66 FOBAGE CEOPS IN DENMAEK 



in which position he remained for twenty-seven years. He 

 published several botanical treatises. In 1869 appeared his 

 first publication on the improvement of grass fields, and in 

 1878 he read a paper before the Eoyal Agricultural Society 

 of Denmark, 1 in which the results of his investigations appeared 

 in a clear and reasoned form, which established his position as 

 an authority on the question of rotation grasses. He showed 

 how red clover (trifolium pratense) generally fails during the 

 second year's grass ; and as this was at the time the only 

 leguminous plant sown in rotation grass, the fields were often 

 without this important ingredient after the first year. It was 

 therefore necessary to use other leguminosae besides red clover. 

 Eyegrass (lolium perenne) and particularly Italian ryegrass 

 (lolium italicum) he found unreliable, and timothy to appear 

 too late. In order to ensure a better crop the second and 

 third year, he therefore recommended such grasses which, 

 even if appearing sparsely the first year, grow more freely when 

 the first year's plants leave them room to develop. As such 

 grasses he recommended cocksfoot (dactylis glomerata), tall 

 oat grass (avena elatior), and meadow fescue (festuca pratensis). 

 For a number of years he put his theories into practice on the 

 extensive grass fields on farms belonging to E. Tesdorpf, a 

 president of the Eoyal Agricultural Society of Denmark. It 

 lies beyond the scope of this book to describe P. Nielsen's im- 

 portant work, which has had a great influence on agriculture in 

 his own country, and has been duly appreciated among agri- 

 cultural experts in other countries. Numerous reports of his 

 are found in Tidsskrift for Landfikonomi, and other periodicals. 

 A resume of his analytical investigations of the plants of grass 

 fields during the years 1877 to 1888 was written in 1908 by 

 E. Lindhard, formerly his assistant, now his successor as 

 director of the State Experimental Station at Tystofte. 2 The 

 State bought a farm at Tystofte, and in 1886 appointed P. Nielsen 

 as its manager, in order to enable him to continue his investiga- 

 tions, which hitherto he had carried out on the small-holding 



1 Tidsskrift for Landflkonomi, 12 vol., K0benhavn, 1878, p. 620. 



2 E. Lindhard, "En Analytisk Unders0gelse af Plantedsekket i en-og 

 fleraarige Grsesmarker," 1877-1888, Tidsskrift for Landbrugets Planteavl, 15 vol., 

 K0benhavn, 1908, pp. 185 to 312. 



