“The nitrogen is as high as one would expect but is lower than is necessary for fertile soils. It would be necessary therefore to encourage the growth of leguminous crops to increase the quantity of nitrogen in the soil and to employ nitrogenous manures. It must be borne in mind that in soils of this class the nitrogen is usually in a highly insoluble and un-nitrifiable form.
“The salt is in no case high; 0.25% is usually considered to be the limit for satisfactory growth; all the samples are well below this limit.”
I had complete analyses made of numbers (1) and (2). The results were as follows:
| No. 1 | No. 2 | |
|---|---|---|
| Silica etc. insol in mineral acid | 74.76 | 73.85 |
| Lime (Ca.O.) | 6.07 | 4.56 |
| Carbonic Acid (C.O.₂) | 3.64 | 2.40 |
| Equal to Chalk (Ca.C.O.³) | 8.27 | 5.46 |
| Potash | 0.23 | 0.34 |
| Phosphoric Acid | 0.14 | 0.12 |
| Organic Matter | 2.88 | 4.07 |
| Nitrogen | 0.075 | 0.062 |
| Calculated on soil dried at 100°. | ||
Though none of these specimens contained salt in excess, Nile deposit in certain localities has very large proportions of common salt and sulphate of soda. The dark soil near the Atbara mouth at El-Damer is largely exploited for common salt, while similar soil south of Khartoum is free from it.
The extent of this Nile deposit soil is very great indeed and if irrigation could be assured, there would be a great future before the Sudan.
In Mr. Dupuis’s Report which is the last appendix to Sir William Garstin’s Report, he speaks of this soil as being met with on the Blue Nile, on the Rahad, on the Atbara and on the Gaash. From Khartoum northwards the main Nile flows between berms of this soil.
The extent and quality of this soil may therefore be considered as an undisputed asset of the Sudan. We have next to consider the seasons.
A reference to [tables 76], [77], and [80] will show how much warmer the Sudan is than Egypt, and any attempt to introduce Egyptian methods into the Sudan without modifications will not at once turn the Sudan into Egypt. I allow that extensive plains of irrigated land greatly moderate the heat as they have already done in Middle Egypt; but we have to begin from the beginning in the Sudan, and there are no extensive plains of irrigated land. Basin irrigation will be a failure in the Sudan unless it is supplemented by two or three waterings in the winter, for all crops except the cheapest and coarsest leguminous crops. Wheat must be irrigated in winter whether sown in a basin or on the Nile berm, except in a few choice, low and damp localities. Cotton, on the other hand, which has to be sown in spring in Egypt and reaped in autumn will need such an extraordinary quantity of water to pull it through the summer that it will be found preferable to grow it in June with the rising flood and reap it at the end of the winter. Irrigation therefore from June to October for Indian corn, from June to February for cotton, and from November to February for wheat will be essentials of a good harvest in the Sudan.
We now come to the question of the water supply. Unless permits are given for pumps to work from the 15th June to the 15 February, the cultivation of cotton and wheat on any scale in the northern part of the Gezireh, along the main Nile between Khartoum and Dongola, and on the lower reaches of the Atbara will be out of the question. Maize and millets and some of the coarser leguminous plants might be developed by pumps with permits to work from 15th June to 15th October, but it would pay no one to put up pumps on these terms.