140 VAEIOUS KINDS OF MANUEE. 



gas is evolved from the bottom of lakes. When it accumulates in 

 large quantities, however, it destroys plants as well as animals. 



Manuring with Green Chops is sometimes practised. The 

 mode adopted is to sow certain green crops, the roots of which extend 

 deeply into the soil ; and when the plants have advanced considerably 

 in growth, to plough them in, and sow a crop of some kind of grain. 

 In this way the nutritive matter from the deeper part of the soil is 

 brought within reach of the roots of the grain crop. Manuring with 

 seaweeds is also resorted to in cases where they are accessible. They 

 supply abundance of carbonate, phosphate, and sulphate of lime, be- 

 sides chloride of sodium. There are considerable differences in their 

 chemical composition ; thus, while in Laminaria saccharina, alkaline 

 carbonates, potash, and iodine, predominate ; in Fucus vesiculosus and 

 serratus, sulphates and soda are in excess, and iodine is less abundant. 

 In the cultivation of the Coco-nut Palm seaweeds act beneficially. 



Liquid Manures have of late years been much employed, and 

 the formation of tanks for their reception has been strongly recom- 

 mended, in which the ammonia is fixed by the addition of sulphuric 

 acid or charcoal. They can be applied after vegetation has advanced, 

 and they are in a state to be at once available to the crop. Some 

 have advocated steeping seeds and grains in certain solutions before 

 sowing them. Professor Johnston suggests a mixture of phosphate 

 of soda, sulphate of magnesia, nitrate of potash, common salt, and 

 sulphate of ammonia (1 lb. of each), in ten gallons of water, to steep 

 300 lbs. of seeds, which are afterwards to be dried with gypsum or 

 quicklime. 



The following experiment, conducted by Mr. Wilson, at Knock, 

 near Largs, shows the mode of estimating the effects of manures. The 

 land was a piece of three-year-old pasture, of uniform quality. It was 

 divided into ten lots, and these. were treated with different kinds of 

 manure. The quantity of well-made hay is given in lbs. — 



Lot 1. Left untouched ..... 

 „ 2. 2 J barrels Irish quicklime . 



,,3. 20 owt. Lime of gasworks 

 ,,4. 4J- cwt. Wood charcoal powder 

 ,,5. 2 bushels Bone-dust 



,, 6. 18 lbs. Nitrate of potash 



„ 7. 20 lbs. Nitrate of soda . 



„ 8. 2^ bolls Soot 



,,9. is lbs. Sulphate of ammonia . 



,,10. 100 gallons Ammoniacal liquor of gas 



works, 5° Twaddell's hydrometer t 



The value of each application was the same, all were applied at the 

 same time, and the grass also was cut at the same time. 



