422 MAIZE 



CHAP, and thus allow the land to be harrowed free of those kinds of 

 x - weeds which are not affected by winter tillage. One of the 

 advantages of a catch crop like teff is that it is a short-season 

 crop, which allows the farmer time for a certain amount of 

 summer fallowing, while it also enables him to get some cash 

 return the same season, for his labour. Teff, velvet beans 

 and some other crops are useful as " smother-crops " ; if sown 

 thickly they will sometimes clean the land by choking-out a crop 

 of such weeds as grow more slowly than the smother-crop. 



Mangels and potatoes are useful " cleaning crops " for maize, 

 as the cultivation necessary for these crops greatly reduces the 

 stock of weeds stored in the land. Cabbages would have the 

 same effect, but it is said that a cabbage crop greatly reduces 

 the subsequent crop of maize, possibly because of the poisonous 

 nature of the decomposition products of the cabbage stem and 

 roots. 



386. The Best Time to Kill Weeds. — " The best time to kill 

 weeds is just as the seeds are germinating, or while they are 

 yet very small. When this is done, but little moisture is lost 

 through them, and they render but little plant food insoluble. 

 In the thorough and early preparation of the seed-bed many 

 weeds are destroyed by killing them just as they are coming 

 up. So, too, in the case of a grain field which is rolled after 

 being seeded, and is then harrowed ; the rolling hastens the 

 germination of the weed seeds, and the harrowing then throws 

 them out into a dry soil, which kills them. If such a field is 

 again harrowed just after the grain is up, a second crop of 

 weeds may be destroyed, and the yield made greater as a con- 

 sequence. In the case of potatoes and maize it is very easy 

 to destroy at least two crops of weeds before the maize or 

 potatoes are large enough to cultivate, by harrowing before 

 and just after the plants are up. This is very important, 

 because it not only saves plant food for the crop, but it can 

 be done so much more cheaply and rapidly with the broad 

 light harrows and weeders than it can later with the cultivator " 

 {King, 1). 



387. Weed Seeds do not all Germinate at onee. — " It must 

 be remembered in handling soils to kill weeds that the seeds 

 do not all germinate at once. The first harrowing which is 

 done to kill weeds may itself bring up from below seeds which 



