174 ACID PLANTS ERADICATED. 



mentioned. Sorrel (rumex acetocella) is the most plentiful and 

 injurious weed on the cultivated acid soils of lower Virginia ; an 

 unmixed growth of poverty grass (aristida gracilis) is spread over 

 all such lands, a year after being left at rest ; at a somewhat later 

 time broom-grass (andropogon) of different kinds covers them 

 completely; and if suffered to remain unbroken a few years longer, 

 a thick growth of young pines will succeed. But as soon as such 

 land is sufficiently and properly marled, there remains no longer 

 the peculiar disposition or even power of the soil to produce these 

 plants. Sorrel is totally removed, and poverty grass no more is to 

 be found, where both in their turn before had entire possession. 

 The appearance of a single tuft of either of these plants is enough 

 to prove that the acid quality of the soil on that spot still remains, 

 and that either more marl, or more complete intermixture, is still 

 wanting. Thus, the presence of either of these plants is the most 

 unerring as well as most convenient and ready indication of a soil 

 wanting calcareous manure. The most laborious analyses, by the 

 most able chemists, directed to ascertain the different characters 

 of soils in this respect, are not to be compared for accuracy to the 

 tests furnished by either the appearance or total absence of sorrel 

 or poverty grass. In regard to broom-grass and pines, the change 

 is not so sudden, or complete ; but still the soil will have been 

 made manifestly unfriendly to both. Some striking apparent ex- 

 ceptions to these rules have caused some persons to doubt of their 

 correctness, when full examination of the circumstances would 

 have confirmed my positions. I have known a mere top-dressing 

 of marl, left for some years on a worn-out old field, to eradicate 

 the before general growth of broom-grass, and substitute a cover 

 of annual weeds. Yet on other tillage land, after marling and one 

 crop of wheat on fallow, I have seen the growth of broom-grass 

 return, and seemingly with greater than its former vigour. But 

 this return and vigour were but temporary, and the land is now 

 comparatively free from this injurious weed. When soil, already 

 filled with its seeds, is very imperfectly mixed with marl by plough- 

 ing, there is nothing to prevent the broom-grass springing from all 

 the spots not touched by the marl, whether these spots be above 

 or below or between unmixed masses of marl. And the growth 

 being thin and scattered, and not covering the surface completely 

 as formerly, will cause the separate tufts of broom-grass to be 

 much more luxuriant, and greater impediments to tillage, than 

 previously. But the next course of tillage will -serve to mix the 

 marl and soil completely, and remove all this appearance of marl 

 being favourable, instead of destructive to broom-grass. Sorrel 

 may often be seen growing out of the heaps of pure marl, dropped 

 from the carts on acid land, and the heaps left thus, unsprcacl, 

 through a summer. But this apparent and very striking exception 



