A 2-year study was conducted in the Vrana Valley (Mediterranean region of Croatia) to evaluate the effects of application of different mulching materials and drip-fertigation on nitrate leaching in bell pepper (Capsicum annuum L.) cultivation. Nitrate-N leaching from the root zone of bell pepper was compared in three treatments: control without mulch, with black polyethylene (PE) mulch and with biodegradable cellulose mulch. In the first year, the highest quantities of nitrogen were leached in the treatment without mulch (26 kg ha À1 ) following by the treatment with cellulose mulch (18 kg ha À1 ) and the lowest nitrogen leaching (10 kg ha À1 ) was observed in the treatment with black PE mulch. At the end of the harvest, cellulose mulch, a microbiologically degradable material, started to decompose and disintegrate, which resulted in the cellulose mulch treatment behaving similarly than the control treatment without mulch. In the second year, significant leaching occurred after the last harvest in September. As the bell pepper yield was significantly lower than expected and calculated for fertilisation, the crop did not take up all nitrogen supplied by fertilisation, which resulted in higher concentrations of nitrate in the soil solution. These nitrate concentrations were subjected to leaching caused by precipitation, a regular occurrence in the autumn and winter in this region. However, mulched surfaces showed lower quantities of nitrate leached in comparison with the treatment without mulching. Mulching with black PE film, besides producing higher yields, reduces the leaching of nitrate fertilisers, and combined with fertigation can reduce a potential risk of surface and ground water pollution by nitrate. #

Plastic mulch and nitrogen fertigation in growing vegetables modify soil temperature, water and nitrate dynamics: experimental results and a modeling study. Agricultural Water Management, 176.

No abstract

The experiment was set up in the Neretva River Valley in southern Croatia, with the aim to determine the influence of increasing salt concentrations in irrigation water using different irrigation systems (sprinkler and drip) in watermelon production on plastic mulch. Saline drip irrigation reduced the development of salinized plants. Under drip irrigation, salinity did not cause plant mortality, but it led to a reduction in the number and length of vines. Saline sprinkler irrigation caused plant mortality. Soil solution ion composition was remarkably altered by saline drip irrigation. Saline irrigation also had detrimental effects on yield. Application of saline water rapidly changed the ion composition of soil solution. Significant changes in Ca, Na and Cl concentrations in soil solution were determined parallel to increasing the irrigation water salinity, whereas changes in Mg and K concentrations were not statistically significant. Marketable yield was reduced by salinity. Saline drip irrigation had detrimental effects on yield (26 and 35% yield reduction). In the trial treatment involving saline sprinkler irrigation, plants were completely damaged and no yield was attained. Copyright # 2008 John Wiley & Sons, Ltd. RÉ SUMÉUne expérience a été réalisée dans la vallée de la Neretva en Croatie méridionale dans le but de déterminer l'influence des concentrations croissantes en sel dans l'eau d'irrigation sous différents systèmes d'irrigation (arroseurs et goutte à goutte) pour la production de pastèque sur paillis en plastique. L'irrigation par goutte à goutte salée a réduit le développement des plantes salinisées. Sous goutte à goutte, la salinité n'a pas provoqué la mort des plantes mais une réduction du nombre et de la longueur des pieds de vignes. Par contre, l'irrigation saline sous pression a été cause de mortalité des plantes. La composition en ions de solutions de sols a été significativement modifiée par l'irrigation saline par goutte à goutte, laquelle a également eu des effets néfastes sur le rendement et entraîné une modification rapide des compositions en ions d'une solutions de sol. Des changements importants des concentrations en Ca, Na et Cl dans la solution de sol ont été notés en même temps que l'augmentation de la salinité, au contraire des concentrations en Mg et K dont les compositions en ions n'ont pas changé de façon significative. Les volumes commercialisables ont été réduits par la salinité. L'irrigation saline par goutte à goutte a eu des effets néfastes sur le rendement (réduction de 26 et de 35%). Dans l'essai réalisé avec irrigation saline sous pression, les

No abstract

In order to describe seasonal flight activity of the cabbage maggot Delia radicum (L.) adults in relation to Julian days (JD), degree-day accumulations (DDA) and precipitation, flight dynamics were followed weekly with the use of yellow sticky traps (YST). Climatic data were collected and DDA were calculated using the lower developmental threshold of 4.3 °C. The efficacy of four insecticides applied either as standard foliar treatment or through dipping the seedlings before transplanting was determined. Seasonal flight activity during the cultivation season of a mid-early variety of white cabbage was correlated with DDA and JD and was characterized by having two peaks. The first peak occurred between 119 ± 7.5 JD and 125.5 ± 8 JD when DDA was 471.35 ± 74.97 °C. The second occurred between 172.8 ± 6.1 JD and 179.3 ± 6.7 JD when DDA was 1,217.28 ± 96.12 °C. The DDA, cumulative capture of flies and JD are suitable for predicting the timing of insecticide application. Spraying with insecticides should be applied when the cumulative capture of flies reaches 100 flies/YST and when DDA reaches 400 °C. If only one parameter reaches the threshold, additional visual surveys should be employed to establish the level of infestation. Insecticides were able to ensure only partial control. In the future, alternative control tactics which employ seed treatments and nonpesticide measures should be investigated in Croatia.

No abstract

No abstract