418
Scottish soils supplied with potash 419
Sources of potassic manures 419
Stassfurt potash salts 420
Relative merits of sulphate and muriate of potash 421
Application of potash manures 422
Soils and crops suited for potash manures 423
Rate of application 423

CHAPTER XVI.--MINOR ARTIFICIAL MANURES.

Scutch 427
Shoddy and wool-waste 427
Soot 428

CHAPTER XVII.--SEWAGE AS A MANURE.

Irrigation 431
Effects of continued application of sewage 433
Intermittent irrigation 434
Crops suited for sewage 434
Treatment of sewage by precipitation, &c. 436
Value of sewage sludge 439

CHAPTER XVIII.--LIQUID MANURE 442

CHAPTER XIX.--COMPOSTS.

Farmyard manure a typical compost 446
Other composts 447

CHAPTER XX.--INDIRECT MANURES.

Lime 449
Antiquity of lime as a manure 449
Action of lime 449
Lime a necessary plant-food 450
Lime of abundant occurrence 452
Lime returned to the soil in ordinary agricultural
practice 452
Different forms of lime 453
Caustic lime 453
Lime acts both mechanically and chemically 455
I. Mechanical functions of lime 455