WEED SEEDS IN THE SOIL. 369 



Farmers often report that certain weeds, as red sorrel and white top, for 

 example, spring up in the meadows in great abundance, although they had 

 not been seen there for several years. The story of wheat turning into cheat 

 is no doubt familiar to all. Some farmers also think they have reasons to 

 believe that timothy will turn into red top, cultivated oats into wild oats, 

 and that weeds come up sometimes spontaneously. The followers of such 

 beliefs have evidently not yet realized that the seeds of many weeds may 

 lie dormant in the soil and retain their vitality for many years, and start 

 into growth whenever a favorable opportunity presents itself. The sudden 

 disappearance from the field of some weeds can sometimes be accounted for 

 in a similar way. 



As regards the number of viable weed seeds found in the soil several 

 investigations have been made in the past, and some very interesting find- 

 ings have been reported. 



The l-i'irst Annual Report of the New York (Geneva) Agricultural Ex- 

 periment Station contains a statement that "On June 22 a single square 

 foot of soil in the garden, which had been plowed and harrowed in the spring, 

 contained 356 gro^ving plants, comprising seven distinct species, not counting 

 clovers and grasses." 



Professor Prentiss,^ of New York, who investigated seven samples of 

 soil taken from different sites and types reported the following results: 



A sample taken beside a brook, where the soil had been washed and 

 deposited, contained viable weed seeds at the rate of 13,000,000 per acre. 



Another sample taken from a garden also contained Aveed seeds at the 

 rate of 13,000,000 per acre. 



Samples from a compost heap and potting soil produced viable weed 

 seeds at the rate of 34,000,000 and 23,000,000 per acre, respectively. 



Muck soil yielded only about 1,000,000 seeds per acre. 



A strip of recently plowed sod produced weeds during the season at the 

 rate of 175,000 per acre. Another strip of old sod ground, but cultivated for 

 two or three seasons, produced 80,000 weeds to the acre during the same 

 season. 



Dr. Arthur,* reported the following results from his investigations at the 

 New York (Geneva) Experiment Station: 



8,826 weeds, comprising 45 species, were picked from a strip, covering 

 one-twentieth of an acre, of old pasture land ploAved in the spring. Almost 

 one-half of this number was Canada thistle, and over one-fourth foxtail. 

 Another strip of the same size but which had been cultivated during the pre- 

 ceding four years, produced 4,095 weeds, comprising 37 species. Almost 

 one-half of the number was fox-tail. 



Two other plots, each one-twentieth of an acre in size, yielded as follows: 

 The first plot which had been cultivated in the spring and cropped the 



3 Transactions of the New York Agricultural Society, 1883-1886, pp. 298-299. 

 « New York (Geneva) Agricultural Experiment Station Annual Reports 1885, pp. 

 262-265; 1886, pp. 281-283; 1887, pp. 356-363. 



