30 STATE BOARD OF AGRICULTURE. 



If these soils were broken down so that no aggregates remained, and 

 supposing all of these grains were of the same size, and these were 

 packed in the closest possible manner, there would be still about 26 per 

 cent of unoccupied space between the grains, but if the grains were not 

 of the same size they might be packed so that not over 10 per cent or 

 even 6 per cent of space remained between the grains. But as a matter 

 of fact it is difficult, with the soil above described, to reduce the pore 

 space to 50 per cent. In the field the pore space would be even greater. 



The chief difference, according to Prof. Whitney', between the worn 

 out tobacco lands of Virginia and the best wheat lands of Maryland, is 

 a difference of jjhysical structure. A chemical analysis shows the so- 

 called ''worn out" lands to be richer in plant food than the productive 

 wheat lands. Apparently the aggregate grains of the Virginia soils 

 have been broken down; in other words, their tilth has been destroyed. 

 It is a case of destruction rather than of exhaustion. The capacity of 

 these soils to gather and hold moisture and to have an abundance of air 

 has been destroyed. This is possibly an extreme view to take of the 

 matter, but it olfers material for thought. 



Air we have with us always, and in aJbundance. Not so with mois- 

 ture. And yet our moisture resources are great, if we could but control 

 them. 



In 1898 the rainfall at the College from April 1 to July 31 was 13.38 

 inches — enough to produce a crop of 44 bushels of wheat per acre, GO 

 bushels of barley per acre, 80 bushels of oats per acre, 80 bushels of 

 corn per acre, GOO bushels of potatoes per acre. 



The rainfall between April 1 and September 30 was 15.50 inches — 

 enough to produce 3I/2 tons of clover hay per acre, 7 tons of fodder and 

 corn per acre, or 11 tons of silage. 



The moisture in the upper five feet of soil on the first day of April 

 available for plant use would give very nearly the above yield, if it could 

 be made to do its fullest duty. 



Combining the moisture present in the soil with that which falls dur- 

 ing the growing months, what enormous yields would be possible, so far 

 as the moisture side of the question is concerned. And yet the amount 

 of moisture used in the actual growth of crops scarcely exceeds one-half 

 of either amount. Why? Partly because we have not yet learned to 

 use the means at our compiand to conserve and to utilize this moisture. 



Every farmer may become a soil physicist. He may increase the 

 capacity of his soil both to gather and to hold moisture; he may increase 

 its air supply and regulate its temperature. 



The Campbell method of soil culture has for a few years past created 

 quite an interest in certain sections of the west. Its object, primarily, 

 is to so handle the soils of the semi-arid regions as to fully utilize the 

 rainfall in growing crops. 



The system may be briefly described as follows: 



1. Before plowing, the ground should be gone over with a disc har- 

 row. 



2. Plow deeply — six to eight inches. 



3. Follow the plow within a few hours with a sub-surface packer. 

 This implement consists of a series of narrow-edged wheels set about 

 five inches apart upon a common axle. The packer is heavily weighted, 

 so that the wheels sink well into the soil, crushing the heavier clods 



