56 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



})& used with great care, and do not need any addition of mineral fer- 

 tilizers. They should be well rotted before application to the crop, or 

 they should be applied sufficiently in advance of planting to insure this 

 condition. 



From calculations on the basis deduced from his experiments, the best 

 formula for a fertilizer for beets on very poor soil would be : 



Poucds. 



Acid calcic phosphate - 160 



Sodic nitrate, (Chili saltpeter) 940 



Gypsnm, (land-plaster). - 900 



This mixture should be applied at the rate of 1,000 pounds per acre. 

 The quantity may, however, be very materially reduced when applied 

 to soils comparatively fertile, but lacking in constituents necessary for 

 complete nutrition of the crop. 



With reference to mineral plant-poisons, a remarkable exception to 

 the rule for the influence of aluminium salts has been observed by 

 Bergstrand in a locality near Westerbotten, in Sweden, where Euhus 

 articus was found in a flourishing condition upon a sandy soil contain- 

 ing as high as 3 per cent, of alum. The dry plants yield 4.G8 per cent, 

 of ash, containing 12.60 per cent, sulphuric acid and 5 per cent, alumina; 

 but these figures are very much reduced when the percentage of alum 

 in the soil is sufficiently low to admit of the growth of grass and grain. 

 In such case the sulphuric acid of the ash amounts to only 5 per cent. 



Eug. Peligot ha^ discovered a veritable plant-poison in the compounds 

 of boracic acid. Ho has determined that the free acid and its com- 

 pounds are distinctly poisonous to vegetation, and, when present in the 

 soil in moderate quantity, may cause the death of plants in a very short 

 time. 



The contributions to our knowledge of organic and atmospheric nitro- 

 gen in their relation to vegetable nutrition have been numerous, and 

 most of them exceedingly valuable. Yv^ith reference to the compound 

 most favorable for plant-nutrition, Lehman has determined that it varies 

 with the stage of development of the plant, ammonia being more favor- 

 able in the early stages, and nitrates during the later, though some 

 plants require nitric acid throughout the entire period of growth for 

 normal development. In the course of his experiments he found that 

 lupines growing in sterile soils have the power of taking up nitrogen 

 from external sources to such an extent that he considers them the cheap- 

 est possible source of nitrogen for such sterile soils. Their power in 

 this particular has received a clear and remarkable explanation in the 

 late discoveries of Berthelot, who, by a series of careful and ingenious 

 experiments, has found that the proximate organic constituents of plants, 

 under tbe influence of the electrical tension always existing between the 

 soil and the atmosphere immediately above it, may combine with atmos- 

 pheric nitrogen to form compounds which, on decomposition at 300*^ to 

 400'^ C, in presence of soda-lime, are capable of forming ammonia. 

 This explanation of the manner of the absorption and assimilation of 

 atmospberic nitrogen has been tbe subject of careful and laborious re- 

 search at the hands of the leaders of chemical science since the study 

 of vegetable nutrition began, and has been supplemented by the results 

 of tbe late investigations of Boussiugauit upon the influence of the 

 soil upon the nitrification of nitrogenous organic matters employed as 

 manures, in which he made an extended series of experiments with dif- 

 ferent substances in admixture with sand, chalk, and garden-soil. As 

 a result of these experiments, ho found that the garden-soil determined 

 a formation of the greatest amount of nitrogen and a production of the 



