544 Transactions ot section m. 



)jlots, which had been fallowed during 1912, were higher than they liad been 

 for nearly sixty years — since 1854 and 1857 : several of the plots yielded over 

 60 bushels of grain, 30 cwt. of straw, and 7,000 lb. of total produce per acre. 

 Pari; of this result was due to the season, which was very favourable to barley — 

 the spring being moist, and the summer damp and cool. But a considerable 

 part must be attributed to the fallow, for on the Agdell rotation-field, where 

 there had been no fallow in the preceding year, the yields were by no means 

 extraordinary, the highest crop being 33 bushels of grain, 15 cwt. of straw, 

 and 3,500 lb. of total produce — results which are frequently obtainable on the 

 same plots. The fields are not contiguous, and comparisons must not be pushed 

 too far ; nevertheless, where the conditions were comparable the yields were 

 not dissimilar : the unmanured plot in Agdell field (which had virtually been 

 fallowed during the preceding year, the turnip crop having failed) gave 18'5 

 bushels of grain and 8 cwt. of straw, nearly the same as the unmanured Hoos- 

 field plot, 21 bushels of grain and 10 cwt. of straw. Only where the turnip crop 

 on Agdell had succeeded in 1912 were the barley yields markedly less than on 

 Hoosfield. But so far as our experiments go these effects can all be obtained 

 with late summer or autumn fallows. On a farm near to our own it is found 

 worth wliile in a dry year to break up the seeds ley immediately after the first 

 cut so as to get some summer cultivation done, and give a bastard fallow before 

 putting in the winter corn. 



On a well managed farm on the Brick Earth of the Sussex coast the corn 

 is got in July : the steam tackle is put on to break up the land at once, and 

 a fallo.v if given during August and September. If these months are fairly 

 dry, as is usually the case, the loss of nitrate is not great and the cultivations 

 1-qill weeds. If, in addition, the weather is hot, the soil benefits further. Hot- 

 weather cultivation improves nearly all soils, probably because it has some 

 partial sterilising action : the only soils that do not benefit so far as I know are 

 the fen soils, and I do not quite understand why this should be. Thus the 

 possibility of co-ordinating the cropping with the biochemical activities in the 

 soil promises considerable saving of valuable soil materials. 



2. The more serious diflticulty is the pests, of which the number seems amaz- 

 ing. The more intensive the cropping the greater the opportunity for the various 

 pests to live, till finally in the glass-house nursery industry the trouble becomes 

 acute. At present our methods of dealing with them are not very discriminating. 

 and in practice we only attempt to control two in the open field — finger-and-toe 

 by liming, and potato disease by spraying, while two or three — wireworm and 

 turnip-flea — are more or less kept in check by the adoption of special cultivation 

 or other devices. All the rest are simply suffered. This year, for instance, our 

 corn was attacked in various places by wireworm, by turnip-flea, by rats and by 

 rust, by smut, frit- fly and aphis, to say nothing of birds, rabbits, game, against 

 many of which the farmer is at present powerless. 



In glass-houses it is possible to adopt the heroic method of sterilising the 

 soil and killing everything, but this is not yet practicable on the farm, and 

 even if it weie it does not prevent re-population. Further, most pests have 

 their parasites, and wholesale sterilisation may help the pest by destroying 

 the parasites. Imms has recently noted two cases where this is said to have 

 happened ; scale insects, which are helped by spraying the parasitised insects : 

 and a «heat-pest {Diplosis tritici. a Cecidomyiid) which was helped I'ather than 

 hindered by burning the cavings from affected wheat, because the pupse thus 

 destroyed were parasitised, while those remaining in the soil were not. 



Nothing much can be done to deal with soil-pests until we know more about 

 them, and it is to obtain this knowledge that recent work is being done. 



When intensive cultivation is carried to an extreme it is followed^ by a falling 

 off of bacterial efficiency, finally leading to ' sickness ' in soil, which has been 

 investigated in some detail in our laboratory. 



But the waste of nitrates is not the only nitrogen loss taking place in the 

 soil. On certain of our plots a nitrogen balance-sheet is set up : an analysis 

 of the soil is made every twenty years, account is taken of the nitrogen put in 

 as manure and taken out again by the crop, and a statement can then be drawn 

 up showing the income, the known outgoings, and the residue left in the soil. 

 Three distinct cases are found. On the poor unmanured soil a balance i.'^ 

 obtained, the nitrogen removed in the crop being about equal to that supplied 



