590 THE SMALL GRAINS 



It is seen in the table that as height or number of 

 branches increases the yield also increases. There is 

 some tendency for the yield and number of branches to 

 increase as the length of the first internode decreases. 



655. Soil relations. In the matter of soils, buck- 

 wheat is not especially exacting, as it does well on various 

 kinds of soil. On infertile, poorly tilled lands, it will 

 produce a better crop than will any other kind of grain. 

 It responds to better treatment, however, with increased 

 yields. The rather light, well-drained soils, such as the 

 sandy loams, seem best suited. It seems to prefer an 

 acid soil, best results not being obtained where there is a 

 large amount of lime present. Rich soils, especially those 

 high in nitrogen, are not suited, as on these the crop 

 usually lodges badly. When once the plants go down, 

 they have no means of rising again, such as the true cereals 

 have, and ruin to the crop may result. Although the 

 growing period is short, root development is vigorous 

 and of such a nature that relatively unavailable mineral 

 foodstuffs in the soil can be utilized. 



656. Climatic relations. Buckwheat is very sensitive 

 to cold, being quickly killed by frost or freezing tempera- 

 ture ; nevertheless, it is grown far toward the north, even 

 to 70 N. latitude. This is due to the short growing season 

 of the plant, amounting to ten to twelve weeks, and to 

 the small amount of heat units required to bring the crop 

 to maturity. Haselhoff states that 1000 to 1200 C. 

 are required for the buckwheat crop, while, in comparison, 

 oats require from 2340 to 2730 C. 



Buckwheat is also sensitive to high temperatures and 

 dry weather, especially when both day and night are hot. 

 In such conditions the flowers are blasted and produce no 

 grain. In the hot, dry summer of 1913 the crop was an 



