28 On Liquid Manure. 



magnesia, sulphuric acid, silica, and even potash, are found in 

 such abundance, that we need not care to replace them in 

 the measure in which they are carried off the land in the 

 different crops of a rotation. There are a few soils upon which 

 we can continue to grow paying crops of roots, clover, or corn, 

 without restoring in the shape of manure the more valuable 

 minerals, such as phosphoric acid ; but where it is yet necessary 

 to replace the nitrogenised food of plants, which, it appears, is 

 diminished in a high degree by the growth of white crops. 

 Upon land rich in available mineral matters, purely nitro- 

 genised or ammoniacal manure may be used with far more safety 

 (and in many instances with true and permanent economy) than 

 upon soils deficient in available mineral food. The injurious 

 effects of an excess of ready-formed ammonia and nitrogenised 

 matters readily furnishing ammonia on decomposition, show 

 themselves nowhere plainer than upon poor sandy soils. Daily 

 experience tells us to use ammoniacal manures but sparingly 

 in such cases. Now liquid manure, we have seen, always con- 

 tains a considerable proportion of nitrogenised organic matters, 

 as well as ready-formed ammonia, but it is deficient in phos- 

 phoric acid and other mineral matters which, under ordinary 

 circumstances, are furnished to the plant by the soil. The 

 liquid manure produced on a farm, when applied in a concen- 

 trated state, of course cannot penetrate the soil to any great depth, 

 or, at any rate, cannot soak so deeply into the soil as it would 

 had it been previously diluted with three or four times its bulk 

 of water. There are many sandy soils in which lime, magnesia, 

 phosphoric acid, and other minerals occur but in very small 

 quantities. If such soils are manured with a too concentrated 

 description of liquid manure, there will not be a sufficient 

 quantity of mineral food in the soil and the manure to counter- 

 balance the injurious effects which an overdose of purely nitro- 

 genised food is well known to produce. Grass land under such 

 circumstances will produce abundant, but rank, innutritions, bad- 

 Keeping hay ; wheat will give abundance of straw, but little and 

 inferior corn ; swedes, turnips, and other root-crops will make 

 rapid progress, and then become attacked by disease. 



For these reasons it is necessary to dilute liquid manure 

 largely if we wish to put it on poor sandy soils. Diluted with 

 much water it penetrates a larger mass of soil, and, so to speak, 

 becomes more saturated with the mineral fertilizing matters 

 that are wanted by the plant, and are so sparingly distributed 

 throughout the soil. 



And this leads me to observe that liquid manure is particu- 

 arly well adapted for porous sandy soils, because it penetrates 

 them when properly diluted deeply and uniformly, which is a 



