4iS 



THE TROPICAL AGRICULTURIST. 



[November i, 1882. 



AGEICULTDRE ON THE CONTINENT OF 

 EUROPE. 



(Special Letter.) 

 NiTRATKs, Phosphates, Potash and Soils. 



Paris, September 9. 

 What is the tme theoiy of a rotation of cropping? 

 Doctors differ . n the point : there is a school in this coun. 

 tiy that reduces the question of the fertility of the soil 

 to a matter of strange give anil take. Here, they say, is 

 a general table of analyses of soils auil also of cultivated 

 crops : of certain mamu'es, &c. Nothing is easier than to 

 calculate the total jdeld of a crop, to know the quantity 

 of phosi^hates and of potash, etc., carried oiT: the analysis 

 of the mamu'e vd]l enable the quantity of these salts to 

 be estimated and requisite to be rettu'ned to the soil : if 

 in excess, the richness of the land wiU be augmented. It 

 is further laid down that cereals and industrial plants 

 draw largely on the soU for nitrogenous princiiiles, but as 

 the erops are succeeded by forage plants, the deficit is 

 made up by the intervention (hyiiothetical) of atmospheric 

 azote. Fm'ther: the necessity to practise a rotation of 

 cropping is explained by plants not requii-ing the same 

 mineral substances, so that, what one leaves the other 

 will appropriate, and that after a lapse say of five years. 

 Thanks to periodical manurings and dissimUiarity of 

 tiBages, the alternate exhaustion and the renovation of 

 the soil will be found equalized. 



Now what is om' stock of precise, demonstrated know- 

 ledge on this subject of rotation? It is exact : that the 

 mineral food removed must be restored. By the suc- 

 cessive cropping of lands in Sicily with wheat, the phos- 

 phates had been exhausted, and the soil has become 

 impoverished. The same fact was in process of realization 

 in the north of France, till M. Corenninder called atten- 

 tion to the necessity of employing phosphates, and since 

 fertility has retiu'ned. Now for plants, as for manures, 

 there is no constancy either in mineral or nitrogenous, 

 or even in any other elements. Analysis shews that a 

 large number of different maniu'es vary in composition ; 

 from one to four times in the ease of the same element. 

 Similarly for plants ; wheat for example, where the jaer- 

 centage of nitrogen, as in gluten, varies from one to 

 thi'ee, there are analogous differences for the potash and 

 phosphoric acid carried off. Hence, there is no mean, 

 no Pi'ocrustean standard, that can be declared off laud, 

 applicable to a special soU. Strictly speaking, each parti- 

 cular case demands a new analysis ; one field may pro- 

 duce a forage five times more nutritive than another. 



A popiUar eii'or exists that» Boussingaidt asserted that 

 forage plants take nitrogen dii-ectly from the air, but even 

 his latest experiments demonstrate the exact contraiy. 

 Then the attempt has been made to explain the restitution 

 of nitrogen to the soil by the agency of meteors and ram. 

 It is a fact that ammoniacal salts and nitrates are cons- 

 tantly present in the ail', and conveyed along mth other 

 saline and dust matters to the soil by the rain. But 

 the latter falls on the just and unjust alike ; upon all 

 cultm-es indistinctly, not upon any particular rotation, 

 and not specially on forage plants. It is assumed, but 

 not proven, that electricity nitrifies the azote of the au' 

 in the interior of the soil by a imion with hydro-car- 

 bonaceous matters ; or effects a similar end in the interior 

 of plants by theii' stai'ch, sugar &c. We know, however 

 tha t the azoteous matters in the soil can be nitrified, 

 but that is not an augmentation of richness ; also. 

 Cavendish has shown in 1784 that an electric spark, 

 traversing an atmosphe, enriched with oxygen, can 

 produce nitric acid. Now if electricity makes ammoniacal 

 salts and nitrates in the atmosphere, that iuteivention 

 is for all rotations and crops alike. 



