CONTENTS xiii 



PAGE 



The problem of alkali soils 65 



What causes alkali ....... 65 



The effect of alkali 66 



Treatment for alkali ...... 67 



The subsoil 69 



What it is 69 



Its fertility 70 



Different types ....... 70 



Analysing the soil at home ...... 71 



Weighing the humus ...... 72 



Separating the sand, silt, and clay .... 73 



CHAPTER IV. SOIL WATER 



The amount of water needed by plants . 



How plants drink ....... 



Rainfall insufficient or unevenly distributed 



The capacity of different soils to hold water 



Influence of the subsoil on water-holding capacity . . 82 



Height of the water table . ... 82 



How to increase the water-holding capacity of soils . . 83 



The influence of forests upon the water supply . . 84 



The loss of soil water by seepage ..... 84 



The extent of the loss ...... 85 



Plant food lost in seepage water ..... 85 



How to prevent loss by seepage ..... 87 



The movement of film water ..... 87 



How film water creeps from grain to grain ... 87 



Capillary action 89 



How to prevent the loss of film water by evaporation . 90 

 The function of a mulch . . . . . .91 



The soil mulch 91 



The water-moving ability of different soils ... 92 



How to test the water-holding capacity of soils . . 93 



How to test the water-moving ability of soils * . . 95 



CHAPTER V. THE BENEFITS OF TILLAGE 



The present emphasis on good tillage .... 97 



Tillage to prepare the seed bed ..... 98 



The competition between plants in the wild ... 98 



Culture an improvement on nature .... 99 



The reward of thoroughness 100 



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