Water and nitrogen use efficiency, dry matter accumulation and nitrogen uptake in fertigated processing tomato

A three year field experiment was carried out in Northern Italy (Po Valley) to assess the water and nitrogen use efficiencies (WUE & NUE) of two fertigation strategies (static and dynamic) in comparison with Non-Irrigated/Non-Fertilised and Irrigated/Non-Fertilised controls, and to define the better strategy to be applied for environmental and economical purposes in a sub-humid area on fertile soils. Dry matter accumulation and nitrogen uptake curves were calculated to compare treatments and to verify the effectiveness and applicability of the WUE and NUE enhancement. Economical WUE and NUE values were also calculated considering the gross margin in order to evaluate the economic self-sustainability of the proposed fertigation strategies. Fertigation efficiency and crop profitability were enhanced and non-point pollution risks reduced by applying "dynamic" fertilisation principles on a daily basis. Managing the crop using dynamic criteria reduces plant nitrogen uptake and produces more fruit dry matter per gram of nitrogen.