Evaluation of optical sensor technology to minimize environmental impacts and maximize production efficiencies associated with N applications in corn

摘要

Nitrogen (N) amendment based on soil mineral N content prior to planting is unreliable in humid regions. A field experiment was conducted for three years to evaluate the ability of non-destructive plant-based optical sensor technology in comparison with pre-sidedress soil nitrate concentration (PSNC) test in discriminating fertilization N application rates near sidedress time. Two hybrids were grown under 8 combinations of rates and tuning of N application in a factorial experiment. Leaf greenness and canopy reflectance were simultaneously measured from the V5 to V8 growth stages. Plant total N and soil available N (NO_3~- and NH_4~+) from 0-30 cm depths at V6 were analyzed. In two years (2000 and 2002), grain yields increased significantly with fertilizer rates up to 120 kg N ha~(-1); yields were similar for 120 to 250 kg N ha~(-1) treatments. Both leaf chlorophyll meter readings (SPAD) and canopy reflectance (NDVI) measured at V6 responded linearly to fertilizer N up to 120 kg N ha~(-1) and werestrongly correlated (r>0.92) to each other. We concluded that both leaf chlorophyll and canopy reflectance measurements could be used as crop-based indicators for early season N amendment.