Developing an improved model for simulating a relay intercropping system of wheat and maize

Publikations-Art

Kongressbeitrag

Autoren

Knörzer, H, Graeff-Hönninger, S., Claupein, W.

Erscheinungsjahr

2009

Veröffentlicht in

Mitteilungen der Gesellschaft für Pflanzenbauwissenschaften: Pflanzenbauwissenschaften Systembezug und Modellierung

Herausgeber

B. Märländer, O. Christen, C. Kenter, A.. Düker u. Gesellschaft für Pflanzenbauwissenschaften

Verlag

Verlag Liddy Halm , Göttingen

Band/Volume

21/

Tagungsname

52. Jahrestagung der Gesellschaft für Pflanzenbauwissenschaften

Tagungsort

Halle (Saale)

Tagungsdatum

01.09.-03.09.2009

Interspecific competition is more than the survival of the fittest. Wherever there are competition effects there are also synergistic effects which can be utilized to turn cropping systems like intercropping into more resource use efficient systems. Especially in Asian and African countries intercropping is a widespread and traditional cropping system because land is scarce and field size very small, thus intercropping bears the potential to increase natural resources in space and time. In Northern China, farmers are able to harvest wheat and maize within one growing season in a so called relay intercropping system. The maturing wheat is interplanted with seeds of maize or alternatively young maize plants just a few days or weeks before wheat harvest in order to elongate the maize growing period enabling the maize to mature. Relay intercropping showed that it is possible to have an additional maize harvest without a decrease of winter wheat productivity even wheat is sown with only 75 % of its usual plant density. To further adjust those cropping system and to study the underlying processes crop growth models could be a useful tool. Field trials at the University of Hohenheim, Germany, were conducted with alternate plots of winter wheat and maize. Species parameters like dry matter accumulation, leaf area index, plant height, tiller and cob number, grain weight increase, final grain and dry matter yield were measured during the growing season. In addition, environmental parameters like shading patterns, soil temperature, soil moisture, N_min and wind speed were evaluated to detect and quantify those influences. In a new model approach, a shading algorithm was introduced into the DSSAT crop growth model and the model was evaluated for the tested wheat and maize varieties, both, their monocropped and intercropped variation. First modeling results showed that the modified DSSAT model was able to simulate general competition and beneficial effects due to different incoming solar radiation and soil temperature in a winter wheat/maize intercropping system. The results indicated that it is of high importance not only to consider the competition factor solar radiation like in most other modelling studies, as solar radiation could not explain yield differences in any case. It seems to be necessary to include also effects of changed soil temperature and wind speed patterns to explain yield changes of wheat and maize in an intercropping system.