.'u2 .tot^xal of the department of agriculture. 



Complete Analysis. 



1. The folloAviii*)' is a statement of a " coniijlrU' analysis" of a 

 soil as carried out by the Division of Chemistry: — 



I'ci- cent. 

 Stones, o^(M• >\ nun. diameter ... ... 1.5 



C/iijij)(>sil/o/i of Air-diij Fine Koiih. 



Moisture ;].40 



Loss on ignition ... ... ... ... 9.4t'^ 



Insoluble matter ... ... ... ... 56.99 



Iron oxide and alnmina ... ... ... 28.65 



Lime 0.09 



Magnesia ... ... ... ... ... 0.14 



Potash 0.12 



Phosphoric oxide ... ... ... ... 0.04 



Total 99.86 



Containing" — 



IN'itrogen ... 0.106 



''Available" potash 0.0078 



" Available " phosphoric oxide ... 0.0007 



Calcinm carbonate ... ... ... 0.02 



Such a statement can convey but little information Xu I lie average 

 fanner so that some explanation is necessary: — 



(a) Stones. — When the soil sample is received it is spread out to 

 lu'come air-dry, that is, to assume such a moisture content that no 

 further moisture will be gained or lost while the sample is handled. 

 W'lie)) air-dry, the sample is lightly crushed, until all lumps are 

 lirolcen iip, and passed through a sieve having round holes <3 mm. in 

 diameter. The portion failing to pass this sieve, and which actuall.y 

 consists of stones of greater size than 3 mm. diameter, is weighed, the 

 percentage calculated, and entered as "stones." This portion of the 

 soil is of no use whatever as a source of nutriment for plants, though 

 the piesence of a considerable ^quantity of small stones may 

 undoubtedly affect the texture of a soil. A samj)]e of soil recently- 

 examined contained nearh^ 50 i)er cent, of stones greater than 3 mm. 

 in diameter, almost all of which were less than 6 mm. The remainder 

 of the soil consisted of still smaller pebbles and clay, and had it not 

 been for the high proportion of stones, the soil must have been heavy 

 to work whereas actually it behaved like a free working loam. Such 

 cases are, of course, exceptional, and we may be, satisfied by consider- 

 ing the " stones " as a measure of the inert valueless material present 

 in a soil. 



(h) Moisture. — The air-dry soil still retains, some water. The 

 percentage of this gives some indication of the water-retaining 

 capacity of the soil. Loose, sandy soils retain less " moisture " than 

 clays or loams or soils with much organic matter. In twenty-five 

 sandy soils the average percentage of moisture in the air-dry samples 

 was 0.72 while the average of twenty-five samples of " black turf," 

 well known as a heavy soil which retains water well, was 8.42 per cent. 



