A method for the recovery of decayed agricultural plantations, preferably fruit orchards, or wine or table grape vineyards, where the plantation decay is due mainly to localized irrigation and the use of inadequate exploitation techniques, such as the traditional ones. The method consists in the use of non-localized irrigation in the plantation; the inclusion of Ca.sup.++ providing substances in the soil; and the inclusion of a Chitosan solution (poly-D-glucosamine) in the irrigation water.