Using data of optic sensors and pigment content in leaves for efficient diagnostics of nitrogen nutrition
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Opportune monitoring and diagnostics of a condition of crops permit to make prompt and proper activities on dressing nitrogen fertilizers. This will allow the plants to use the nitrogen applied efficiently, and therefore reduce their use in field. Since nitrogen that has not been utilized by plants is able to escape into the atmosphere or be washed out of the soil with water. The most accurate diagnostic method is to determine the chemical composition of plants, but it takes quite a long time and requires laboratory conditions, which is not always possible in the field. One of the promising methods is photometric diagnostics of crops using optical instruments. Experiment is carried out in contrasting weather conditions, on soddy-podzolic soil with spring barley and spring rapeseed being investigated. Results of research show the efficiency of using optic sensors (N-testers) for efficient diagnostics of nitrogen nutrition of plants. The readings of the device (N-tester) were compared with the concentration of a and b chlorophyll, determined by a chemical method. Results of diagnostics with portable photometric device ‘Yara’ are correlating with concentrations of chlorophylls a (r=0.96) and b (r = 0.91) in spring rapeseed. Moreover, correlation of rapeseed yield and concentrations of chlorophylls a and b has quantity and inverse relation similar to device indication (r = -0.81 and r = -0.70 respectively). Results of diagnostics with N-tester ‘Spectroluxe’ are strongly correlating with chlorophyll concentration. Device indication correlates stronger with chlorophyll b concentration in spring barley and chlorophyll a concentration in spring rapeseed (rapeseed was investigated in dryer conditions). Thus, such a modern optical device as N-tester, whose action is based on measuring the concentration of leafy chlorophyll, can replace chemical methods and increase the efficiency of nitrogen fertilization, which means increasing the productivity of plants and reducing the negative impact of unreasonable use of nitrogen fertilizers.