Purple Vetch was brought into the United States by the Office of Foreign Seed and Plant Introduction in 1899 from Naples, Italy. All introductions since that time have been of the same variety. The crop has been tested most extensively in the Pacific Coast States, where it has given very favorable results. In California in experimental work it has proved one of the best crops, if not the best crop, for use as a green manure, and in commercial plantings it has been thought well of by the orchardists who have used it. In western Oregon and western Washington, experimental work has demonstrated that purple vetch can be grown successfully as a seed crop, and at the present time it is being grown commercially in western Oregon and northwestern California. Purple vetch has not been sufficiently tested in the Southern States to determine definitely its value in localities where common vetch can be grown. However, as it requires conditions similar to common vetch, it seems probable that it may serve an excellent purpose in this region as well as in the western United States.

Every farmer knows that when a crop is grown on the same field year after year, it becomes inferior in quality and the yield steadily diminishes.