18 The Profitable Culture of Vegetables. 



they could use. Mr. Hall, of Rothamsted, an authority on 

 soils previously quoted, says: 



" In all cases the amount of water transpired by the crop is a notable 

 fraction of the total annual rainfall, particularly so in the case of a root- 

 crop like mangolds, which in the south and east of England will often 

 require a full half of the total rain falling within the year. As much of 

 the rainfall runs straight off the surface into the ditches, and another 

 portion is lost to the land by percolation into the springs, as again a 

 considerable fraction is evaporated at certain seasons from the bare 

 surface of the soil, it is evident that the water supply, even in our 

 humid climate, is far from sufficient for the maximum of production 

 and may easily fall below that which is required for an average crop. 

 Indeed we may take it as a truism that the crop obtained is more often 

 determined by the water available than by lack of the other essentials 

 of growth light and heat, manure, &c. Of this we can have no better 

 proof than the enormous crops grown by irrigation on sewage farms. 

 Where the conditions are favourable, and the farm is situated on a 

 free draining sandy or gravelly soil, so that the water can be often 

 renewed and drained away to keep the soil supplied with air as well as 

 water, the production of grass, cabbages, and other green crops is 

 multiplied five or even tenfold by the unlimited supply of water. 

 Speaking generally, over a great part of England, where the annual 

 rainfall is from 35 to 25 inches, a large proportion of which falls in the 

 non-growing season, it is necessary to husband the water-supply, and 

 it will be found that one, at least, of the objects of many of our usual 

 tillage operations is the conservation of the moisture in the ground for 

 the service of the crop." 



This evidence is corroborated and strengthened by that of 

 Mr. F. H. KING, Professor of Agricultural Physics in the 

 University of Wisconsin, U.S.A., who says, in his book on 

 The Soil : 



" There are very few countries, indeed, where the distribution of 

 rainfall in time and amount is such as to permit fertile soils to 

 produce the largest crops they are able to bear ; and this being true, 

 those soils which are able to store the largest quantities of rain in a 

 condition which shall permit vegetation to use it to the best advantage 

 are likely to be the most productive." 



From this evidence it will be seen how extremely important 

 it is that crops should have all the moisture they need at the 

 time when they are making their most vigorous growth. In 

 this matter land which has been drained of stagnant water and 

 deeply worked shows an enormous advantage over land which 



