NITROGEN AND PHOSPHORUS FERTIGATION OF TOMATO AND EGGPLANT

Field studies, on Pellic Vertisol, were designed to investigate the response of drip-irrigated tomato (Lycopersicon esculentum L.), to conventional soil P fertiliser application as Triple Superphosphate (TSP) and fertigation when P is applied in the form of Urea Phosphate (UP), Monoammonium Phosphate (MAP) or Diammonium Phosphate (DAP). The N and P applied in soil were 300 and 94 kg/ha.
An equivalent amount of P and an amount of 70 kg P/ha in a combination with 150, 300 and 450 kg N/ha were applied with irrigation water at a total amount of 200 mm of water.
The K applied was 450 kg/ha in all treatments.
Irrigation was applied when the soil water potential was between 0.03 and 0.04 Mpa and at full growth of plants was equivalent to 0.8 of pan evaporation from a screened USWA Class A pan.
Similar treatments were tested with eggplant (Solanum melongena L.) The results indicate that fertigation irrespective of the combination of fertilisers is superior than soil application.
With less N by 50% higher yield was obtained with fertigation suggesting that N is more efficient when applied with the irrigation water.
UP as a source of P gave the highest yield with both tomato and eggplant even when P supplied was by 25% less.
Most probable explanation is the "double acidification effect" of the UP fertiliser.
The mechanism is elaborated in the paper.

XXV International Horticultural Congress, Part 1: Culture Techniques with Special Emphasis on Environmental Implications – Nutrient Management

I. Papadopoulos, Leena M. Ristimäki

Drip irrigation, fertilisers, N, P fertigation, Urea phosphate

https://doi.org/10.17660/ActaHortic.2000.511.8