Environmental governance is a challenge for many developing countries, and soil pollution is typically overlooked by authorities in the Global South. Soil governance should protect people and environment from the hazards of pollution and promote sustainable remediation of polluted sites through legislation and soil policies that facilitate the use of appropriate technology. Today, however, the soil governance landscape is highly fragmented and often fails to adequately address these concerns. Combining soil remediation with profitable activities (alone or in combination) such as food and fiber production, biomass energy production, erosion control, carbon sequestration, favoring biodiversity, etc. is potentially an appropriate strategy to promote the decontamination of polluted agriculture soil in low-income countries. Many potential pitfalls follow such a strategy but decision support tools may provide insights from the latest scientific remediation findings to stakeholders in their exploration of policy options. This chapter explores challenges and opportunities for sustainable soil governance in developing countries.
Global sustainability challenges associated with increasing resource demands from a growing population call for resource-efficient land-use strategies that address multiple sustainability issues. Multifunctional agroforestry-based phytoremediation (MAP) is one such strategy that can simultaneously capture carbon, decontaminate soils, and provide diverse incomes for local farmers. Chinandega, Nicaragua, is a densely populated agricultural region with heavily polluted soils. Four different MAP systems scenarios relevant to Chinandega were created and carbon sequestration potentials were calculated using CO2FIX. All scenarios showed the potential to store significantly more carbon than conventional farming practices, ranging from 2.5 to 8.0 Mg CO2eq ha−1 yr−1. Overall, carbon sequestration in crops is relatively small, but results in increased soil organic carbon (SOC), especially in perennials, and the combination of crops and trees provide higher carbon sequestration rates than monoculture. Changes in SOC are crucial for long-term carbon sequestration, here ranging between 0.4 and 0.9 Mg C ha−1 yr−1, with the most given in scenario 4, an alley cropping system with pollarded trees with prunings used as green mulch. The adoption rate of multifunctional strategies providing both commodity and non-commodity outputs, such as carbon sequestration, would likely increase if phytoremediation is included. Well-designed MAP systems could help reduce land-use conflicts, provide healthier soil, act as climate change mitigation, and have positive impacts on local health and economies.
Soil pollution is a threat to food security and ecological and human health. Cd is one of the most common pollutants in agricultural soil and, due its human toxicity, one of the most hazardous. Amaranth is a documented hyperaccumulator of Cd and other pollutants, and it is commonly grown in Asia and South America. A considerable amount of amaranth is grown in suboptimal conditions, including nutrient-poor acidic soils. The objective of this experimental study was to examine the capacity of Amaranthus hypochondriacus to extract Cd from a nutrient-poor, acidic substrate that was spiked with different concentrations of Cd (2 and 20 mg kg−1 dw) during a period of 180 days. The plants grown in the substrate that was spiked with 20 mg Cd kg−1 dw did not develop into mature plants, but the plants grown in substrate that was spiked with 2 mg Cd kg−1 dw extracted a significant amount of Cd from the substrate by accumulating it into the above-ground biomass. The Cd levels varied from 113 to 176 mg kg−1 in the stems at the four measuring points, and from 64 to 94 mg kg−1 in the leaves. The concentrations in the plants increased with time and reached a maximal concentration of 176 ± 45 mg kg−1 dw for stems and 94 ± 41 mg kg−1 dw for leaves after 180 days. The mean bioaccumulation factor in the plants was 86 ± 15 after 90 days, 72 ± 12 after 120 days, 105 ± 37 after 150 days, and 99 ± 31 after 180 days, which confirms the previously reported capacity of Amaranthus hypochondriacus to hyperaccumulate Cd. Amaranthus hypochondriacus may, thus, be used to improve ecological and human health by remediating moderately Cd-polluted soils, even in nutrient-poor acidic soils.
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