The best Manures for Potatoes 



43 



4 cvvt. dissolved coprolites to sulphate of am- 

 monia, as in plot 5, gave an increase of 3 

 tons 4 cwt. 2 qr. 8 lb. per acre above sulphate 

 of ammonia alone, and an increase of 6 tons 

 19 cwt. 3 qr. 18 lb. above the nothing plots. 

 Superphosphate and kainit, as in plot 6, gave 

 an increase of i ton 3 cwt. 22 lb. above the 

 nothing plots. Sixteen loads dung per acre 

 gave, taking the average of the two plots, 

 Nos. 2 and 15, 6 tons 13 cwt. potatoes, being 

 I ton 9 cwt. 2 qr. 6 lb. more than the nothing 

 plots ; while the addition of 2 cwt. sulphate 

 of ammonia, 3 cwt. superphosphate, and 2 

 cwt. of kainit per acre gave, taking the ave- 

 rage of plots I and 16, 9 tons 6 cwt. 4 lb. 

 per acre, being an increase over the dung 

 alone of 2 tons 13 cwt. 4 lb., and over the 

 plots without manure, of 4 tons 2 cwt. 2 qr. 

 10 lb. per acre. Plot 4, however, without 

 dung, and with very nearly the same quanti- 

 ties and kinds of artificial manures as plots i 

 and 16, gave a larger return than they did, 

 while plot 5 gave by far the largest return of 

 any. The influence of artificial manures, and 

 especially of sulphate of ammonia, and super- 

 phosphate of lime in conjunction, on the po- 

 tato crop on the field under notice, was very 

 marked ; while potash salts, on the whole, 

 were only of slight benefit. 



THE MIXTURE AND APPLICATION OF 

 MANURES. 



On the 13th March last, the different plots 

 were again dressed over, the diseased and 

 decayed tubers thrown out. and the sound 

 ones weighed. About one-third of the tabers 

 were found to be more or less diseased, the 

 proportion of diseased being somewhat larger 

 in the plots which got dung than in those 

 which got artificial manure alone, but the 

 difference between any of the plots in 

 this respect was not very striking. The 

 experiments, as a whole, have, in my opinion, 

 been very successful, and present fewer 

 anomalies than agricultural experiments often 

 do, and I hope that the details which I have 

 now had the pleasure of laying before you 

 may prove ^of some value as a guide to prac- 

 tice on soils similar to that on which the 

 experiments were carried out. I would, how- 



ever, caution those who grow potatoes on 

 the lighter class of soils, which are so com- 

 mon in this county, against using such a 

 large quantity of ammoniacal manure as that 

 which produced the greatest results in the 

 experiments which I have laid before you, 

 because, from experiments which I have 

 noticed carried out on light land, and from 

 my own observation and experience, I am of 

 opinion that on the light soils of this county 

 the action of ammoniacal manures will be 

 less marked, and that of superphosphate and 

 potash salts more marked than in the 

 heavier classes of soil ; and that, therefore, 

 as the land gets lighter, the proportion of 

 ammoniacal manure should be reduced, and 

 that of superphosphates, bones, and potash 

 salts increased. 



I have thus endeavoured to direct your 

 attention to the principles which should 

 be a guide to us in forming mixtures of 

 the artificial manures for the potato crop. 

 When once these principles are understood, 

 what the farmer has to do is to purchase the 

 necessary materials at the cheapest rate, and 

 mix them for himself. The same material 

 can be got in different forms. For instance, 

 you can get nitrogen, the valuable element 

 in ammonia, in guano, in sulphate of 

 ammonia, in nitrate of soda, &c., but the 

 relative prices of these articles vary from 

 year to year, and sometimes you can buy the 

 desirable nitrogen cheaper in one form than 

 the other. The same holds true with regard 

 to superphosphate of lime, potash salts, and 

 other manurial substances. From this you 

 will see that " the most suitable manure for 

 the successful cultivation of the potato 

 crop, having regard to the quantity and cost 

 per acre," may vary from year to year, in 

 accordance with the fluctuating prices of the 

 different substances from which the desirable 

 manurial elements are derived ; and it is only 

 by knowing the principles which should be 

 followed in forming the most suitable mix- 

 tures for the different kinds of soils that the 

 farmer can enter the manure market to 

 the greatest advantage, and purchase the 

 different articles which he requires in the 

 cheapest and most suitable terms. 



