Abstract
Two field experiments were conducted to evaluate the use of relative chlorophyll content (RCC) in sweet corn leaves as an indicator of nitrate concentration in soil. Study objectives were (1) to evaluate the effect of manure types (chicken and dairy), rates (0, 168, 336, and 672 kg ha−1 equivalent N), and application frequency (one and two applications) of organic amendments on (a) nitrate nitrogen (NO3-N) concentration within and below the crop root zone and (b) the RCC of sweet corn leaves and (2) to quantify the relationship between RCC and NO3-N concentrations. The results showed a significant increase in NO3-N concentrations within and below the root zone and plant leaf RCC under chicken manure treatments. Manure application rates and frequency had a significant effect on both NO3-N concentration within and below the root zone and leaf RCC. It appears that leaf RCC can be used as an indicator of NO3-N availability for sweet corn cultivated under the study conditions.