Topsoil Bacterial Community Changes and Nutrient Dynamics Under Cereal Based Climate-Smart Agri-Food Systems

Abstract

Soil microorganisms play a critical role in soil biogeochemical processes, nutrient cycling, and resilience of agri-food systems and are immensely influenced by agronomic management practices. Understanding soil bacterial community and nutrient dynamics under contrasting management practices is of utmost importance for building climatesmart agri-food systems. Soil samples were collected at 0-15 cm soil depth from six management scenarios in long-term conservation agriculture (CA) and climatesmart agriculture (CSA) practices. These scenarios (Sc) involved; ScI-conventional tillage based rice-wheat rotation, ScII-partial CA based rice-wheat-mungbean, ScIII-partial CSA based rice-wheat-mungbean, ScIV is partial CSA based maize-wheat-mungbean, ScV and ScVI are CSA based scenarios, were similar to ScIII and ScIV respectively, layered with precision water & nutrient management. The sequencing of soil DNA results revealed that across the six scenarios, a total of forty bacterial phyla were observed, with Proteobacteria as dominant in all scenarios, followed by Acidobacteria and Actinobacteria. The relative abundance of Proteobacteria was 29% higher in ricebased CSA scenarios (ScIII and ScV) and 16% higher in maize-based CSA scenarios (ScIV and ScVI) compared to conventional-till practice (ScI). The relative abundance of Acidobacteria and Actinobacteria was respectively 29% and 91% higher in CT than CSA based rice and 27% and 110% higher than maize-based scenarios. Some taxa are present relatively in very low abundance or exclusively in some scenarios, but these might play important roles there. Three phyla are exclusively present in ScI and ScII i.e., Spirochaetes, Thermi, and Euryarchaeota. Shannon diversity index was 11% higher in CT compared to CSA scenarios. Maize based CSA scenarios recorded higher diversity indices than rice-based CSA scenarios. Similar to changes in soil bacterial community, the nutrient dynamics among the different scenarios also varied significantly. After nine years of continuous cropping, the soil organic carbon was improved by 111% and 31% in CSA and CA scenarios over the CT scenario. Similarly, the available

Long‐term conservation agriculture helps in the reclamation of sodic soils in major agri‐food systems

“…As a result, CaCO 3 , as well as IC concentration reduced and soil pH and ESP, decreased through natural reclamation of sodic soils. In CA‐based management, a higher fungal and bacterial population and higher abundance of copiotrophs resulted in the accelerated crop residue decomposition (Choudhary et al, 2020; Choudhary, Datta, et al, 2018; Choudhary, Jat, et al, 2018; Choudhary, Sharma, et al, 2018). Kim et al (2020) observed increased CaCO 3 dissolution due to increased soil water storage and transport resulting from agricultural management such as crop cultivation.…”

Climate-smart agricultural practices influence the fungal communities and soil properties under major agri-food systems

“…The treatments are described as scenarios because they are varied in multiple indicators, namely, tillage, crop establishment, residue management, irrigation management, system intensification, etc. Initially, the experiment started with four scenarios, and later on, in 2016, two more scenarios (ScV and ScVI) were added (Choudhary et al, 2020 ; Jat et al, 2021b ) with minor changes in ScIII and ScIV, and only irrigation management was precise (subsurface drip irrigation was used instead of border irrigation). The details of all the scenarios along with their management practices are presented in Table 1 .…”

“…To adapt to extreme events and to manage natural resources, climate-smart agriculture (CSA)-based management practices on the principles of conservation agriculture (CA) (zero tillage, residue retention, and crop rotation) and mitigation co-benefits may prove an excellent option for conventional agriculture to maintain the sustainability of soil and cropping system. In CSA practices, the conventional management practices switch over to resource-conserving management practices by layering with zero/no-tillage, residue retention/incorporation, crop diversification, precise irrigation water, and nutrient management practices to sustain soil and farm productivity and environmental quality (Choudhary et al, 2020 ). In CSA, residues are managed through retention or incorporation, which are burnt by the farmers under conventional management practices.…”

Integrated-Smart Agriculture: Contexts and Assumptions for a Broader Concept

“…In this perspective, this part will be structured in the following subsections: environmental impacts and climate change; new technologies and approaches; food supply and security; farming systems and crop management; multifunctionality and agricultural/rural development. [2] The new technologies and approaches are not exempt of risks and vulnerabilities [40] CSA approach is a promising solution for the sustainability [41] Some studies use the terminology of Environment-Smart Agriculture (ESA) [19] CSA is a concept presented by FAO in 2010, is known as the "triple win" approach [42] CSA practices improve the soil resilience and quality [43] The Internet of Things (IoT) and the Internet of Everything (IoE) may bring relevant added value for the farms [44] The wireless sensor network is an interesting tool to collect data [45] The biosensors are other techniques to collect information [46] Mobile applications, big data analytics and information systems, cloud computing, drones, blockchain, artificial intelligence [47] An efficient use of the agriculture resources, such as water, soil and energy, is crucial for competitiveness and food and security [48] Agriculture is one of the most vulnerable sectors to the global warming [49] The agricultural sector contributes with about a third of the anthropogenic GHG emissions worldwide [50] The eco-efficiency is the buzzword for the sustainability [51] The rice-wheat cropping systems concern particularly the researchers specifically in South Asia [52] Africa is another world region where it is important to promote cleaner farming systems [53] Sometimes the sustainable practices are misunderstood in these countries [54] In other cases and contexts there is not a convergent view about the CSA practices [20] CSA concept has a narrow perspective about the current farming contexts and a wider debate is needed [55] Rural development may benefit from the concept of smart villages [56] Sometimes is easier to convince the entrepreneurs than the policymakers [57] For an effective CSA implementation the farmers should be involved in the policy design process [58] Vocational training and the extension services may contribute for the adoption of the CSA practices [59] The European Union invested over the last years a significant part of its budget to promote CSA practices…”

“…In these frameworks, the energy management, in an efficient way [71], is critical [72], as well as the soil use [73]. CSA practices improve the soil resilience and quality [42]. Nonetheless, for the policy and planning design, it is important to find metrics that allow to put together the three aims [74] and to bring more insights about this concept [75].…”