1922] GREAVES—SOIL 177 
the soil and of raw rock phosphate (36, 37). This, however, does 
not indicate that it is less available, for, as pointed out by TRruoc 
(38), the mixing of floats with manure caused an immediate decrease 
in the solubility of the phosphorus in o.2 per cent citric acid solution, 
yet when thoroughly mixed with the feeding area of the soil its avail- 
ability was increased to such an extent that some species of plants 
apparently were able to secure almost an adequate supply of phos- 
phorus from this material. The addition of manure to the soil 
greatly increased the carbon dioxide production, and for a short 
time measurably increased the solvent action on floats. Where 
there is a decrease for a time of water-soluble phosphorus in fer- 
TABLE X 
TOTAL WATER-SOLUBLE PHOSPHORUS PLUS ORGANIC PHOSPHORUS IN SOIL TO WHICH 
ARIOUS SALTS HAD BEEN APPLIED AND LEFT FOR THREE WEEKS, ~— 
THE UNTREATED SOIL BEING TAKEN AS 100 PER CENT 
Chloride Nitrate Sulphate Carbonate 
ON a Ss csi css ae 124.0 O08 6 dase so cass 105.3 
ROAM os As 106.6 O57 OA ee ews 102.1 
Les 6 se 4+ con nueene’ 101.6 105.9 88.4 99.1 
mehgnedinn. oe. 103.1 105.3 108.4 85.2 
MAINE. 99.3 86.1 IOI.1 135.1 
We water's Ce Ne SoCo Too. 2 103.4 118.3 92.5 
menting media, it is probably due to the formation of phospho- 
proteids within the bodies of the bacteria (31), and these would 
later be rendered soluble, due either to further bacterial activity or 
autolytic enzymes. This increased bacterial activity should and 
actually does result in an increased water-soluble and organic 
phosphorus of the soil, as may be seen from table X, in which the 
water-soluble phosphorus plus the organic phosphorus in the 
untreated soil has been taken as 100 per cent. 
In all except seven cases where the salts had increased bacterial 
activities there also resulted an increase in the available phosphorus. 
Moreover, associated with this increase of available phosphorus 
go increased crops as found in field and pot experiments, and the 
significant feature of these facts is that there is also an increase 
in the phosphorus of these plants (7, 10). 
