86 STATE BOARD OF AGRICULTURE. 



Of the artificial causes, we may mention: (a) The plowing or cultiva- 

 tion of the soil when it is too wet; (b)The running of stock upon fields 

 when the soil is wet, or the hauling of loads over such soil, and (c) 

 The failure in spring to plow at the proper time, — delaying the ]»lowing. 



Theory of puddling. — Soils, in proper tilth, are loose and crumbly. Ou 

 first examination, the grains of such a soil appear to be separated one 

 from another, or the grains may appear to be gathered in large masses 

 or lumps, and so open does the whole soil seem that a handful of it im- 

 presses us as being light. As a matter of fact, however, Avhat appear to 

 us to be grains of soil are not grains, but aggregations of much smaller 

 grains so stuck or cemented together as to form a loose open mass, but 

 having the appearance to the naked eye of a single grain. And these 

 small masses may be further combined into larger masses, but what- 

 ever the size of the mass, whether small or large, the important charac- 

 teristic is the openness above referred to. This openness is found in all 

 virgin soils. Nature secures this condition largely by the action of 

 frosts, the roots of plants, the action of animal life — ants, earthworms, 

 etc., and by the cementing influence of various salts in the soil. Chief 

 among these cementing salts are those most desirable as fertilizers. 

 The farmer to keep his soil in proper tilth must give nature a chance, 

 or copy her methods. It is not often that we can improve upon them. 



Let us see now what takes place in the puddling of a soil. (1) If 

 water stands upon soil for a few days the cementing materials that 

 hold the individual grains in these masses, are dissolved, the water 

 itself acts as a sort of lubricant, and the individual grains of their own 

 weight, settle down into a compact mass, which becomes more compact 

 in the process of drying. 



(2) In the case of a heavy rain the dissolving is hastened by the 

 pounding action of the rain drops. In this case it is seldom, if ever, 

 that the puddling occurs so completely, or so deep, as in the case of 

 standing water upon soils. 



In the case of artificial puddling : 



(1) A soil may be wet enough to partially dissolve or to soften the 

 cementing material. If at this point no further wetting takes place, or 

 if drying begins, the soil if undisturbed would retain its openness. 

 But if at this point a tool of any kind were put into the soil, or tramping 

 of any kind were done upon it, the pressure thus brought to bear would 

 slide these individual grains together and the whole mass would be 

 compact or puddled. 



(2) Perhaps the most interesting case of all is the last one mentioned 

 above, — that of failing to plow or otherwise loosen the soil Avhen it is 

 in a proper moisture condition to work after a protracted moist period — 

 usually most noticeable in spring. The sunshine and heavy winds may 

 dry the soil too rapidly with the result that a single week of delay may 

 cause a very bad condition of baking — or puddling. 



A very interesting case of this kind is on record by Professor King. 

 One-half of a small field was plowed April 28tli and the soil was in per- 

 fect tilth and remained so. Seven days later the other half was plowed, 

 but turned over in large clods. This last plowed ground had to be gone 

 over twice with a loaded harrow, twice with a disc harrow and twice 

 with a heavy roller before it could be brought into a condition even 

 approximating what it would have had it been plowed six days earlier; 



