Agricultural Experiments in the Field. 517 



shall save what wc have to pay the manufacturer who prepares ma- 

 nures, which should produce an immediate effect for the benefit of 

 root crops — mangolds, swedes, or turnijis. Manures which are used 

 as top-dressings may be used on wheat-land in autumn with quite as 

 much benefit as in spring, provided the land is sufiiciently retentive 

 to absorb ammonia, potash, or other valuable fertilizing constituents ; 

 for nitrates, it is of considerable practical importance to observe, are 

 not absorbed by the soil. They pass, as we know from experiments 

 which were performed by Professor Way (whom 1 am happy to see 

 present on this occasion), into the drainage water; and this is one 

 reason why we obtain contradictory results with the same manuring 

 matters when they have been used at dificrent periods of the year. 



Then, with respect to the mode of aj^plyiug manures, we should be 

 very careful to secure a uniform distribution, especially of concentrated 

 manures, such as guano or superphosphate of lime. This can only be 

 done by an admixture of some indifferent substance ; such as dry soil, 

 or sharp sand, or common bm-nt clay ; or, in the absence of these, 

 sifted coal ashes. For experimental purposes all concentrated maniu'es 

 should be mixed with three times their bulk of some diluent or other. 

 On grass land my own. experience leads me to recommend the use of 

 the manure-distributor, which may be also adopted with gi-eat ad- 

 vantage for corn crops. A far more unifoi-m distribution is thus 

 secured than can possibly be attained by hand. On the other hand, 

 lor root crops, it may be desirable in most instances to ridge up the 

 land, apply the manure by hand, and then split the drill again, so as 

 to cover up the manure. 



A third condition which it is essential to take into account is the 

 composition of fertilizers. The composition of manures used in field- 

 trials should be perfectly well known, and their ajjplication to the 

 land should be made by careful weight. 



In the next place 1 would observe that the experiment should be 

 arranged in as simple a manner as possible. The great fault of most 

 field trials is that too much is attcmj^ted. There are so many 

 disturbing elements in complicated trials, that in most instances 

 it is impossible to say what fertilizer produces the beneficial effect, 

 or to what cause the failure has to be referred. We should 

 -endeavoiu" as much as possible to eliminate disturbing elements. 

 With this object in view, I suggested in the last number of the 

 Journal a series of field experiments which may jjerhaps appear to 

 some practical agricultm-ists to be too simple. Allow me to refer 

 briefly to some of them. In the case of one series of experiments 

 which I suggest to the farmer, 1 am anxious to ascertain the effect 

 which the artificial supply of potash is capable of producing. Now, 

 in order to apply potash in an economical form, we must necessarily 

 take with it some other fertilizing matter. Perhaps the cheai)est form 

 in which potash can be applied to the land is that of the recently- ' 

 discovered salts of potash, which are now imported in considerable 

 <_[uantities from Germany ; not, however, so much for agricultural 

 jiurposes as for the pui-pose of converting nitrate of soda into nitrate 

 •of potash. 



