164 



THE KOTHAMSTED EXPERIMENTS. 



Practical 

 aspects of 

 the subject. 



Enriching 

 poor soils. 



An Oxford- 

 shire ex- 

 periment 



Alternat- 

 ing nitro- 

 gen-accum- 

 ulating 

 crops and 



in association, or in alternation, with Leguminosse. Lastly, 

 the fact that at any rate many leguminous plants, including 

 papilionaceous shrubs and trees, as shown by Nobbe, are sus- 

 ceptible to the symbiosis, and under its influence may gain 

 much nitrogen, serves to explain the source of some at least 

 of the large amount of combined nitrogen accumulated through 

 ages in our soils and subsoils, and also the comparatively slow 

 exhaustion of their stores of it by cropping, drainage, and in 

 other ways. 



We will, in conclusion, refer to some of the more directly 

 practical aspects of the subject. It may be observed that in 

 Germany, Schultz, of Lupitz, has for some years devoted a 

 considerable area of poor, gravelly, and sandy soil, to the growth 

 of leguminous crops — various clovers, lupins, serradella 

 (Ornithopus sativus), &c, by means of kainit and phosphatic 

 manures, and he has found that the land was thereby very 

 much enriched for future cereal and other crops. He finds, 

 however, that it is necessary to vary the description of legu- 

 minous crop grown. In other parts of Germany, too, the 

 system is gradually extending of growing lupins, serradella, 

 or other leguminous crops, especially on poor sandy soils, 

 with a view to their enrichment in nitrogen. And, on a 

 large estate in Hungary, visited by one of us in 1891, it was 

 found that the results of the recent investigations indicating 

 the fixation of free nitrogen in the course of the development 

 of leguminous crops were being carefully studied with a view 

 to practical application. 



In our own country, Mr Mason, of Eynsham Hall, Oxford- 

 shire, after first making some experiments with various Legu- 

 minosse on small plots, and then a considerable series in 

 specially built tanks or pits, devoted about 200 acres to the 

 practical application of the recently acquired knowledge in 

 regard to nitrogen fixation. Stated in a few words, his idea 

 is to reduce his area under roots, and to grow instead mixed 

 crops of Leguminosse — beans, various clovers, &c. — liberally 

 manured with basic slag and kainit, and to convert the pro- 

 duce in the first year into silage, and in the second into hay. 

 The land is thus occupied for two years ; and the assumption 

 is that in this way highly nitrogenous crops will be obtained 

 with mineral, but without any nitrogenous manure, and that 

 the land will be left in high condition so far as nitrogen is 

 concerned, for the growth of saleable crops, such as grain and 

 potatoes, which require nitrogenous manuring. In other 

 words, his plan is, as he puts it, first to grow nitrogen- 

 accumulating crops for home consumption, and afterwards 

 nitrogen-consuming crops for sale. The experiment has been 



