THE WASTE AND CONSERVATION OF PLANT FOOD. 217 



little e»xcess or deficiency of water is of far more importance to the 

 growing crop than tlie quantity of the excess or deficiency of its other 

 foods. Soils richest in i^laut food will produce a small harvest if there 

 be a great excess or deficiency of water, while soils which are poor in 

 plant food will produce an abundant crop if the water be present in 

 proper amounts and have jiroper and timely access to the rootlets of 

 the plant. The study, therefore, of the water movement in the soil, 

 wlietlier laterally, upward, or downward, is of the utmost practical 

 importance. The methods of a study of this kind have been well estab- 

 lished by King.' 



The plant food of the soil, it is well understood, only has access to 

 the absorbent organs of the plant when presented in a proper soluble 

 or semisoluble form in connection with water. From a chemical stand- 

 point, in connection with the subject under discussion, the movement 

 of water in the soil should be considered in connection, not alone Avith 

 its power of dissolving plant foods, but with especial reference to its 

 j)Ower of carrying them not only away from the reach of the roots of the 

 l)lant, but even out of tbe field and into the streams and rivers and 

 eventually into the sea. For our present purpose, therefore, we have 

 only need to examine lysimetric observations for the i)uri)ose of deter- 

 mining the kinds of plant food Avhich are most exposed to waste. It 

 is not my purpose to take your time here with a vast array of figures, 

 but I desire only to call your attention to the faet that of the chief 

 plant foods potash and tlie nitrates are the ones which are most 

 exposed to loss. 



The earliest systematic investigations of the quantity and composi- 

 tion of drainage were commenced at the Eothamsted Station byLawes 

 and Gilbert.^ in 1870. Lysimeters were constructed for the collection 

 of the drainage water from 30, 40, and GO inches depth of soil, respect- 

 ively, the soil and subsoil being kex)t in the natural state of aggregation. 



Lawes and Gilbert call attention to the fact that probably at the 

 Eothamsted Station not more than 5 pounds of nitrogen are secured 

 l)er acre each year from the atmosphere and the rain water, while the 

 average loss of nitrogen tlirongh the drainage water is over 30 pounds 

 per acre. The quantity of course varies with the amount of rainfiill 

 and the activity of nitrification. They speak of the possible exaggera- 

 tion of the loss of nitrogen on account of the fact that the air had 

 access to the soil both from below and above, and therefore the process 

 of nitrification where the lysimeters were placed might have been 

 intensified. 



Among tlie latest researches on this subject are those of Deherain.^ 

 It is pointed out by this author that the character of the crop grown 

 ui)on the cultivated field has much to do with the determination of the 



• Ninth Annual Report of the Wisconsin Experiment Station, page 129 et seq. 

 2 Jour. Roy. Agri. Soc, a'oI. 17. pages 241-279 and 311-350 ; Vol. 16, pages 1-71. 

 ^Annates Agrouomiques, February 25, 1893, page G5 et seq. 



