Medicago sativa L., alfalfa, is the mostknown plant species within the Medicago genus. Theplant has been extensively studied for its content ofsaponins, mainly consisting of triterpene glycosidesof medicagenic acid, possessing several biologicalproperties including a biocidal activity on differentsoil microorganisms. Phytoparasitic nematodes areresponsible for heavy economic damages to numerousagricultural crops and, due to their large distribution,they are among the most difficult crop pests tocontrol. Attention on environmental safety andhuman and animal health has led to the progressivedismission of many synthetic formulations for thecontrol of those pests and to the search of alternativestrategies, including the use of natural metabolitesfrom plants. Saponins from M. sativa may be goodcandidates for natural nematicide formulations, as inour in vitro studies the saponin mixtures fromM. sativa tissues have been found effective in vitroagainst the virus-vector nematode Xiphinema index,the root-knot nematode Meloidogyne incognita andthe potato cyst parasite, Globodera rostochiensis. Astructure–activity relationship among saponins andrelated prosapogenins and sapogenin, respectively,has also been analyzed. The nematicidal efficacydiffered among the three assayed nematode species,G. rostochiensis being the most susceptible to theactive compounds from alfalfa. The in vitro resultswere also confirmed by experiments in potting mixesinfested by M. incognita or G. rostochiensis andamended with dry top and root material fromM. sativa, and in field trials on M. incognita andcarrot cyst nematode Heterodera carotae withM. sativa pelleted meal. All amendments reducedroot and soil population densities of target nematodespecies compared to non-treated and chemical controls,with a general improvement of plant growth andyield performances.

Suppressiveness of soil amendments with different rates of composted biowaste materials, olive pomace, municipal green wastes, sewage sludge and spent mushroom substrate, was evaluated against the root-knot nematode Meloidogyne incognita on tomato in potting mixtures. Soil amendments were applied at 0, 10, 25, 50 and 100 g kg-1 soil, according to a randomized block design with five replications for each treatment. Sixty days after tomato transplanting, nematode population density on plant roots and in soil and root gall infestation were assessed on each root system, and plant top and root weight were also recorded. Soil pH, dry and organic matter content, total and ammoniacal nitrogen were analyzed at the same time. Olive pomace-based composts resulted in the highest nematode suppression (73 – 97 %, according to the rate) and significantly reduced gall formation on tomato roots. Olive-waste compost affected positively tomato growth only in combination with sheep wool wastes, but it caused phytotoxicity when mixed with chicken manure and urea. Soil amendments with composted mushroom substrate also provided a consistent nematode suppression and a significant increase of plant growth, whereas composted municipal green wastes were more suppressive and positively affected tomato growth when combined with sewage sludge. Soil chemical parameters were scarcely affected by compost amendments, as organic matter was significantly increased only by the olive pomacederived composts and nitrogen content only at the highest rate of the five composts. Data from the experiment confirmed the potential of compost amendments for sustainable management of root-knot nematodes both in field and greenhouse container media, though their technical effectiveness and economic convenience are strictly dependent on a correct proportion and local availability of raw materials used in the composting process