ROOT CROPS. 17!l 



It is only by selection that desirable types and high-yielding stra 

 potatoes can be retail km 1. more especially since the advenl of such diseases as 

 Leaf Roll (see page 509), which so largely contribute to the degeneration 

 of this crop. A system of continual selection on these lines would resull very 

 largely in the elimination of run-out or diseased plants. 



The main trouble with our potato soils is the lack of organic matter. In 

 new land there is always a good supply of humus, and the land when 

 broken up is in good physical condition, but after a few years of cultivation 

 all the organic matter becomes exhausted, and unless additional supplies 

 are returned to the soil, either in the form of farmyard or green manure, 

 the soil soon becomes compacted and consequently cannot produce a maxi- 

 mum crop. 



The presence of humus in the soil improves its texture, lightening and 

 loosening it, and preventing the compaction of the surface, so that it is of 

 special value in the preparation of potato soils. The humus in the soil is the 

 ingredient which is most subject to alteration and destruction, and under 

 dry conditions it is more or less rapidly destroyed. As soon as it has lost its 

 moisture and become dry, it is rapidly burnt out by the combined action 

 of sun and air. As its presence is most essential where it is most liable to 

 destruction, the necessity for renewing it is apparent. 



In order to maintain this supply of humus, the following rotation is 

 recommended : — 



(1) Potatoes. 



(2) Oats or wheat. 



(3) Field peas or rape. 



The cultivation of the potato crop prepares the soil for the cereal crop, 

 which in potato districts is usually oats for hay. After the hay crop is 

 harvested the land should be ploughed as soon as possible so as to participate 

 in the usual February rainfall, after which rape (February sowing) or field 

 peas (March sowing) should be planted. Of the two, field peas are recom- 

 mended. These crops can be utilised as sheep-feed during the winter, but 

 they should not be completely eaten off, and care should be taken that 

 the soil is not trampled out of condition by grazing heavily during wet 

 weather. The crop residues should be turned under during late winter, and 

 not later than August, the ploughing being fairly deep. The soil should 

 occasionally be harrowed to conserve moisture, and should be in a fit con- 

 dition for planting with potatoes during November. 



Seasons of Growth. 



For the purposes of this crop the State is divided into two sections as 

 regards season, viz., coastal and tableland, the time of planting varying in 

 different parts of the State, and growers must be guided largely by local 

 conditions. 



In the warm coastal districts two crops of potatoes can be grown each 

 season. The first crop is planted in July or August, and is called the " spring 

 crop"; the second, in January or February, is designated the "autumn 

 crop." 



The weather conditions generally prevailing throughout the growth of the 

 spring crop are such as to be unfavourable to the development of Irish 

 blight, and consequently damage is very rarely caused. This crop usually 

 meets with a big demand, owing to the market being bare, and it realises 



