110 



Green Man ukin g . 



[May, 



and made profitable almost solely by the use of green manures, 

 mainly leguminous; the pioneer work of Schultz at Lupitz, in 

 Saxony, is a well-known instance in this connection. Again, 

 in America green manures are widely used, both for farm crops, 

 and, especially in California, for orchards. It is, however, in 

 tropical countries, perhaps, that green manures find their widest 

 application. Thus in India, in many districts where animal 

 manure is practically unobtainable, the whole of the require- 

 ments of the soil for organic matter and nitrogen are obtained 

 by the use of leguminous green manures. 



Results of Green Manuring Trials. — Although there are a 

 certain number of results on record showing that distinct and 

 valuable crop increases can be obtained by green manuring, 

 there are very few critical experiments designed to test the 

 relative values of different green crops and different methods of 

 application. The most extensive series of experiments in this 

 country is that carried out by Voelcker at the Eoyal Agricultural 

 Society's Station at Woburn. In these experiments vetches, 

 rape and mustard were grown side by side as spring-sown 

 green manure crops which were turned in before winter wheat. 

 The experiment has been in progress for over twenty years, 

 and the results are summarised below : — 



Yield of Wheat after Green Manures, Woburn, Lansome Field (Light 



sanely soil). 



Average of results for eight seasons 1899, 1901, 03, 06, 08, 10, 12, 15. 



Dressed grain, 

 bush, per acre. 



After vetches, grown with mineral manures ... ... 16*3 



rape „ „ ,. 20"4 



„ mustard „ „ „ ... ... 25'2 



For comparison : — 

 Wheat on Stackyard Field, complete minerals only ... '.'"I 

 ,, „ „ farmyard manure (eqtiiv. to 



200 lb. ammonia per acre) ... ... ... ... 20"4 



Unfortunately there are no control plots on Lansome Field, 

 so the values for Stackyard Field (continuous wheat) which have 

 been added for comparison, are not necessarily strictly com- 

 parable, but they serve to indicate the sort of result that can 

 be obtained with green manures compared with mineral or 

 farmyard manure. An experiment on similar lines was carried 

 out at Rothamsted. Here the land was given up to spring- 

 sown green crops for two seasons, the crop being turned in each 

 autumn, and in the third season winter wheat w 7 as grown. The 



