New York Agricultural Experiment Station. 71 



crops in the rotation to grow on an acid soil for the sake of making 

 it easier to combat scab on potatoes. In New York State the potato 

 industry has developed on soils naturally containing lime carbonate 

 as well as on acid soils. Also it is significant that at the Rothamsted 

 Experiment Station, England, potatoes have been grown for 30 

 years successfully and with large yields on land which naturally con- 

 tains as much as 30 to 50 tons of calcium carbonate per acre to the 

 depth of the plow line. In some of our western states, notably 

 Colorado, where the potato industry prospers and where they some- 

 times raise from 400 to 600 bushels per acre, the soil naturally con- 

 tains from 10 to 30 tons of carbonates (limestone) to the plowed 

 soil of an acre. 



Of course in comparing different forms of lime the question of 

 price must always be considered. And the fact that in using burned 

 lime one has less weight to handle must also be taken into account. 

 When the haul from the railroad station is very long and the roads 

 rough and where ground limestone costs as much as its equivalent 

 in burned lime, it may be more economical to use the caustic material. 

 However, in many such instances there is some question whether 

 lime at the present price can be used profitably. It may be better 

 in these cases simply to grow such crops as are least sensitive to a 

 deficiency of carbonates in the soil, to make large use of farm manure, 

 which has some tendency to neutralize acids, and to avoid the use 

 of those particular fertilizers that tend to increase an acid condition 

 in the soil, such as acid phosphate and ammonium sulphate. 



Good grades of ground limestone can be obtained from twelve or 

 more producers in New York State at from SI to $2 per ton in 

 bulk, car lots, f. o. b. quarries. Throughout a large part of the state 

 the prices at the farmers' nearest railroad station are $1.50 to $3 

 per ton; and if he will order direct from the companies, sending cash 

 with order, he can obtain better prices than these. To equal these 

 prices good grades of burned lime would have to sell for $2.50 to 

 $5 per ton; but even then limestone would of course be preferable, 

 because of the many other advantages given above. In some other 

 states where ground limestone has been used more generally the 

 prices are now much lower than here and there is every reason to 

 believe that in the near future we shall be able to obtain it at lower 

 figures. It can be produced at almost the cost of the coal used in 

 burning lime. It is our greatest hope of an economical supply of 

 lime for replenishing the soil. In view of all the facts should we 

 not encourage the use of ground limestone in preference to that of 

 burned lime? 



FINENESS OF GROUND LIMESTONE. 



The ground limestone used in the Ohio experiments was of such 

 fineness that the total passed only a 10-mesh sieve (10 openings to 

 the linear inch); about 60 per ct. passed a 40-mesh. Yet in these 



