Optimization of water and fertilizer management improves yield, water, nitrogen, phosphorus and potassium uptake and use efficiency of cotton under drip fertigation

As a fiber crop and oil crop, cotton plays an important role in the economic development of northwest China, but the lack of appropriate field water and fertilizer management strategies has restricted the harmonious development of cotton industry and environment. Field experiments were implemented to explore the coupling effects of various drip irrigation and fertilizer levels on the dry matter, yield, water and fertilizer use efficiency of cotton. The three drip irrigation levels included 1.0 ETC (full irrigation), 0.8 ETC (20% deficit) and 0.6 ETC (40% deficit), where ETC is the crop evapotranspiration. The five fertilizer (N-P-K) levels were F1 (150–26.2–24.9 kg ha−1), F2 (200–34.9–33.2 kg ha−1), F3 (250–43.7–41.5 kg ha−1), F4 (300–52.4–49.8 kg ha−1) and F5 (350–61.1–58.1 kg ha−1). The results revealed that the seed cotton yield and lint yield showed increasing trends as the irrigation water amount increased at the same fertilizer level during 2012–2014. When full irrigation (1.0 ETC) was applied, the dry matter accumulation, seed cotton yield, N, P and K accumulation in plants and water productivity were the highest under F4 (300–52.4–49.8 kg ha−1) in 2012 and 2014. However, the lint yield was highest in 2012 and 2013 under F3 (250–43.7–41.5 kg ha−1). At the same irrigation level, N, P and K use efficiencies were higher at low fertilization rates than those at high fertilization rates in 2012 and 2013. Deficit irrigation and fertilization levels led to a severe decrease in cotton yield. N, P and K use efficiencies were low under F4. Comprehensively considering cotton yield, N, P and K uptake and use efficiency, the application of irrigation amount of 1.0 ETC and N-P-K rate of 250–43.7–41.5 kg ha−1 was the best drip fertigation strategy for cotton production in arid regions of northwest China.