xii Contents 



PAGES 



The Proper Depth of Surface Tillage and Ridged and Flat 

 Cultivation. Depth of early tillage Deep ridges objec- 

 tionable Ridge cultivation may be advisable for potato 

 culture . . . 165,166 



Rolling in Relation to Soil Moisture. Firming the surface 

 to establish capillary connection with the soil below 

 Boiling may warm soil Boiling may bring water to the 

 surface The press drill 166,167 



Destructive Effects of Winds. Conditions for injury De- 

 structive effects on sandy lands Influence of groves 

 and hedgerows on evaporation Protective influence of 

 grass The value of hedges in windy sections 168-170 



CHAPTER IV 



THE INCREASE OF YIELD DUE TO IRRIGATION IN HUMID CLIMATES 

 (pages 171-195) 



Importance of the Amount and Distribution of Water in 

 Potato Culture, and the Advantage of Irrigation in Cli- 

 mates like Wisconsin. Time and method of planting 

 Amount of water used Differences in yield 171-175 



Effect of Supplementing the Rainfall in Wisconsin for Cab- 

 bage Culture. Method of planting Weight of heads 

 Influence on yield of thick and thin planting Amount 

 of water given crop 175, 1 7(> 



Effect of Supplementing the Rainfall with Irrigation on the 



Yield of Corn. Difference in yield and in water used. . 176-178 



Effect of Supplementing the Rainfall with Irrigation on the 



Yield of Clover and Hay 178,179 



A Crop of Barley and a Crop of Hay the Same Season 179-181 



Effect of Supplementing the Rainfall for Strawberries 181 



