Responses of some soil enzymes and cotton plant to foliar application of ferrous sulfate in a calcareous alkaline soil

Abstract

Ferrous sulfate application is important in improvement of agricultural production, elimination of micronutrient deficiencies in human and animal populations, and promotion of sustainable food and feed production. This study was carried out to investigate the effects of different doses of foliar iron sulfate (FeSO4) applications on cotton plant yield and yield components, soil enzyme activity and chlorophyll content (SPAD value) and Normalized Difference Vegetation Index (NDVI) values of cotton plants. The results of both growing periods indicated that 0.4% FeSO4 application dose was more effective than the other doses compared to the control (Co), therefore, the evaluations were carried out based on 0.4% FeSO4 application dose. The application dose increased the cotton yield by 20.53 and 19.08% in the 2020 and 2021 season, respectively. The SPAD value increased by 54.88 and 98.68% in the 2020 and 2021 season. The NDVI values were 0.83 and 0.85 in the 2020 and 2021 seasons, respectively. Soil enzymes responded positively to FeSO4 application. The urease enzyme activity at this application dose varied between 17.81 and 18.76 µg N g−1 dry soil h−1 (13.73 to 26.33% increase compared to Co), and the highest value was recorded in 2021. The Dehydrogenase (DHG) enzyme activity was between 18.38 and 16.05 µg TPF g−1 dry soil 24 h−1 (39.8 and 46.30% increase compared to Co). The Catalase enzyme activity (CAT) was 36.40 and 38.73 ml O2 g−1 dm 5 min−1 in (51.23 and 39.32% compared to control) and the highest value was recorded in 2021. Nitrate Reductase Activity (NRA) was 18.66 and 17.14 µg N g−1 dm 2 h−1 in 2020 and 2021 seasons. The values of NRA were 54.11 and 59.54% lower in 2020 and 2021 seasons compared to the NRA in Co.