Vol. XIV. No. 354. 



THE AGRICULTURAL NEW 



379 



THE TEMPERATURE OF THE SOIL UNDER 

 DIFFERENT CONDITIONS. 



In the .'/• i 



Indi'i, Chemical Series, Vol. IV. So. 2, appears an accou 

 I )■•. Leather of important studies in soil temperatures, and 



a summary of this ace il is repi ed below, [ts impoi 



lies chiefly in the fan. thai c irrelal ion bas been 



established between the temperature ol the air and the 



so that it now becomes possible in [ndia to calculate the soil 



temperature under onditions of soil and climate. 



Several series of observations on soil temperature have 



made in the West [ndies, amongst which ma) be men- 



d those made by Mr. W. R. Dunlop in St. Kitts (see 



Agricultural News, Vol. XI, p. 125, April 27, 1912 



more recently therecordsof Dr. 11. A Tempany in connexion 



with the Dominica i icao plots (see West Indian Bulletin, 



Vol \l\- N >" '-'• 1914). tn the former investigation, apart 



from interesting synchronical observations in two different 



parts of the island, the extent of the diurnal range in exp ised 



soil at shallow depths was shown to bp.very considerable 



it ."> inches), and markedly influenced by such conditions 



:is cultivation, colour and as[ (. At 2 feet the temperature 



was found to be practically istant, though even here the 



cooling effect of rainfall, referred to both by Dr. Tempany md 

 Dr. Leather, was found to be observable. In the Domin > 

 observations, the chief point brought out was the equable 

 nature of the soil temperature under cacao trees, both from 

 month to month and at different depths. The range was 

 only about 2° in the course oi man) mouths, including the 



cool and let periods, while between deaths of 6 inches and 



Is inches there was only a difference of a fraction of 

 a degree. The temperature of the soil of a cacao planta 

 tion under Dominica conditions is about 23°C. at 6 im 

 while in an ordinary exposed - 'il it may be regarded as being, 

 forpurposes of comparison, about 30 .luring the hotter hours 



of the day. 



In India, as elsewhere, the temperature of the surface 

 soil naturally varies, both with the hour of the day and with 

 the season. 



1 »r. Leather states that, as regards the seasonal variati 

 the minima are in January and the maxima in May. 



In bare-fallow soil the diurnal change of temperature 

 extends to between 1 '_' inches and 24 from the surface on 

 most days in the year. At l^ inches it amounts to about 

 1 i . but at 24 inches it is doubtful whether it ever exo 

 01 ('. in Bihar, and probably does nol exceed 0'2° C. in any 



part of India. 



'There is a fairly close correspondence between the 

 temperature of bare-fallow soil at 1 inch from the surface and 

 that of the air in the shade; approximately the soil minimum 

 at this depth is about 2*0 C. higher than the air minimum, 



and tin- soil maximum is about 3'0°C.,higher thin the air 

 maximum. 



'There is also a similarly close relation between the 

 diurnal change of temperature in the soil (bare-fallow) at 

 1 inch from tie- surface and in the air (shade), the diurnal 

 change being about t'5 C. greatei in the soil at this depth 



than in the air. This diurnal change is least during the 

 monsoon and greatest during the 'In season; at the former 

 season (.June to September) it is about IOC. in the soil 

 (bare-fallow) at I inch deep, and during the latter (in March 

 and April) it frequently approaches 20 C. 



'The temperature of the soil near the surface (down to 

 :> inches or 1 inches) is above the mean temperature for only 

 about eight hours daily, whilst it is below ii for ab iuI sixteen 

 hours. 



' The lag in temperat lire is about two 

 deep and about eight hour- at 18 inches from the 



'A change in the sj ific heat of the soil, duet. 



oi moisture c intent, doe ■ not ji em to efl 

 minima; but rainfalls during the drj season, cau ing 

 ible change in th va >ral ing, have 



a marked effect. 



'It is pos ibl ■ te approximate^ I he tem] 



to which the soil rise-: under specified cond other p irts 



of I ndia. 



'The effect ol i o ii roj the soil temperature is 



naturally very marked, for il both prevents th I from 



rising to the temperature which fallow land im 



modifies the diurnal change. Thus whilst the temperature of 



exposed soil at 1 inch deep rises to about 3 ( above I I 



the air, that of cropped land is about 2 C. below it; and 

 whilst the temperature of exposed soil at the surface rises to 

 probably some 20 C. above that of thi air, the corresponding 

 figure for cropped land is onljj some 2 or 3 0. even in x -i 

 whilst in the rains it is actually lower than thai of the air. 

 Also in respect of diurnal change at 1 inch deep, whilst 

 exposed soil suffers a change of some 20 C. in Mai 

 cropped hind is only about 13°C. at the same depth; and 



during the mons whilst expi sed -"il -nil', t - , diurnal change 



of some 1 n't '. at I inch deep, I hat "t croppi 'I land is mlj 

 about :; to i (V 



RUBBER AND COCO-NUTS IN THE 

 STRAITS SETTLEMENTS. 



The planting of fresh land in rubber . 



settlement of the colony, and shows that the planters -'ill 

 retain their confidence. The area under rubber culti. 

 in Malacca is 117,200 acres. 



Catch crops under rubber are being abandoned generally. 

 The result is an enormous diminution in the output of 

 tapioca. The area under this crop has dropped from 16,643 

 acres in L912 t" 7,353 acres m L913. 



Along with the decrease of tapi'.ci, there has been 



i correspondingly large diminution in pig raising It was, 



and still is, tile custom for squatters to rear pig- under the 



Chinese-Owned I lUt palms, fattening them on the ampas, 



or refuse of tapioca manufacture. In past years the pigs 

 so raised met the whole deinand oi Malacca, and-were 

 to the Federated Malay Mates in large numbers. Now, how- 

 ever, the export has almost ceased, audio fatten the supply 

 for local demand an import of the refuse is required. 



The rice harvest was fair in Province \\ ellesley. and I'd 

 in I'enang and Malacca. In Malacca, not only was 



unfavourable to the growing crops, but then- was a smallei 

 ivr.i than usual under cultivation, owing to the attractions 

 offered by fairly high pay and moderately easy work upon 

 the rubber estates. 



Coco-nut estates in Singapore have Largely failed to 



attain their estimates. In SOI vises thi- has I n due to 



iullated expectations and a want of knowledge of the nature 

 and yielding power of the trees on the estate and in 



t i want of attention to the tree-. This In- especially 1 n 



the case where there have been joint interests in rubber and 



C nut-. 



Somelargei tati in the Dindings are. however, said to 



be doing well. 



Coco-nut pests were troublesome in Singapore There 



was an increase of the palm weevil in the Centre 'I the 

 island, and a serious outbreak of the moth Brack SI 

 catoxanthn in tin' east ol the island, which will affect the crop 

 of nuts in L914. (Go'onial Reports Annual for 1913.) 



