IX.] 



ACTION OF LIME 



J w 3 



food rendered available also tends to prolong the dura- 

 tion of growth. On very light soils the addition of lime 

 acts to a certain extent as a binding material, and in- 

 creases the cohesion and water-retaining power of the 

 soil, but it is not so effective in this respect as humus. 

 Besides its physical effect upon the texture of stiff soils, 

 lime has a very powerful chemical effect, liberating freely 

 the reserves of plant food of all kinds in the soil and 

 rendering them available to the plant ; so that on soils 

 naturally deficient in carbonate of lime, manures of all 

 kinds can only find their proper value if lime be also 

 used from time to time. On soils that have been 

 under intensive cultivation for a long time immense 

 reserves of plant food have been accumulated, which 

 only require the addition of lime to bring them into 

 action. As an example may be quoted the result of 

 applying lime to an old hop garden at Farnham, 

 Surrey, where the soil consisted of an alluvial loam, 

 very deficient in carbonate of lime, and heavily dressed 

 with organic manures for many years previously. The 

 plots chosen for comparison received a complete artificial 

 manure with or without I ton of lime per acre ; the 

 figures for the crops in the following table have been 

 reduced to percentages to eliminate the great fluctua- 

 tions due to season. 



Of course, as lime itself supplies no food to the 



X 



