=====================================+======+======+======= Ingredients. |Max %.|Min %.|Mean %. -------------------------------------+------+------+------- Silica etc., insoluble in strong acid|66 |53 |60 Total Lime | 3·80 | 2·50 | 3·34 Total Potash | 1·19 | ·46 | ·74 Total Potash available | ·072| ·020| ·042 Total Phosphoric Acid | ·49 | ·20 | ·35 Total Phosphoric available | ·090| ·029| ·066 Carbonic Acid = Chalk | 3·52 | 1·79 | 2·69 Nitrogen | ·106| ·056| ·084 =====================================+======+======+====== We have here a general sufficiency of phosphoric acid, plenty of potash and lime, and a low proportion of nitrogen. The salts of the soil, when in excess, are chlorides and sulphates of soda: the carbonates are present in very small quantities indeed. The following selection from a paper by Mr. Lang Anderson in the December 1903 number of the Journal of the Khedivial Agricultural Society is interesting. “Voelcker’s analyses of the two samples of soil taken from the drained bed of what was Lake Edku near Alexandria give the following results:-- ============================+=======+======= | No. 1.| No. 2. ----------------------------+-------+------- Oxide of iron | 11·69 | 11·04 Iron pyrites | 0·08 | 0·11 Aluminium | 6·36 | 10·88 Lime | 2·08 | 7·73 Magnesia | 1·79 | 0·93 Soda | 0·79 | .. Sodium chloride | 8·11 | 8·56 Potash | 0·65 | 1·23 Sulphuric acid | 2·23 | 2·56 Carbonic acid | 0·19 | 4·75 Phosphoric acid | 0·16 | 0·19 Insoluble silicates and sand| 62·23 | 45·81 Organic matter | 3·64 | 6·21 | | Total |100·00 |100·00 ----------------------------+-------+------- Containing nitrogene | 0·035| 0·070 „ ammonia | 0·042| 0·079” ============================+=======+======= 28. =Basin irrigation.=--Considering the times of flood and low supply, the climate of Egypt, the turbidity of the Nile flood, and the deltaic formation of the Nile valley, no better system than basin irrigation as practiced in Egypt could possibly have been devised. If the flood had come in April and May and been followed by a burning summer, or if the actual autumn floods had been followed by the frozen winters of Europe or the warm winters of the Sudan, basin irrigation would have been a failure or a very moderate success; but, given the Egyptian climate, basin irrigation has stood without a rival for 7000 years.