Effects of straw incorporation and nitrogen application rates on nutrient uptake and nitrogen use efficiency of rice in saline-alkali soils of Western Jilin Province

To investigate the effects of nitrogen application rates on nutrient uptake and nitrogen use efficiency (NUE) of rice under straw incorporation conditions in the saline-alkali soils of Western Jilin Province, a field experiment was conducted in Baicheng City. A two-factor split-plot design was employed, featuring two straw management treatments: full in-situ autumn incorporation of rice straw with rotary tillage (straw incorporation) and straw removal, along with six nitrogen application levels: 0 kg∙hm⁻²(N0), 120 kg∙hm⁻²(N120), 150 kg∙hm⁻²(N150), 180 kg∙hm⁻²(N180), 210 kg∙hm⁻²(N210), and 240 kg∙hm⁻²(N240). Results show that the content of nitrogen (N), phosphorus (P) and potassium (K) and their accumulation in both stems and grains as well as rice yield are higher under straw incorporation treatment than that of the straw removal treatment. Under both straw management regimes, the N, P, and K contents, and their accumulation in the aboveground parts and rice yield increase initially with the increased nitrogen application rates, with maximum rate of 210 kg∙hm⁻² for straw incorporation treatment and 180 kg∙hm⁻² for straw removal treatment. In addition, straw incorporation significantly improves the partial factor productivity and apparent efficiency of nitrogen fertilizer compared to straw removal. However, the agronomic and physiological utilization efficiencies of nitrogen fertilizer in rice are higher under straw removal compared to straw incorporation. This study demonstrates that based on full straw incorporation via autumn in-situ rotary tillage, the application of 210 kg∙hm⁻² nitrogen fertilizer maximizes nutrient uptake and achieves the highest rice grain yield in saline-alkali soils of Western Jilin Province.