"稻鸭共生"生态系统稻季N、P循环

稻鸭共生是对我国传统农业稻田养鸭的继承与发展。在长江流域双季稻主产区湖南布置了稻田养鸭田间试验,以常规稻作为对照,研究"稻鸭共生"生态系统N、P循环。结果表明:"稻鸭共生"生态系统N、P输出分别为153.50 kg/hm²和59.03 kg/hm²,其中鸭产品N、P输出分别是23.98 kg/hm²和3.10 kg/hm²;"稻鸭共生"系统在目前的N、P养分投入水平下,土壤存在严重的N和P亏缺;鸭子系统N、P输入对系统外饲料投入依赖高,自持能力较差;鸭粪N、P参与当季的稻田养分循环,其循环率分别为10.66%和28.16%。

Nitrogen and phosphorus cycling from rice-duck mutual ecosystem during late rice growth season

The pattern of raising duck in paddy field is a model in Chinese traditional agriculture. Which is a combination system of planting and breeding in rice paddy field in subtropical region. This model can increase the efficiency of using rice paddy field. Field experiments on N and P cycling from a rice- duck mutual ecosystems in double cropping rice region in Hunan Province were conducted from July to October in 2009, and a conventional rice field was used as control. This study applied Input-Output Analysis method to analyze N and P cycling in both rice-duck and conventional rice fields. The main objectives of this study were to provide theoretical and practical basis for further development and utilization of this classical agricultural technique. Neither chemical pesticides nor herbicides were applied throughout the growth period of rice in rice-duck mutual ecosystems, N fertilizer appliation was also reduced, and the surface water was maintained about 10 cm in depth during the period of raising ducks. Ducks of 50-day-old were introduced into the paddy field based on the holding capacity of 450 ducks per ha 17 days after seedling transplantation. These ducks were retrieved after the complete heading stage of rice in the experiments. The results showed that N and P outputs in conventional rice field were 127.76 and 62.02 kg/hm² respectively while the N and P outputs in the rice-duck mutual ecosystems were 153.50 and 59.03 kg/hm²,respectively. Raising ducks resulted in the increase of N outputs compared to the conventional rice field. Furthermore, N and P outputs from ducks were 23.98 and 3.10 kg/hm², respectively. Soil N and P occurred deficit in rice-duck mutual ecosystems. The N and P inputs from feeds were very high in the duck sub-system. In rice-duck mutual ecosystems, N and P input from chemical fertilizer were 72 kg/hm² and 13.10 kg/hm², respectively; N and P input from feed were 64.44 kg/hm² and 36 kg/hm², respectively; N and P input from duckling were 0.81 kg/hm² and 0.14kg/hm², respectively. During Late Rice growth season, duck growth increased feces N 14.27 kg/hm², feces P 16.10 kg/hm², and feces organic carbon was 157.54 kg/hm². Duck feces N and P cycling rate were 10.66% and 28.16% kg/hm², respectively.