Nutrient levels and nutrient budgeting in organic, integrated and conventional olive orchards located in different agroecological zones [Thesis (M.Sc.)]
2013
Shaimaa Esmail
A comparative case study was constructed on 24 olive orchards located at 8 different sites in West Messara Valley, Crete, Greece, a typical Mediterranean olive producing area, on 4 sites lying on plain areas and another 4 on surrounding hills. Three neighbouring organic, conventional and integrated orchards were studied in each site. Farm-gate nutrient budgets supported with soil and leaf analyses were used as indicators for sustainability and nutrient use efficiency in the respective orchards. Soil and leaf chemical composition was measured in two sampling periods, pre- and post-fertilization, during the olive growing season 2011-2012. Moreover, NPK inputs and outputs have been identified and quantified, so balances, based mainly on hectare and tree levels, were calculated being averaged across two seasons (2010/11 and 2011/12), using the formula: Nutrient balance = sum(Inpputs) - sum(Outputs). Comparisons at tree level didn't show big differences at the hectare level due to the similarities in tree densities. Whether positive or negative, these imbalances, caused by the investigated orchards, are not sustainable in the long-term in adding nutrient surpluses to the soil and the surrounding environment causing potential hazardous effects or depleting soil nutrient resources. Linking nutrient balances to soil and leaf analyses results indicated clear inefficient fertilizer utilization in the hilly orchards.
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