Field Crop 2024, Vol.7, No.3, 145-157 http://cropscipublisher.com/index.php/fc 149 4.4 Impact on local flora and fauna Different rice cultivation systems impact local flora and fauna differently. Lowland rice fields, with their high water and pesticide use, have the most significant negative impact on human health and freshwater ecotoxicity. The use of biochar and wood vinegar has been shown to mitigate these impacts by reducing N2O and CH4 emissions and improving soil health (Feng et al., 2020). 4.5 Pesticide and fertilizer impact Pesticide and fertilizer use in rice cultivation systems have varying environmental impacts. Lowland rice fields have the highest pesticide residues, including chlorpyrifos and glyphosate, which are harmful to both human health and the environment (Toolkiattiwong et al., 2023). Integrated nutrient management, combining inorganic fertilizers with organic amendments like Azolla compost, can enhance soil carbon storage and reduce the global warming potential, although it may increase CH4 emissions (Bharali et al., 2018). The co-application of wood vinegar and biochar has also been effective in reducing GHG emissions and improving rice yield (Feng et al., 2020). In summary, the comparative analysis of different rice cultivation systems highlights the trade-offs between water use, soil health, greenhouse gas emissions, and environmental impacts. Effective management practices, such as water-saving irrigation, reduced tillage, and integrated nutrient management, can mitigate these impacts and promote sustainable rice cultivation. 5 Case Studies 5.1 Case study of traditional paddy cultivation Traditional paddy cultivation, often referred to as conventional transplanting of rice (CTF), involves the flooding of fields and transplanting seedlings. This method has been widely practiced due to its simplicity and effectiveness in weed control. However, it is associated with high water usage and significant greenhouse gas (GHG) emissions, particularly methane (CH4) (Nirmala et al., 2021; Kumar et al., 2023). Studies have shown that traditional paddy fields can emit substantial amounts of CH4 due to anaerobic conditions created by continuous flooding (Li et al., 2019). Additionally, the conventional method has been found to have lower water productivity and soil microbial activity compared to more modern techniques. 5.2 Case study of system of rice intensification (SRI) The system of rice intensification (SRI) is an innovative method that aims to increase rice yields while reducing water usage and environmental impact. SRI involves planting fewer seedlings, maintaining soil aeration through intermittent drying, and using organic fertilizers. Research in India has demonstrated that SRI can significantly enhance grain yield, water productivity, and soil health compared to traditional methods (Figure 2) (Nirmala et al., 2021). SRI has also been shown to reduce GHG emissions by 21% compared to conventional methods, making it a more environmentally friendly option (Kumar et al., 2023). Furthermore, SRI management has been associated with higher soil microbial populations and beneficial nematodes, contributing to improved soil health. The research of system of Mallareddy et al. (2023) shows that rice intensification (SRI) demonstrates notable advantages in water-saving rice production methods. SRI achieves 20-40% water savings, making it efficient in water use. It maintains low percolation rates and effectively controls weed growth compared to other methods. SRI is suitable for a variety of soil types, particularly loamy to clay soils, and operates well in irrigated ecosystems. In terms of environmental impact, SRI shows low emissions of both methane (CH₄) and nitrous oxide (N₂O), contributing to a reduced global warming potential (GWP). The irrigation strategy involves maintaining soil moisture in field capacity, with an irrigation depth of less than 5 cm, which helps in conserving water. Additionally, SRI is characterized by low energy input and cost, making it a sustainable and economical choice for farmers. The method also has low labor requirements, further enhancing its practicality and attractiveness as a water-saving rice cultivation practice.
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