According to research carried out by scientists of the AGR224 Group and the CIAIMBITAL of the University of Almería (UAL), the amounts of nitrogen fertilizer used in the greenhouses of Almería are too high with respect to the crops' needs.
The study, entitled 'Crop response of greenhouse soil-grown cucumber to total available N in a Nitrate Vulnerable Zone' and published in the European Journal of Agronomy, concludes that Almeria's producers follow "standard recipes in the planning of fertilizer applications, which entails not taking into account the residual nitrogen present in the soil by previous campaigns, or mineralized from manure or other forms of organic matter."
They said that the greenhouses in Almeria are located in a region declared by the European Union as a Vulnerable Zone to Nitrate Pollution (ZNV), and that there is regional legislation aiming to curb both the contributions of nitrogen fertilizer to crops and the associated environmental pollution.
The study's researchers focused on the cultivation of cucumbers in greenhouses and studied their response to nitrogen fertilizer applications through field work carried out at the Experimental Station of the UAL-Anecoop Foundation. There were three tests, each in a different cultivation cycle: autumn-winter, early spring and late spring.
Commercial cucumber varieties were used in all of them, with three different varieties being compared in the late spring trial. By means of fertigation, increasing doses of nitrogen fertilizer were applied in each of these tests.
The study concluded that 230 kg / ha-1 of such a fertilizer is recommended for a greenhouse cucumber crop with a usual cycle of 70-84 days, specifying that if there was mineral residue or previous contributions of organic matter, "it would be advisable to estimate these amounts and subtract them from the given recommendation."
To perform these calculations, it is recommended to use the free computer application VegSyst-DSS, developed by the working group.
The transfer of the study's results serves to conclude that the nitrogen fertilizer limit of 4 kg N t-1 (ton of fresh fruit) recommended in the regional action plans of the Government of Andalusia are "excessive and could be reduced to about half," to around 2 kg N t-1.
Source: Efe / lavanguardia.com