It may be hiid doivu as an axiom that every system 



of cidture which does not biing from an outside soiu'ce 

 the materials — whether nitrates, phosphates or potash, 

 Ac. — rare in a soU and earned off by the produce, must 

 ultimately suffer in fecundity. There is a necessity, 

 apart from these food considerations, to rotate crops. 

 The plan affords the means for extirpating weeds, for 

 cleaning the gi'oimd, and of destroying insects, since, if 

 the latter, peculiar to a distinct crop, be deprived of its 

 special food for one or two years, it must die of starv- 

 ation. To keep a soil rich, depend upon manure rather ' 

 than on — t)ie au'. 



The extent of vineyards in France is 4J million acres. 

 One-quarter of this area is invaded by the phylloxera, 

 and the new ravages of the insect are estimated at 

 the rate of 200,000 acres annually. Thi'ee official reme- 

 dies are recognized : sulp-earbonate of potassium and 

 sulphuret of carbon, submersion, and American stocks 

 for gi'afting on the affected vines. To these must be 

 added a relatively high manui-ing. It has been foimd 

 that purely nitrogenous manm'es, as wool clippings, horn 

 palings, (hied blood, oil cakes, etc., develop the vine at 

 the expense of the fruit; but fai-myard maniu'e, or a 

 composition of potash salts, soluble phosjihates, and a 

 proportionate dose of azoteous matters have the opposite 

 effect. A lugh authority, M. Rommier, recommends a 

 new and cheap insecticide — bi-sidpho-carbouate ; he also 

 recommends the summer fioodings of vineyards. He 

 doubts the efficacy of autiminal inigations, because at 

 that period the bug is prepared for its hivernal sleep, 

 is encased in a kind of wax watei-proof, and has a 

 sufficient prorision of air to guard against being di'owned. 

 Even M. Faucon, to make the submersion process more 

 certain, has had to prolong the floodiugs to 45 con- 

 secutive days. Some persons of late dissolve the insect- 

 icide in the water intended for UTigating the vines. 



In several parts of France, and notably in the southern 

 vine making districts, the residue of the gi'apes, after 

 being pressed or distilled, is conserved in cement cis- 

 terns for cattle feeding; the layers, of 12 inches, are 

 dusted with salt, the whole when pressed down being 

 covered with puddled clay: occasionally the latter is 

 represented by a thin sheet of weak brine. Some peo- 

 ple take the stalks out of the residuum, as the mass 

 then keeps better. Stock relish the feed from its alco- ' 

 holic fiavoiu-, and is given simUaily to beet pulp. In 

 the district of Mont-d'Or, famous for its cheese, pre- 

 pai'ed from sheep's miU^, the sheep are house fed all 

 the year round; in summer, etc., on the leaves of the 

 vine, and in ivinter on the residue of the winepress. 

 In Gemiany, brewers' gi'ains are similarly preserved as 

 the grape residue, save, that the cistern has a cover 

 battened down on the gi'ains. being itself covered by a 

 layer of water 8 inches deep. 



The beet crop has been attacked by the same fungus 

 this year as in 18-52 ; it is a species of mushi'oom that 

 settles on the leaves, producing a kind of rust. In some 

 cases all the leaves had been destroyed ; in others, new 

 leaves had succeeded. On analyzing the root, it was 

 foimd to have suffered to the extent of 3 per cent in 

 richness as compared ivith healthy roots. 



Water-distributing flexible pipes are generally length- 

 ened or joined by the additions screwing together. M. 

 Beaume simply aiTanges that one end of the pipe passes 

 into that of the other, the imion being secm-ed by a 

 lever, which locks ; an iuiUarubber rmg prevents all 

 leakage. 



i'rench farmers are becoming also manufacturers : thus, 

 the distillation of molasses, of maize, and of beet, has 

 been improved by employmg the electrolysem-, which 

 sends 'an electric current into the mass that decomposes 

 the water ; the liberated oxygen then displays an affinity 

 for foreign products of objectionable taste and burning 

 them. It is thus that beet brandy has been debarrassed 

 of its bad flavour; the tii-st shot distUlation yields f5 

 per cent, 'An electrolysem- «t11 produce 4,000 gallons 

 of brandy in 24 hoiuB. 



