OUTLINE OF CROP MANAGEMENT 



85 



rotation of plants is determined largely by the presence or absence of 

 such excreta. 



Some of the reasons why rotation-farming is considered to be advan- 

 tageous (under present teaching) may now be mentioned. 



(1) One crop tends to correct the faults of another crop. The contin- 

 uous growing of one crop usually results in the injuring of the soil in 

 some respect ; a rotation tends to overcome and eliminate such effects. It 

 evens up and works out the inequalities. The general average of many 

 or several kinds of treatment is better than the effects of one treat- 

 ment. 



(2) Plants differ considerably in the proportions of the kinds of foods 

 that they take from the soil. In rotations, the different plants make the 

 maximum of their draft on the soil at different times in the year, 

 thereby allowing the progress of the seasons to even up the inequalities. 



(3) By a judicious choice of crops, different plant-food materials 

 may be incorporated in the soil in available condition, through the decay 

 of the parts plowed under or left in the ground. The most marked 

 benefit of this kind probably comes from incorporation of nitrogen com- 



Pig. 116. ' 'The irrigator, ' ' pictured 

 in 1823. " This machine Is cal- 

 culated to -water meadow- 

 grounds, cotton and provision 

 land, and with a boy and horse, 

 ought to water one or two acres 

 per day. according to the dis- 

 tance of the river from the 

 field." " No. 1, The Cask ; 2, 

 The Axle; 3, Felloes; 4, Bung; 

 5, Plug holes at both ends; 6, 

 Seat for the boy." 



Fig. 117. Woodside's macliine for harrowing, sowing and rolling, 1833. The seeder or sieve is at H; har- 

 row at B; roller at I. " From the above it will be perceived that I can of a truth affirm, that I can 

 sit in the front of my cart, under a canvas covering, sow the grain, harrow and roll it in, without 

 exposure to the sun, leaving the ground without any impression of the horses' feet, my own feet, or 

 the cart wheels." 



pounds through the use of leguminous 



plants. These plants have the power, 



by means of their root nodules, of 



fixing the free atmospheric nitrogen 



of the soil ; and the new compounds 



are turned back 



to the soil in 



condition to be 



utilized by plants 



that do not have 



the power to 



appropriate the 



nitrogen of the 



air. Since nitro- 



gen is the most expensive and usually the most easily lost of the plant-food elements that the farmer 

 has to buy, this role of the leguminous plants is most important. It is significant that most of the 

 early rotations, developing before rational expla- 

 nations of them could be given, comprised some 

 legume. 



(4) Some plants have the power, more than 

 others, to utilize the content of the subsoil. Such 

 plants may not only make less proportionate draft 

 on the upper soil, but by their decay may add to 

 the richness of such soil. It has been determined, Flg.„ii8. Bacheiaer's corn-pianter, as mustratea in 1846. 



uiiB xii^iiucoo ui oui^ii o" > " The seed is put into the hopper above the beam, and as 



for example, that lupines are able to take more the planter moves along, the share below opens the fur- 



food from the subsoil than oats. Most of the row; the com is then dropped byarms moved by a crank." 



legumes have similar power, largely because of their deep-rooting 

 habit ; and this affords additional explanation of the good results 

 accruing from the use of such plants in the rotation. 



(5) A rotation of crops can be so planned as to maintain the 

 supply of humus in the soil. This humus, coming from the decay of 

 organic matter, adds to the plant-food content of the soil and, what 

 is usually more important, exerts a great influence in securing a 

 proper physical texture of the land. The Bureau of Soils recently 

 asserts that the chief value of humus is to cleanse the soil of toxic 

 excreta. The humus is chiefly supplied by the grass crops and clover 

 crops in the rotation. The practice of "green-manuring" rests chiefly 

 on the need of supplying humus. Green-manure crops are those that 



Fig. 119. Permock's seed and 

 planter, from a picture of 



eiain 



_ ._ 1846. 



This machine will plant wheat, 

 rye, Indian corn, oats, peas, beans, 

 rutabagas and turnips: and can be 

 regulated to drop any reauired 

 quantity on an acre." 



