Chapter 20

Influence of manures in increasing soil-fertility 474 Influence of farmyard manure on the soil 475 Farmyard manure _v._ artificials 476 Farmyard manure not favourable to certain crops 477 Conditions determining the application of artificial manures 477 Nature of the manure 478 Nitrogenous manures 478 Phosphatic manures 480 Potash manures 480 Nature of soil 481 Nature of previous manuring 482 Nature of the crop 483 Amounts of fertilising ingredients removed from the soil by different crops 484 Capacity of crops for assimilating manures 486 Difference in root-systems of different crops 488 Period of growth 489 Variation in composition of crops 490 Absorption of plant-food 490 Fertilising ingredients lodge in the seed 491 Forms in which nitrogen exists in plants 491 Bearing of above on agricultural practice 492 Influence of excessive manuring of crops 492