August, 1911.] 



143 



Scientific Agriculture. 



if they yield any grain at all it is only 

 a very small quantity. A similar 

 appearance is noted in the case of 

 irrigated crops such as sugar-cane or 

 turmeric when the irrigation channels 

 are kept flooded with rain or irrigation 

 water. Even paddy will present an 

 unhealthy appearance, if the fields are 

 submerged to too great a depth, or if 

 water is allowed to stand for too long 

 an interval at a time. 



In all these cases the cause of this 

 appearance is excessive moisture. It is, 

 - however, sometimes stated that it is 

 due to lack of sun, but that this is not 

 the real reason is shown by other plants 

 in the same field being green and 

 vigorous, although they do not receive 

 any more sun than the unhealthy plants. 

 Besides requiring moisture plants must 

 have air. Whec flooding occurs, the 

 aii is driven out of the soil, water takes 

 its place, and the land is then said to 

 be water-logged. Under such conditions 

 the roots cannot get air, and they are 

 unable to grew and spread in the soil as 

 they ought to do, hence the plants 

 present the appearance described above. 



Again, it is observed, more particular- 

 ly in the case of the irrigated crops 

 already mentioned, that besides giving 

 a poorer yield than those grown under 

 more arid conditions, crops which have 

 been subjected to this treatment seem 

 to exhaust the soil more, and in time of 

 drought are the first to show signs of 

 suffering from lack of moisture. The 

 reason for this is obvious. 



Since the channels are kept flooded, 

 the roots of the plants are unable to 

 penetrate deeply into the soil, but are 

 restricted to the upper layer for their 

 supply of food. As a result they remove 

 much more plant food from this layer 

 than a deeper rooted crop, which is not 

 confined to such a limited area for its 

 supply, and, therefore, the crop appears 

 to be an exhaustive one. As an instance 

 of this, the case of paddy after sugar- 

 cane may be mentioned. It is never 

 expected that a good yield will be 

 obtained from the first crcp of paddy 

 taken after a crop of sugar-cane. That 

 the yield is poor is simply because for 

 the reasons given above, the sugar-cane 

 crop has been compelled to become a 

 surface feeder to the detriment of the 

 succeeding crop. What has been said 

 with regard to food supply applies to 

 moisture. In time of drought the sur- 

 face layer is the first to dry up, and 

 with it, unless irrigation can be done, 

 the roots of these plants- which have 

 been prevented from striking deeper. 

 Thus, while a deep-rooted plaut, drawing 

 upon supply of moisture stored up in 



the lower depths of the soil presents a 

 fresh and vigorous appearance, the 

 shallow-rooted plant is withering and 

 dying. 



Further, it is well-known, that when 

 land is newly brought under wet culti- 

 vation, it very often yields well. After 

 a time, however, it begins to appear 

 alkaline and the yield falls. This 

 goes on until the land becomes so 

 alkaline that the crops fail altogether 

 and its cultivation has to be abandoned. 

 Iu such cases it is usually noticed that 

 while care has been taken to arrange 

 proper means of irrigation, very little 

 or no attention has been paid to the 

 facilities for drainage, and in con- 

 sequence this unfertile condition has 

 resulted.' 



These are a few of the disadvantages 

 of defective drainage ; it will be noted 

 that they tend to diminution of yield, 

 even to total loss of the crop and to 

 waste of water. 



The following recommendations are 

 therefore made : — 



(1) Dry Crops. — Where the land is 

 of a clayey nature and therefore likely 

 to be water-logged during heavy rains, 

 attention should be paid to the natural 

 drainage channels to see that they are 

 free from obstruction. Small depres- 

 sions should be levelled up, but where 

 larger ones exist trenches should be 

 made to connect them with the drainage 

 channels. These trenches should be 

 about 1 foot in width and of sufficient 

 depth to drain the depression complete- 

 ly. Where isolated fields of dry crops 

 are cultivated in wet land aieas, a 

 trench of the same width as already 

 indicated and as deep as the level of the 

 ground will permit should be made all 

 round the field to intercept and drain 

 away the water which percolates 

 through from the wet lands. 



(2) Irrigated Crops. — The advantages 

 of good drainage in the case of the sugar- 

 cane crop were dealt with in an article 

 in last year's calendar. What was said 

 there applies equally well to other crops, 

 where the system of beds and trenches 

 is adopted. Where irrigation is done by 

 means of furrows, these should be 

 straight, of uniform slope, and should 

 lead into a drain of slightly greater 

 depth, and care should bt taken that 

 this drain is kept free, otherwise water 

 will stagnate in the furrows. 



(3) Tsoudu Land. - In this case it is 

 advised that the affected land be divid- 

 ed up into small polts of about 25-50 

 cents in extent. These should be 

 separated from one another by a deep 

 trench, the deeper the better, which 



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