Guidelines for fertilizer use in vineyards based on nutrient content of grapevine parts

Plant analysis plays a major role in fertilizer recommendations for perennial tree crops and vines. Plant analysis, however, does not quantify the rate of nutrients to apply. The approach developed in this work takes into account the content of the nutrients in grapevine parts and their dynamic within the plant to assist in the estimation of the amount of fertilizer to apply. Groups of three vines were cut at ground level on four different dates from September 14th to November 28th. On the first sampling date the vines were separated into trunk, cordons, canes, leaves and clusters for determination of dry matter content and elemental composition. On the following dates the vines were separated into the plant parts that were still present, since the clusters were only present on the first sampling date and the leaves on the first two. To assess the mobility of nutrients within the plant, samples of phloem vessels and sawdust of the entire trunk were taken as well as samples of chlorotic and green leaves. Nitrogen (N), potassium (K), phosphorus (P) and boron (B) showed mobility within the plant whereas calcium (Ca) and magnesium (Mg) did not. The removal of nutrients in clusters is critical for estimating N and K fertilizer rates. Clusters removed 19.9kgNha−1 and 28.7kgKha−1. In the case of N, it is also important to assess the system's ability to recycle the nutrient contained in the leaves and canes which amounted to 49.4kgNha−1. Phosphorus, calcium and magnesium applications might not justify being taken into account in the annual fertilization plan. Thus, the establishment of the fertilization programme should be a nutrient-specific exercise which takes into account all sources of information, including target yield and nutrient content in clusters, the vineyard management strategies influencing nutrient use efficiency from fallen leaves and prunings and soil testing and plant analysis.