Agronomic application of olive mill wastewaters with phosphate rock in a semi-arid Mediterranean soil modifies the soil properties and decreases the extractable soil phosphorus

Olive mill wastewater (OMW), a by-product of the olive-mill industry, is produced in large amounts in Mediterranean countries. The presence of indigenous phosphate deposits in some countries like Tunisia provides an incentive for direct application or local chemical treatment at low cost to improve the solubility of low reactive phosphate rocks (PRs). The use of naturally occurring low-molecular weight organic acids (LMWOAs) that are present in OMW represents a new perspective in PR research and a possible solution for the recycling of the OMW. The present work was aimed at evaluating, under natural situations (field of olive trees), the effects of agronomic application of OMW (amounts applied: 30, 60 m(3) ha(-1)) with PR (amounts applied: 150 kg ha(-1)) on olive trees soil properties. We measured organic C, nitrogen (N), extractable phosphorus (P), exchangeable calcium (Ca), and exchangeable potassium (K), as well as other properties (pH and electrical conductivity). Our data provide evidence that agronomic application of OMW with PR has important effects on soil properties. Increases in organic C, total N, extractable P and exchangeable potassium (K) were found after the first agronomic application of OMW and PR. These increases were only temporary, following the second agronomic application of OMW and PR, significant reductions were detected in the extractable soil P (19.67 mg kg(-1) in the control soil vs. 8.99 mg kg(-1) in the amended soil). Changes in the extractable soil P could alter plant productivity and plant community structure because shifts in nutriment availability can affect the balance between limiting and non-limiting nutrients.     

Coastal Zone Problems and Environmental Strategies to be Implemented at Edremit Bay, Turkey

This case study examines the coastal zone problems focusing on the existing conflicts between tourism and commercial activities on the coasts of Edremit Bay, Turkey, and attempts to suggest solutions to these problems. Edremit Bay is a characteristic example of such a conflict in collective use of natural resources. The study area, with its 100-km-long sandy beach, naturally attracts different coastal user groups with different beneficial expectations: in terms of rest and recreation for one group and commercial gain offered in a variety of ways for another group. Significant coastal zone problems exist in the study area. Deterioration of shoreline due to tourism activities and illegal constructions, damage to the coastal ecosystem due to domestic/industrial wastewater discharges and some agricultural activities, and disordered urbanization are only a few of the many problems. The data presented here were partly derived from field study and partly collected from local state or private organizations. In this study, it is emphasized that there is a need for viable economic and environmental strategies to be designated in Edremit Bay, Turkey, in order to provide sustainable resource use. For this purpose, an integrated project together with a relevant planning chart including subprojects is also suggested. The success of a local environmental protection management project depends on active participation of all stakeholders including governmental organizations and nongovernmental organizations.