Pulse crop and organic amendments in cropping system improve soil quality in rice ecology: Evidence from a long–term experiment of 16 years
Chaitanya Prasad Nath, Narendra Kumar, Asik Dutta, Kali Krishna Hazra, C. S. Praharaj, Singam Suranjoy Singh, Krishnashis Das
Abstract
The degraded cultivated soils must be restored urgently in the rice ecologies of South Asia including the Indo-Gangetic Plains (IGP) by using sustainable soil management strategies. Pulse crops are normally used to diversify/intensify cereal systems in different agroecologies. However, the effect of pulse-based crop rotations with integrated nutrient management (INM) on soil quality is rarely contemplated in rice ecologies. The objective was to find out sustainable cropping system involving pulses for enhanced soil quality after 16 years of field experimentation in Inceptisol of Indian IGP. We evaluated four cropping systems (i) rice–wheat, (ii) rice–wheat-mungbean, (iii) rice–wheat-rice-chickpea, (iv) rice-chickpea each with three degrees of soil fertilization techniques (i) unfertilized control (CT), (ii) integrated nutrient management (INM), and (iii) chemical fertilization (RDF). Rice–wheat–mungbean system resulted in an 8 % higher soil quality index (SQI) compared with the rice–wheat (p < 0.05). Also, INM increased by 5 % SQI than the RDF (p < 0.05). Macroaggregated and microaggregated phosphorus content, available sulphur, water-stable macroaggregates, alkaline phosphatase, and water holding capacity came out as the indicators of soil quality after 16 years in the rice ecology. Notably, water holding capacity and alkaline phosphatase contributed 60 % and 11 % of total SQI, irrespective of the treatments. Rice-wheat–mungbean (INM), rice–wheat–rice–chickpea (INM), and rice–chickpea (INM) increased 16–20 % water holding capacity over the rice–wheat (RDF) (p < 0.05). Rice–wheat–mungbean (INM) increased 47.8 % soil organic carbon (SOC) stock (19.6 Mg C ha−1) more than the rice–wheat (RDF) (13.3 Mg C ha−1) (p < 0.05). Pulse-based systems had the higher available nitrogen (8–29 %), phosphorus (3–35 %), and sulphur (3–13 %) over the rice–wheat (p < 0.05). Rice–wheat–mungbean (INM) enhanced (p < 0.05) the soil microbial biomass carbon by 63 %, alkaline phosphatase by 59 %, and β-glucosidase by 61 % over the rice–wheat (RDF). Thus, pulse inclusion in the cropping system and INM can enhance soil quality in the cereal dominating agroecologies over time.