Note to readers, attached is the complete final report for FNE96-154
Mr. van Achterberg tried three non-chemical means of controlling weeds in his potato field. He applied a leaf mulch to one-third of his field in the fall; to another third of the field he did the same thing, but followed this up with a second application of leaf mulch in the spring, shortly after planting, and in the remaining third he planted hairy vetch between the rows of potatoes. In half of each of these three areas he sowed the early-maturing Norland Red variety of potato, and in the rest he sowed Yukon Gold. Mr. van Achterberg made several interesting observations: 1) Hairy vetch took over completely wherever it was planted; he obtained no potato yield from these plots. 2) Weed suppression was successful where the dual applications of leaf mulch had been made; however 3) these same areas suffered most from Colorado potato beetle. 4) The Yukon Gold variety yielded better where it had received dual applications of leaves than where it had received only the fall application. Apparently the more successful weed suppression in the former plot more than made up for the greater numbers of beetles. 5) Norland Red yielded the same in the plot receiving only the fall application of leaves as it did in the dual-application plot. 6) Norland Red yielded 1.8 to 2.8 times better than Yukon Gold. Mr. van Achterberg attributed this to the fact that Norland Red, because it matures earlier, escaped the worst of the Colorado potato beetle infestation.
Mr. van Achterberg strongly recommends the use of leaf mulch. Quite apart from the matter of weed suppression and potato yield is the salutary effect it had on his soil which, after two years of mulching, had a fine friable structure, and a healthy population of earthworms.