DECIMAL CLASSIFICATION 
631.6 
61 
O11 
612 
613 
014 
615 
616 
617 
64 
63 
64 
6 
JI 
12 
73 
74 
75 
76 
17 
78 
70 
3 
81 
B11 
812 
813 
814 
B15 
816 
817 
818 
Reclamation Drainage 
Agricultural engineering 
Initial operations 
Prairies 
Waste lands: rocks and bushes 
Hilsides: terracing 
Forests 
Marshes Swamps 
Lands under water Polders 
Deserts 
See 631.7 Irrigation 
Drainage methods 
Ditches Drains (open, coverd, tile) 
Drainage systems 
Plans, layouts 
Dikes and embankments 
Water removal by machinery 
Pumps, windmils, etc. 
Irrigation, water supply 
Conservation of moisture. Rainfall, streams 
Source of water: wels, reservoirs 
Irrigating canals 
Systems of irrigation 
Plans, etc. 
Mesure and distribution of water 
Cost of water 
Machinery 
Methods of conserving moisture 
Mulching 
See also 631.586 Dry farming; 631.8 Fertilizers, amendment of soils 
Fertilizers 
History, nature, uses 
Nutrition of plants; necessary principles 
Production, preparation, collection. conservation 
Composition 
Loss of fertilizing principles 
Economic value 
Use Methods of application and distribution 
Purchase Transport Cost 
Frauds Adulterations Control; legislation, inspec: 
tion, analysis 
Any special fertilizer may be subdivided like 631.81; e. g. 
631.8525 Economic value of bone as a fertilizer 
621.8722 Composition of seaweed