IMPROVING FARM LAND 
161 
also collects and conserves moisture, aids the growth of 
useful bacteria and furnishes food for growing plants. 
Practical plant growers realize the important function of 
humus in the soil and are working to add more of this 
material to their soils each year. 
Sources of Organic Matter.—One of the best and 
cheapest ways of adding organic matter to the soil is 
through the application of barnyard manure. The kind 
of livestock and the method of handling the manure will 
Fig. 119.—Terraces prevent washing. 
determine its value. The manure from old animals is 
richer in plant food than the manure from the young 
stock, because the old animal can not digest its food as 
well as the young animal. If the manure is thrown from 
the barn into holes, if the chickens are allowed to scratch 
it around and the rain wash out the plant food, it will be 
of little use to the farmer. The best way to apply manure 
to the soil is to haul it directly from the barn to the field 
and scatter it evenly and plow it under. Usually the best 
time to manure the soil is in the fall. Apply from 8 to 
25 tons to the acre and plow it under deeply. ,This gives 
