It is generally conceded that the mineral elements are of greatest importance in the growing of beans. This is unquestionably true with the field class and late-maturing varieties which have the entire season to provide themselves with nitrogen from the atmosphere. In the districts where dry beans are grown extensively, it is seldom that more than 2 per cent of nitrogen is used in the fertilizer. Many farmers omit this element altogether. Some producers of field beans apply six to eight tons of stable manure an acre and the mineral elements are used quite freely.
In trucking and market gardening, fertilizers are generally employed that contain high percentages of the three elements. Voorhees ("Fertilizers," p. 269) suggests 500 to 600 pounds an acre of a 4-8-10 mixture, supplementing if necessary with 20 to 30 pounds of phosphoric acid and 60 to 75 pounds of potash. While potash is regarded essential, experiments in Mississippi show that the addition of kainit lowered rather than increased the yield of snap beans. The same station recommends 125 pounds of cottonseed meal (or its equivalent), 62.5 pounds of nitrate of soda and 250 pounds of acid phosphate an acre. The Georgia Station secured the highest yield of Valentine beans by applying 400 pounds of acid phosphate, 100 pounds of nitrate of soda and 100 pounds of muriate of potash. Several experiment stations have found potash highly beneficial, while phosphoric acid has made the best showing in tests made at most institutions. Unless the soil requirements are definitely known, the only safe course is to apply a complete fertilizer carrying a fair percentage of each element.
Various methods are used in the application of fertilizers for beans. Drilling or broadcasting after plowing is the most common plan. Fertilizer is often applied along the rows with side distributing machines. Hill applications of manure as well as fertilizers are frequently made for pole beans.
The selection of high-grade seeds is significant. When a small quantity is to be saved, pods may be chosen from the most vigorous and the most productive plants. It is especially important to avoid anthracnose by intelligent seed selection (317). Nearly all the beans sold for seed purposes by American seedsmen are grown in this country. The prices paid the growers for seed beans of most dwarf varieties vary from $1.30 to $2.50 a bushel. Seedsmen base their contract prices on a yield of 8 to 12 bushels an acre, while much larger yields are often secured (315). Nearly all the seed lima beans are grown in California; prices range from $2.75 to $4.00 a bushel.