● In low-salinity soil, straw-returning did not change necromass contribution to SOC.

Salinization affects microbial-mediated soil organic carbon (SOC) dynamics. However, the mechanisms of SOC accumulation under agricultural management practices in salt-affected soils remain unclear. We investigated the relative contribution of microbial-derived and plant-derived C to SOC accumulation in coastal salt-affected soils under straw-returning, by determining microbial necromass biomarkers (amino sugars) and particulate organic C (POC). Results showed that, straw-returning increased necromass accumulation in low-salinity soil but did not change its contribution to SOC. In medium-salinity soil, straw-returning did not increase necromass accumulation but decreased its contribution to SOC. In low- and medium-salinity soils, the contribution of POC to SOC showed the opposite direction to that of the necromass. These results suggest that under straw-returning, the relative contribution of microbial-derived C to SOC decreased with increasing salinity, whereas the reverse was true for plant-derived C. Our results highlighted that straw-returning reduces the contribution of microbial anabolism to SOC accumulation in salt-affected soils with increasing salinity.

● Land use type affects the physicochemical properties of soil.

Soil fertility is affected by land-use types and land management, which exacerbates soil erosion and various other forms of soil degradation in the mountainous regions of Vietnam. This study was conducted in A Luoi District, Thua Thien Hue, Vietnam to identify the effects of land-use types on specific soil physicochemical characteristics related to soil fertility. Soil physicochemical properties, such as organic matter (OM), total nitrogen (TN), total phosphorous (TP), and K⁺ were significantly affected by land-use type. The results showed that the soils were sandy in rice but clay loam for acacia and cassava. The mean bulk density value of acacia soil was significantly greater than that of other soils. TN were higher in the acacia soils than those in the rice, maize, and banana soils. The OM content was significantly higher in the acacia, cassava, and banana soils than those in the rice and maize soils. The mean of exchangeable K⁺ in the rice soil was higher compared to those in other soils and was affected by land-use type. The high exchangeable acidity content in the soils was probably due to intensive precipitation. However, both land use type and management did not affect the CEC value. Overall, the inappropriate land use caused the disturbance of soil physicochemical properties, indicating that the conditions of rice and maize soils are becoming worse than acacia soils. Therefore, lowering the intensity of cultivation, adopting incorporated soil fertility management, and applying organic fertilizer should preserve the existing conditions and enhance soil properties.

• Resource-conservation practices are emerging for attaining sustainability in agriculture.

Besides contributing majorly in the growth of a country, agriculture is one of the severely affected sectors at present. Several modifications and adaptations are being made in agricultural practices to cope-up with the declining soil fertility and changing climate scenarios across the world. However, the development and adoption of a single agricultural practice may not help in the holistic mitigation of the impacts of climate change and may result in economic vulnerability to farmers. Therefore, it is high time to develop and recommend a group of agricultural practices i.e. package-based agriculture system having some compatibility for one another in the long term. In this article, a viewpoint has been given on some emergent agronomic practices adopted in the tropical agro-ecosystems which have potential to be developed as compatible agricultural package in combination. Moreover, we also emphasized on exploring some key indicators/environmental factors to assess the compatibility of different agronomic practices. For identifying the research transition from single to combined agricultural practices, a bibliometric analysis was performed by using conservation agriculture (CA), the system of rice intensification (SRI), organic agriculture and soil (biochar) amendment as the major agronomic practices being used for improving agro-ecological services such as improving nutrient cycling, soil fertility and crop productivity as well as climate change mitigation. The results revealed that scientific communities are now paying attention to exploring the role of combined agricultural practices for agro-ecological balance and climate change adaptation. Moreover, the limitations of the adoption of agronomic packages under different agro-climatic zones have also been highlighted. The recommendations of the study would further help the environmental decision-makers to develop potential measures for climate change mitigation without compromising the agro-ecological balance.

The soil microbial carbon pump (MCP) conceptualizes a sequestration mechanism based on the process of microbial production of a set of new organic compounds, which carry the carbon from plant, through microbial anabolism, and enter into soil where it can be stabilized by the entombing effect. Understanding soil MCP and its related entombing effect is essential to the stewardship of ecosystem services, provided by microbial necromass in the formation and stabilization of soil organic matter as well as its resilience and vulnerability to global change. The mechanism and appraisal of soil MCP, however, remain to be elucidated. This lack of knowledge hampers the improvement of climate models and the development of land use policies. Here, I overview available knowledge to provide insights on the nature of the soil MCP in the context of two main aspects, i.e., internal features and external constraints that mechanistically influence the soil MCP operation and ultimately influence microbial necromass dynamics. The approach of biomarker amino sugars for investigation of microbial necromass and the methodological limitations are discussed. Finally, I am eager to call new investigations to obtain empirical data in soil microbial necromass research area, which urgently awaits synthesized quantitative and modeling studies to relate to soil carbon cycling and climate change.