Effects of Different Sowing Methods on Winter Rapeseed (Brassica rapa L.) Growth and Soil Properties in Saline–Alkali Land

A field experiment was conducted in three ecological zones to evaluate the effects of broadcast sowing (BS), drill sowing (DS), and ridge–furrow precision sowing (RFS) on winter rapeseed (Brassica rapa L.) grown in lightly saline–alkaline soils, using two cultivars (L6 and L7). RFS improved soil temperature and soil moisture conditions across the zones. Its warming effect was most pronounced in the JT zone, where soil temperatures at seedling and flowering stages were 9.7% and 10.3% higher than under BS, respectively. RFS also showed a moisture-conservation advantage at regreening, with soil moisture 13.8% and 6.6% higher than under BS and DS, respectively. In addition, RFS reduced soil salinity and increased soil total carbon, available potassium, and ammonium nitrogen contents. Plants under RFS showed higher SPAD values, net photosynthetic rates, and transpiration rates at seedling and regreening stages, along with higher antioxidant enzyme activities and lower MDA accumulation. RFS advanced key phenological stages, improved overwintering survival, and produced the highest yield. Compared with BS and DS, respectively, RFS increased the mean yield of L6 by 11.46% and 6.97%, and that of L7 by 16.02% and 10.52%. Overall, RFS promoted yield formation by improving soil conditions, photosynthetic activity, and stress resistance.