Optimal combination of potassium fertilizer and drip irrigation for potato production based on entropy weight method and TOPSIS analysis

  Objective  To explore the combination of water and potassium for optimized yield, quality, and production efficiency of potato under drip fertigation conditions in northern Shaanxi Province.

  Methods  Field experiments were conducted to study the responses of potato growth, yield and quality to different types of potassium fertilizer and irrigation amount in Yulin, northern Shaanxi. ‘Qingshu No. 9’ was used as the test material. The three irrigation levels were 60%, 80%, and 100% of the crop water requirement (W1, 60% ET_c, 198.4 mm; W2, 80% ET_c, 246.2 mm; W3, 100% ET_c, 294 mm). The four K fertilizer treatments were - no K fertilizer control (K0), KCl, K₂SO₄ and KNO₃. The water use efficiency (WUE) and partial fertilizer productivity (PFP) were calculated.

  Results  The K fertilizer type, irrigation level and their interaction significantly affected potato yield and qualities, WUE and PFP. Under the same K fertilizer, the yield, starch content and net income of W3 treatment were 19.8%, 3.8%, 33.9% higher than W1, and 8.1%, 1.6% and 15.8% higher than W2 treatment, respectively. K fertilizer had different yield increasing effect under different irrigation amount. At W1, the dry matter accumulation and yield of KCl were significantly lower than those of K₂SO₄ and KNO₃. At W2 and W3, the dry matter accumulation, total and marketable yield, and net income of KNO₃ were significantly higher than those of KCl and K₂SO₄, while the latter two had no significant difference. Considering the irrigation × fertilizer interaction, the yield of W3+KNO₃ was 9.2%−55.0% higher than other treatment combination. W3+K₂SO₄ had the highest starch and the lowest reducing sugar content. W3+KCl elicited the largest production to investment ratio, while W1+KNO₃ had the highest WUE. Based on entropy weight method and TOPSIS analysis, the comprehensive effect was in order of W3+KNO₃>W3+KCl>W2+KNO₃>W3+K₂SO₄>W2+K₂SO₄>W3K0>W2+KCl>W1+KNO₃>W1+K₂SO₄>W1+ KCl>W2K0>W1K0.

  Conclusions  According to entropy weight method and TOPSIS, the optimum combination for high yield, quality and efficiency of potato in sandy soil is KNO₃ with 100% of potato water requirement in northern Shaanxi Province.