_Fineness of Soil-particles._ The second quality in a soil on which its absorptive power depends is the fineness of its particles. The great benefit which a soil derives from a good tilth, in this respect, was one of the reasons why Tull's system of horse-hoeing husbandry was so successful in its results.[35] The finer the soil-particles, it may be said generally, the greater is the absorptive power of the soil. _Limit to Fineness._ There is, however, a limit to the fineness to which the particles of a soil ought to be reduced; for it has been found by experiment that when a certain degree of fineness is reached, the absorptive power decreases with any further pulverisation. A German experimenter found, for example, that a garden loam, capable of absorbing 114 per cent of water in its natural state, when pulverised very fine was able to absorb only 62 per cent of water. Here, clearly, the limit to which it is advisable to pulverise a soil had been exceeded. _Reason of the above._ It is not difficult to see why this should be so. The amount of water that a soil can soak up is due to the number of pores, or air-spaces, it contains of a certain size. If these pores are large and few in number, the amount of water absorbed will be naturally less than when they are numerous and smaller in size. Up to a certain extent, the more a soil is broken the greater will be the number of pores created, of a size to permit the water to soak in. Beyond that point the pores become too minute, and the soil becomes too compact, each particle clinging together too closely. _Retentive Power of Soils for Water._ Now closely connected with this absorptive power of soils, which we have just been considering, is the power soils possess of holding or retaining the water they absorb. This power, it will be seen at a glance, must have an important bearing on the fertility of a soil. _Importance of Retentive Power._