Linking Remote Sensing to Crop Production
TERRECO Cluster A-04
From 10/2012 to 01/2016Principal Investigator: John Tenhunen, Jonghan Ko, Dennis Ochuodho Otieno, Christiane Werner
Staff: Wei Xue
Abstract: Worldwide, the total harvested area of irrigated rice is about 79 M ha. Almost half of the world population depends on rice as a staple food. With the intent of producing maximum agricultural yields, intensive application of fertilizers occurs in most Asian countries leading to enhanced yield per hectare, but simultaneously to altered agricultural carbon balances and to export of nutrients in rivers and streams. Nitrogen is one of the most important nutrients required by agricultural crops to produce the enzymes required in metabolism and photosynthesis. It is applied in concentrations up to 400 kg ha-1 or more in Haean Catchment.
The physiologically-based model PIXGRO has being calibrated and tested to simulate carbon and water balances from landscape to regional scales in mountainous regions of Europe, and tentatively as well for South Korea. For typical crop management in Haean Catchment, the model performs well with respect to crop water use, crop CO2 fixation, allocation of fixed carbon to biomass and agricultural yields at local (plot) scale. However, it is critically important to determine from field studies the sensitivity of key model parameters to variation in fertilizer application. This information will allow use of PIXGRO in planned scenario studies that relate to reducing nutrient exports to Lake Soyang and to optimizing ecosystem services, and will allow evaluations of regional spatial variation in plant production that occur.
Several key photosynthetic parameters of PIXGRO related to carbon uptake capacity vary seasonally as well as spatially depending on soil conditions, and are clearly related to observed changes in canopy reflectance (see also poster 18 – Bora Lee). The goal of this project is to gain new understanding of these variations via a multi-dimensional, multi-scale investigation of ecosystem physiology, developing canopy structure and remote sensing. The reflectance spectrum obtained at different heights and with different sensing platforms serves as a rapid and powerful way to quantify temporal and spatial variations in carbon balance (see poster 24 of this project). Thus, our project will be conducted in rice paddies both with normal management and with variation in available nutrients. The extensive field investigations on photosynthetic physiology, canopy structure and biomass accumulation of rice, and linking with canopy reflectance provides information needed to improve and calibrate the simulation models CERES-Rice and PIXGRO, which are used to assess carbon balance and crop production within Soyang Watershed in the context of planned scenarios.
Key words: rice, photosynthetic parameters, photosynthetic physiology, canopy structure, canopy reflectance, nutrient application
