289 



The preceding tabulated results exhibit several points of interest, on which a few 

 observations may be offered : 



1. In the first place it will be seen that the two nnmauored portions of the experi- 

 mental field yielded a fair crop of mangolds. One of these plots produced 22^ tons per 

 acre, and the other 21 tons ; or, on an average, the nnmanured plots produced 21f tons 

 of mangolds per acre. The diiierence in the weights of the crops on plot 1 and plot 6, 

 is not greater than can be expected in field experiments. The experimental field thus 

 was tolerably uniform in character and well adapted for the trial. 



2. Mineral superphosphate alone gave only an increase of If ton, and thus appears 

 not to be the kind of manure which ought to be employed for mangolds on light land. 



3. The addition of two hundred- weight of salts of potash to three hundred- weight of 

 mineral superphosphate proved very successful, inasmuch as it raLsed the produce to 29^ 

 tons, and gave an increase of 7i tons over the average yield of the nnmanured portions 

 of the field. 



4. In these experiments, the addition of two hundred-weight of salts of potash had a 

 better effect than the addition to superphosphate of one hundred- weight of Peruvian 

 guano, or than three hundi-ed-weight of Peruvian guano alone. 



5. Peruvian guano alone answered better than mineral superphoshate applied by 

 itself, but didfcot appear to be the best artificial maniu'e that can be used on light 

 lands for mangolds. 



We may learn from this that neither the exclusive use of a purely mineral phos- 

 phatic manure, nor a manure containing, like Peruvian guano, an excess of nitrogenous 

 compounds, produces the best crop of mangolds on light laud. 



6. A moderate amount of an anunoniacal salt, or of nitrate of soda, added to a manure 

 composed of available phosphates and salts of potash, api>eared to be very useful. 



The mixture of three hundred-weight of superphosphate, two hundred-weight of salts 

 of potash, and one hundred-weight of nitrate of soda, it will be seen, produced 31J 

 tons of mangolds, which, considering the natural povei'ty of the soil, must be consid- 

 ered a very good crop indeed. 



The same mixture, it will also be observ^ed, had a better effect than 20 tons of farm- 

 yard manure ; for while plot 9 gave an increase of 10 tons over the nnmanured plots, 

 20 tons of rotten dung per acre produced only an increase of i>i tons. 



7. A heavy dressing of dung proved to be less beneficial than the addition of some 

 euperjdiosphate to a moderate dose of dung. The best crop, it will be noticed, was ob- 

 tained by 10 tons of rotten dung and li; hundred-weight of superphosphate. 



On the whole, the results obtained at Escrick agree well with those described in the 

 series of experiments which were tried by ilr. Ellis, at Iver Moor. Both sets plainly 

 show that potash salts are very useful to mangolds, and that, in order to obtain the 

 best economic results from their use for this crop, they should be mixed with super- 

 phosphate and a small quantity of either sulphate of ammonia or nitrate of soda. 



I have repeatedly observed that a small quantity of nitrate of soda helps on the 

 mangold plants in a striking manner, provided other fertilizers are used at the same 

 time, or the land is in a high agricultural condition. The mixture of three hundred-weight 

 of superphosphate, two hundred-weight of salts of potash, and one hundred-weight of 

 nitrate of soda per acre, can be recommended both as an economical and beneficial arti- 

 ficial mangold manure for light land. 



The result of these researches will lead to other and more extended 

 experiments with salts of potash. They afford additional evidence of 

 the importance of mixing together our artificial manures, and of avoid- 

 ing the rapid conclusions at which we are apt to arrive from imperfe^it 

 examinations. That we have, during the present century, made great 

 advances in our knowledge of artificial fertilizers is an untloubted lact, 

 but then we are well aware that many a vegetable mystery has to be 

 unravelled, many a discovery yet made, before we can conclude that no 

 farther advances are to be made in rendering our soils more productive. 

 We are, in all i^robability, ever treading on the verge of some discovery 

 relating to the food of jjlants, a knowledge which our former experience 

 tells we are often much nearer to than we are always willing to believe. 

 We have an instance of this in some of the laborious trials of the cele- 

 brated Arthur Yoimg. It was in the year 1782, that among many ex- 

 perimental dressings he used various salts of ammonia and of potash ; 

 several acids, such as the nitric, the muriatic, and the sulphuric ; and 

 also impure varieties of phosphate of lime — as in the dung of poultry, 

 (Annals of Agriculture, vol. 1, p. 150, vol. 3, p. 122.) Had he but mixed 

 some of these together he would have found that superphosphate of lime 



