Scientific Agriculture. 



[November, 1908. 



" Haberlaudt found that oat-plants 

 covering one hectare transpired 2,277,760 

 kgs. during a single vegetative period, 

 while barley plants covering a similar 

 area exhaled 1,23(3,710 kgs. of water." 

 This means that an acre of oats evapor- 

 ated nearly 900 terns of water, and 

 barley well on to 500 tons during their 

 respective periods of growth. 



Whatever accuracy these men may 

 claim for their figures in their own con- 

 ditions, my point is that, although 

 plants may differ in the relative amounts 

 of water transpired from them during 

 a given time and in various conditions, 

 it is a well-known fact that all plants 

 do transpire a very considerable amount 

 of water during the 24 hours. 



It is evident, then, that from the 

 point of view of the farmer cultivat- 

 ing lands in a drought country, the 

 lands should be kept clear of weeds. 



Again, it is well-known that on bare 

 land which is fairly consolidated right 

 to the surface, more moisture will even- 

 tually be lost by evaporation than on 

 land the surface of which has been well 

 pulverised and kept stirred to the depth 

 of a few inches. 



One might very roughly explain this 

 by saying that the water raising up 

 the walls of the minute openings be- 

 tween the soil particles can, in the case 

 of the compacted soil, rise right to the 

 point where it can be quickly evaporated 

 by coming directly in contact with the 

 dry winds sweeping over the surface of 

 the land- 



As the moisture at the surface is eva- 

 porated, more is induced, to take its 

 place, and as it must come from below, 

 we have a comparatively rapid current 

 of water being brought upwards and lost 

 by evaporation. 



In the case of the soil of good tilth, the 

 surface, few inches of which are stirred 

 up loosely, the openings between the 

 particles are too coarse to allow the 

 moisture to rise freely in these few inches. 

 Also in the large interspaces between 

 these particles a considerable volume of 

 air is trapped and forms a semi-damp, 

 more or less stationary protective cush- 

 ion of air between the quickly changing 

 dry atmosphere above, and the point to 

 which the water is comparatively easily 

 brought up. 



Whatever the real theoretical explan- 

 ation may be, however, the point of 

 practical importance is, that a soil, the 

 surface few inches of which is well 

 pulverised and stirred, does conserve 

 the moisture much better than a more 

 compact one, and that farmers who 



wish to retain the moisture in any parti- 

 cular area of land, should not simply 

 plough the soil and leave it in large 

 rough lumps, and great openings between 

 the f urrows, but should pulverise and 

 stir the surface by harrows or other 

 suitable means. 



This pulverising of the surface should 

 be done the same day as the land is 

 ploughed on all soils, but especially on 

 stiff clays, not only because of the 

 saving in moisture effected, but also 

 because of the greater ease with which 

 the lumps can be broken- 



Treated promptly in this way, a fine 

 tilth may be got cheaply and with ease 

 even on stiff lands where no amount of 

 work can procure a good tilth if the 

 lumps are allowed first to get dry. 



A third way of conserving moisture is 

 often practised in various parts of the 

 world. It is called "mulching." 



Some fairly open or porous material 

 such as refuse litter, inferior grass, or 

 inferior straw, leaves, or other organic 

 substance, is spread in a thin layer over 

 the surface of the land ; the idea being 

 to form a layer of matter which wifi 

 retain a considerable volume of air in 

 the spaces between its component 

 particles, and so retard the swift ex- 

 change of the dry air of the atmosphere 

 for the more or less moist air that is in 

 contact with the soil surface. Mulching, 

 therefore, has underlying it the same 

 idea as the stirring and pulverising of 

 the upper few inches of the soil. 



Unfortunately, mulching, though very 

 useful, is difficult to carry out on large 

 areas. In some parts of India, however, 

 I believe it is a common practice for 

 special crops, such as tea, coffee, and 

 some market garden crops. 



The implements used in tillage oper- 

 ations here appear to me of considerable 

 interest in relation to conservation of 

 soil moisture, and I think a study of 

 these from this point of view might give 

 some results worth having. 



Take, for example, the ordinary native 

 plough and compare it with the common 

 Euglish or American ploughs. 



The native implement differs essen- 

 tially from the other two quoted, in the 

 fact that while the others partly or 

 completely invert the soil, the native 

 one stirs but does not invert it. 



The difference appears to me to hold 

 in it a question of considerable interest, 

 for if a slight mulch causes a material 

 reduction of the amount of water 

 evaporated from the soil, then, may 

 there not be a material difference in the 



