January, 1910,] 



49 



Scientific Agriculture. 



ing introduces the most fatal error of all, 

 a selection biased by the preconceived 

 opinion of the experimenter. It is also 

 incorrect to make allowances for missed 

 plants, as is sometimes done by counting 

 the number of roots and calculating 

 what the weight per acre would have 

 been had there been a perfect plant. 

 Most manures affect the texture of the 

 soil, and therefore the number of plants 

 which establish themselves is one of the 

 factors in the result that is directly 

 affected by the manure. 



One or two other practical points are 

 also raised by the recognition of an 

 average error of 10 per cent, in the 

 results of a single plot. In designing 

 field experiments, it is useless to include 

 small differences in treatment which are 

 not likely to induce more than 10 per 

 cent, differences in the yield, unless the 

 experiment is going to be repeated very 

 widely or carried on for several years. 

 For example, in dealing with hay it 

 would be of little use to set out con- 

 clusions from comparative plots, one 

 with one cwt. and the other i\ cwt. per 

 acre of nitrate of soda, or in an experi- 

 ment on roots, one plot with 4 cwt. of 

 superphosphate per acre as against 

 another with 6 cwt.; in each case the 

 differences due to the manuring are 

 likely to be smallar than the experi- 

 mental error. Finally, in view of a 

 10 per cent, experimental error, it is 

 no good pretending to an accuracy in 

 recording the results. 



For example, we have read the follow- 

 ing figures : — 



Weight of roots per acre. 

 Tons. Cwt. lb. 



Swedes, Champion ... 11 9 28 

 „ Crimson King ... 14 16 48 

 Now, putting aside the barbarous units 

 ot tons, cwt., lb., so cumbrous to write 

 and difficult to read, what possible value 

 can be attached to the figures represent- 

 ing cwt. and lb. As only the pi oduce from 

 1-40 acre was actually weighed and then 

 multiplied up to obtain the figures 

 quoted, the inclusion of a few clods of 

 earth more or less with the roots, or an 

 error of a few inches in the measure- 

 ment of the plot so as to include one 

 root extra would make a difference in 

 the cwts. moreover as duplicate plots 

 would be likely to differ in the tons, 

 very little attention need be given to 

 the cwts. Had the results been written 

 11'5 and 14*8 tons respectively, the 

 figures would still be a degree more 

 accurate than the reality. Of course, 

 the experimenter must record what he 

 actually obtains to the nearest pound or 

 ounce if his scales tell it to him, but to 

 set out such figures in the published 



report is to make a parade of accuracy 

 which cannot be sustained. 



Returning, however, to our original 

 point of view, we may conclude that 

 as absolute correctness in our results 

 is impossible, it is only by recognising 

 and measuring the extent of the inevi- 

 table error that we can reach a due 

 measure of accuracy in the conclusions 

 we draw from them. 



INOCULATION OF LEGUMINOUS 

 CROPS IN THE WEST INDIES. 



(From the Agricultural News, Vol. VIII., 

 No. 184, May 15, 1909.) 



During the year 1908, the effect of 

 inoculating the soil, or in some eases the 

 seed to be sown, with prepared cultures 

 of nitrogen-gathering bacteria was tried 

 at Antigua and Grenada, with the 

 object of ascertaining whether such a 

 procedure would stimulate the growth 

 and increase the crop returns of various 

 leguminous crops. At Antigua, where 

 cowpeas, woolly pyrol, and alfalfa were 

 the crops under experiment at the 

 instance of Messrs. Henckell, Du Buisson 

 & Co., Professor W, B. Bottomley's 

 ' Nitro-Bacterine ' was the inoculating 

 material used, but at Grenada, a culture 

 preparation sent out from the United 

 States Department of Agriculture was 

 employed. It may be added that experi- 

 ments in which a small number of sugar- 

 cane plants were inoculated with a 

 special culture prepared by Professor 

 Bottomley, in the hope that it might 

 be beneficial in increasing the yield, 

 were also carried out at Antigua and 

 Barbados. 



At Antigua inoculation experiments 

 were conducted at the Experiment 

 Station, and also at Fitches ' Creek, 

 Gambles, and Cassada Garden. 



Seed of the different crops sown was 

 inoculated at the Laboratory, and part 

 of the culture solution was used in 

 inoculating the soil, and later on the 

 growing crops. Where crop and soil 

 inoculation was carried on, two appli- 

 cations of the solution were made, at an 

 interval of a fortnight. 



No effect of inoculation could be traced 

 in the case of the cowpeas grown. 

 Practically no differences were observ- 

 able between the treated and the un- 

 treated plots. It is therefore to be 

 presumed that the soils in the experi- 

 ment plots were well stocked with the 

 bacteria responsible for nodule forma- 

 tion on this crop, or that they were well 

 supplied with available nitrogen. 



