part, but both were attacked nearly in the same man- 

 ner by the fly. 



Mixtures of soot and quicklime, and urine and 

 quicklime, will probably be more efficacious. The 

 volatile alkali given off by these mixtures is offensive 

 to insects ; and they afford nourishment to the plant. 

 Mr. T. A. Knight* informs me, that he has tried 

 the method by ammoniacal fumes with success ; but 

 more extensive trials are necessary to establish its gen- 



Mr. Knight has been so good as to furnish me with the following note on 

 this subject. 



" The experiment which I tried the year before last, and last year, to pre- 

 serve turnips from the fly, has not been sufficiently often repeated to enable me t 

 speak with any degree of decision ; and last year all my turnips succeeded per- 

 fectly well. In consequence of your suggestion, when I had the pleasure to meet 

 you some years ago at Holkham, that lime slaked with urine might possibly be 

 found to kill, or drive off, the insects from a turnip crop, I tried that preparation. 

 ia mixture with three parts of soot, which was put into a small barrel, with gim- 

 blet holes round it, to permit a certain quantity of the, composition, about four 

 bushels to an acre, to pass out, and to fall into the drills with the turnip seeds. 

 Whether it was by affording highly stimulating food to the plant, or giving some 

 sUvour which the flies did not like, I cannot tell ; but in the year 1811, the adjoin- 

 ing rows were eaten away, and those to which the composition was applied, as 

 above described, were scarcely at all touched. It is my intention in future to drill 

 my crop in, first, with the composition on the top of the ridge ; and then to sow 

 at least a pound of seed, broad-cast, over the whole ground. The expense of this 

 will be very trifling, not more than 2s. per acre ; and the horse-hoe will instantly 

 sweep away all the supernumeraries between the rows, should those escape the 

 flies, to which however they will be chiefly attracted ; because it will always be 

 found that those insects prefer turnips growing in poor, to those in rich ground. 

 One advantage seems to be the acceleration given to the growth of the plants, 

 by the highly stimulative effects of the food they instantly receive as soon as their 

 growth commences, and long before their radicles have reached the dung. The 

 directions above given apply only to turnips sewed upon ridges, with the manure 

 immediately under them ; and I am quite certain, that in all soils turnips should 

 be thus cultivated. The close vicinity of the manure, and the consequent short 

 time required to carry the food into the leaf, and return the organizable matter to 

 the roots, are, in my hypothesis, points of vast importance ; and the results in 

 practice are correspondent.'* 



