Abstract: 【Objective】Chemical nitrogen fertilizer reduction, potassium fertilizer application and organic manure substitution are useful methods to increase crop resource use efficiency, enhance agro-environment, improve quality of agricultural products and decrease the disease risk in China. The understanding on the effects of reduced chemical nitrogen fertilizer dressing, organic manure substitution and potassium fertilizer application on potato dry matter assimilation and water utilization, are helpful to apply the efficient managing strategy of water and nutrient resource.【Method】A 4-year field experiment was carried out from 2011 to 2014 with three treatments: (1) traditional chemical fertilizer application (PM), (2) chemical nitrogen fertilizer reduced by 25% and dressing at flowering stage, and potassium fertilizer application (PMN), and (3) chemical nitrogen fertilizer reduced by 50% and organic manure substitution, and potassium fertilizer application (PMO). The soil moisture, potato biomass and yield had been investigated, crop water consumption, potato growth rate, water use efficiency (WUE) and partial factor productivity from applied fertilizer (PFP) were calculated to understand the effects of different nutrient management methods on potato dry matter assimilation and water-nutrient use efficiency, as well as its regulations on potato water use process on semiarid rain-fed area.【Result】The potato water consumption decreased by 17.4, 28.7, 26.8, 34.2 mm in pre-flowering stage, but increased by 31.1, 34.7, 36.7, 49.2 mm in post-flowering stage in PMN treatment, compared with PM. PMO increased the potato water consumption by 17.8, 24.3, 11.2, 10.3 mm than PM in post-flowering stage, but had no significant effect in the pre-flowering stage. Compared with PM, PMN increased potato above- and under- ground biomass, as well as the growth rate after early blooming, caused 2 595.1 kg·hm^-2 tuber yield increment from 2012 to 2013 averagely; the water use efficiency (WUE) increased by 14.4% and 6.3% in 2013 and 2014, the significant difference observed in these years. PMO significantly increased potato above- and under- ground biomass, and the growth rate, resulted in 2 945 kg·hm^-2 tuber yield increment in 4 experimental years on average. Its WUE was significantly higher than PM from 2012 to 2014. PMN and PMO increased potato fertilizer partial factor productivity from applied fertilizer (PFP_T), chemical fertilizer partial factor productivity from applied fertilizer (PFP_C), nitrogen partial factor productivity from applied fertilizer (PFP_TN) and chemical nitrogen partial factor productivity from applied fertilizer (PFP_CN) as compared with PM. It was indicated that PMN and PMO increased nutrient and water use efficiency synergistically, both realized the objective to regulate water utilization by fertilizer application, and improve nutrient utilization by water management. In 2011 (dry year), PMN and PMO regulated the water consumption between pre- and post- flowering stage, increased above- and under- ground biomass, growth rate and PFP, but the potato tuber yield and WUE didn’t increase significantly.【Conclusion】Both PMN and PMO regulated potato water consumption between pre- and post- flowering stage significantly, and increased potato biomass and growth rate, resulted in increased tuber yield, WUE and PFP. However, PMO showed more significant effects than PMN on the increment of tuber yield, PFP and WUE, so it was the more efficient nutrition management model for higher resource use efficiency and yield under whole field plastics mulching and ridge-furrow planting system on semi-arid areas.

Key words: semi-arid area, potato, chemical nitrogen fertilizer reduction, organic manure substitution, potassium fertilizer application, water-fertilizer use efficiency, yield