Effects of different organic amendments on soil, vine, grape and wine, in a long-term field experiment in Chinon vineyard (France)

In a long-term experiment carried out in Chinon vineyard (37, France) during 23 years, the effects of several organic amendments were studied on soil, vine, grapes and wine. Four main treatments were compared on a calcareous sandy soil: control without organic amendment, dry crushed pruning wood at 2.1.t-1.ha-1.year-1 (D1), cow manure at 10 t-1. ha-1.year-1 (D1) and cow manure applied at 20 t-1.ha-1.year-1 (D2). D1 levels were calculated to fill the annual humus losses by mineralization. During the experiment, the organic matter content of topsoil (0-30 cm) decreased from 13.9 g.kg-1 to 11.1 g.kg-1 in control. Other treatments maintained or strongly increased the organic matter content of soil, according to applied organic manure levels (21.9 g.kg-1 measured in 1998, in cow manure D2 treatment). Soil CEC, soil moisture at field capacity, and amounts of available P, K and Mg were significantly improved in different organic treatments.

The weight of pruning wood and grape yield were not modified in D1 organic amendments, but were significantly lower in D2 cow manure. Nitrogen rate in leaves, as well as in berries and in wine, was higher in this last treatment. Also, in D2 cow manure grape composition was unfavourably modified. Consequently, alcoholic rate, colour intensity, anthocyanins and phenolic compounds of wine were lower, but total acidity and pH were higher than in other treatments.