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Olive oil byproducts show differences according to the olive oil extraction systems, which are called olive mill solid wastes, olive oil wastewater and olive oil wastewater sludge. Three different kinds of composts, including two-phase and three-phase olive mill solid wastes, and olive oil wastewater sludge were produced with separated dairy manure, poultry manure, and straw. The composts obtained from two-phase and three-phase olive mill solid wastes and olive oil wastewater sludge were named as two-phase, three-phase, and water sludge composts, respectively. They were separately enriched by rock phosphate and potassium salt. These composts were mixed with peat in a ratio of 0%, 25%, 50%, 75%, and 100% (v/v). Tomato seeds were sown in all mixtures on 3 February 2016. All the seeds were sown into 2 trays and each plug included 2 replicates. The trays were left in a germination room for 3 days, then moved to a heated greenhouse which is specialized for growing seedlings, and the seedlings were grown there for 3 weeks. The results showed that increasing compost ratios in the growing medium and also the enrichment of the growing medium increased organic matter content, electrical conductivity, and macro and micro nutrient concentrations. The germination period lasted longer with increasing compost ratios. The shoot length was lower at a compost ratio of over 50% excluding water sludge compost, which reacted to over 75%. The highest plant dry weights were obtained in the plants grown on the media with compost ratios of 50%, 25%, and 25% for water sludge compost, enriched two-phase compost, and enriched three-phase compost, respectively. We concluded that the composts obtained from two-phase and three-phase olive mill solid wastes and olive oil waste water sludge can be used without any need of enrichment and a ratio of 25% was found appropriate in most of the measured properties.

A study was conducted to investigate the effect of different irrigation programs and nitrogen (N) levels on N concentration, uptake and utilisation by the processing tomato (Lycopersicum esculentum). The amount of water used was determined based on a screened class-A pan. Irrigation treatments consisted of 2 different irrigation intervals (I5, 5 days; I10, 10 days) and 3 plant-pan coefficients (Kcp0.50, 0.50; Kcp0.75, 0.75; Kcp1.00, 1.00). Nitrogen treatments consisted of 3 N levels (N0, 0 kg/ha; N80, 80 kg/ha; N160, 160 kg/ha). The irrigation interval, plant-pan coefficient and N fertiliser rate affected all parameters examined; however, the N fertiliser rate had the greatest impact. Nitrogen applications increased N concentrations in the leaf, tomato and vegetative biomass. Plant total N uptake and benefit rate from fertiliser was highest with the N160, I10 and Kcp0.75 and Kcp1.00 treatments. Results show that the N160, I10 and Kcp0.75 treatments can be used for increasing plant N uptake and the benefit rate from fertiliser.

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2 This study investigated the effect of high humic substance (HS) levels (0, 500, 1000, and 2000 mg HS kg −1 ) on growth and nutrient concentrations of corn grown on calcareous soils. For these, soil samples were collected from the six different provinces of Turkey. According to the average values, HS levels had no significant effect alone on dry weight, nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) concentrations. Soil differences significantly affected dry weight, N, Mg, and Cu concentrations (p ≤ 0.05). Looking at HSxsoil interactions on K, Ca, Fe, and Mn concentrations, it could be seen that there was no effect or that the effect was negative. Only plant Fe concentrations obtained from Konya and Urfa provinces were positively affected from HSxsoil interaction. It was concluded that high level of HS had no or negative effect on corn growth and some nutrient concentration under calcareous conditions.