70 
Experiments upon Swedes. 
single field-experiment is as likely to lead us in a wrong as in a 
right direction. Few persons have the inclination or are in a 
position to persevere in such a laborious, expensive, and in many 
respects unthankful course of investigation. But little trust- 
worthy experience and no knowledge is gained from the great 
majority of published experiments with artificial manures which 
meet our eye from time to time in the agricultural newspapers, 
from the want of this continuity of action. For this reason I 
have continued field-experiments upon swedes, similar to those 
published in this Journal in 1855 and 1858, and have now 
the pleasure of presenting to the Royal Agricultural Society a 
third report on field-experiments upon swedes. I regret to say 
that in 1858, and again in 18i)0, my experiments were failures; 
and only in 1859 did I succeed in getting an even plant and 
results on which reliance can be placed, and from which I trust 
some useful information may be gathered. 
Although I completely failed in securing an even crop in 
1858, it still appears to me advisable that 1 should describe 
briefly the kind of experiments which I then made, and give the 
weight of the produce ; for sometimes useful lessons may be 
learned from failure as well as from success. 
In previous trials, extending over five seasons, I found that, 
on the soils on our farm : — 
1. Ammoniacal salts, such as sulphate of ammonia, used 
alone, had a decidedly injurious effect upon the turnip-crops, 
even when used in small quantities. 
2. Ammoniacal manures applied to swedes at first checked 
the growth of the plant, and had ultimately no beneficial effect 
on the crop, either alone or in conjunction with phosphates. 
3. Guano proved a less economical manure than superphos- 
phate of lime. 
4. The addition of salt to superphosphate seemed to benefit 
the crop. 
5. In dry seasons the best artificial manures are often of little 
or no more service to the produce than inferior and all but 
worthless manures. 
With a view of verifying these general conclusions, and ob- 
taining at the same time information on some other points on 
which I shall have to speak presently, I made the following 
experiments. 
Part of a 40-acre field, marked Nos. 6 and 10 in the map of 
the farm attached to the Royal Agricultural College, was divided 
into 20 plots, of 8 poles each : — 
