FACTORS DETERMINING FERTILITY 



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Fig. 30. — A fertile soil. This soil possesses all the qualities, properties and conditions 



which impart to it productive power. 



Fig. 31. — Harvesting hemp in Wisconsin. Crop growth is the indicator of soil fertility 

 This particular soil is in a high state of fertility. 



Positive factors: (1) A suitable moisture supply in the soil. 

 (2) Sufficient air in the soil. (3) Good tilth (Chapter V). (4) 

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