VEGETABLE GROWING IN NEW SOUTH WALES. 



feed only in the surface soil ; others draw their supplies from the deeper soil 

 and subsoil. It is the business of the grower to take advantage of these 

 variations in the habits and characters of his crops to ensure that the fertility 

 of his soil shall at least be maintained, if not increased. 



The supply of organic matter in the soil is much more easily maintained if 

 crops of varying habits aYid purposes follow one another. Peas and beans, 

 for instance, though grown only for their pods, produce a good bulk of top 

 growth, which, when turned under adds humus to the soil. Roots and crops 

 of the cabbage family, on the other hand, deplete the humus rapidly, and 

 cannot be grown in successive seasons without a reduction in the fertility of 

 the soil. Where large quantities of organic manures stable or farmyard 

 refuse or street sweepings are easily available, this may beof less consequence, 

 but to the grower whose supply is limited and who is obliged to depend largely 

 on chemical fertilisers, it is very important that there should be maintained 

 in his soil the proper proportions of decayed and decaying plant matter from 

 which the soil bacteria can liberate fresh supplies of plant- food. Rotation, 

 indeed, may thus be a means of saving considerable sums that would otherwise 

 have to be expended on chemical fertilisers. 



Some crops, such as peas and beans, haye the power of obtaining nitrogen 

 the dearest of all plant foods from the air, and storing it in their own 

 systems and in the soil ; they are, therefore, doubly valuable in a rotation. 

 Plants of thi group are called legumes, and to the vegetable grower whose 

 soil is of lower fertility than he might desire, they have a special utility. 



Rotation has the effect, too, of controlling insect, fungus, and weed 'pests. 

 The eggs and larvae of the insect pests of a crop may remain in the soil to 

 infest next year's crop if it is of the same or similar habits, while a complete 

 change of crop may starve them out. In the same way, the spores of a 

 fungus attacking a crop in one season may remain in the soil, and find easy 

 prey next year if a similar crop is on the same ground. 



One suburban gardener some years ago approached the Department, asking 

 why his potatoes were diseased they were so every year now, he said, though 

 some years ago he got good crops of healthy tubers on the same ground. 

 Inquiry elicited that he grew potatoes in the same spot each year, peas on 

 the same trellises, cabbages in the same rows. When urged to change his 

 crops round, he objected to the work of moving the trellis, &c. ; but it was 

 not until he complied with the advice that he got better results. His method 

 of growing the same crop year after year on the same patch was simply 

 carrying disease forward from one crop to the next, and though the potato 

 patch was the first to show the effects, the pernicious principle was also at 

 work on the other patches. 



The preparation of a soil for a crop of a different class, as well as the 

 absence of the natural food, may destroy the larvae or young, or kill the 

 spores, and thus keep the pests in check. Much the same applies to weeds, 

 the seeds and the seedlings of which are much more likely to be destroyed if 

 the land is not devoted to the same crop year after year. 



