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In this study, the agronomic viability of Pleurotus ostreatus (Jacq.: Fr.) P. Kumm. was studied by reusing spent substrates that were previously used for crops of this mushroom. After the physical and chemical characterization of the substrates, we evaluated the quantitative production parameters for one growing season. The experiment used wheat straw (WS) and spent Pleurotus substrate (SPS) as a base material to generate prepared substrates that could be reutilized for mushroom production. These base substrates were supplemented with wheat bran (WB) (two doses, 300 and 600 g/6 kg) and the commercial supplement Calprozime® (120 g/6 kg). We obtained a biological efficiency (BE) between 50 and 63%, a high quantity of mushrooms (between 26 and 39 mushrooms/bag) and an excellent unit weight of the fruiting bodies (between 24.34 and 39.54 g) with the substrates supplemented with a 120 g/6 kg dose of Calprozime®.

Nitrogen fertilization has a significant environmental impact in Europe due to the problems of wide-spread pollution. This paper deals with a series of field experiments conducted in a semiarid region of Southeast Spain. Irrigated maize was grown under different N fertilizer rates: control as in no nitrogen applied (C; 0 kg N ha -1 ); conventional amount of nitrogen (Nc; 300 kg N ha -1 ); and theoretical optimum (No; 130 kg N ha -1 ) in a randomised block design with three replications.In 1999 and 2000, when 175 and 150 kg N ha -1 were respectively applied to No treatment, no significant differences were found. With the Nc treatment, a grain yield of 17.6 Mg ha -1 was obtained in 2001, being significantly higher than the yield obtained with the No treatment (15.8 Mg ha -1 ). This means that No rate was under the technical optimum, but both treatments were higher than C treatment (7.2 Mg ha -1 ). A fertilizer rate of 130 kg N ha -1 was lower than necessary to obtain maximum yields, although the rate of 150 kg N ha -1 did not show significant differences with regard to Nc treatment (300 kg ha -1 ) (2000).Studies about crop response to different N rates could be very useful for farmers. Regional Technology Transfer Centres are incorporating the results of these studies in a Decision Support System (DSS).