Environmental Implications from Long-term Citrus Cultivation and Wide Use of Cu Fungicides in Mediterranean Soils

Abstract

Citrus fruits are cultivated in more than 100 countries around the world. The main citrus fruit–producing counties are Brazil, China, and the USA although the whole Mediterranean region ranks first worldwide. In Greece, citrus occupy an area of about 40.000 ha, representing 43% of total fruit crops. Soil quality is affected by long-term citrus cultivation. Soil organic matter is depleted in long-term citrus cultivation, in contrast to nutrients that seemed to increase in the following descending order: POlsen > Naecxh > NO3-N > Kecxh > Caecxh > Mgecxh due to usual management practices. To evaluate the environmental impact due to broad use of Cu fungicides in long-term citrus cultivation, Cu total fraction and DTPA-extractable in agricultural soil were determined. Soil contamination rate was evaluated via proper indices of different sensitivities on their calculations. In particular, 22% of samples in older orchards were highly polluted based on the single-factor pollution index (PI). The index geo-accumulation index (Igeo) presented hysteresis in comparison with PI, which was more sensitive, comprehensive, and reliable, able to describe better the pollution classification of citrus soils. The calculation of monomial potential ecological risk for Cu showed that in older citrus groves, the average value was 11.8, while the max value was 49.8 indicating moderate ecological risk suggesting the negative environmental impact of intensive citrus cultivation. These results denote the need to preserve soil fertility and prevent potential toxic element accumulation due to long-term cultivation management practices, aiming to achieve soil sustainability and food security in National or Euro-Mediterranean scale.