November 27, 1920
SCIENTIFIC AMERICAN
549


1. Yield of potatoes in fields over which the air was fertilized with carbonic acid gas and left unfertilized. 2. A similar comparison for cauliflower plants.
3. An open-air carbonic-acid fertilizing plant.

1. Yield of pota­toes in fields over which the air was fer­til­ized with car­bon­ic acid gas and left un­fer­til­ized.  2. A sim­il­ar com­par­is­on for cauli­flower plants.  3. An open-air car­bon­ic-acid fer­til­iz­ing plant.

Fer­til­iz­ing the air with car­bon di­ox­ide to pro­mote plant growth

Carbonic Acid Gas to Fertilize the Air

By Dr. Alfred Gradenwitz

ONE of the prin­cip­al con­stit­u­ents mak­ing up the body of a plant is car­bon, repre­sent­ing about one-half of its or­gan­ic sub­stance. The opin­ion that this car­bon is de­rived from the soil has long been aban­doned, mod­ern in­vesti­ga­tion hav­ing shown at­mo­spher­ic car­bon­ic acid to be ab­sorbed by means of the chloro­phyl or green mat­ter of the leaves and de­com­posed in­to its ele­ments, the car­bon, in con­junc­tion with the root sap and at­mo­spher­ic mois­ture, be­ing worked in­to or­gan­ic com­pounds.

Where­as at­mo­spher­ic air at present is re­l­at­ively poor in car­bon­ic acid, of which it con­tains only about .03 per cent, at an early peri­od in the de­vel­op­ment of our plan­et, when this was covered with the lux­uri­ant forests our coal de­pos­its are de­rived from, it com­prised in­com­par­ably great­er quant­it­ies of this gas. This fact sug­ges­ted the idea of height­en­ing the fer­til­ity of the soil by in­creas­ing its car­bon­ic acid con­tent and thus pro­du­cing con­di­tions re­sem­bling those of antedi­lu­vi­an ages. In or­der to en­able such a pro­cess to be car­ried out on any­thing like a com­mer­cial line, a cheap source of car­bon­ic acid had, of course, to be pro­vid­ed.

This was found by Dr. Fr. Riedel of Es­sen-on-Ruhr in the com­bus­tion gases es­cap­ing from all factor­ies, but most abund­antly from blast-fur­naces, and which so far had been al­lowed to flow out in­to the at­mo­sphere without serving any use­ful pur­pose. He ac­cord­ingly set to work design­ing a pro­cess for which pat­ents were ob­tained and which was put to prac­tic­al tests on a large scale. Three green­houses were at first erec­ted, one of which served as test­ing room, while the two oth­ers were used for check­ing pur­poses. The test­ing room was sup­plied with pur­i­fied and burnt blast-fur­nace ex­haust gases through a line of punc­tured pip­ing tra­vers­ing the whole green­house in a for­ward and back­ward dir­ec­tion. The gas sup­ply was star­ted on June 12th, that is to say, at a time when plant growth was at its height.

On ac­count of the care­ful cleans­ing and com­plete elim­in­a­tion of con­stitu­ents such as sul­fur, the gas was found to ex­ert no harm­ful ef­fects. On the con­trary, even a few days after start­ing the test, there could be ob­served In the test­ing room a more lux­uri­ant ve­get­a­tion than in the check­ing houses. The leaves of the castor-oil plant in the green­house sup­plied with gas were found to reach more than one meter in span, where­as the largest leaf in the check­ing houses was only about 58 cen­ti­meters in width. Plants sub­mit­ted to the in­flu­ence of car­bon­ic acid gas also showed a marked ad­vance with re­gard to their height. With the to­ma­toes planted in an­oth­er part of the green­house a crop of 29.5 kilo­grams was ob­tained for a giv­en num­ber of fruits, the weight of the same num­ber of fruits in the test­ing room be­ing 81.3 kilo­grams, that is, 175 per cent more. With the cu­cum­bers planted at the same time a some­what slight­er dif­fer­ence was noted, the yield in the check­ing houses be­ing 138 kilo­grams, in the test­ing house, how­ever, 235 kilo­grams, cor­res­pond­ing to an in­crease in yield of 70 per cent. An in­ter­est­ing phe­nomen­on noted in this con­nec­tion was that, while the cu­cum­bers in the check­ing houses would ex­hib­it bright spots, those in the test­ing house, on ac­count of the more plen­ti­ful form­a­tion of chloro­phyl were of a dark green col­or throughout.

