1905.] 



Green Manuring. 



3i 



manuring on heavy land, and its employment for other crops, 

 such as vegetables, fruit and forest trees, hops, and grass land ; 

 the value of serradella, &c. 



Schultz took the view that the plants should be ploughed-in 

 deeply enough to completely bury them, but Causemann and 

 other practical agriculturists maintain that experience has 

 shown shallow covering both of green and farmyard manure 

 to be more satisfactory, and in this they have the support 

 of Dr. Hiltner, of Munich. The explanation offered is that the 

 more easily the oxygen of the air reaches the buried manure, the 

 quicker and more completely does it become available as plant 

 food. The bacteria which play such an important part in the pro- 

 cess of nitrification require oxygen, so that a too deep burying 

 or burying in wet, undrained land, or the formation of a surface 

 crust, hinders the formation of nitrates, whilst the admission of 

 air and the addition of lime to the soil promote it. By shallow 

 ploughing, heavier crops have been obtained than those grown by 

 Schultz on the same class of land. It is also considered that the 

 work should take place late, rather than early, in the autumn, 

 and that the sowing of winter grain should follow imme- 

 diately after the breaking up of the field. Although, apparently 

 practical experience in Germany is, on the whole, favourable to 

 the view that the ploughing-in both of green crops and farm- 

 yard manure should be shallow rather than deep, the opposite 

 view is not without its supporters, and the comparative merits 

 of the two methods may be regarded as a subject for further 

 experiment. 



The advantages of green manuring as compared with bare 

 fallow have also attracted attention. On this point Fruwirth 

 made experiments at Hohenheim in 1901 and 1902. Two plots 

 of similar size were selected, one being sown after corn harvest 

 with beans, blue lupins, peas and vetches, while the other was 

 ploughed at the same time. The green crop was buried about 

 9 in., and the other plot again ploughed. The subsequent 

 crop (mangolds) on the former plot exceeded that on the latter 

 by 2f tons per acre, or a gain of 26s. per acre ; deducting the cost 

 of green manuring (20s.) there was a net gain of 6s. per acre. 

 More favourable results have been obtained in certain instances 

 by bare fallow than by green manuring ; and experiments are 



