164 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Weed Seeds, Buried. By Winifred E. Brenchley {Jour. Agr. Sci. vol. ix. 



Part 1 ; 191 8). — It is often stated that crops of weeds, especially charlock and 

 poppy, appear when " old pasture " is ploughed up. On inquiry, however, 

 it is usually found that the land in question was under the plough at no very 

 distant date. But there are cases in which this was not so, and it has been 

 established by P. Becquerel, the British Association (experiments of 1840-57), 

 and others that the seeds of some species of plants are capable of germination 

 after being buried in the soil for eighty years. Since 1915 the author has been 

 conducting experiments to test the germinating power of seeds buried at different 

 depths in the soil under natural conditions. Her method consisted in taking 

 borings to a depth of twelve inches from various fields of known history and 

 examining the soil thus obtained in successive layers each one inch thick. The 

 layers were separately transferred to sterilized pans placed in a greenhouse and 

 watered. The seedlings which appeared were identified and counted. The land 

 examined was of three classes, viz. (a) old pasture never, so far as was known, 

 under the plough ; {b) pasture originally arable ; (c) arable. As might be 

 expected, seedlings were most numerous in the upper three or four layers, but 

 a fair number, altogether, were obtained from the bottom layer twelve inches 

 below the surface, the lowest layer from the arable land giving the greatest 

 number. 



In the case of a pasture which had certainly been under grass for 300 years 

 four borings gave four seedlings of arable weeds (one from the seven-inch deep 

 layer), 372 of grassland plants (one from the twelve-inch layer, ten from the 

 ten-inch layer, and eighteen below six inches and not so deep as ten inches), and 

 29 of grasses. Four borings from pasture land which was arable fifty-eight 

 years ago gave 30 arable weed seedlings, 100 seedlings of grassland plants, and 

 13S seedlings of grasses. One-third of the first named occurred in the five-inch 

 layer and there was one seedling arable weed in the seven-inch layer. There was 

 none at a greater depth. As many as ten seedlings of Orache (A triplex patula) 

 occurred and came from the third, fourth, and fifth inch layers. Another field 

 under grass since 1885 gave 74 arable weed seedlings which came from all depths 

 from 1 to 12 inches. A third field under grass since 1906 gave no fewer than 

 457 arable weed seedlings (twenty-six of these from the twelve-inch layer). As 

 compared with this number of 457 there were only 121 seedlings of grasses. 

 As regards arable land two borings having a total volume of half a cubic foot 

 of soil and taken from a field cultivated under an ordinary rotation produced 

 782 arable weed seedlings, 35 seedlings of plants common to grassland and arable, 

 and 57 seedling grass plants. 



The general conclusion is that there is a striking difference between the 

 buried seed flora of true permanent pasture and that of land which was at some 

 time under the plough, even though nearly sixty years have elapsed since the 

 latter was laid down. The permanent pasture land is largely colonized by 

 species of grasses and of miscellaneous plants definitely associated with pasture 

 and never with arable. On land that was originally arable occur a large number 

 of plants common to both arable and grass land such as chickweed, hardhead, 

 and ribwort, and in addition a fair number of true arable weeds also. It is 

 almost certain that these last have survived fifty-eight years, and the strongest 

 argument in favour of this belief is the regular change in proportion of arable 

 land seedlings corresponding to the number of years which have elapsed since 

 the land was grassed down. On the other hand, the case for the appearance of 

 large crops of charlock, poppy, or other arable weed on ploughing up old pasture 

 must be regarded as non-proven, since these particular weeds were not obtained 

 from the three hundred vear old pasture nor from that laid down nearly sixty 

 years before.—/. E. IV. E. H. 



