COVER-CROPS 



COVER-CROPS 



259 



are grown between the rows of other crops, as 

 turnips grown between potatoes. The purpose of 

 the catch-crop is to utilize the land to the utmost, 

 securing an incidental crop. Green-manure crops 

 are those grown for the purpose of enriching the 

 land, whereas cover-crops are grown to protect the 

 land, or trees, or other plants that may be growing 

 on it. Cover-crops may or may not be green-manure 

 crops. Cover-crops usually remain on the ground 

 in winter. [See the article on Fruit-gromng for 

 another discussion of cover-crops.] 



Uses of cover-crops. 



Cover-crops are used, (1) to prevent the loss of 

 soluble plant-food, which occurs when lands are 

 left uncovered during the late fall and winter, 

 especially in the case of corn, potato 

 and tobacco lands, and for small-fruits 

 or cultivated orchards ; (2) to prevent 

 the galling or surface erosion of hill- 

 sides or slopes by winter rains ; and 

 (3) to prevent root injury by excessive 

 freezing of orchard lands, which danger, 

 however, is apparent chiefly in the North 

 and West, from Nebraska to North 

 Dakota, Minnesota, Wisconsin and Can- 

 ada. In all of these cases, the benefits, 

 in addition to those mentioned, are due 

 to the introduction into such soils of 

 vegetable matter. 



The advantages of cover-crops in 

 conserving and increasing fertility may 

 be stated more in detail as follows : 

 They absorb the plant-food from insolu- 

 ble sources, and convert it into organic 

 forms; they retain plant-food, particu- 

 larly of a nitrogenous character, that 

 would be carried away from a bare soil 

 by leaching ; and they regulate temperature and 

 moisture conditions, thus promoting nitrification 

 when seasonal conditions are favorable. Cover- 

 crops improve physical character by providing 

 roots to break up the soil particles and make 

 them finer, besides adding vegetable matter or 

 humus-forming material to the land, thus making 

 the moisture conditions more favorable. They 

 encourage the deeper rooting of orchard trees and 

 prevent deep freezing by acting as a mulch. The 

 effect of the cover-crop on the land will depend, to 

 some degree, on the root habit of the crop. The 

 clovers are very deep rooters (Pig. 369), and are 

 prized for this reason as well as for other merits. 



Crops that are used as a cover to accomplish 

 these results should not be confused with those 

 which are used for green - manures. If they are 

 made to serve as green-manures the real advantage 

 of the cover-crop may be lost, for if a cover-crop 

 is left too late in the spring it may cause injury 

 by robbing the main crop of the needed moisture ; 

 and when plowed down, after making too large a 

 growth, it will injure spring-sown crops by cutting 

 off the capillary supply of ground-water. These 

 points should be carefully observed, for while many 

 coVer-crops may serve a specially useful purpose as 

 green-manures, the direct manurial effect should be 



regarded as an incidental gain, secondary to that 

 secured from their use as cover-crops. 



Plants used as cover-crops. 



A very large number of plants have been used 

 for cover-crops in the United States. These may 

 be divided into two groups, viz., the legumes, or 

 nitrogen-gatherers, and the non-legumes, or those 

 which are sometimes distinguished as nitrogen-con- 

 sumers. Of the legumes, the following have been 

 used with considerable success : the several varie- 

 ties of red clover and Canada field-peas, widely 

 useful in the northern tier of states ; alfalfa, in the 

 western states and California ; soybeans, cowpeas 

 and crimson clover in the central, and southern 

 states ; velvet bean and beggarweed, especially 



Fig 368 



Crmison clover as an orchard cover crop Dsually it should be 

 'plowed under hefore it blooms. 



useful only in the South; hairy vetch and spring 

 vetch, most successfully used in the South, though 

 rather generally grown in the northern states ; 

 sweet clover and sometimes, for peculiar conditions, 

 serradella. Of the non-legumes, rye, wheat, oats 

 and barley of the cereals are probably more com- 

 monly used than any others ; rape and turnips of 

 various varieties are used commonly, though they 

 are not hardy in the northern sections of the coun- 

 try ; buckwheat, white mustard and spurry have 

 also been used with satisfaction under special con- 

 ditions. Various mixtures and combinations of 

 these plants are sometimes used, in order that the 

 cover may extend through a longer period, or to 

 insure a covering of the land should conditions 

 be unfavorable for one or more members of the 

 combination. 



The knowledge gained through experiment sta- 

 tion work as to the usefulness of cover-crops, is 

 constantly increasing, and they are now considered 

 an important part of rational agricultural prac- 

 tice. 



Kind of crops to use. 



The principle that should govern in the use of 

 cover-crops is to employ such crops as may accom- 

 plish the special purposes desired. To get the best 



