196 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



of nodule formation does not seem to hinder a healthy development of 

 the plants, careful comparisons from analyses have shown the greater 

 protein contents of those well supplied with nodules. The amount of 

 nitrogen contained in a soy bean crop* was found in one case to be 

 118*55 lb. to the acre for the inoculated plants, and 75*98 lb. to the 

 acre of those not inoculated, yet the appearance in the fields was the 

 same. With cow-peas, inoculated and uninoculated, the nitrogen was 

 found to be 139*21 lb. to the acre for the former and 118*45 lb. for the 

 latter. In each case, therefore, the inoculated crop, although apparently 

 not improved, was in reality more valuable for feeding or for green 

 manure than the uninoculated crop. 



In addition, it should be noted that with the inoculated plants the 

 gain of nitrogen came largely from the air, while the plants lacking 

 nodules drew upon the combined nitrogen of the soil. When the gain 

 in nitrogen from inoculation is accompanied by largely increased plant 

 growth, the beneficial effect of nodule formation is, of course, most 

 pronounced. Some chemical analyses f of Canadian field peas, inoculated 

 and uninoculated, serve to show, in a striking manner, the comparatively 

 rich growth of the inoculated peas. The plants bearing nodules had a 

 nitrogen content of 2*29 grammes per cent, of dry substance ; the plants 

 without nodules grown in the same soil had 1*60 grammes per cent, of 

 dry substance. The average dry weight of inoculated and uninoculated 

 plants was 11*2 and 2*3 grammes respectively. It is evident, therefore, 

 that the inoculated plants supplied more than seven times the amount 

 of nitrogen furnished by those not inoculated, viz. 0*255 gramme to the 

 plant, as compared with 0*035 gramme to the plant respectively. 



Generally speaking, the experience of scientific farmers and the tests 

 of agricultural experiment stations agree in ascribing an unusual benefit 

 to succeeding crops from green manuring with leguminous crops ; and 

 this is clearly due, in a considerable degree, to the nitrogen fixed by the 

 root nodules, and not to the length of the root system or other 

 peculiarities of leguminous plants. Unfortunately, investigators have 

 not given sufficient attention to the relative abundance or scarcity of 

 nodules when experimenting with different leguminous crops for green 

 manures. 



Many planters in the West Indies will tell you that the ideal manure 

 for cacao is sheep manure, but unfortunately the supply is limited and 

 costly ; also leading authorities maintain that the manurial value is 

 uncertain. Bird manure, guano, or poultry droppings are best, as a 

 rule, for sustaining and building up the strength of the trees ; but 

 unfortunately these manures are still more scarce than the sheep 

 manure. In nearly every plantation the quantities of home-made 

 manures are insuflicient to give the whole plantation an adequate 

 manuring ; hence the necessity of using artificials, which, judiciously 

 applied, not only increase the bearing capacity of the cacao tree but 

 also strengthen the vitality and vigour of growth, so that they can 



* tfrown at Agricultural College, Mich. For description, see Bulletin 224 of the 

 Michigan Station. 



f Analyses made by the Bureau of Chemistry, U.S. Department of Agriculture. 



