Acid soils are not suitable for cultivation of agricultural crops as increased concentrations of hydrogen ions hinder the uptake of most nutrients. The adverse effects of increased soil acidity also include release of aluminium (Al) ions from the adsorption complex and hence, an increase in their concentration in the soil solution and plants. Aluminium ions block phosphorus and potassium uptake by the crop, thus leading to disturbance of plant growth and development, as well as to a substantial decline in crop yield and quality. This suggests that the use of such soils is not justified in terms of successful plant production. The objective of this study was to use liming to neutralise excess acidity of pseudogley soil under oat crop and evaluate the effect of soil pH improvement measures on the aluminium content of both the leaf and root of oat ( Avena sativa L.) cv. Mediteran. Three liming treatments were employed [1.0, 3.0 and 4.0 t ha -1 calcium carbonate (CaCO 3 )]. The treatments with 3.0 and 4.0 t ha -1 CaCO 3 induced no Al presence in oat plants, suggesting that liming in these treatments was successful in terms of aluminium content. Key words: Aluminium, leaf, oat, pseudogley, root.

There has been greatly increasing interest in orthogonal frequency division multiplexing (OFDM) for broadband wireless transmission due to its robustness against multipath fading. However, OFDM signals have high peak-to-average power ratio (PAPR), and thus, a power amplifier must be operated with a large input power backoff (IBO). Recently, OFDM combined with time division multiplexing (OFDM/TDM) using minimum mean square error-frequency domain equalization (MMSE-FDE) has been presented to reduce the PAPR, while improving the bit error rate (BER) performance of conventional OFDM. In this article, by extensive computer simulation, we present a comprehensive performance comparison of OFDM-based schemes in a nonlinear and frequency-selective fading channel. We discuss about the transmission performance of OFDM-based schemes with respect to the transmit peak-power, the achievable capacity, the BER performance, and the signal bandwidth. Our results show that OFDM/TDM using MMSE-FDE achieves a lower peak-power and capacity than conventional OFDM, which means significant reduction of amplifier transmit-power backoff, but with a slight decrease in signal bandwidth occupancy.