Development of an integrated soil quality index under prolonged green manure application of oilseed radish in crop rotation
Vinnytsia National Agrarian University, Faculty of Agronomy, Horticulture and Plant Protection, Soniachna Street, 3, UA21008 Vinnytsia, Ukraine
Abstract:
Over a 12-year study period, the effectiveness of using intermediate green manuring with oilseed radish (Raphanus sativus L. var. oleiformis Pers.) – applied once every two years – was evaluated under conditions of repeated application in the same field within a crop rotation system (including green manuring of crops such as grain sorghum (Sorghum bicolor L.), pea (Pisum sativum L.), soybean (Glycine max (L.) Merrill), sunflower (Helianthus annuus L.), chickpea (Cicer arietinum L.) and maize (Zea mays L.), with three assessment checkpoints in 2014, 2019, and 2025.
The results showed that the green-manured treatment, averaged across the entire evaluation period, produced positive changes in the physical and chemical soil fertility parameters within the 0–30 cm soil layer compared with the unfertilized control. Increases were observed in humus content (by 24.65%), water absorption capacity (by 30.04%), easily hydrolyzable nitrogen (by 33.67%), available phosphorus (by 25.72%), exchangeable potassium (by 23.10%), and total porosity (by 25.04%). Decreases were recorded in bulk density (by 19.05%), particle density (by 9.95%), soil hardness (by 33.95%), and pH (by 5.60%).
Green manuring also contributed to optimizing the proportion of humic acids in the humus structure by a factor of 1.2 and to achieving a total organic carbon to total nitrogen ratio of 10.36:1, representing an 11.92% increase compared with the control. As a result, the application of green manuring was reflected in an improved integrated Soil Fertility Index, with a value of 0.692 compared with 0.499 in the non-manured control.
Key words:
agro-physical soil properties, agrochemical soil properties, fertilization, soil conservation, soil fertility