Potato Culture. 45 



not with the rows, else a number of plants might be damaged. Har- 

 rowing is very effective in keeping the weeds under control, and in 

 destroying any hard crusts that may form. 



Cultivation should start as soon as the harrow can no longer be 

 employed. This operation should be continued until after the 

 flowering stage. At that period the crop should be ridged or earthed 

 up so as to cover up the tubers, and protect them from frost and tuber 

 moth injury. Ridging is sometimes done gradually— a little earth 

 being thrown towards the row with each cultivation. 



As to the number of cultivations that should be given, no hard 

 and fast rules can be laid down, but the grower should be guided by 

 soil and climatic conditions. The same applies to the number of 

 irrigations when the crop is grown under irrigation. The crop should 

 be kept well supplied with moisture, otherwise malformed tubers will 

 re&ult. Experience has shown that water should not be applied 

 during the heat of the day as this practice predisposes the crop to 

 disease. Water-leading, therefore, should take place early in the 

 morning or in the evening when the soil, the plant, and the water 

 have about the same temperature. 



Manueial Eequirements. 



The potato is classed among the plants called surface feeders, 

 and is also a short-lived crop, and for these reasons the soil intended 

 for same should be in a high state of natural fertility, otherwise 

 lieavy applications of manures and fertilizers should be given to 

 stimulate and promote growth. It does not pay to attempt to grow 

 potatoes on poor soils. Of all crops the potato requires a very rich 

 soil for maximum yield. 



Results obtained by growers show that the following applications 

 of manures have given satisfactory results: — 



Ten tons of well rotted kraal manure ploughed imder, preferably 

 during the Avinter months so as to give it ample time to decompose 

 thoroughlj^ together with 300 lb. of bone-dust or superphosphate 

 which should be applied in the row on the day of planting. 



The potato growers in the Bethal District use from GOO to 900 lb. 

 of potato fertilizer per acre, and no kraal manures, whereas the far- 

 mers in the Eauresmith District use from 10 to 12 tons of sheep 

 manure, and no artificial fertilizers of any description. 



The experience at the different experiment stations in the Union 

 has been that a combination of kraal manure with mineral fertilizers 

 has given much better results than either alone. The organic matter 

 ?eems essential for successful potato propagation. 



The following Co-operative Experiments planned by Mr. T. D. 

 Hall, Research Chemist, at the Experiment Station, Potchefstroom, 

 and carried out by Mr. G. S. Leslie, Secretary of the Marico Agricul- 

 tural and Stockbreeders' Society, contains some illuminating results 

 on this subject. It will be noted that complete mineral fertilizers 

 (plot 16) gave no better result than 8 tons of kraal manure per acre 

 by itself. The best yield was obtained from 400 lb. superphosphate, 

 400 lb. of wood ash, and 4 tons kraal manure, and the next best with 

 kraal manure and superphosphate alone. It would be as well when 

 wood ash is not available to use in its place 80-150 lb. of sulphate of 

 potash. 



