70 THE CEREALS IN AMERICA 



foimd to be greater and the amount taken up by the wheat 

 smaller. 



113. Accumulation of Soil Constituents at Different Stages 

 of Growth. — The wheat plant for its best development needs to 

 have its early growth in the cool part of the year. A long 

 period of growth consequent upon cool weather encouriges til- 

 lering and gives better opportunity to get sufficient plant growth. 

 Adorjan has shown that wheat takes up the greater portion of 

 its food in the early stages of growth, stores it up, and draws 

 upon it later for the development of the grain.^ (123) 



At the Minnesota Station during two years the weight and 

 composition of spring wheat was determined (i) at fifty days 

 when it was eighteen inches high, (2) at sixty-five days when it 

 was fully headed, (3) at eighty-one days when grain was in the 

 milk, (4) at 105 days when wheat was ripe. 



At the end of fifty days the plant had produced nearly one 

 half its dry matter and nearly three-fourths its total mineral 

 matter ; when fully headed, sixty-five per cent of its dry matter 

 and eighty-five per cent of its mineral matter. When the grain 

 was in the milk the plant had produced ninety per cent of its 

 dry matter and practically all its mineral iTxatter. Nearly 

 seventy-five per cent of the potash, eighty per cent of the phos- 

 phoric acid, and eighty-six per cent of the nitrogen was taken up 

 in the first fifty days. The fiber was formed largely before 

 the plant was tuUy headed ; after the grain was in the milk a 

 slight loss of fiber occurred in the plant. The starch stored up 

 in the seeds was formed mainly during the last half of the 

 period of growth.^ 



114. Winter Killing. — ^In a country of cold winters it is better 

 to have the ground covered continually with snow. Alternate 

 freezing and thawing with the plant exposed to the wind is very 

 destructive to wheat. Winter wheat kills in two ways, by free*- 



I Jour. Landw. 50 (1902), No. 3, pp. 193-230. (E. S. R. XIV, 436^ 

 tMlnn. BuL 29, pp. 1^2-160 



