October 8, 1914J 



NATURE 



157 



■untries, possess immense districts that are little more 

 nan desert. Of the European countries, Germany has 

 taken the lead in endeavouring to bring into use this 

 undeveloped capital; her population is rising rapidly, 

 and her fiscal policy has caused her to feel severely the 

 recent increase in the prices of foodstuffs, which she 

 has determined to relieve so far as possible by extend- 

 ing the productivit\' of her own land. It has been esti- 

 mated that Germany possesses something approaching 

 to ten million acres of uncultivated land, and a Govern- 

 ment department has been created to reclaim and 

 colonise this area. 



Before dealing with the processes by which the 

 rough places of the earth are to be made straight, 

 there is one general question that deser\-es considera- 

 tion : Is it more feasible to increase the production of 

 a given country by enlarging the area under cultiva- 

 tion, or by improving the methods of the existing culti- 

 vators? There is without doubt plenty of room for 

 the latter process even in the most highly farmed 

 countries : in England the average yield of wheat is 

 about 32 bushels per acre — a good farmer expects 40 ; 

 the average yield of mangolds, a crop more dependent 

 upon cultivation, is as low as 20 tons per acre when 

 twice as much will not be out of the way with good 

 farming. .\ large proportion of the moderate land in 

 England is kept in the state of poor grass — even as 

 grass its production might be doubled by suitable 

 manuring and careful management, while under the 

 plough its production of cattle-food might easily be 

 trebled or quadrupled. Why, then, trouble about add- 

 ing to the area of indifferent land when so much of 

 what has already been reclaimed, upon which the 

 first capital outlay of clearing, fencing, roadmaking, 

 etc., has been accomplished, is not doing its duty? 

 We are at once confronted by the human factor in 

 the problem. The existing educational agencies which 

 will have to bring about better farming will only 

 slowly become effective, and however imperfect they 

 still may be in England, they are mainly so because 

 of the lack of response upon the part of the farmers. 

 The present occupiers of the land do obtain in many 

 cases a very inadequate return from it, but they make 

 some sort of a living and they hold it up against others 

 who, though the}- want land, cannot be guaranteed 

 to use it any better. Improved farming means more 

 enterprise, more knowledge, often more capital, and 

 the man who can bring these to the business is far 

 rarer than the man who, given a piece of land even 

 of the poorest quality, will knock a living out of it 

 by sheer hard work and doggedness. While, then, 

 there should be no slackening in our efforts to improve 

 the qualit}- of the management of existing land, there 

 is a case for also using every effort to increase the 

 cultivable area ; indeed, it is probable that for some 

 time to come the second process will add most to both 

 the agricultural production and the agricultural popu- 

 lation. 



Let us now consider what are the factors which 

 determine the fertility of the land that is first brought 

 into cultivation and remains the backbone of farming 

 in the old settled countries. Foremost comes rainfall, 

 and the distribution is almost as important as the 

 amount. Winter rain is more valuable than summer, 

 and though cereal-growing is none the worse and may 

 even obtain better results with a rainless summer, 

 stock-raising and the production of fodder crops are 

 the better for a rainfall that is distributed fairly evenly 

 throughout the year. Rainfall, again, must bear some 

 relation to temperature; some of the best farming in 

 the Eastern Counties of England is done on an average 

 rainfall of 20 inches ; there are great areas in South 

 Africa with the same average rainfall that are little 

 better than desert. In temperate regions we may say 

 that the naturally fertile land requires a rainfall of 



NO. 2345, VOL. 94] 



from 20 to 50 inches per annum, not too much segre- 

 gated into seasons, and some at least falling in the 

 winter. 



If the rainfall is excessive or the drainage inadequate 

 to carry it off, the formation of peat is induced, result- 

 ing in such uncultivated areas as the bogs of Ireland 

 and the moors of Eastern England, Holland, and 

 Germany. 



Given suitable rainfall and temperature the texture 

 of the soil becomes a factor of importance; if too 

 coarse and sandy, so little of the rainfall is retained 

 that we get all the effects of drought secondarily pro- 

 duced. In itself the open texture of a coarse, sandy 

 soil is favourable to plant development ; under irriga- 

 tion, or where the situation is such as to result in 

 permanent water a short distance below the surface, 

 fine crops will be produced on sandy soils that would 

 remain almost barren if they only depended upon the 

 rainfall for their water. In Western Europe large 

 areas of heaths and waste land owe their character 

 to the coarse and open texture of the soil. At the 

 opposite extreme we find clays so heav)- that their 

 cultivation is unprofitable ; such soils, however, will 

 carry grass and are rarely left unoccupied. For 

 example, in the south-east of England there are a few 

 commons, i.e., land which has never been regarded as 

 worth enclosing and bringing into particular owner- 

 ship, situated on hea\y claj" land ; most of such land 

 is pasture, often of the poorest, or, if at any elevation, 

 has been covered with forest from time immemorial. 



One last factor in the soil is of the utmost import- 

 ance to fertility, and that is the presence of lime — of 

 calcium carbonate, to be more accurate — in quantities 

 sufficient to maintain the soil in a neutral condition. 

 Old as is the knowledge that lime is of value to the 

 soil, we are only now beginning to realise, as investi- 

 gation into the minute organisms of the soil proceeds, 

 how fundamental is the presence of lime to fertilit}-. 

 I A survey of the farming of England or western Europe 

 will show that all the naturally rich soils are either 

 definitely calcareous or contain sufficient calcium car- 

 bonate to maintain them in a neutral condition even 

 after many centuries of cultivation. Examples are not 

 lacking where the supply of calcium carbonate by 

 human agency has been the factor in bringing and 

 keeping land in cultivation. I have discussed c«ie such 

 case on the Rothamsted estate, and several others have 

 come under my notice. The amelioration of non-cal- 

 careous soils by treatment with chalk or marl from 

 some adjacent source has been a traditional usage in 

 England and the North of France : Pliny reports it as 

 prevailing in Gaul and Britain in his day, and the 

 farmer of to-day often owes the value of his land to 

 his unknown predecessors who continuously chalked 

 or marled the land. Upon the presence of carbonate 

 of lime depends the t}-pe of biological reaction that will 

 go on in the soil, the beneficial bacterial processes that 

 prepare the food for plants only take place in a medium 

 with a neutral reaction. The Rothamsted soils have 

 provided two leading cases. I have shown that the 

 accumulation of fertility in grass-land left to itself and 

 neither grazed nor mown, so that virgin conditions 

 were being re-established, was due to the action of the 

 organism called Azotobacter, which fixes free nitrogen 

 from the atmosphere, and was indirectly determined by 

 the presence of calcium carbonate in the soil, without 

 which the .\zotobacter cannot function. Examination 

 of typical examples of black soils from all parts of the 

 world, the prairies of North America, the steppes of 

 Russia and the Argentine, New Zealand and Indian 

 soils, showed in all of them the Azotobacter organism 

 and a working proportion of carbonate of lime. Now, 

 as we know, all virgin soils are not rich, and only in 

 a few parts of the world are to be found those won- 

 derful black soils that are often several feet in depth 