Ex­per­i­ments in the open air were made simul­ta­ne­ously with these green­house tests, a square plot of ground be­ing en­circled by punc­tured ce­ment pipes from which a con­tinu­ous sup­ply of ex­haust gases was es­cap­ing. The wind, mostly strik­ing the ground at an angle, would drive the car­bon­ic acid in a vari­able dir­ec­tion to­ward the plants, thus al­low­ing ex­ten­sive areas to be sup­plied with the fer­til­iz­ing gas. On the op­pos­ite side of the green­house plant there was pro­vid­ed for check­ing pur­poses a plot of the same size sub­mit­ted to no car­bon­ic acid gas, the soil in the two plots be­ing of the same qual­ity. Samples were de­rived from the best por­tions of the check­ing field, but from the cen­ter of the field sub­mit­ted to the ac­tion of car­bon­ic acid gas, the in­crease in yield in the case of spin­ach be­ing found to be 150 per cent, with pota­toes 180 per cent, with lupines (a legume) 174 per cent, and with bar­ley 100 per cent. The pota­toes in the field sub­mit­ted to the ac­tion of car­bon­ic acid gas were found to ripen much more quickly than in the check­ing plot.

The test­ing plant in view of these sur­pris­ingly fa­vor­able res­ults was even­tu­ally ex­ten­ded, three green­houses of the same size as those ex­ist­ing be­ing ad­ded, while the small open-ground plant was in­creased con­sid­er­ably and more ex­tens­ive grounds30,000 square meterswere pro­vid­ed with an un­der­ground cent­ral pipe and branch pipes en­circ­ling lengthy plots. Es­pe­cially fa­vor­able res­ults were ob­tained on this field with pota­toes, a 300 per cent in­crease be­ing re­cor­ded in con­nec­tion with tests on a large scale.

All ex­per­i­ments so far made go to show that fer­til­iz­ing the air by means of car­bon­ic acid gas is a much more ef­fi­cient pro­cess than even an in­creased fer­til­i­za­tion of the ground with stable ma­nure and cow dung. If, on the oth­er hand, a plot fer­til­ized from the air. at the same time be sub­mit­ted to soil fer­til­i­za­tion, the lat­ter, on ac­count of the in­creased need for oth­er ele­ments (ni­tro­gen, phos­phor­us, po­tassi­um, etc.) en­tailed by the in­creased ab­sorp­tion of car­bon­ic acid, can be driv­en much farther than oth­er­wise.

Ac­cord­ing to Dr. Riedel's cal­cu­la­tions an iron works deal­ing in its blast-fur­naces with about 4,000 tons of coke per day will daily pro­duce as much as 35 mil­lion cu­bic meters of com­bus­tion gases, con­tain­ing 20 per cent car­bon­ic acid gas. This is such an enorm­ous amount that even in the case of a par­tial util­iz­a­tion most ex­tens­ive plots of ground can he sup­plied with the pre­cious air fer­til­izer. Dr. Riedel there­fore be­lieves that car­bon­ic acid works for sup­ply­ing ag­ri­cul­ture will be­fore long be quite as com­mon a fea­ture as elec­tri­city and gas works, the large in­dus­tri­al cen­ters at the same time be­com­ing cen­ters of in­creas­ing ag­ri­cul­tur­al pro­duc­tion.

Care­ful ana­lys­is has shown the in­crease in the per­cent­age of car­bon­ic acid in the air to re­main far be­low the lim­it where the gas be­comes li­able to en­dan­ger the health of man.


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Related:  [1], [2], [3] & [4] (derivative articles);   [5] (plant growth database);  [6], [7], [8], [9], [10] & [11]; (F.A.C.E.);   [12] & [13] (Prof. Dyson)

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DOI: 10.1038/scientificamerican11271920-549

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