2 



INTRODUCTION. 



The experiments noted herein are exclusive of those made in the 

 grass garden on the grounds of the Department, and relate wholly 

 to the work done on about 4 acres of land on the Potomac Flats. 

 These 4 acres constitute a part of an area of some 22 acres, which 

 has been used during the past season by several divisions in the 

 Department for conducting experiments with plants and vegetables, 

 and which was primarily set apart for the use of the Division of 

 Botany. The land in question is on an island just south of Wash- 

 ington, D. C. , near Long Bridge, and was originally a tidal marsh. Its 

 present condition is the result of dredging out the channel between it 

 and the main land, now forming the city water front, and pumping 

 the mud over upon the marsh. The surface was thus raised from 

 two to ten feet above high tide. This work was done by the War 

 Department, and the use of the land by the Agricultural Depart- 

 ment was through permission of the Secretary of War. The land 

 is exceedingly rich, being the city drainage and harbor deposit of 

 many years' accumulation. 



On the higher, well-drained areas the soil is loose and porous, 

 washing badly with heavy rains, but on the lower portions it forms 

 a hard surface crust as it dries after having been packed by floods. 

 As might be expected from the origin of the island, the subsoil is 

 very porous, so much so that the surface water frequently breaks 

 suddenly through the firmer upper crust into subterranean cavities, 

 new openings of this character being apparent after every heavy 

 rain. It will be readily seen that the soil is peculiar to the island, 

 and can in no way be considered typical of this or any other region. 

 This fact does not especially injure its value for comparative 

 experiments. 



The ground was cleared and plowed in the spring of 1899 and 

 fallowed during that season. In the late fall it was plowed three 

 times, at intervals of about three weeks, and left rough over winter. 

 In the spring of the present year an Acme harrow was used fre- 

 quently, being run over the field in both directions to keep down, the 

 weeds. Ever since the formation of the land some ten years ago, 

 weeds have been growing and seeding unrestrained, and they cov- 

 ered the surface with a dense and luxuriant growth. On the higher 

 part the most abundant were sweet elder {Sambucus Canadensis 

 L.), velvet leaf {Abutilon Avicennae Gaertn.), lamb's quarter 

 {Chenopodium album L.), purslane {Portulaca oleracea L.), and 

 morning glory {Convohmlus sepium L.) On the low ground, 

 wormseed {Chenopodium anthelminticum L.), and a species of 

 heartsease or smartweed (Polygonum) were so abundant and so vig- 

 orous as to call forth the most strenuous efforts to prevent their 



