WHEN TO DRAIN LANDS. 77 



and consequent preparation for seed sowing, very simple 

 artificial surface drainage is usually effective. This can 

 be mainly accomplished with the plow, first by opening 

 drainage furrows at proper intervals, and this is often 

 all that is needed to dispose of surplus water; second, 

 by ridging with the plow which prepares long seed beds 

 a little above the general surface and at the same time 

 leaves channels for the escape of the water; third, by 

 opening deeper surface-drains to act directly or to re^ 

 ceive and speed the departure of the outflow from the 

 open furrows. All of these forms of treatment, selected 

 according to the degree of the need of drainage, have 

 proved widely satisfactory and have facilitated magnifi- 

 cent winter growth of vegetables upon heavy adobe soils 

 in some of our regions of heaviest winter rains. The ac- 

 tion is quicker than underdraining because percolation is 

 notably slow in such soil. It removes the surplus from 

 the surface just at the time that its absence is most de- 

 sirable and it leaves the moisture stored below to rise 

 as the demand for it advances. On the other hand, under- 

 drainage, where it is not imperatively demanded by ex- 

 ceptional conditions, has clearly acted too slowly to bring 

 the surface speedily into satisfactory condition and has 

 acted too long in drawing away more water than is desira- 

 ble from below and has then continued as a very effec- 

 tive hot-air system for farther drying of soil-substance 

 which should have retained more moisture to supply the 

 plant and foster capillary action from still lower layers. 

 In the writer's own experience shallow-rooting plants 

 have dwindled over tile lines while those midway be- 

 tween the lines were growing rapidly. 



Conditions Determining Recourse to Underdrainage, 

 It may be well to specify a few of the conditions which 

 should determine whether underdrainage should be pro- 

 vided in land under consideration for vegetable growing. 

 Of course, the claim already alluded to, that any piece 

 of soil selected for gardening must be first underdrained, 



