ChileanJAR

Based on three trials on fresh consumption tomatoes, it can be concluded that, when the soil has a low level of N and P, and the yield is about 50 ton/hectare, there is a positive response, up to 120-180 kg of N/hectare and 90 kg of P₂O₅/hectare, with a clear interaction between these nutrients. No response to K was obtained, in spite of the low level of K in the soil (55 ppm). At the maximum yield, N extraction varied between 100-120 kg/hectare, and P extraction was about 20 kg/hectare. Nitrogen treatments ceused a notable iricrease in the extraction of the other nutrients; P absorption was more related to the addition of N than of P. Nitrogen efficiency was calculated as 50%. Considering this value, N needs (2.7 kg/ton), and soil supply, a model is propposed to calculate N fertilization needs, in relation to potential yleld. With 120 N, P absorption efficiency was 15°/o. Split application of N did not show advantage. However, late applications of N, produced more fruit at the end of the season. A preliminary foliar standard for fresh consumption tomatoes could be, in NO₃-N: more than 5,400 ppm, at early bloom; more than 3,300 ppm, .at fruit forming; and over 800 ppm, at the beginning of color formation.