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Evaluation of the effectiveness of soil-applied plant derivatives of Meliaceae species on nitrogen availability to peach trees

Toselli, Moreno, Baldi, Elena, Sorrenti, Giovambattista, Quartieri, Maurizio, Marangoni, Bruno
Scientia horticulturae 2010 v.124 no.2 pp. 183-188
Prunus persica, peaches, fruit crops, Melia azedarach, neem kernel meal, organic fertilizers, leaves, soil amendments, nitrification inhibitors, fruits (plant anatomy), plant growth, nutrient uptake, nitrogen, soil microorganisms, soil respiration, application rate, nitrification, ammonium nitrogen, nitrate nitrogen, rootstocks, dry matter accumulation, nutrient availability
We assessed the effect of soil-applied derivatives of melia (Melia azedarach L.) and neem (Azadirachta indica A. Juss) on nitrogen (N) soil availability, root uptake and peach (Prunus persica L.) growth. First we evaluated the effectiveness of experimentally prepared amendments made with fresh ground melia leaves or commercial neem cake incorporated into the soil as nitrification inhibitors, then we evaluated the effect of fresh ground melia fruits and neem cake on growth and N root uptake of potted peach trees, and on soil microbial respiration. Soil-applied fresh ground melia leaves at 10 and 20gkg⁻¹ of soil as well as commercial neem cake (10gkg⁻¹) were ineffective in decreasing the level of mineral N after soil application of urea-N as a source of mineral N, rather they increased soil concentration of nitric N and ammonium N. The incorporation into the soil of fresh ground melia fruits (at 20 and 40gkg⁻¹) and neem cake (at 10 and 20gkg⁻¹) increased N concentration in leaves of GF677 peach×almond (Prunus amygdalus) hybrid rootstock alone or grafted with one-year-old variety Rome Star peach trees. An increase in microbial respiration, leaf green color and plant biomass compared to the control trees were also observed. The Meliaceae derivatives did not affect, in the short term (7 days), N root uptake efficiency, as demonstrated by the use of stable isotope ¹⁵N, rather they promoted in the long term an increase of soil N availability, N leaf concentration and plant growth.