88 SCHOOL AND HOME GARDENING 



A good maxim among gardeners and farmers is " Xever 

 let tlae soil be bare." As soon as one crop is taken oft' another 

 must go on, even if that crop is ]iot to return any money 

 directly. Cover crops are used in winter and catch crops in 

 summer. 



Humus. — As green manures and other forms of organic 

 matter decay in soils they form a substance called humus. 

 It gives the soil a blackish color. Dark-colored soils in most 

 cases have humus in them. Xewly cleared woodlands are 

 dark in color because of the decay of leaves, roots and twigs 

 of the former forest. Leaf mould found in forests is largely 

 humus. The richness of such newly cleared land* is prover- 

 bial. But the farmer and gardener can plan a careful system 

 by which organic matter is constantly added in the rotation 

 of crops. Materials such as weeds, stubble, roots, vines, leaves 

 and special green manure crops should be plowed in and never 

 burned. Humus improves all soils and increases their produc- 

 tivity. It will absorb and retain more moisture than any 

 other part of the soil. This is a benefit of greatest value to 

 sandy soils. Clay soils are loosened by it, thus helping the 

 circulation of air and moisture. Clay with humus present 

 is less likely to clod and crust. The texture and structure of 

 the soil is much helped, drainage and ventilation are im- 

 proved and roots will feed to a greater depth. Humus is the 

 main inmiediate source of nitrogen, and when the humus is 

 being formed other plant-foods are liberated for the use of 

 crops. 



Barnyard manure is used on nearly all farms and crops 

 as the chief means of improvement. In nearly all school gar- 

 dens well-rotted manure is preferalile to coarse manure. 



The benefits of manure are: (1) It adds the three main 

 fertilizing elements for plants, nitrogen, phosphoric acid and 

 potash. (2) The vegetable matter contained in the manure 

 is a great sovirce of humus. (3) The soil is given a better 

 physical condition. (4) It becomes a better home for soil 



