Objectives This study evaluated the effects of single-basal application of controlled-release nitrogen (N) fertilizer and drip fertigation on soil N leaching, soybean growth, and N nutrition, and compared the differential responses of soybean cultivars in terms of growth, nodule enzyme activity, and yield components under the two technologies.

Methods A field experiment was conducted in Shangqiu, Henan Province in 2023, using two summer soybean cultivars ‘Zhonghuang 301’ and ‘Zheng 1307’ as the test materials. Three fertilization treatments were set up: conventional fertilization (CF), single-basal application of controlled-release N fertilizer (C_RNF), and drip fertigation (DF). At the seedling (V6), full flowering (R2), seed-filling (R6), and harvest stages (R8), soil samples from the 0−60 cm profile at 10 cm intervals were collected to determine ammonium-N and nitrate-N contents. Soybean plant samples were collected to measure plant height, dry matter accumulation in above- and under-ground parts, and nodule enzyme activity. Yield and yield components were determined at harvest. Redundancy analysis was conducted to identify the key factors closely related to the yield of soybean cultivars.

Results 1) For Zhonghuang 301, the C_RNF treatment significantly reduced ammonium-N contents in all soil layers during the V6−R6 stages compared with CF treatment, whereas DF treatment significantly reduced ammonium-N contents during the R6−R8 stages. For Zheng 1307, both C_RNF and DF treatments reduced nitrate-N contents below the 40 cm soil layer. 2) For Zhonghuang 301, above-ground dry matter under C_RNF and DF treatment increased by 95.40% and 71.06% at the R2 stage, and by 12.82% and 26.41% at the R6 stage, respectively, compared with CF. For Zheng 1307, above-ground dry matter under DF increased significantly by 45.45% and 51.04% at the V6 stage, 19.02% and 21.71% at the R2 stage, 13.63% and 12.16% at the R6 stage, and 12.91% and 20.79% at the R8 stage, respectively, compared with CF and C_RNF. The responses of nodule enzyme activity to N treatments differed significantly between the two cultivars. No significant differences were observed among treatments for Zhonghuang 301, whereas that of Zheng 1307 under C_RNF and DF treatments were 33.19% and 59.65% higher than that under CF treatment. 3) Yield responses to C_RNF and DF treatments differed significantly between cultivars. Compared with CF, DF treatment increased the yield of Zhonghuang 301 by 26.80%; C_RNF and DF treatment increased the yield of Zheng 1307 by 9.50% and 18.50%, respectively.

Conclusions Both single-basal application of controlled-release N fertilizer and drip fertigation reduced nitrogen accumulation in deep soil layers during the early soybean growth stage, thereby decreasing the risk of N leaching and alleviating the “nitrogen suppression” phenomenon. These treatments also enhanced nodule enzyme activity at the full flowering stage, ensured N supply during the late growth stage, promoted dry matter accumulation, and ultimately increased yield. Drip fertigation performs better than single-basal application of controlled-release N fertilizer as its significant effect on both cultivars, while single-basal application of controlled-release N fertilizer merely showed promotion on cultivar Zheng 1307.