Orchard Cover Crcps ik Delaware. 195 



rnpe and turnips, but considerably less tlian tlie clover. The vetcli is especially 

 desirable for soils varying from a light clay loam to heavy clay. Its behavior 

 on sandy loam will be discussed later 



Hairy vetch and cow peas. — Tliese were sown together at the rate of G4i^ 

 pounds of seed each. The cow peas were such vigorous growers that they 

 smothered out the vetch ; a few spindling sickly vetch plants managed to 

 keep alive until November. Sown at tlie rate of 40 pounds of cow peas and 20 

 pounds of vetch per acre the results ought to be satisfactory. The cow peas 

 would make the fall protection, and the vetch the winter and spring protection 

 to the soil. 



Cowpeas (Vifjno Catjavff. Wulp.) ^yhippl/on(^iU rariciy. — The seeding of 

 •cowpeas was rather lieavy, 130 pounds per acre. About 90 pounds sown broad- 

 cast will give good results. There was an excellent stand, and a rank, heavy 

 growth, which choked out all grass and weeds. The plants continued growing 

 until the latter part of October when they were killed by frost. They then were 

 a mass of vegetable matter 2 feet or more high. (See Plate III, .4. and B.). After 

 being frozen the leaves dropped to tlie ground and the stalks soon broke over and 

 held them fairly well ; thus most of the material was retained where grown. 

 This cccui's only in case of a heavy crop : with a light crop the leaves could easily 

 he blown away. 



The cowpea is grown considerably in Delaware as a general farm crop botli 

 for seed and for stock food. As yet it is not mucli used in orchards as a cover 

 <?rop. The objection that can be raised against it for this purpose is that it is 

 so susceptible to injury by frost. The first heavy frost kills it and then its value 

 as a cover deteriorates. The dead material forms a partial protection to the 

 soil for a time, but before spring the ground is entirely bare. This undesirable 

 condition should be overcome by a light seeding of cowpens supplemented with 

 rye or vetch for the spring cover. 



The weight of green tops and air-dry roots to a depth of ]2 inches, 

 plants 31^ months old. was 6,327 pounds per acre. In this material there were 

 ■fin pounds of nitrogen, 50 pounds of potash and 19 pounds of phosphoric acid 

 (see Table IK In nitrogen it is somewhat richer than vetch and one-third 

 richer than crimson clover, pound for pound. The vetch is not quite so rich in 

 potash as the cowpea, and crimson clover has only a little more than half as 

 much potash as has the cowpea. In amount of phosphoric acid these three 

 plants rank very nearly the same. 



As a quick-growing plant for enriching poor soil the cowpea is one of the 

 best. The seed may be sown either broadcast or in rows. When full grown 

 the tops may be plowed under or may be cut for hay, leaving only the stubble 

 for plowing under. By use of some other crop for fall and spring growth to 

 supplant the cowpea, the soil may readily be built up for orchard purposes. 



Hoy bean (Olycine hispida, Maxim). — This was seeded the same as the cow- 

 pea. 130 pounds per acre, whereas 90 pounds would have been sufficient. It 

 is a little more vigorous and robust than the cowpea. It will stand much more 

 frost than the cowpea ; which the latter was killed by frost only the top leaves 

 of the soy bean were killed. With such rank growth no grass or weeds could 

 survive. Because of a heavier growth this made a little better late fall and 

 early winter cover than did the cowpea. Like the cowpea the soy bean is an 

 upright grower and for this reason these are not ideal cover crop plants as 

 ;ire the clovers and vetch. (See Plate IV, J5). 



The weight of green soy bean plants nearly four months old, including 

 air-dry roots to a depth of 12 inches, was 11,708 pounds per acre or nearly 

 double that of the cowpea. In nitrogen and phosphoric acid these crops are 

 about equal, but in potash the cowpea is about twice as rich as the soy bean. 

 (See Table I). 



Velvet bean (Mucuna utilis. Wall.) — This was sown at the rate of 27 pounds 

 of seed per acre. There was a very thin stand and the growth was weak. Frost 

 killed the plants in October. The velvet bean was a failure as a cover crop in this 

 test. 



