584 



SOYBEAN 



SOYBEAN 



The soybean seems to profit by the addition of 

 nitrogenous fertilizers, but these should not be 

 needed after the soil becomes thoroughly inocu- 

 lated. If nitrogen be used it may well be in the 

 form of nitrate of soda and in small quantities, 

 chiefly to stimulate very young plants. 



Seeding. — For seed, the rows should be thirty to 

 thirty-six inches apart, and one plant should be 

 left every two or three inches in the North, or 

 every three to eight inches in the South. For 

 forage, the drills may be of the above width on 

 poor land, while on rich land the seed may either 

 be drilled, sown broadcast, or planted with a grain- 

 drill as is wheat. For seed-growing, about one-half 

 bushel of seed per acre will suffice. For forage in 

 drills wide enough for cultivation, three pecks will 

 be required, and for broadcast-sowing more than 

 one bushel. For drilling the seed, one may employ 

 hand-dropping, a one-horse planter, a corn-planter, 

 or a grain-drill with enough of the tubes stopped 

 to leave thirty to thirty-six inches between the 

 rows. Soybeans are sometimes planted in the South 

 betwfeen the rows or hills of growing corn. 



Time to plant. — Soybeans must not be planted 

 until all danger of frost is past and the soil has 

 become warm. In the northern part of the United 

 States the planting of this crop occurs just after 

 corn-planting. In the Gulf states the best time 

 is from the beginning of May to the middle of 

 June. Planting may continue to the middle of 

 July, but germination and early growth and yield 

 are less satisfactory from this delay. From Kansas 

 southward it is practicable under favorable con- 

 ditions to mature soybeans grown as a catch-crop 

 after wheat or, in the Gulf states, after oats. 



Cultivation should be shallow and level, and 

 similar to that given corn. 



Inoculation. — No soybean plant is doing its best 

 work for the farmer unless its roots bear a number 

 of tubercles or root nodules. On this plant, the 

 root tubercles are roundish enlargements that 

 when fully developed are about the size of peas 

 (Fig. 590). On any soil in which root tubercles 

 fail to develop spontaneously, it is advisable to 

 effect artificial inoculation by the introduction 

 into the soil or on the seed of the nitrogen-fixing 

 germs appropriate to soybeans. This may be done 

 by moistening the seed with a dilution of pure 

 cultures of the germ, directions for which accom- 

 pany each package; or, more certainly, by the use 

 of soil from a field where soybeans have recently 

 produced abundant tubercles. 



If this soil be drilled in with the seed, in a dry, 

 finely powdered condition, 600 to 1,000 pounds per 

 acre may suffice, but if applied broadcast, and not 

 in immediate contact with the seed, at least one 

 ton will be required. If only a very small quantity 

 of soil is available, a peck of it may be stirred in 

 about ten gallons of water, and the same day the 

 seed moistened with this liquid. By this process, 

 apparently a smaller number of plants become 

 inoculated than by the use of larger quantities of 

 dry soil. It has been found that it is less easy to 

 cause a sufficient number of germs to adhere to 

 soybeans than to cowpeas, for the reason that soy- 



beans are so smooth and free from indentation or 

 cracking. Hopkins prefers not to attempt thorough 

 inoculation the first year, but to use only about 

 100 pounds of inoculating soil per acre, reseeding 

 the land to soybeans the second year and relying 

 on the natural spread of the germs from the decay- 

 ing tubercles produced by this partial inoculation. 



In Kansas, Connecticut, Illinois, and apparently 

 in most states, the soybean when first grown 

 developed no tubercles, but when grown for several 

 years in succession in the same land, inoculation 

 gradually increased. On lime soil at Lexington, 

 Kentucky, tubercles were abundant the second 

 year, but not the first; in experiments in Connecti- 

 cut, there were no tubercles for at least three 

 years. The gradual self-inoculation of soils is 

 probably due to germs carried on the seed in such 

 small numbers as to produce an insignificant num- 

 ber of tubercles the first year, which few would 

 constitute the parent stock of a far larger number 

 the second year, and so on. On medium and poor 

 soils, inoculation may greatly increase the yield 

 of seed or forage and the extent of soil-impove- 

 ment. On rich land, soybean plants without tuber- 

 cles are sometimes as thrifty and productive as 

 plants bearing nodules. But even here inocu- 

 lation is beneficial in decreasing the draft on the 

 soil and in the enrichment of the land for future 

 crops. 



Inoculation sometimes greatly improves the com- 

 position of soybean forage and seed. At the Michi- 

 gan Experiment Station there was little difference 

 in the appearance and yield between plants with 

 and those without root tubercles, but the pres- 

 ence of nodules increased the percentage of nitro- 

 gen in the dry matter of the leaves and stems 

 from 1.77 to 2.78, and in the seed fropi 5.41 to 

 6.20, while the percentage of nitrogen was de- 

 creased in the roots from which nodules had been 

 removed. At the Kentucky Experiment Station, 

 the roots contained in the air-dry material 1.81 

 per cent of nitrogen when not inoculated and 2.7 

 per cent of nitrogen when covered with tubercles. 

 At the Connecticut (Storrs) Experiment Station, 

 the presence of tubercles raised the nitrogen per- 

 centage in the seed from 6.28 to 7.08. 



Place in the rotation. — The place of soybeans in 

 the rotation is as a cleaning or fallow crop, put- 

 ting the land in good condition for an immediately 

 following crop of small grain, alfalfa or other 

 crop. In the South, soybeans may be grown as a 

 catch-crop after wheat or oats. Hopkins suggests 

 (Illinois Experiment Station, Bulletin No. 99) sev- 

 eral rotations for the southern part of Illinois, in 

 which the soybean may enter ; for example, four- 

 year rotation : 



First year, corn, with cowpeas or soybeans as a 

 catch-crop. 



Second year, cowpeas or soybeans. 



Third year, wheat (with clover to be seeded in 

 spring). 



Fourth year, clover. 



Varieties. — There are many varieties of soy- 

 beans, differing chiefly in the time of maturity, 

 size of plant, and color and shape of seed. In the 



