THE TILLAGE OF STUBBLE LAND 163 



harrowing. If weeds are present and the surface soil 

 quite firm it is generally advisable to harrow. If weeds 

 are not present and the soil contains sufficient moisture to 

 produce a good crop, harrowing is not advisable except 

 as a preventive measure against weeds in potatoes or 

 corn. Neither is harrowing advisable where there is any 

 tendency of the soil to drift. 



Harrowing a growing crop is a practice in which judg- 

 ment must be used. A thin stand means later maturity. 

 Harrowing invariably pulls out some of the plants, thus 

 leaving a thinner stand. This is particularly true on 

 light, loose soils, or on fields carrying considerable rub- 

 bish in the form of stubble. On fields in this condition, 

 harrowing, if done at all, must be practised with care. 

 A light lever harrow with the teeth tilted slightly back- 

 wards is often to be preferred for this work. 



136. General Observations on Plowing Stubble Land. — 

 The best time to plow, whether in fall or spring, and the 

 best depth to plow, whether deep or shallow, varies con- 

 siderably under different conditions. It has been point- 

 ed out that each of these four practices has in different 

 seasons produced the largest yields. The plowing that 

 proved best generally was that done at the time the soil 

 was in the best condition. 



Early shallow fall plowing, well worked down, has 

 given at Saskatoon slightly larger average yields than 

 spring plowing of any depth; but spring plowing has 

 given us larger average yields than late fall plowing. 

 The data at present available do not favor the teaching 

 often advanced that deep fall plowing is always best for 

 the second or third crop after fallow in climates such 

 as ours where dry autumn, winter and spring seasons 

 are the rule. At the same time, when plowing is done 



