. The soil, its nature, relations, and fundamental principles of management . — vShowing the influence of free-nitr()<;en-fixing germs on thegrowth of peas. The large plants all grew in sand containing thenitrogen-fixing bacteria, while the small plants grew in soils iden-tically the same except that all bacteria were excluded from Hellriegel. proving of any help to them. A full study of theseproblems may lead to an explanation of why it is some-times difficult at first to get clover to do Avell on certainsoils, and also what is the cause of clover-sick lands. To show how great i
. The soil, its nature, relations, and fundamental principles of management . — vShowing the influence of free-nitr()<;en-fixing germs on thegrowth of peas. The large plants all grew in sand containing thenitrogen-fixing bacteria, while the small plants grew in soils iden-tically the same except that all bacteria were excluded from Hellriegel. proving of any help to them. A full study of theseproblems may lead to an explanation of why it is some-times difficult at first to get clover to do Avell on certainsoils, and also what is the cause of clover-sick lands. To show how great is the service of these free-nitrogen-iixing germs, there is given below the results of eighttrials made by Hellriegel with lupines, in which all ofthe plants were treated alike except that four of them Free-Nltroyen-Fixiny Germs. 127 were, at the start, given loam water in order to add thenecessary bacteria, while the other four ])ots receivednone. Taking the amount of nitrogen in the jjlantsforced to grow unaided by the nitrogen-fixing germs as1, the amounts stand, —. Fig. 19. — Showing the growth of rye, oats, peas, wheat, tlax. andbuckwheat in soils fertile in all elements of plant food except nitro-gen, and illustrating the power of the pea, through its root tuber-cles, to procure nitrogen from the air. After P. Wagner. Nitrogen. No. 1, without germs 1 No. 3, ^ 1 No. 5, 1 No. 7, 1 . If, however, we. compare the weights of dry ,;these stand,-— Nitrogen No. 2, with germs No. 4, u iL No. 6, u U No. 8, i( (( 128 The Soil. Dbt Mattke. Drt Mattbr. No. 1, without germs 1 No. 2, with germs No. 3, U (( 1 No. 4, U (( No. 5, u u 1 No. 6, u u No. 7, u u 1 No. 8, (( (( These two comparisons bring into strong relief thegreat help the lupines received from the nitrogen-fixinggerms which grow upon their roots; for they show that,while there is a strong difference between the amountsof dry matter produced under the two
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectsoils, bookyear1895
