Conservation of Traditional Rice Varieties in a Globally Important Agricultural Heritage System (GIAHS):Rice-Fish Co-Culture

The traditional rice-fish farming system is selected as a ＂globally important agricultural heritage system＂ （GIAHS） by the Food and Agriculture Organization （FAO）,United Nations Development Programme （UNDP）,and Global Environment Facility （GEF）,etc.In Zhejiang Province of China,where the pilot site for this GIAHS farming system is located,we compared the use of traditional rice varieties in rice-fish co-culture and rice monoculture.Further,we determined how traditional rice varieties were performed in this rice-fish system.Only 19% of the farmers who practiced rice monoculture planted traditional varieties while 52% of farmers who practiced rice-fish co-culture planted traditional varieties.Traditional varieties represented 13% of the total land cultivated under rice in the rice-fish system but only 2% in the rice monoculture system.In the rice-fish system,yield was lower for traditional rice varieties than hybrid varieties but application of fertilizers and pesticides was also lower.In a field experiment in the rice-fish system without pesticides,rice planthopper numbers and sheath blight incidence were lower from three traditional varieties than one hybrid variety;yields were 8 to 32% lower from the traditional varieties than the hybrid.Our results showed that traditional rice varieties can be preserved through conserving GIAHS rice-fish co-culture.Our study also indicated that traditional rice varieties can survive in the rice-fish system because these varieties are helpful to the whole system and beneficial to the farmers.

Effect of Different Rice-Crab Coculture Modes on Soil Carbohydrates

Traditional agricultural systems have contributed to food and livelihood security. Rice-crab coculture （RC） is an important eco-agricultural process in rice production in northern China. Recognizing the soil fertility in RC may help develop novel sustainable agriculture. Soil carbohydrates are important factors in determining soil fertility in different culture modes. In this study, soil carbohydrates were analyzed under three different culture modes including rice monoculture （RM）, conventional rice-crab coculture （CRC） and organic rice-crab coculture （ORC）. Results showed that the contents of soil organic carbon and carbohydrates were significantly higher in the ORC than those in RM. The increasing effect was greater with increased organic manure. Similar tendency was found in CRC, but the overall effect was less pronounced compared with ORC. Carbohydrates were more Sensitive to RC mode and manure amendment than soil organic carbon. Compare to RM, the （Gal＋Man）/（Ara＋Xyl） ratio decreased in all the RC modes, indicating a relative enrichment in plant-derived carbohydrates due to the input of crab feed and manure. While the increasing （Gal＋Man）/（Ara＋Xyl） ratio in ORC modes with increased organic manure suggested that crab activity and metabolism induced microbially derived carbohydrates accumulation. The lower GluN/MurA ratio in ORC indicated an enhancement of bacteria contribution to SOM turnover in a short term. The findings reveal that the ORC mode could improve the quantity and composition of soil carbohydrates, effectively, to ensure a sustainable use of paddy soil.

Ecosystem service tradeoff between traditional and modern agriculture： a case study in Congjiang County, Guizhou Province, China

Besides crops, agriculture supplies all three major categories of ecosystem services （ES）. However, agriculture also supplies an array of ecosystem dis-services （EDS） that may harm other ecosystems. The flows of ES and EDS are directly dependent on the management of agricultural ecosystems. The traditional method of Chinese agriculture, which supports sustainable agriculture, has been proven to increase ES and reduce EDS. However, there is a lack of a detailed understanding of the ES and EDS associated with traditional agriculture, and also of differences between traditional and modem agriculture. In this study, an investigation was conducted on the ecosystem services （ES） and ecosystem dis-services （EDS） of traditional and modem agriculture in Congjiang County, Guizhou Province, China. Afterwards, the economic values of ES and EDS were quantified experimentally and calculated based on the market price. The results show that： the net economic value of traditional rice-fish agriculture was 3.31 x 104 CNY.haI （6.83 CNY = 1 USD as of July, 2009） and that of rice monoculture was 1.99 x 104 CNY.ha ~. Significant differences existed between traditional rice-fish and rice monoculture fields for their economic values of some ES or EDS. A benefit and cost analysis （BCA） model was used to adjust the conflict between the economic income and environmental loss from traditional and modem agricul- ture. The BCA model not only calculates the net income but also monetizes the EDS of the agricultural systems. The results showed that the net income of rice-fish agriculture was 1.94x 104CNY.ha-1 higher than that of rice monoculture. However, the benefit to cost ratio （BCR） of rice-fish agriculture was lower than that of rice monoculture, indicating that the traditional agricultural model was not the most optimized choice for farmers. The value of the rice-fish agriculture was much higher than that of the rice monoculture. Thus, when considering the benefits that rice-fish agriculture contributes to the large- scale society, these agricultural methods needs to be utilized. Furthermore, the labor opportunity costs were calculated and the comprehensive value of rice mono- culture was negative. Finally, the compensation standard was calculated based on the comprehensive benefit analysis. The lowest level was 1.09×103 CNY.ha-1, and the highest level was 1.21 × 104 CNY.ha-1.