Growth of Caragana korshinskii using runoff-collecting microcatchments under semiarid condition

SummaryA field study was conducted to explore the effectiveness of using microcatchment water harvesting to grow Caragana korshinskii in the semiarid loess region of China between 2002 and 2004. The experiment involved four different size microcatchments (5, 15, 30 and 50 m2) and the control (0 m2) with six replications to supply runoff water for C. korshinskii. For the microcatchments, runoff volume (m3) increased with increasing catchment size, following a positive linear function, whereas runoff depth (mm) decreased with increasing catchment size, following a negative power function. Runoff efficiency was 3.09–13.69%, 1.05–6.25%, 0.39–4.49% and 0.30–3.25% for the 5, 15, 30 and 50 m2 microcatchments, respectively, and varied between years. Microcatchment rainwater harvesting treatments supplied additional runoff water to the infiltration basin occupied by C. korshinskii tree. Total rainfall and runoff water collected in the plant area was significantly higher for the rainwater harvesting treatments than the control, and total runoff to the planted area increased with the size of the microcatchment, thus resulting in significant higher soil water storage and evapotranspiration in the water harvesting treatments. Water harvesting treatments had a pronounced effect on the growth of C. korshinskii. Tree height, crown diameter, collar girth, above-ground biomass and water use efficiency were significantly higher for the water harvesting treatments than the controls. This demonstrates that C. korshinskii can be grown successfully using microcatchments on rainfed lands. From the perspective of soil water storage efficiency and the minimum acceptable slope length, catchment/planted area ratio of 19–38 for the catchment area between 15 and 30 m2 was most suitable to grow C. korshinskii under semiarid condition.