Runoff efficiency and the technique of micro-water harvesting with ridges and furrows, for potato production in semi-arid areas

A field study was conducted to determine runoff efficiency and the effects of different ridge: furrow ratios and ridge-covering materials on tuber yield, soil moisture storage and water use efficiency (WUE) in the ridge and furrow micro-water harvesting system in a dry semi-arid region of China, during two consecutive years of 2002,and 2003. The average runoff efficiency of ridges with compacted soil (SR) was very low (24.6-28.8%) compared to that of ridges covered with plastic film (MR) (91.1-94.3%). The minimal rainfall necessary to produce runoff was 2.76-2.78 mm for SR, only 0.23-0.47 mm for MR. The field experiments using potato as an indicator crop showed that tuber yields in the MR system were significantly higher than that in the flat planting (control), with an average increase of 158.6-175.0% during 2 years. In the SR system, the average increase was valued of 14.9-28.4% during 2 years. Regression analysis between tuber yields and ridge widths indicated the optimum ridge; furrow ratio for MR was 39: 60 cm in 2002 and 48: 60 cm in 2003 respectively. The WUE values of potato in MR were 1.50 times greater than that of the controls in 2002 and 1.62 times greater than the controls in 2003. No differences were found in the WUE between the SR and the controls on average of 2 years. Due to the different runoff efficiency between two ridge-covering materials and absence of runoff occurrence in the controls, the soil water content in the MR was higher than that in the SR, both of which were greater than the controls. With the soil crust development, the distribution of soil water at the bottom of the furrow, at the side of the furrow and at the top of the ridge, is similar between the SR and the MR.