l6 AGRICULTURAL RESEARCH AND THE FARMER I 



with water in stages until it has taken up almost enough water to 

 saturate it ; and the required quantity of ammonium sulphate 

 solution is carefully applied, so as to avoid loss of nitrogen. By 

 this time the temperature of the stack has risen considerably. 

 The manure can then be allowed to stand for any length of time, 

 according to the shortness of the manure desired by the farmer, 

 All the nitrogen is absorbed during the first three weeks, and after 

 this the manure can be left uncovered with no risk of loss through 

 the leaching of nitrogen by rain, etc. 



Two series of field experiments with straw manure made in 

 this manner, carried out in 1920 and 1921, indicate its fertilising 

 value. In 1920, on light soil at Woking, the straw manure gave 

 as good a return as an equal weight of high quahty farmyard 

 manure. The season was wet, and the manures had therefore 

 little opportunity for showing their valuable moisture-retaining 

 properties. In 192 1, however, on the heavier soil at Rothamsted,. 

 these qualities were clearly demonstrated. The plot treated 

 with farmyard manure gave 3 tons per acre of potatoes ; that 

 treated with an equal weight of straw manure gave 2f tons per 

 acre ; while other plots dressed with the weight of sulphate of 

 ammonia required to supply an equivalent quantity of nitrogen 

 yielded little more than a ton to the acre. 



In view of the somewhat enthusiastic references that have 

 been made to this discovery in various places, a word of caution 

 may be advisable. The work so far has been carried out with 

 comparatively small quantities of straw and under conditions 

 which can be controlled bj^ the scientist. In devising a method 

 for use by the farmer, many practical difficulties have to be over- 

 come, such as the supply of water, the means of conveying it 

 to the straw and distributing it throughout the stack ; the 

 necessity of ensuring that the straw is properly saturated with 

 water, and that the required quantity of nitrogen salts is absorbed 

 by the straw. It is towards the solution of these practical 

 difficulties that the work is now proceeding, and already an 

 experimental plant capable — it is believed — of turning out 2,000 

 tons of straw manure per annum, and costing probably less than 

 £500, has been designed. 



An important side-issue arising out of this investigation may 

 be briefly referred to. In making artificial straw manure, 

 it is important that just the right quantity of ammonium 

 sulphate solution must be incorporated with the straw. This 

 fact led to a consideration of whether, in the ordinary 

 process of manufacture of farmyard manure, importance should 

 be attached to the adjustment of litter to the manure made 

 by the animals. It was found that there is a proper pro- 



