Effectiveness of soil-applied fresh-ground melia (Melia azedarach l.) fruits on nitrogen uptake for peach trees.

We assessed the effect of soil-applied fresh-ground fruits of melia (Melia azedarach L.) on N uptake for peach nutrition. We placed each of 40 one-year-old ‘Rome Star’ peach trees (Prunus persica) grafted to GF677 peach x almond hybrid rootstocks in a 20-L pot in April 2006. On 16 May, 20 pots were fertilized with compost at a rate of 100 g/pot and 20 pots were dressed with urea at 1.4 g/pot. On September 11, the two sets of trees received the same amount of N (0.64 g/pot) as urea (urea-treated pots) and blood meal (compost-treated pots). The following compounds were applied as nitrification inhibitors to 4 pots each: untreated control; 3,4-dimethylpyrazole phosphate (DMPP) at 10 mg/pot; commercial neem cake at 20 g kg-1 of soil; and fresh-ground fruits of melia at 20 and 40 g kg-1 of soil. All inhibitors were incorporated in the soil at planting except for DMPP, which was supplied along with the second urea and blood meal applications. The application of neem cake increased soil NO3--N on both sampling dates. An increase in leaf N concentration and microbial respiration was observed after application of neem cake and ground melia fruits at both concentrations, although only the latter increased shoot length.