SLOW PERCOLATION OF LIME THROUGH PEAT. 21 



elusion was reached that the reason why the growth of the plants had 

 not been affected was because the lime had not penetrated sufficiently 

 into the soil. Another and more drastic experiment was therefore 

 determined upon. 



On March 10, 1909, six blueberry plants in 4-inch pots containing 

 a good blueberry soil were set apart from their fellows and watered 

 ^Yith ordinary limewater, a saturated solution of calcium oxid, 1.25 

 grams per liter of water. The af)plications made*were of such an 

 amoimt that the soil in the pot was thoroughly wetted each time, and 

 usually a small excess quantity ran through the hole in the bottom 

 of the pot. 



For more than seven months, until October 22, 1909, these pots 

 received no other water than limewater. During this period the 

 plants continued to grow in a normal manner, their average height 

 increasing from 4| to 14 inches. The lime appeared to have no 

 deterrent etfect whatever on the growth of the plants. A computation 

 based on the total amount of limewater used showed that each pot 

 must have received about 18 grams of lime. An analysis of the soil 

 in one of the pots after the limewater applications had ceased gave 

 14 grams. This amount was enormous, considered from the stand- 

 point of agricultural usage. The soil, which had about one-third 

 the weight of a*i ordinary soil, was over 8 per cent lime. This is the 

 equivalent of about 25 tons of lime per acre mixed into the upper 

 6 inches of the soil. 



Now, it was already known from the experiment described on page 

 23 that in this soil when containing as much as 1 per cent of lime 

 blueberry plants should either die or barel}^ remain alive. As a 

 matter of fact these limewater plants were making excellent growth. 

 A careful examination of the contents of one of the pots was then 

 made. The surface of the soil was covered with a hard gray crust 

 of lime. Immediately underneath for a depth of about half an inch 

 the soil was black and contained no live blueberry roots. There was 

 a zone of the same black rootless soil along the wooden label that 

 reached from the top to the bottom of the pot. In all other parts 

 of the dark-brown peaty soil there was a dense mass of healthy 

 roots, which reached down also into the open spaces among the 

 broken crocks in the bottom of the pot. The lime appeared to have 

 penetrated only into the superficial portions of the soil. A chemical 

 test showed that the black rootless layer was densely impregnated 

 with liuie, while the brown peaty portion containing the growing 

 roots still o'ave the acid reaction that was characteristic of the whole 

 potful of soil before the limewater applications began. 



Since all the water that the limeless root-bearing portion of the 

 soil had received during the preceding seven months had come from 

 the limewater applications, it was evident that the lime contained 



193 



