700 Journal of Agriculture, Victoria. [10 N"ov., 1917. 



disease may do harm in a wet summer. Should weather conditions 

 conspire to peiTnit bunch contamination, which is far from impossible, 

 grave damage might result. That spray protection will prove much 

 more efficient here than in France can confidently be promised. It is 

 hoped, therefore, that growers will familiarize themselves with the usual 

 methods of treatment outlined, above, keep a sharp look out for the first 

 appearance of the disease, and above all, make arrangements to secure 

 without delay, should occasion arise, the necessary outfit and materials. 



Delays are always dangerous ; with this particular fungus they might 

 prove fatal to the crop. 



UNDERGROUND DRAINAGE AND ITS BENEFITS. 



By T. H. Grass, Potato Inspector. 



Underground drainage serves to relieve the land of free water, which 

 is harmful to most plants if left to stagnate in the earth near the sur- 

 face. This serves, not only to dry the land in early spring, but indirectly 

 to warm it, for, if the water be removed, the heat of the sun warms the 

 soil instead of cooling it by evaporation of the surplus water. 



If much of the free water in spring-time be carried through the soil 

 by under drains, then the superabundant water of mid-summer will, in 

 like manner, be removed. The rain in the spring-time is warmer than 

 the soil, and if it percolates through the land to the drain, it parts with 

 its heat and indirectly warms the soil, while the rain in the summer is 

 cooler than the soil, and in passing down to the drains cools the land. 

 Under drainage prevents the small channels of the soil from becoming 

 blocked or filled with fine particles of earth held in suspension, that is, 

 it prevents puddling to a great extent. Clayey soils shrink if they be- 

 come dry, and swell when wet. Under drains tend to prevent the 

 swelling and closing of pores which have been produced l)y drying. 



As soon as air is admitted to the subsoil, the dead roots of plants are 

 decomposed and minute channels are formed in the soil which prevent 

 the formation of large cracks that admit the air too freely, and thereby 

 cause excessive evaporation. Under drains also promote fertility by 

 opening up the soil to the o.xidizing action of the air, and by making 

 the soil more suitable for the nitrifying organisms. The more water 

 that can be made to pass through the land in a reasonable time the 

 better, for in passing through the ammonia is taken up by the soil, 

 which thus becomes better aerated and more friable, and decomposition of 

 organic matter is hastened, plant food of all kinds is liberated, and the 

 productive power of the land is increased in many other ways. Under- 

 ground drainage increases the fertility of the soil and prevents or miti- 

 gates some of the diseases. 



Fields thoroughly drained suffer less from droughts than those which 

 are undrained. 



