Chlorophyll index is an instantaneous measurement of leaf greenness without the destruction of the plant and a new tool to determine plant nitrogen content and associated yield. A pot experiment was conducted under controlled conditions. Olive solid wastes were mixed with soil at the rates of 0, 3, 5 and 7% with and without additional nitrogen and phosphorous sources. Sunflower was grown in pots for two months. Plant length, leaf number, stem thickness, and chlorophyll meter readings were performed weekly. Plant nitrogen contents and plant weights were determined at harvest. Chlorophyll index and plant nitrogen contents were significantly related (r(2) = 0.86) at the V12 stage. The correlations between chlorophyll meter reading and plant biomass was 0.87 while plant N and plant biomass was 0.96. On the other hand, chlorophyll meter estimation of plant N contents in early stages (V2 and V4) of sunflower growth was not statistically significant. Additions of olive solid waste in the soil reduced chlorophyll meter readings and sunflower biomass.