The Chlorophyll Meter SPAD-502 is a compact, easy-to-use meter for measuring the chlorophyll content of plant leaves without damaging the plant. Chlorophyll content is an indication of the plant condition and can be used to determine when to add fertilizer to produce larger crop yields of higher quality.br br Checking the nutritional condition of plantsbr The chlorophyll present in the plant leaves is closely related to the nutritional condition of the plant. As can be seen from the graph below, the chlorophyll content (represented by the measured SPED value) will increase in proportion to the amount of nitrogen (an important plant nutrient) present in the leaf. For a particular plant species, a higher SPAD valueindicates a healthier plant.br br Determining when additional fertilizer is necessarybr A decrease in the SPAD value indicates a decrease in the chlorophyll content and nitrogen concentration. This decrease may be due to a lack of nitrogen available int he soil.