The objective of this experiment was to evaluate in the long-term (9 years), the suitability of compost as a fertilizer in commercial peach orchard. The experiment was carried out on nectarine trees (Prunus persica var. nectarina), Stark RedGold grafted on GF677 peach · almond (P. amygdalus L.) hybrid. The treatments were: (1) unfertilized control; (2) mineral fertilization including phosphorus (P at 100 kg ⁄ ha) and potassium (K at 200 kg ⁄ ha) applied at planting and nitrogen (N at 70-130 kg ⁄ ha ⁄ yr) split in two applications at 40 days after full bloom (60%) and in September (40%); (3) cow manure supplied at planting [10 t dry weight (dw) ⁄ ha] and then, from the forth year at the rate of 5 t dw ⁄ ha ⁄ yr in spring; (4) compost supplied at planting (10 t dw ⁄ ha) and then, from the forth year at the rate of 5 t dw ⁄ ha ⁄ yr in spring; (5) compost supply at a rate of 5 t dw ⁄ ha ⁄ yr, and (6) 10 t dw ⁄ ha ⁄ yr, both treatment 5 and 6 split as described for treatment 2. Nitrate-N soil concentration was usually not affected by treatments. Soil microbial carbon, organic matter, total N, P, K were increased by application of organic fertilizers. SOM and total N were positively correlated to soil microbial biomass. Aggregate stability, humic and fulvic acid concentration were not affected by fertilization treatment. Only the application of compost at 10 t dw ⁄ ha ⁄ yr (6) increased fruit production.

Background and Aims:  Copper accumulation in soil may promote phytotoxicity in grapevines. Nutritional implications of potted vines to increasing concentrations of copper (Cu) in either clay loam soil or clay loam soil mixed with 85% sand were tested on Vitis vinifera (L.) cv Sangiovese and crop toxicity threshold and symptoms determined. Methods and Results:  Soils were mixed at planting with Cu at the rates (mg Cu/kg) of 0 (control, native soil Cu only), 50, 100, 200, 400, 600, 800 and 1000, and non‐bearing vines were grown in these for two seasons. Reduction of root growth was observed after addition of ≥400 mg Cu/kg to both soils; reduction of shoot growth, leaf number and chlorosis of leaf edges were detected only in sand‐enriched soil. Root Cu concentration increased in response to soil Cu addition. Unlike that of leaf Cu and N, the amount of P and Fe (in both soils) and Mg and Ca (in sand‐enriched soil only) were reduced by soil Cu. Conclusion:  Vines grown in sand‐enriched soil tolerated lower concentrations of Cu than in clay loam soil, probably because of the lower nutritional status and the higher root Cu concentration. Significance of the Study:  Results provide information on the concentration of soil Cu that grapevine can tolerate and on the nutrients involved in the response to toxic levels of soil Cu in clay loam and sandy clay loam soils.

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Recycled organic fertilizers may be used to replace chemical source of nutrients; however, some nutrients such as nitrogen and heavy metals released by mineralization can become potential pollutants. The objective of this experiment was to compare, over a 3-year-period of time, the effectiveness of two organic fertilizers (cow manure and compost) with a traditional mineral fertilizer on soil fertility, tree nutritional status, heavy metal concentration in soil and plant in a mature nectarine orchard. Trees were subjected, since their plantation (made in 2001) to the following treatments: (1) mineral fertilization (including nitrogen at 130 kg ha -1 year -1 );(2) cow manure (5 t DW year -1 ha -1 ); (3) compost (5 t DW year -1 ha -1 ). Soil organic matter and total nitrogen concentration increased as a consequence of compost application. Soil nitrate concentration was increased by mineral fertilizer and compost applications. In summer, macro and micro nutrient concentrations in leaves were not affected by treatments with the exception of N that was increased by mineral fertilization. At the end of the season, leaf N, K and Zn were remobilized to storage organs, while Ca, Mg, Cu, Fe and Mn accumulated in abscised leaves and returned to the soil, with no differences among treatments. Nitrogen and K were found principally in fruit flesh. With the exception of Cu and Zn, the concentration of heavy metals in leaves and fruits was below detection limits. Total and DTPA-extractable heavy metals in soil were not increased by organic fertilization if compared with mineral fertilizer.

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