8 - 



agriculture and are one of the main reasons why " rotations " of 

 crops are so advantageous. The other class of bacteria which are 

 capable of causing combination of nitrogen are those known as Azoto- 

 bacter ; these are present in most soils and are found to be very 

 abundant in many of the more fertile soils of this country. Although 

 they add to the soil's store of nitrogen they do not appear to play so 

 important a part as the other class which supplies the leguminosce 

 with their nitrogen. 



Now let us see how this question affects this country and what are 

 the possible developments. Before the war Egypt expended some 

 L.E. 600,000 annually on fertilizers, the most part of this was for nitrate 

 of soda and sulphate of ammonia. One cannot possibly be exagger- 

 ating in saying that this could easily be increased to an annual purchase 

 of at least one million pounds worth of fertilizers. Among the various 

 nitrogenous fertilizers now being produced in large quantity, the 

 question naturally arises: which is a suitable manure for Egypt, and if 

 so, can we produce it in the country? 



So far as the former part of this question is concerned, I much 

 regret that practically no really reliable experiments have been, so 

 far as I am aware, made with nitrate of lime on Egyptian soils. A few 

 pot experiments have been made by myself with maize* and the 

 results showed conclusively that the nitrate of lime could very well 

 replace nitrate of soda and was indeed slightly superior. If we argue 

 on a priori grounds I think we may safely conclude that nitrate of 

 lime should prove a very suitable fertilizer for this country. As 

 many, and probably all of you are aware, one of the gravest troubles 

 against which cultivators in this country have to contend is the 

 presence of small quantities of various sodium salts in the soil. The 

 salts usually met with are the chloride, sulphate and bicarbonate. 

 More rarely we have carbonate, which is the most troublesome of all. 

 Now the plant does not require sodium as one of the essential elements 

 for its growth, and it is quite possible that when sodium nitrate is 

 applied to the soil that it is not absorbed by the plant in this very 

 form but undergoes a chemical change ; the nitrogen may be taken up 

 in the form of nitrate of potash or possibly as nitrate of lime. Now 

 when nitrate of soda is employed the soda will be left behind and will 

 add to the amount of soda salts already present. It is a small amount 

 perhaps, but if this process is continued we shall, unless drainage 

 is good, run a risk of adding to instead of reducing the salinity of the 

 soil. On the other hand, even if the lime of the nitrate is not taken up 

 by the plant to its full extent, what is left would be in the form of 

 carbonate, which is not only harmless but in many cases actually 

 beneficial to the soil and crops. There are two drawbacks to the use 



* See Appendix. 



