VALUE OF FARMYARD MANURE FOR GRASS 165 



Another feature in these two Plots, 10 and 4-2, which receive 

 nitrogen but no potash, is the weakness of the stems ; short as 

 the grass is, it is often laid before it is ready to cut. The grass 

 is also found to be more susceptible to fungoid attacks on these 

 plots than elsewhere. 



The diagram Fig. 28 shows a comparison of the yields of 

 the unmanured plot, the plot receiving mineral manures only, 

 and the plots receiving mineral manures and varying amounts of 

 nitrogen as nitrate of soda or ammonium- salts. 



Y. The Action of Organic Matter. 



In the early years of the experiments farmyard, manure 

 was applied every year to two of the plots, but owing to 

 the accumulation of unrotted material on the surface it was 

 found necessary to discontinue the experiment in this form. 

 On another of the plots, however, an attempt was made to 

 ascertain the effect of the organic matter present in dung 

 by adding to a complete artificial manure, such as is sup- 

 plied to Plot 9, 2000 Ib. of chaffed wheat straw every year. 

 The wheat straw contains so little manurial matter, compared 

 with the quantities artificially supplied, that it may be neglected ; 

 thus the straw should be regarded as simply providing organic 

 matter. If we compare the crop on this Plot 13 with that of 

 Plot 9, we see that the straw has had its effect, and that on the 

 average a larger crop by about 7 cwt. per acre per annum has 

 been produced.* The effect of the wheat straw has been due 

 partly to the shelter it provides in the early spring (for it is 

 noticed that the grass starts more quickly on this plot than on 

 the others), and partly also to the water-retaining power of the 

 humus produced by its decay. Of late years the organic 

 matter added accumulated to such an extent as to form a 

 peaty layer that was beginning to injure the growth of the 

 plant; in consequence the application of straw has been 

 discontinued. The Value of occasional applications of farmyard 

 manure to grass land is. thus seen to be a mechanical factor 



* Up to 1902 the average yields were : Plot 9, 54-1 cwt. ; Plot 13, 61-3 cwt. 



