86 



IRISH GARDENING. 



Water in relation to Soils. Current Topics. 



E A R I N G in mind 

 the importance of a 

 sufficiency of water 

 for the complete de- 

 velopment of crops 

 it becomes a matter 

 of practical interest 

 t o cultivators t o 

 know something de- 

 finite about the com- 

 parative absorptive 

 power of different types of soil. In other 

 words, different soils have different capacities 

 for storing" water that falls upon it as rain. In 

 drv seasons this particular property of the soil 

 is one of the factors that materially influences 

 the successful production of crops. The total 

 amount of water that reaches the soil in a year 

 is very considerable ; for example, during" the 

 last month (April) 2 3^ inches of rain fell. How 

 much water does an inch of rain represent ? It 

 represents just a little over 4^ g"allons per 

 square yard. What becomes of this water? 

 Most of it is absorbed by the soil, and when the 

 absorptive capacity of the soil is satisfied the 

 superfluous water passes dc)wn into the depths 

 of the underlying" strata or else into the drains. 

 In any case, such water as escapes throug"h the 

 reg"ion of soil traversed by the roots is lost to 

 the crop. The importance of a soil having" hig"h 

 water-holding" power will be now apparent. 



From carefully conducted experiments it has 

 been ascertained that 100 volumes of each of 

 the following" types of soil will absorb and retain 

 the number of volumes of water set out in the 

 first column. The second column gives the 

 percentag-e of increase in weig"ht of the soil. 



(1) (2) 

 Sand ..... 38 28 



Loam (60 per cent, clay) . 51.4 40 



Heavy clay (89 per cent, claj') 62.9 61 

 Humus ..... 69.2 190 



But while it is of importance that a soil 

 should be able to hold a large quantity of water 

 it must, at the same time, be able to hold a 

 sufficient quantity of air. Sand has a very low 

 water-holding capacity but a high air-holding 

 capacity ; while clay is the very reverse of this, 

 its partxles are too fine and too close to admit 

 much air. Hence a mixture of these two (in 

 other words a loam) is the best type of soil for 

 ordinary cultivated crops. Humus absorbs and 

 retains much moisture, and as it keeps the soil 

 open its presence increases the air-holding 

 capacity also. From this it will be seen that, 

 quite apart from its manurial value, ordinary 

 dung increases the water-holding power of light 

 soils and increases the air-holding property of 

 stiff clays. 



T 



By PETER BROCK, Horticultural Instructor, Co. Fermanagh. 

 HE winter spraying- of fruit trees has become a 



recog"nised necessity in keeping" the bark in a 

 clean and healthy condition and in destroying the 

 egtfs of various injurious insect pests. Considerable 

 interest has recently been manifested in the insecticidal 

 effects of the two scientifically prepared proprietory 

 Vv inter spray fluids, \'' and No. i. As far as their 

 fiMigicidal properties are concerned, they appear to be 

 equally efficacious in cleaning" the bark ; but whether 

 they have destroyed, or even reduced, the more 

 tenacious fungus Fusiclndimn — better known as apple 

 and pear scab — more time is required to ascertain the 

 results. The eggs, liowever, which they are reputed to 

 destroy liave produced, in many cases, an injurious 

 crop of apple sucker (Psylla mali), aphides and winter 

 moth caterpillars. No tjlame can he attached to ineffi- 

 cient spraying, as the trees experimented on were as 

 thoroughly damped as if they had been dipped. Experi- 

 ments on trees infested with mussel scale show that a 

 comparatively small proportion of eggs have been 

 destroyed. At the lime the eggs were hatching I had 

 specimens from several districts which were sprayed 

 under various atmospheric conditions and with different 

 waters microscopically examined. Those sprayed with 

 the above fluids showed an entire absence of red, mite 

 eg-g-s compared with those from unsprayed trees ; but 

 apple psylla anti aphides were found to be numerous 

 and hatching. Specimens from trees in an orchard which 

 had previousl}- been badly infested with psylla, aphides, 

 and winter moth caterpillars, spra^•ed in March, 1907, 

 with the \\'oburn iron sulphate-caustic soda-cnndsion, 

 were also microscopically examined this year. Although 

 they have not been sprayed since last season they were 

 found to be zoologically the cleanest, showing only 

 some eggs of red mite and apliis. On a recent inspec- 

 tion of the latter trees and others Itreated this year 

 they show at a distance by the iminjured condition of 

 the foliage the superiority of the W'oburn formula, which 

 acts like a motor-car in comparison to other donkey- 

 cart or wobeg^one applications for destroying egg"s of 

 injurious insects. The formula of the Woburn vs'inter 

 spray mixture referred to is as follows : — 



Sulphate of iron (copperas), i^ lbs; caustic soda, 

 2 !4 lbs. ; paraffin, 5 pints ; water to make up to 10 

 gallons. 



Some growers varied the above by using a little less 

 paraffin, but the best results have been obtained with 

 the full amount. 



" Paraffin emulsion is the substance generally used 

 for spraying against sucking insects. It is prepared by 

 dissolving ^4 lb. soft soap in I gallon of boiling water, 

 and adding this to 2 gallons of paraffin ; the mixture 

 must then be churned up with a force-pump so as to 

 form a cream}" emulsion of even composition. Before 

 use, the emulsion must be diluted with to gallons of 

 soft water." 



The above is the formula given in tlie Department's 

 leaflet No. 85, page 5, and appears to contain a printer's 

 error. Having had some experience with paraffin 

 emulsion, I think the last sentence is surely meant to 

 read : — Before use, the emulsion must be diluted with 

 100 g-allons of soft water. This gives an effective emul- 

 sion for sucking" insects, as it contains nearly 2 per 

 cent, of paraffin. Under certain atmospheric conditions 

 and on some tender foliage emulsion at this strength 

 will sometimes cause scorching. I have had best 

 results, and without injury to trees or bushes, by using" 

 the above stock emulsion — the " Hubbard-Riley " 

 formula — in the proportion of i g"allon to from 40 to 60 

 gallons of rain water. If soft soap in the proportion of 

 y, lb. to every 10 gallons is added to the dilute emulsion 

 it forms a better summer cleaning wash. 



