Optimization of irrigation amount and fertilization rate of drip-fertigated potato based on Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods

Abstract

As a cash crop, potato plays an important role in the economic development and ensuring food security. Reasonable management of irrigation and fertilization can promote the uptake of water and nutrients by potato, thereby improving the tuber yield and quality, and reducing fertilizer residues in the soil. A four-year field experiment was carried out to explore the effects of different irrigation amounts and fertilization rates on potato yield, economic benefit, tuber quality, water productivity (WP) and fertilizer use efficiency (FUE), and soil nutrient residues during 2016–2019. Multi-objective optimization of irrigation amount and fertilization rate was conducted based on data in 2018 and 2019 using the Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods. In 2016 and 2017, three irrigation levels (W1, 60% ETC; W2, 80% ETC and W3, 100% ETC) and three fertilization (N-P-K) rates (F1, 100–17.5–124.5 kg/ha; F2, 150–26.2–186.7 kg/ha and F3, 200–34.9–248.9 kg/ha) were applied. The highest tuber yield was obtained under F3 in 2016 and 2017. Two fertilization rates (F0, 0 kg/ha and F4, 250–43.7–311.2 kg/ha) were further considered in 2018 and 2019. Results showed that the highest tuber yield, net income, WP, dry matter and the residues accumulation of nitrate nitrogen, available phosphorus, and available potassium were obtained under F4 in 2018 and 2019. However, the differences in tuber yield, net income and WP between F3 and F4 were not significant under W3. Deficit irrigation reduced tuber yield, ET, net income, shoot dry matter, tuber dry matter, LAI, relative chlorophyll content, starch and vitamin C content and FUE, and increased the residues of nutrient in the soil and reducing sugar content. Besides, W1 showed the highest irrigation water productivity, but the starch and vitamin C content of W3F2 were largest. The highest FUE was obtained under W3F3 (56.33% in 2018 and 53.33% in 2019). Increasing fertilization rate decreased the fertilizer partial factor productivity and sink/source. Based on the economic benefit, tuber quality, WP and FUE and soil environmental benefit, the multi-objective optimization was evaluated by the Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation methods. When the irrigation amount was 100% ETC (W3) and the fertilization rate (N-P-K) was 200–34.9–248.9 kg/ha (F3), the multi-objective optimization was obtained. The results can provide a theoretical basis for the optimization of water and fertilizer regimes of potato in northern China and other regions with similar environments.