June, 1900.] £ 



creek ; while his neighbour, across the 

 way, held the opposite belief, and had 

 this season cultivated to an extra depth 

 to conserve moisture- The determin- 

 ation of the moisture held by the soil 

 in July to the depth of six feet gave 

 the following results : — 





Outivated. 



Uncultivated. 



Depth in Soil, 



Per 



Tons per 



Per 



Tons per 



cent. 



Acre. 



cent. 



Acre. 



First; Foot 



..6-4 



128 



4-3 



86 



Second Foot 



...5-8 



116 



4-4 



88 



Third Foot 



...6-4 



128 



3-9 



78 



Fourth Foot 



..6 5 



130 



5-1 



102 



Fifth Foot 



..6-7 



134 



3-4 



68 



Sixth Foot 



..6'0 



120 



4-5 



90 



Total for 6 feet. 



6'3 



756 



4-2 



512 



The difference of 244 tons per acre of 

 ground shown by the analyses is quite 

 sufficient, according to the data given 

 at the beginning of this bulletin, to 

 account for the observed difference in 

 the cultural result. The cause- of this 

 difference was that in the uncultivated 

 field there was a compacted surface layer 

 several inches in thickness, which forci- 

 bly abstracted the moisture from the 

 substrata and evaporated it from its 

 surface ; while the loose surface soil on 

 the cultivated ground was unable to 

 take any moisture from the denser sub- 

 soil. This .is well illustrated by the 

 familiar fact that while a dry brick 

 will suck a wet sponge dry, a dry sponge 

 (corresponding to the loose surface soil) 

 is unable to take any water from wet 

 brick. Besides, the tilled surface soil 

 forms a non-conducting layer protecting 

 the subsoil from the sun's heat and the 

 dryness of the air. 



In the East, where the principle is well 

 understood, it is considered that a sur- 

 face layer three inches in thickness is 

 sufficient to afford effective protection. 

 But what is adequate in the region of 

 summer rains is quite insufficient in 

 California and in the arid region gener- 

 ally. It takes fully twice the thickness 

 mentioned, and perferably more, to 

 afford protection against the drought 

 and heat lasting five or six months at a 

 stretch. Here, again, we find an im- 

 portant point in which our practice 

 must differ from that of the East and of 

 the Old World. 



The beneficial effects of summer fallow 

 in California are assuredly due quite as 

 much to the conservation of moisture 

 brought about by the tilled surface 

 layer, as by the weathering of the soil 

 to which the efficacy of the fallow is 

 commonly ascribed. Witness the fact 

 that weeds come up freely on summer- 



! Scientific Agriculture. 



fallow as late as August, when un- 

 ploughed land is as bare as a barn floor. 



Similarly on our mostly new and un" 

 exhausted lands, the bad effects of 

 weed growth are doubtless due fully as 

 much to the waste of moisture going on 

 through their leaves as to the competi- 

 tion with the crop in plant food. Hence 

 all good orcharclists are very careful 

 about keeping their ground clean in 

 summer ; but it must not be forgotten 

 that by doing so they quickly deplete 

 their lands of vegetable matter, which 

 requires systematic replacement if pro- 

 duction is to continue normally. Yet of 

 the two evils, the loss of moisture is 

 more to be dreaded, and very generally 

 in practice the more difficult to remedy. 



INCREASED YIELDS OBTAINABLE 

 THROUGH ADDITIONAL CULTI- 

 VATION OF THE SOIL. 



By R. W. Thornton, 

 Government Agriculturist. 



(From the Agricultural Journal of the 

 Cape of Good Hope, January, 1909.) 



This simple experiment has been 

 carried out for two years in succession. 

 The increases gained from additional 

 cultivation were so remarkable the first 

 season that it was thought that perhaps 

 the cause might be in the land itself, so 

 the plots were reversed this year, and 

 those that gave the heaviest returns last 

 season, instead of being thoroughly 

 worked and reduced to the best mechan- 

 ical condition possible, only received the 

 usual cultivation, and, true to last year's 

 experiment, gave the smallest yields, 

 whereas those that gave the small yields 

 last season under the usual methods of 

 cultivation have this year given the 

 maximum returns under increased culti- 

 vation, This proves conclusively that 

 the increase was not due to difference in 

 the soil of the various plots, but to the 

 increased cultivation. 



In India, where the peasants often 

 find it difficult to obtain fertilisers and 

 labour is cheap, they depend largely on 

 obtaining good crops by increased culti- 

 vation, and will frequently plough their 

 land four or five times. The good results 

 they obtain are amply borne out by the 

 result shown by this experiment. 



Last season the experiment was carried 

 out at tho Robertson Experiment Sta- 

 tion with oats on the following lines 



