SOIL FATIGUE.

Colonist, Volume LIV, Issue 13410, 7 May 1912, Page 8

SOIL FATIGUE.

The continued cultivation of such fod-

der plants as clover and lucerne on the "same land is accompanied by a progressive decrease in the crop. This phenomenon has been called "soil fatigue," and various explanations of it have bcon given. Tho recent experiment's of

Pouget and Chouchak, in America, prove that soil fatigue is not caused by the exhaustion of plant food alone, but

but that clover and lucerno, like- hops, I'vcrote poisonous substances, which accumulate in the soil and finally arrest the growth of the crop. Rich soil.that had never borne a crop of lucerne- produced & crop rather smaller than the* normal on the addition of the- dried aqueous extract of the soil of a lucerne fU'ld, but no sueii decrease in crop was observed when the extract was roasted before it was mixed with tho soil. On

the other hand, the application of an

extract of soil that had never borntlucerne and been abandoned to spontaneous vegetation for two years, caused an increase in crop oi lucerne. Th-esv results indicate that lucerne c«cretes substances which arc detrimental to it; own growth. The action of these substances is analogous to that of toxins. Alcoholic extracts of the soil of a lucenu Hold exerted no injurious effects upoi: the growth of lucerne, and tlie soil that had been sterilised by heat yielded larger crops that unsterilised soil.