Oe ARLE ee Oe ee ee ee eS a ee 
1918.] The Fijth Indian Science Congress. xcix 
General Discussions. 
Recent Investigations on Soil Aeration—By ALBERT 
WARD, Imperial epee! Botanist, and R. 8. Howe 
Imperial Forest Botanis 
e growth of a crop is only possible through the simultaneous 
operation of a number = soil factors—water, mineral salts, temperature 
and oxygen. If any one factor is in engae 1 growth is "replated by pas 
amount of this factor sie nt, and is not influenced by an increase in 
of the one factors. The chief abject - sig hacingucheas is the ser tak f 
, of any possible limiting fac 
: The. aeation of the soil is a factor in ocho which has gap neglected 
in the past. It has only mares ps Dts re zed in the importance 
attached to a Ronse soil texture. ie ject is now Pere more 
oo and it is propos sad to refer of the recent work and to 
eate the directions in which ietiae snvtoastheataiea ki is enor rable. 
AERATION AND THE AMOUNT OF GROWTH, 
Various determinati e been made of the amount of growth in 
cultures in which the only variable factor is the de; oe of aeration. 
(1) The effect of increased aeration on the root development of barley. 
In water cultures , Hall 2 fo — that both root development and growth 
depend - the amount of ae 
Errclopenent and growth fell off as the soil was more consolida 
(3) The effect of adding potsherds or sand to a sotl.4 di- 
tion of inert ting s like sand, potsherds or ene epost yi apres 
{a calcareous silt which readily loses its ure) in 
text 
stowth very markedly. In the case of Java i ndigo, ue both etree 
and oxygen are required, the increase is as high as 40 per 
To follow the subject further, the structure of ‘he’ alk sere be 
e po 
row 
ti eh of oxygen is necessary and which results in a continuous produc 
on ana carbon dioxide. Efficient soil ventilation is therefore essential for 
: Recent investigations at Rothamstead® on the composition of the 
soil atmosphere bhaee that the amount of oxygen in the soil falls as the 
— of carbon amc ah rises. The water films contain little oxygen 
ut much —— dioxide, that is, the oxygen is used up as rapidly as it 
is supplied 
2. hieih give OF THE SOIL AND THE SYSTEM OF FLOOD 
IRRIGATION IN Nort InpIA. 
by Flood i rigation on fine alluvial soils interferes with their Mra ae 
crust pep destroying the texture and by forming a compact surface 
an eee eae air. One tniting factor—water—is entoved 
another the ne Borel ate pagers us over-irrigation 
Qu tually diniinnabos the yield. This is shown by results obtained at 
®tta where 13 mau nds of wheat were ubtaiaed sea one —— and 
the ' In the case say the temperature factor, bead is also Linniten when 
thaw ise oe 
2 Hall Dd, 1913 
: Hunter, C., fiery of the Uni oof ‘Purkous Phil. Soe. T IV, p. "a 
5 veeag ge A., Bulletin 61, pone esearch Institute, Sik. 
ussell, E, a and Appleyard, A., Jour. of Cha e., Vil, p- 1, I 
