682 IOWA DEPARTMENT OF AGRICULTURE 



except on some of the highest points where a good application of ma- 

 nure seems necessary. Soils which are light and friable, due to a large 

 per cent of sand are not usually well adapted to alfalfa because they 

 are rather low in fertility. This difficulty may be corrected by the free 

 use of manure when excellent results may be expected. Though good 

 fields are occasionally found on heavy soils, such as contain considerable 

 clay, this is exceptional. Heavy soils seem well adapted to sweet clover, 

 however, and the grow^th of that crop for a couple of seasons helps to 

 put the land in condition for alfalfa seeding. The roots of the more 

 hardy clover open the soil to some depth and leave considerable amounts 

 of organic matter and readily available fertility. 



DRAINAGE 



It is useless to attempt to grow alfalfa upon land which is not thor- 

 oughly well drained, either by nature or by the use of tile or open 

 ditches. Some of the best results secured have been on drained bottom 

 lands, likely because of their fertility. But the fertility alone without 

 good drainage would not have produced these results. This does not 

 mean that the highest ground available should be chosen as this ground 

 is likely to be quite unfertile. Land which is slightly rolling or nearly 

 level and well drained is usually considered the best. 



MANURE 



Eight to twelve tons per acre of good manure should be applied be- 

 fore plowing for alfalfa, for the use of manure is by far the most 

 important factor in securing successful results on Iowa soils. It is a 

 notable fact that of 23 correspondents who make special mention of the 

 fact that they manured their fields before plowing but one failed. 



Courtesy R. E. Buchanan, Ames, Iowa. 



Fig. 19. — Tubercles such as are formed on alfalfa and sweet clover 



roots by bacteria which feed upon the free nitrogen of the air. This 



liitrog-en finally becomes available to the host plant, and ultimately to 



other crops which may follow in the rotation. 



