THE BAD WEEDS PRODUCED BY CALXING. 173 



the old, though the latter may produce as heavy grain crops. The 

 remarkable crops of clover raised on some very poor clay soils, after 

 marling, have been already described. This grass, even without 

 gypsum, and still more if aided by that manure, will add greatly 

 to the improving power of marl ; but it may do as much harm as 

 service, if we greedily take from the soil all of the supply of 

 putrescent matter which it affords.* 



Some other plants, less welcome than clover, are equally favoured 

 by marling. Unless both the tillage and the rotation of crops be 

 good, greensward (^poa pratensis), blue grass (poa compressa)j 

 wire-grass (cynodon dactylon), and the vetch, or partridge pea 

 (yicia sativa), will soon increase so as to be not less impediments 

 to tillage, or to the grain crops, than manifest evidences of an 

 entire change in the character and power of the soil. 



[The power of calcareous manures is still more strongly shown 

 in the eradication of certain plants, as has been before incidentally 



[* There is great difficulty, and frequent failure of securing a " stand" 

 of the young clover plants, even when the subsequent growth of those 

 which escape early destruction is ever so vigorous. This is not owing to 

 any defect of soil (after calxing), but to our climate. It is necessary to 

 sow clover seed before the close of winter, to avoid, by its early growth, 

 the greater evils of the following summer's drought, which most affects the 

 youngest plants. The time of sowing is usually not later than February. 

 It almost always happens that a succeeding warm spell causes most of the 

 seeds to sprout, and then a severe frost kills them, while in their most 

 tender state. Sometimes, the whole young growth is thus killed by late 

 frosts. The danger from drought, and the hot sun, after reaping the 

 shading cover of wheat, is scarcely less than from frosts at the earlier 

 period. One or both of these disasters have occurred for four of the first 

 five seasons for my sowing clover on Marlbourne ; so that but one good 

 "stand" of plants, and of course but one sufficiently thick crop was ob- 

 tained. The loss was the greater, because no clover had previously been 

 on the land, and, of course, there was no volunteer growth, which other- 

 wise and usually furnishes as many plants as the new seed. Indeed, after 

 a field has once been well covered with clover, and the ripe seeds ploughed 

 under, there is not half the danger at any time afterwards of failing to 

 secure a stand of plants. 



But a greater evil has been found than this, since the publication (in 

 18-42) of the passages above reporting so favourably of the growth and 

 hardiness of clover. On the Coggins farm, and elsewhere, on the formerly 

 acid soils marled more than twenty years ago, the clover crops have recently 

 been much more apt to fail, as above, and are much inferior in product, 

 even when not failing to stand, than previously ; and this where the land 

 certainly has not lost anything of its richness, and where other crops than 

 clover show no diminution. It is not certain whether this change is owing 

 to the land being "clover-sick," (a common result in England, but not 

 known here, before), or that the acid of the soil (or sub-soil) is increasing 

 and overbalancing the quantity and effects of the calcareous earth. Some 

 facts sustain this latter supposition, llemarlings, at lighter than the earlier 

 rate, have been found, in some cases, to restore the before reduced power 

 of the land to produce clover. 1849.1 

 15* 



