Scientific Agriculture. 



174 



[February, 1900. 



ultimately exhaust the soil. The 

 minimum of auy one essential ingre- 

 dient rules the crop. It does not matter 

 how great a quantity ot the other con- 

 stituents may be present, good crops 

 cannot be obtained if one substance is 

 deficient. When this is the case a 

 special manure produces as good effect 

 as a manure containing everything 

 necessary to plant growth. The world's 

 experience has proved that it is not 

 advisable to continuously apply farm- 

 yard manure. If a field was dressed 

 every year with farmyard manure, 

 after a time there would be in the soil 

 constituents more than are necessary, 

 and a lai ge store of fertility would have 

 accumulated. And though the field 

 may be said to be in a high state of 

 fertility crops will not prove as satis- 

 factory as might be expected. This is 

 because a large quantity of food is 



LYING IN A DORMANT CONDITION 



in which state plants cannot assimilate 

 it. In such cases a special manure 

 which would convert dormant material 

 into active matter suitable for plant 

 nutrition is valuable. Instances of the 

 above are sometimes seen in land in 

 high condition from previous manuring. 

 As a rule an application of nitrate of 

 soda will cause the crop to grow and 

 bear vigorously, the plants making use 

 of the hitherto dormant matter. The 

 difference between the nitrogen in the 

 nitrate of soda and the nitrogen in 

 farmyard manure is that in the former it 

 is immediately available and is taken 

 up at once by the roots, whereas in farm- 

 yard manure the nitrogen is partly 

 locked up and is only made use of as 

 it becomes available. The effect of a 

 dressing of nitrate of soda is not seen 

 beyond the crop to which it is applied, 

 whereas the effects of a dressing of 

 framyard manure is seen for many 

 years after. Another thing which must 

 not be forgotten when comparing arti- 

 ficial with farmyard manure is the 

 mechanical effects produced by the 

 latter in the soil, artificial having no 

 such effects. By the fermentation of 

 farmyard manure in the soil its texture 

 becomes improved. Carbonic acid, the 

 most powerful disintegrator known, 

 is evolved, and helps to break up the 

 soil and release the stores of food it 

 contains, much more effectively than 

 any process of ploughing and cultiva- 

 tion- 



TILLAGE OF MANURE. 



There is, as a rule, a large quantity of 

 undeveloped natural fertilisers in most 

 soils. If nature were not very conser- 

 vative the careless agriculturist would 

 rob the soil of its most valuable consti- 



tuents faster than he does, either by 

 carrying plant food off, or allowing it 

 to leak or wash away- It is noticed that 

 organic matter, as soon as it ceases to 

 live, is revolved into its original ele- 

 ments, and that these elements in most 

 cases combine with bases — the phos- 

 phoric acid with lime, the potash with 

 silicates, and so on — and Avhen combined, 

 they are often so securely locked up 

 and preserved that this plant food is 

 not available unless the cultivator does 

 something to help along the natural 

 processes. The cultivator has in most 

 cases taken from the land the plant- 

 food which is easily available, has often 

 robbed it of its humus, hence its mois- 

 ture-holding capacity. The crops then 

 suffer from two distinct causes, first a 

 lack of a full supply of available plant 

 food, and second from lack of moisture. 

 Tillage makes the plant-food more avail- 

 able. To provide the moisture and not a 

 sufficent amount of available plant-food, 

 would be like giving a horse all the 

 water it requires, but not enough paddy 

 and grass. 



NO ONE CAN FORETELL 



how much cultivation will be necessary 

 to secure maximum crops. In some soils 

 the plant-food is extremely lazy, in other 

 soils it may be deficient rather than lazy. 

 The soil that contains an abundance of 

 dormant plant-food is more valuable 

 than that which contains a small amount 

 of available food. In the case of annual 

 crops the reason why soluble plant-food 

 is frequently so beneficial is because the 

 plants when young cannot secure from 

 unaided soil sufficient nourishment, and 

 they become dwarfed, and never entirely 

 recover. If a sufficient supply of plant 

 food has not been provided for the 

 young plants by tillage, it is always well 

 to add available plant food which may 

 serve as a starter. A young calf cannot 

 be well nourished on straw. A grown- 

 up animal may subsist fairly well upon 

 this coarse food ; but the calf must have 

 a starter, that is, food that is easily 

 digested, as milk. The same with plants. 

 Only by experiment can it be positively 

 determined whether expense should be 

 incurred for extra tillage or for the 

 purchase of available plant-food. Ex- 

 perience seems to indicate that the extra 

 tillage is the most rational method of 

 indirectly supplying nourishment where- 

 ever it is certain that there is an 

 abundance of lazy plant-food in the soil. 

 In some cases large crops have been 

 received by means of superior tillage 

 on land of moderate fertility. On other 

 soils, without doubt these results could 

 not be reached without some added 

 plant-food, but often in soils that are 

 only moderately productive a great 



