344 SOIL PHYSICS AND MANAGEMENT 



ing as prairie soils because of the lack of organic matter. Even 

 the lighter colored phase of brown silt loam packs badly during 

 winter. If fall plowed, sandy loams are liable to be damaged by 

 blowing. Heavy soils are especially benefited by fall plowing. 



(b) Spring Plowing. A very large amount of plowing must 

 necessarily be done in the spring because the crop of the preceding 

 year was not taken off in time for fall plowing. It is very essential 

 that some preparatory work be done previous to the plowing. This 

 should usually consist of thoroughly disking (Fig. 164) the ground 

 to cut up the vegetable material and mix it with the soil so that, 

 when the furrow-slice is turned and compacted slightly, close capil- 

 lary connection may be established at once. Where corn-stalks are 

 to be turned under, as is frequently done in the corn belt, the cutting 



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Fia. 164. Previous to plowing, disking should be done to cut up the corn-stalks or other 

 vegetable matter and produce a deep mulch. 



up of the stalks by the disk is a very important process, since when 

 plowed the fine soil filters in around the stalks and does not permit 

 the formation of large air spaces that aid in drying the soil. This 

 disking will also prevent evaporation, so that if plowed later it will 

 be comparatively free from clods. 



2. Depth of Plowing. Poor and badly-worn soils should be 

 plowed deeper than rich, productive ones. Our cereals and grasses 

 are shallow rooting plants, the major part of the roots developing 

 in the plowed soil. This forms their natural and most accessible 

 feeding area. Within certain limits the deeper the plowing the 

 better the chance of the crop for getting an abundance of food. 

 If the plowing is done too deep the surface soil with its swarms 

 of bacteria will be buried below the zone of most favorable action 

 and a smaller amount of available food will be developed for the 



