| Water\|nitrogen coupling dynamics under salt leaching during growth stages in saline\|alkali cotton fields |
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| DOI：10.7606/j.issn.1000-7601.2025.03.07 |
| Key Words: cotton salt leaching water\|nitrogen coupling irrigation amount nitrogen agronomic efficiency |
| Author Name | Affiliation | | REN Zhiwen | Key Laboratory of Agricultural Soil and Water Engineering in Arid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China | | CAO Hongxia | Key Laboratory of Agricultural Soil and Water Engineering in Arid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China | | HU Qingyang | Key Laboratory of Agricultural Soil and Water Engineering in Arid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China | | QI Chen | Key Laboratory of Agricultural Soil and Water Engineering in Arid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China | | LI Zhijun | Key Laboratory of Agricultural Soil and Water Engineering in Arid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China |
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| Abstract: |
| To improve the soil water and salt conditions in saline\|alkali cotton fields, as well as to increase seed cotton yield and enhance water and nitrogen utilization efficiency, a cotton leaching experiment with varying irrigation and nitrogen application rates was conducted in 2023. A complete factorial design was used, consisting of three irrigation levels (W1: 1.0 ETc, W2: 1.25 ETc, W3: 1.5 ETc) and four nitrogen application rates (N1: 0 kg·hm-2, N2: 100 kg·hm-2, N3: 200 kg·hm-2, N4: 300 kg·hm-2). The findings indicated that an increase in irrigation flushing rate lowered soil salt content within the rows while raising it between them. The combination of high water and high nitrogen (W3N4 treatment) led to excessive vegetative growth and delayed maturity of cotton plants, intensifying nutrient competition between leaves and bolls which ultimately reduced seed cotton yield. Conversely, optimal flushing fertilization (W2N4 treatment) effectively decreased soil salt concentration in the root zone while enhancing leaf area index and effective boll number during both boll initiation and blooming phases, which resulted in increased dry matter accumulation as well as seed cotton yield. Furthermore, a bivariate quadratic regression model was developed to analyze the relationship between irrigation volume, nitrogen application rate, seed cotton yield, and nitrogen agronomic utilization efficiency. Single\|factor analysis revealed that seed cotton yield initially increased before declining with rising irrigation volume but consistently increased alongside higher nitrogen application rates. Similarly, the nitrogen agronomic utilization efficiency exhibited an initial increase followed by a decrease as both irrigation volume and nitrogen application rate escalated. Two\|factor interaction analysis demonstrated that both seed cotton yield and nitrogen agronomic utilization efficiency first rose then fell with increases in these variables’ levels; notably, the effect of irrigation volume on these outcomes surpassed that of nitrogen application rate. Based on the insights from this regression model, an optimal strategy for managing salt levels while maximizing seed cotton yield through appropriate irrigation practices is proposed. The model was used to optimize irrigation, fertilization, and salt control strategies for seed cotton yield and nitrogen agronomic efficiency. The recommended irrigation level ranges from 1.14 to 1.30 ETc, with a nitrogen application rate of 171 to 228 kg·hm-2. |
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