Vol. XV. No. 3-59. 



THE AGRICULTURAL NEWS. 



47 



INFUSORIAL EARTH AS A MANURE. 

 As the result of a suggestion made in this Journal 

 for November 20, 191.5, as to the possible vahie of infu- 

 sorial earth as a moisture ab.sorlient for the soil, Professor 

 Harrison, Director of the Department of Science and 

 Agriculture, British (Juiana, has furnished this Office 

 with the following hitherto unpublished information 

 relating to experiments and investigations made by 

 him in this connexion many years ago. The infor- 

 mation should be of special interest in Barbados 

 where the work recorded was carried out. 



In 1883-86 a series of trials was made in Barbados 

 using so-called infusorial earth for top dressings on cane fields. 

 The fields were top-dressed with very heavy dressings of 

 these earths, the results noted — in every case an increased, to 

 a greatly increased crop over that of not dressed plots — and 

 finally in 188.5 the earths used for the dressings were 

 analysed. Professor Harrison took the samples of the earths. 

 The results of the analyses were: — 



The nitrogen content was negligible. 

 The order of efficiency was: — 



1. Castle Grant (by far the best) 



2. Canefield (greenish) 



3. Frizers 



4. Canefield (cream) 



The Castle Grant fields yielded increased crops from the 

 application until at any rate, the crop of 1889. 



The Castle Grant earth was a mottled red, pink and 

 yellow oceanic clay, as smootli and soapy in feel as it well 

 could be. It came from a place <lose to or almost on the 

 Castle Grant fault north of the estate house and buildings. 

 The cutting was on the west of the road. The mass of it 

 slipped down the liillside with the road in a landslip, 

 possibly, at the time of the hurricane in 1898. 



The Canefield greenish earths consisted largely of very 

 fine-grained volcanic debris and oceanic clay from one of the 

 beds of the oceanic series below Mount Misery. Canefield cream- 

 coloured sample was a globigerina earth from the bottom of the 

 oceanic series, whilst Frizers was a radiolarian-foraminiferal 

 marl near Vaughans from about the middle of the oceanic 

 series. I'rofessor Harrison remembers noting on the 

 •certificate of the analysis on the Castle Grant earth that it 



did not give up any appreciable quantity of any manurial 

 constituent of plint-food to hot hydrochloric acid, and 

 that whilst chemically speaking it should be inert, its 

 application had produced heavy crops of canes. 



Later Professor Harrison made more complete analyses 

 of some of the earths in a dry state, using fresh samples 

 collected by himself. The figures obtained were: — 



The main fact Professor Harrison recollects about thesa 

 trials is that the highly calcareous earths from which good 

 results were expected were more or less failures, and the 

 argillaceous earths, characterized by their high retentive 

 power for water (compare earlier ar>alyses), were very 

 successful, which was quite unexpected. The former 

 remained on the fields in hard resistent lumps for a long 

 period, the latter rapidly crumbled down and formed 

 a 'mulching', to the land. 



Professor Harrison is of the opinion that it would bfe 

 well worth while repeating these experiments, which ara 

 undoubtedly of much interest. 



