Tuesday, November 14, 2006
141-4
An Attempt to Model Seasonal Dynamics of Available Nitrogen, Phosphorus and Potassium in the Rooted Zone of Arable Land.
Sandor Koos, Tamas Nemeth, and Geza J. Kovacs. Research Institute of Soil Science and Agricultural Chemistry, Hungarian Academy of Sciences, Herman Otto u. 15., Budapest, Hungary
Few data are available for seasonal changes of soil phosphorus and potassium especially considering the whole rooted zone of the soil. In a 30 year long fertilizer experiment of our institute (Nagyhörcsök experimental station, with calcareous loam chernozem.) seasonal dynamics of available NPK nutrients were followed from March to November in 2003. Two parallel average samples were collected from the N0P0K0, N1P1K1, N2P2K2 and N3P3K3 treatments. Each sample was composed of 12–12 sub-samples. There were 19 sampling times. Three layers (0–20, 20–40 and 40–60 cm) were sampled at each plot. A Hungarian CERES based model (4M) was used for modelling the seasonal changes of the available nutrients in the soil, and the dynamics of the whole nutrient balance (uptake, leaching, mineralization, etc.). Changes of soil moisture content of the profile has also been measured and simulated. These data are key for any modeller to test the capability of a given crop model. 4M performed well in estimation of water and nitrogen dynamics. Phosphorus and potassium dynamics are more complicated in nature. Availability for plant uptake is a difficult question to follow and even so to measure. The results certainly give a step forward in modelling of P- and K-cycles.
Handout (.pdf format, 158.0 kb)