Long-term conservation tillage and straw incorporation are reported to improve the soil health, growth, and yield traits of crops; however, little is known regarding the optimal nitrogen (N) supply under conservation tillage with straw incorporation. The present study evaluated the effects of conservation tillage practices (ZTsas: zero tillage plus wheat straw on the soil surface as such, and MTsi: minimum tillage plus wheat straw incorporated) and different N application rates (50, 100, 150, and 200 kg ha⁻¹) on the yield and quality traits of cotton and soil characteristics in a five-year field experiment. The results showed that ZTsas produced a higher number of bolls per plant, boll weight, seed cotton yield, 100-seed weight, ginning out-turn (GOT), fiber length, and strength than MTsi. Among different N application rates, the maximum number of bolls per plant, boll weight, seed cotton yield, GOT, 100-seed weight, fiber length, strength, and micronaire were recorded at 150 kg N ha⁻¹. Averaged over the years, tillage × N revealed that ZTsas had a higher boll number plant⁻¹, boll weight, 100-seed weight, GOT, fiber length, and strength with N application at 150 kg ha⁻¹, as compared to other tillage systems. Based on the statistical results, there is no significant difference in total soil N and soil organic matter among different N rates. Further, compared to MTsi, ZTsas recorded higher soil organic matter (SOM, 8%), total soil N (TSN, 29%), water-stable aggregates (WSA, 8%), and mean weight diameter (MWD, 28.5%), particularly when the N application of 150 kg ha⁻¹. The fiber fineness showed that ZTsas had no adverse impact on fiber fineness compared with MTsi. These results indicate that ZTsas with 150 kg N ha⁻¹ may be the optimum and most sustainable approach to improve cotton yield and soil quality in the wheat–cotton system.

| Water shortage is becoming a serious concern for all crops and particularly for cotton, which has been a major export contributor of Pakistan. In this scenario, reduced tillage could be the best option. A field experiment was conducted during 2019 to study the impact of two tillage systems [reduced (10 cm depth, one tiller followed by rotavator) and conventional (20 cm depth, including disc plough, cultivator, rotavator, and levelling operations)] and five irrigation intervals (10, 15, 20, 25 and 30 days) on cotton yield and lint percentage. Total irrigation water used in irrigation treatments, 10, 15, 20, 25 and 30 days intervals were 1125, 750, 560, 450 and 360 mm, respectively. Results indicated that reduced tillage had higher plant population (32454), plant height (114.8cm), bolls per plant s (18.9), bolls weight (2.42g), seed cotton yield (1812 kg ha -1 ) and lint percentage (36.72%) than conventional tillage. Likewise, frequent irrigation interval of 10 days produced taller plants compared to less frequent irrigations (20-25 days). Irrigation at 20 days interval improved seed cotton yield (48.7%) and lint %age (21.1%). Interaction effects (tillage x irrigation) revealed that reduced tillage with 20 days irrigation interval conserved 60 % more water, produced 60.4% more bolls per plant, 45.8 % heavier boll weight, 21.1% higher lint %age and 41.6% higher seed cotton yield compared to all other combinations. In conclusion, reduced tillage with 20 days irrigation interval is more advantageous and adaptable in agro-ecological conditions of Dera Ismail Khan.