20 CLIMATE AND RESOURCES OF 



The greater the amount of rainfall there has been during the 

 period of the growth of the crop, provided there have also 

 been some periods of dry, hot, sunshiny weather, the more 

 will the soil be caked and hardened, and the greater will be its 

 power of reflecting heat and the less its power of absorption 

 and radiation. This increased power of reflecting heat, and 

 decreased power of absorbing and radiating it, are brought to 

 a high state of perfection, and are fully developed in irrigated 

 lands, particularly in those irrigated from canals with an 

 unlimited supply of water ; for here, as in the case of rain, the 

 greater the amount of water supplied to the land the more will 

 the land become hard and consolidated. I will, as an example, 

 take a field of wheat. The land is prepared by being ploughed 

 and reploughed, or rather scarified some two or three inches 

 deep about ten or twelve times during the rains, and imme- 

 diately after they have ceased. Perhaps not so often on 

 canal-irrigated lands as on lands not so irrigated. The object 

 of these frequent ploughings or scarifyings is said to be to 

 bring all grass and other vegetable matter there may be in 

 the soil to the surface, where it is collected and often burnt, 

 thus further diminishing the amount of vegetable matter in 

 the soil. The seed is sown in the latter part of October, and 

 in a few days, when the blades show above ground, the field is 

 irrigated; the surface- soil is converted into loose mud, which, 

 on drying, forms a crust; this crust cracks in all directions 

 from the heat of the sun ; the water, which had thoroughly 

 soaked the loosened surface-soil and only slightly moistened 

 the upper part of the hard pan below it, is dried up in a few 

 days. Having mentioned the pan, it will be as well to describe 

 it before proceeding further. 



The pan is formed by the treading of men and cattle, and 

 in England the pressure of the sole of the plough has some- 

 thing to do with its formation ; not, however, in India, where 



