CHANGES IN THE NUMBERS OF VIABLE WEED SEEDS IN SOIL UNDER DIFFERENT REGIMES

Summary. In a 4-year experiment with a naturally-occurring population of viable weed seeds, the numbers in the top 23 cm of soil decreased exponentially in the absence of further seeding. The rates of loss were very similar on undisturbed plots which were left bare (34% per year), mulched with farmyard manure (31%) or grassed down (32%). On plots dug twice a year in March and September, the loss was 42% per year, and with frequent cultivation (dug seven times a year) it was 56% per year. The numbers of seedlings in any one year on plots dug twice a year represented approximately 6% of the viable seeds present at the start of the year.
Variations du nombre de semences viables de mauvaises herbes dans le sol selon différents régimes