146 TILTH AND TILLAGE 



Other advantages of late fall plowing are: (a) It favors the 

 development of granular or crumniy structure, and hence good 

 tilth, in lumpy and heavy soils; (6) many crop pests aie destroyed, 

 such as white grubs and aphis.; (c) coarse litter turned under is 

 permitted to decompose partially, thus establishing better contact 

 between the seed bed and the subsoil, and providing a better 

 supply of available plant-food elements; (d) soils plowed in the 

 fall are seldom too wet. 



Fall plowing is usually best for wheat, and is commonly 

 practiced when corn follows sod. 



In dry-farming sections it is often best to plow immediately 

 after a grain crop is harvested, for two mam reasons : (a) the soil 

 plows better because of the moisture it contains, and (6) soil 

 moisture is conserved. 



In some sections farmers hesitate to plow much of their 

 "young" sod land in the fall, because if they do, they may be 

 left without any hay land the next season if, perchance, the new 

 or spring seeding is winter-killed. 



Land that is fall plowed should be left rough, unless it is plowed 

 early and sown to a cover crop or winter grain. 



Spring Plowing. — Usually much plowing is done in the spring, 

 largely because time does not permit all of it to be done in the fall. 

 At this time of the year there is much danger of plowing some of the 

 heavier soils when too wet. This is harmful, because the crummy 

 structure of the soil is destroyed, and a "puddled'' condition 

 results. This explains why some heavy silt loams, clay loams and 

 clays are so hard and lumpy. A puddled soil is not necessarily 

 mud. When a wet clay, for example, is worked, the crumbs, if 

 any, are broken up and the soil particles run together, forming an 

 impervious mass; in other words, the clay is puddled. On drying 

 the mass becomes hard. The action of the plow is sufficient to 

 produce a puddling effect when a heavy soil is plowed too wet. 



Spring plowing is best for sands that are subject to "blowing." 



Late spring plowing permits the plowing under, for soil im- 

 provement, of green crops which ordinarily do not make suffi- 

 cient growth in the fall to turn under at that time. Rye is a 

 good example. 



Moderately Deep Plowing Best. — In general, best results are 

 secured when soils are plowed moderately deep — ^from six to nine 

 inches. In a deep seed bed most plants develop deep, strong root 

 systems, thus enabling them to secure a good supply of moisture 



