Reduction effects of three garden types on runoff, sediment and nutrient loss in the red soil hilly region of China

To develop appropriate models for gardens in the red soil hilly region in southern China, runoff plots with four treatments were constructed. Runoff plots included a natural slope (as the control), oil-tea trees + bamboo level ditch, oil-tea trees + hedgerow and Ponkan trees + level platform + grassed wall. Plots were constructed in Zuoma, a small watershed of Jiangxi Province. Surface runoff, sediment yields and nutrient losses were investigated in response to natural rainfall from January to December, 2010. The results indicate that relative to the control, surface runoff was reduced by 26.51-79.34% in the treatment plots, and sediment rates were reduced by 20.76-72.06%. These results indicated that three typical gardens greatly reduce surface runoff and sediment yield. These gardens are ranked in terms of their ability to reduce runoff in the following descending order: oil-tea trees + bamboo level ditch, Ponkan trees + level platform + grassed wall and oil-tea trees + hedgerow. Compared to the control plot, loss of nitrogen and phosphorus was reduced by 42.56-79.42% and 20.58-66.09%, respectively. The three typical gardens are able to prevent nutrient loss and are ranked in the following descending order: oil-tea trees + bamboo level ditch, Ponkan trees + level platform + grassed wall and oil-tea trees + hedgerow. Therefore, it is recommended that biological measures such as hedgerows and engineering measures such as level platforms and bamboo ditches be applied to gardens for watershed management in the red soil hilly region of southern China.