Water and fertilizer use efficiency of potato under different irrigation patterns in North Yin Mountain Region

The North Yin Mountain Region (NYMR), the main potato production region in Inner Mongolia, is highly limited in water resources. Water-saving cultivation techniques have therefore been increasingly used in this region in recent years. To evaluate the effects of different irrigation methods on water and nutrient use efficiency and the eco-environmental benefits of potato cultivation, field experiments were conducted in 2009-2010 in the Wuchuan Region of NYMR, Inner Mongolia. The field experiment was consisted of four different irrigation patterns - flood irrigation (FI), ground sprinkler (GS), drip irrigation (DI) and under-mulch-drip irrigation (UMDI). The irrigation patterns were compared in terms of potato tuber yield, water and nutrient use efficiency, net economic income and soil inorganic nitrogen residue. The results showed that UMDI increased potato yield over conventional farm practice FI, GS and DI by 35.7%, 26.0% and 12.9%, water use efficiency by 200.2%, 91.8% and 23.7% and net economic income by 37.7%, 30.1% and 10.7%, respectively. Nitrogen fertilizer partial factor productivity under UMDI was respectively 50.6 kg·kg^-1, 39.8 kg·kg^-1 and 22.0 kg·kg^-1 higher than those under FI, GS and DI. Also phosphorus fertilizer partial factor productivity under UMDI was respectively 126.6 kg·kg^-1, 99.4 kg·kg^-1 and 55.0 kg·kg^-1 higher than those under FI, GS and DI. Then potassium fertilizer partial factor productivity under UMDI was respectively 42.3 kg·kg^-1, 33.2 kg·kg^-1 and 18.4 kg·kg^-1 higher than those under FI, GS and DI. Soil inorganic nitrogen residue in the 60~120 cm soil layer after potato harvest was 102.95 kg·hm^-2 under FI, which was 0.36, 1.11 and 1.28 times higher than those under GS, DI and UMDI, respectively. The above results suggested that DI and UMDI not only saved water resources, but also enhanced potato yield, nutrient use efficiency and net economic income in the research area. This was critical for reducing the risk of environmental pollution due to nitrogen leaching. It was therefore important to intensify DI and UMDI irrigation patterns in potato fields in the NYMR for higher yields, resources use efficiencies and low environmental pollution risks.