NEW SERIES. 



VOL. VII. APRIL, 1895. No. 3. 



UPON SOME PROPERTIES OF SOILS, 



WHICH HAVE GROWN A CEREAL CROP AND A LEGUMINOUS CROP 

 FOR MANY YEARS IN SUCCESSION. 



*. 



By SIR JOHN BENNET LAWES, Bart., F.R.S., &c. 



The field upon which our experimental wheat crops are grown is 

 irregular in shape, and the area of the twenty-two experiments for 

 some years differed slightly one from the other, rendering it necessary 

 to make a separate calculation for each in order to bring it into acreage. 

 During the year 1882, thirty-nine years after the commencement of the 

 experiments, it was decided to make the area of all the plots equal, 

 which was done by cutting off a portion of the experimental field at 

 the top and bottom. It is well known that the success of our 

 experiments has greatly depended upon keeping the land as free as 

 possible from weeds, in order that the wheat plants should have to 

 themselves all the food in the soil, and I was very anxious to know 

 what sort of a fight the wheat would make against any vegetation 

 which might spring up if the crop were no longer kept free from weeds 

 by manual labour. Accordingly, instead of cutting the crop upon the 

 portion of land at the top and bottom of the field which would cease 

 to be under experiment, it was left standing to shed its seed for another 

 crop ; so that the whole crop, which in some of the experiments would 

 be over 30 bushels per acre, would be deposited in the land instead of 

 only the two bushels of seed which were sown per acre upon the other 

 portions of the field. The result of this experiment may be summed 

 up in a very few words. Before the next harvest the indigenous 

 vegetation had taken possession of the land to such an extent that 

 nothing to be called a crop was grown in any of the experiments, and 

 in the second and third year the wheat was represented by a few 

 straggling plants which had but a faint resemblance to their original 

 parents ; some of the plants had only one or two small seeds in the ear 

 and the thin stalks were not the least like the straw of wheat. 

 Specimens of the wheat when left to seed itself, with the straw, and 

 a year or two afterwards, are placed in the Museum of the College. 



A reproduction of a photograph to life size of two of the ears of 

 corn for each of the years 1883, 1884, and 1885, accompanies this 

 paper. 



In July, 1886, four years after the top and bottom of the field had 

 been left undisturbed, a careful examination of the vegetation was made 

 by Mr. Willis, and the following is his report " Seventeen orders of 



420041 



