Combined application of controlled-release phosphate and triple superphosphate improved cotton yield and phosphorus supply in saline-alkali land: A short-term trial

Degradation of agricultural productivity in sodic and saline soils is attributed to reducing phosphorus (P) supply capacity. The available P supply intensity and crop yields could be enhanced by artificial P fertilizer application. The effects of blending 70% controlled-release phosphorus (CRP) and 30% triple superphosphate (TSP) on cotton physiological-biochemical properties in sodic and saline soils were investigated by a pot incubation trial. A pot experiment was used two types of P fertilizers and three P levels (120, 96 and 72 kg P2O5 ha(-1)). The results showed that the SPAD value and photosynthetic rate of BBF (blending 70% CRP and 30% TSP) treatments were higher than that of TSP treatments. The root length, root surface area, and root volume of the BBF treatments increased by 10.04% and 5.31%, 3.67% and 6.80%, 3.05% and 13.77% compared to TSP treatments, respectively. In comparison with TSP1 (full-dose of TSP) and TSP2 (to reduce 20% dose of TSP), the average lint yield of BBF1 (full-dose of BBF) and BBF2 (to reduce 20% dose of BBF) were significantly increased by 8.35%, 7.39%, respectively. The phosphorus use efficiency of BBF2 treatment was increased by 16.59%-22.87% compared with TSP2 treatment, with the largest increase range. Furthermore, soil available P content of BBF treatments increased by 4.65%-76.77% compared with TSP treatments from the blooming to maturity stage. In a word, with P fertilization rate reduced by 20%, the combination of two P fertilizers (BBF2 treatment) can achieve high quality and high yield of cotton in sodic and saline soil.