Effects of Diversified Rice-Based System on Nutrient Balances and Yield Gaps in the Philippines
Bernhard Liese1, Reiner Wassmann2, Mathias Becker1
1University of Bonn, Inst. Crop Sci. and Res. Conserv. (INRES) - Plant Nutrition, Germany
The green revolution with the development of high-yielding rice varieties in combination with the use of synthetic fertiliser and pesticides, and the provision of irrigation water, allowed for cultivating two crops of rice per year. However, the high water demand for the dry season rice can no longer be met in water-scarce environments, forcing farmers to replace dry season rice with upland crops. The short turn-over times in rice double cropping require the rice straw of the preceding crop to be removed or burnt. Replacing dry season rice with an upland crop will result in seasonal variations of the soil aeration status that may affect soil C and N contents. On the other hand, the return of rice straw by mulching or incorporation before maize can add K and Si. The inclusion of a pre-rice green manure after maize may contribute to conserve native soil N. We hypothesise that the emerging flooded – aerobic cropping systems enhance nutrient cycling and increase yield and nitrogen use efficiency of rice. Such effects may provide new opportunities for sustainably intensifying production while saving water and reducing the existing gaps between potential and actual yields.
Keywords: Nutrient cycling, Oryza sativa, straw management, Vigna radiate, Zea mays
Contact Address: Bernhard Liese, University of Bonn, Inst. Crop Sci. and Res. Conserv. (INRES) - Plant Nutrition, Karlrobert-Kreiten-Str. 13, 53115 Bonn, Germany, e-mail: blieseuni-bonn.de