The Xinjiang cotton-producing region is the main cotton-growing region in China; however, the combination of excessive application but low utilization of fertilizers has restricted its agricultural development. Estimating the balanced nutrient requirements for cotton is essential to increase its yield and nutrient use efficiency. The results from 372 field experiments performed between 1996 and 2019 were used to build a QUEFTS (quantitative evaluation of the fertility of tropical soils) model to investigate relationships between cotton seed yield and nutrient accumulation, with the data from 2017 to 2020 used to validate the model. The results demonstrated that the QUEFTS model predicted a linear relationship between target yield and nutrient uptake until the target yield reached about 60–70% of the potential yield. To produce 1000 kg of seed cotton, 28.3 kg N, 6.1 kg P, and 29.6 kg K were required for cotton, and the corresponding ratio of N, P, and K was 4.64:1:4.85. The corresponding internal efficiencies (IEs) for N, P, and K were 35.4, 163.2, and 33.7 kg/kg, respectively. Field validation indicated that the QUEFTS model could be used to estimate nutrient uptake at a targeted yield and contribute to developing a fertilizer recommendation strategy for Xinjiang cotton production.

This study aimed to optimize the period of drip phosphorus (P) fertilization to increase P migration distance in soil and content in cotton, so as to achieve the coordinated above and belowground growth of cotton plants. A field experiment was conducted to study soil P in response to P application by drip irrigation during different periods of cotton cultivation using diffusive gradients in thin films (DGT) in situ. The root length density, biomass, P content and lint yield of cotton were investigated. Compared with broadcast P fertilization before plowing, drip P fertilization after sowing significantly increased DGT-P and root length density in the top 0–15 cm soil layer, and significantly increased the biomass P content and lint yield of cotton, but reduced the root/shoot ratio. In addition, drip P fertilization at bud stage could also increase the DGT-P and root length density in the top 0–10 cm soil layer compared with the broadcast P fertilization treatment. Our results indicate that drip P fertilization after sowing is an effective method to expand the vertical migration of P in soil, increase the length, density, and P content of shoot, and improve the growth of cotton.

Imbalanced and excessive fertilization leads to low nutrient utilization efficiency and wastage of fertilizer resources in processing tomatoes in Xinjiang. Determining nutrient requirements is vital for devising fertilization strategies that enhance yield, profitability, and environmental sustainability. This study utilized observational data from 181 farms across Xinjiang’s major processing tomato production areas from 2003 to 2023 to explore the relationship between fruit yield and nutrient uptake in aboveground dry matter. The Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model was employed to estimate nutrient requirements. The results indicated that when the target yield reached 60–70% of its potential, nutrient uptake by processing tomatoes increased linearly with fruit yield. To produce 1000 kg of fruit, the aboveground parts required 1.95 kg of nitrogen, 0.33 kg of phosphorus, and 2.28 kg of potassium, reflecting a N:P:K ratio of 1:0.17:1.17. In contrast, during harvesting, alternative plant parts required 1.31 kg of nitrogen, 0.21 kg of phosphorus, and 0.71 kg of potassium, with fruit nutrient uptake rates of 67.3%, 65.6%, and 74.9%, respectively. Field validation showed a strong correlation between the observed and simulated nutrient uptake rates, demonstrating the model’s accuracy in predicting nutrient demands. These findings provide critical insights for developing optimized fertilization strategies to enhance yield and nutrient use efficiency in Xinjiang’s processing tomato production.