Abstract Background Sowing period has a considerable effect on cotton productivity by regulating the use of thermal resources, but its effect on various soils depth layers has not been properly measured. The current study investigated the impacts of date sowing on cotton yield, cumulative growing degree days (GDD) and soil temperatures using a multi-depth monitoring system. Methods A field study (2022–2024) was chosen to take place in Anyang, Henan Province, China, on the North China Plain, where the climate is that of a temperate continental monsoon. In a randomized block trial, the cotton cultivar CCRI 134 was sown on six different dates; 12 April (S1), 12 May (S6). Mean daily temperature and rainfall during the growing season were 21.9 °C and 656.6 mm in 2022, 23.66 °C and 793.5 mm in 2023, and 23.2 °C and 315.9 mm in 2024. Results Seed cotton yield varied significantly with sowing date, but the optimum differed by year: S3 yielded 3025.9 kg ha⁻¹ in 2022, S5 yielded 3398.5 kg ha⁻¹ in 2023, and S2 yielded 2561.7 kg ha⁻¹ in 2024, compared with 2118.4, 2815.5, and 1506.8 kg ha⁻¹ under S6, respectively. Earlier sowing reduced thermal accumulation under cooler conditions. Soil thermal responses were depth-dependent, with stronger variation in the 0–30 and 30–70 cm layers, while 70–110 cm remained more stable. Conclusions Multi-depth soil temperature monitoring showed that very late sowing should be avoided, and sowing between 18 April and 6 May is the most reliable window for balancing soil heat accumulation and yield.
Khan et al. (Wed,) studied this question.