Methods of Field Manurial Trials. 223 



out the operation a plough which throws either to the right or 

 left. Dr. Wagner begins ploughing down one side of the area, 

 goes on on the other side in the opposite direction, throwing the 

 soil outwards, and so on, until there is finally left a furrow down 

 the centre, along the dividing line between two sets of plots. 

 By subsequent ploughing in the reverse direction, beginning 

 along this centre line, this furrow is again filled in, and the 

 manure is thus thrown back, along the edges, into the proper 

 plots. 



It has been suggested that the use of longitudinal plots (say 

 fifty by five yards), on which the manure is distributed right up 

 to the edges, but from which a strip of half a yard on each side 

 is not harvested, would yield better results. Dr. Wagner objects 

 to this, however, as it is much easier to distribute the manures 

 uniformly on a square plot, particularly if there be any wind ; 

 further, there is a much greater length of boundary — which is a 

 fertile source of error — and there is also the probability that on 

 such an oblong strip there is greater variety of soil, &c, &c. 

 Moreover, as regards the exclusion of a narrow area on the out- 

 sides from the crop harvested, it may be observed that the 

 greatest irregularity in manuring generally occurs along the 

 edges, hence the amount of manure actually put on the 

 harvested strip is not that calculated. By taking the whole 

 crop the true amount of manure used is at least accurately 

 known. 



The cultivation of the plots should of course be performed 

 with the greatest care, and only experienced workers employed. 

 The work should be so arranged that the whole of the plots that 

 make up an experiment are treated uninterruptedly, preferably 

 in a single day. No seed should be used which has not been 

 previously tested. Hoeing and earthing should be done by 

 hand, and, of course, no machinery should be used in harvesting. 

 Weeds should be destroyed without the aid of sulphate of iron 

 or other corrosive, and the plots must be kept as clean as 

 possible. 



Nitrate of soda should not be applied as a top dressing in wet 

 weather or when dew is on the plants, which must be quite dry. 

 The opportunity may be taken, in top dressing, to remedy any 

 irregularities by giving a little more where the plant is thinner. 



