Effects of irrigation frequency and fertilizer rate on growth, tuber yield and nutrient uptake of drip-irrigated potato

Objectives In view of inappropriate irrigation and fertilization as well as low water and fertilizer use efficiency in potato planted in sand soil in Yulin area of northern Shaanxi province, field experiment was conducted to examine the effects of irrigation frequency and fertilizer rate on growth, yield and nutrient use efficiency of potato (Solanum tuberosum L.) under fertigation in order to scientifically regulate water and fertilizer use and provide scientific reference for potato production.

Methods Field experiment was carried out in Agricultural Science and Technology Demonstration Areas of Yulin city, Shaanxi province from May to October in 2016. There were total of 9 treatments combining three irrigation frequency levels, i.e. D1 (4 d), D2 (8 d) and D3 (10 d), and three fertilization levels based on different ratios of N, P₂O₅, K₂O, i.e. F1 (100, 40, 150 kg/hm²), F2 (150, 60, 225 kg/hm²) and F3 (200, 80, 300 kg/hm²). Growth indices were measured during the growing season, tuber yield and its components were measured at harvest.

Results At the same irrigation frequency, there was a positive correlation between growing indices and the fertilizer rates, and the tuber yield increased with increase of fertilizer rates, but the partial fertilizer productivity (PFP) and the nutrient use efficiency decreased. There was no significant correlation between water use efficiency (WUE) and fertilizer rate, and the average tuber yield of F3 was 41518 kg/hm², 11.75% and 8.52% higher than F1 and F2. The PFP of F1 was 128.12 kg/kg, 45.67% and 78.99% higher than F2 and F3. At the same fertilizer rate, there was a quadratic correlation between yield, PFP and irrigation frequency. D2 had the greatest tuber yield of 42932 kg/hm² and highest PFP of 105.88 kg/kg, and D1 resulted in the highest WUE and nutrient use efficiency, but had no difference with D2. As for interaction between irrigation frequency and fertilizer rate, the highest tuber yield and WUE were attributed to D2F3 with 44870 kg/hm² tuber yield and 107.39 kg/(mm·hm²), respectively. D2F1 had the highest PFP of 142.02 kg/kg.

Conclusions Reasonable irrigation frequency and fertilizer rate not only sustained good growth characteristics of potato, but also resulted in the maximum economic benefit. In comprehensive consideration of yield, water and fertilizer saving, the treatment of D2F3(8 d, N 200 kg/hm², P₂O₅ 80 kg/hm², K₂O 300 kg/hm²)was appropriate water and fertilizer combination under the experimental conditions.