained by 

 tillage is a mulch, is further shown l)y the experiments of 

 Prof. Stockbridge, Dr. Sturtevant, and Prof. Sanborn. 

 Each of those investigators found more water in certain 

 depths of soil where the surface Avas tilled, than where it 

 was untilled, which fact indicates that tillage checked the 

 evaporation. 



