THE DEAINAGE OF GEAS8 LAND. 9 



be returned with interest in the course of a very few years. 

 Drainage alone will go a long way towards turning a marsh into 

 a profitable pasture, and it renders other improvements possible 

 at a trifling expense. The important point to be urged here is 

 that in future no undrained land shall be laid down to grass. 

 Otherwise careful tillage, costly manures, and the finest grass 

 seeds will certainly be wasted. The result is only a question of 

 time. Sooner or later the valuable grasses which are sown will 

 be supplanted by sedge and rush and other semi-aquatic vegeta- 

 tion, until the pasture gradually reaches the worthless condition 

 which invariably prevails on undrained land. 



Every year more water passes through land which is natu- 

 rally or artificially drained than through soil which is generally 

 saturated with moisture. Where stagnant water lies no rain can 

 enter : it simply runs ofi" the surface by any outlet it can find. 

 The soil can neither breathe nor digest any fertiliser applied to it, 

 and it is incapable of utihsing the sun's heat for the development 

 of plant-life. 



When rain falls on a well-drained field it does more than 

 merely moisten the soil and supply plants with water. It has 

 been computed that in each year by means of rain alone every 

 acre of well-drained land in this country is benefited to the 

 extent of ten pounds of nitrogen. Indeed, one of the advantages 

 of good drainage is that it allows the atmosphere to be freely 

 carried into the soil by rain, when the oxygen sweetens and 

 converts injurious organic substances into wholesome food for 

 plants. At the same time, carbonic acid gas derived from rain 

 and air performs the same operation for the mineral constituents 



of the soil. 



Another advantage which results from draining is an in- 

 crease in the temperature of the soil. It is well understood that 

 evaporation produces cold, and the more rapid the evaporation 

 the greater the cold. Travellers in the East will recall the 

 delightful surprise experienced when first they drank the cool 

 water from a porous jar while the thermometer registered over 



