1921.] BOTHAMSTED EXPERIMENTAL STATION. 



781 



The meaning of the result is that farmyard manure is more 

 dependable than other fertilisers, though it is not capable of 

 giving as good yields in favourable seasons as a properly- 

 balanced mixture of artificials. 



This is not the place to discuss the scientific reasons for 

 these various effects; a good deal of work is being done at 

 Bothamsted and elsewhere to elucidate them, and until they 

 are fully known it will be impossible to understand completely 

 the best way of using farmyard manure. Tn the meantime 

 there is another and far more urgent problem : how can the 

 supply of farmyard manure or similar materials be increased? 



Two general methods are being studied at Bothamsted. The 

 first, which might be called the anti-waste method, consists 

 in cutting down the wastage from farmyard manure, which is 

 still unfortunately very considerable. The available quantity 

 of manure could be much increased by better making and 

 better storage : both making and storage can be improved by 

 keeping the manure under cover, and by proper adjustment 

 of litter to the amount of nitrogen in the animals' excretions. 



Frequent reference has been made in this Journal to the 

 necessity for better protection of the manure heap, and 

 farmers realise the advantage of providing this. The question 

 of adjusting the litter to the manure, however, has only 

 recently been studied. It is found that there is a proper pro- 

 portion of straw to urine, and if this is exceeded wastage 

 results. If the straw is insufficient for the amount of nitrogen 

 in the excretions, some of the nitrogen is lost; while if the 

 straw is in excess, the manure will not " make " properly 

 and the soil derives less benefit than it should. Experiments 

 have shown that 1 ton of straw can be used for every 100 lb. 

 of digestible protein in the anim a Is' food. As a rule, however, 

 the excretions are too concentrated and some added water is 

 also necessary. When these proportions are maintained, 

 satisfactory rotting of the straw proceeds rapidly, and the 

 losses of nitrogen are at a minimum. Under these ideal 

 conditions manure at Bothamsted has rotted down to half its 

 weight without loss of nitrogen. 



The second method consists in actually increasing the 

 amount of farmyard manure or similar substances on the farm. 

 This could be done by increasing the head of live stock on the 

 farm, assuming the economic situation justified such a course. 

 Farmers are thoroughly familiar with this possibility and it 

 need not therefore be further discussed. 



