A big threat to the farm sector

When envisioning pollution, the stark image of towering cylindrical structures belching dark, noxious smoke into the sky often comes to mind—a reality frequently seen in Nepal’s urban landscapes. This portrayal isn't far from the truth, especially with the prevalence of brick kilns, primarily concentrated in the Tarai region and urban centers like the Kathmandu Valley.

Bricks are an indispensable element in construction and various infrastructure projects. The brick industry is burgeoning due to escalating demand from the expanding urban populace and the reconstruction efforts following earthquakes. As per reports by World bank in 2020, Nepal has approximately 1,600 brick kilns that churn out a staggering 5bn bricks annually. Unfortunately, these kilns also pose a severe environmental threat, contributing substantially to pollution. They release about 1.80m tons of carbon dioxide, 302,200 tons of carbon monoxide, 23,300 tons of particulate matter, 15,500 tons of sulfur dioxide, and 6,000 tons of black carbon into the atmosphere.

The impact, however, extends beyond air pollution, sparking concerns about its impact on soil quality and the crops cultivated therein. The fly ash, a byproduct of brick kilns, disperses as an ash slurry onto nearby lands, water bodies, and vegetation, inevitably diminishing soil fertility and reducing crop productivity. 

Moreover, the geographic positioning of brick kilns poses an additional problem. They’re often situated in the midst of highly productive agricultural lands due to their necessity for quality clayey, silty, and loamy soil, resulting in the extraction of fertile topsoil for brick production, rendering the land even less productive.

The loss of soil fertility presents a significant threat to sustainable agriculture. The soil’s pH plays a crucial role in nutrient availability for crops, ideally ranging between 6.5 and 7.5. However, the proximity of brick kilns causes soil acidification due to coal burning and the release of substantial amounts of sulfur dioxide gas, which, upon combining with water, creates sulfuric acid, lowering the pH. Furthermore, the soil's capacity to retain water diminishes, degrading its quality, while organic carbon, pivotal for soil structure, aeration, water retention, and nutrient supply to plants, also declines in the land near the brick kiln than at the far distance from the various research study conducted in South Asia. The bedrock of crop development hinges on the presence of essential nutrients, notably Nitrogen. However, the emissions discharged from brick kilns disrupt the nitrogen cycle, fluctuating the soil nitrification process. This disruption results in a drastic decline in soil fertility and nutrient levels.

Concurrently, a major concern emerges from the toxicity stemming from heavy metal contamination, particularly arsenic, mercury, chromium, and iron. These metals degrade soil quality, significantly diminishing microbial diversity, and ultimately undermining the overall soil health.

The repercussions extend beyond soil degradation, exerting a direct impact on crops. Depositions such as fly ash, sulfur dioxide, and nitrous oxide settle on leaves, reducing the interception of incident light and causing the clogging of stomata. In addition, heavy metal deposition—cadmium, mercury, and lead—has been detected in crops in close proximity to brick kilns, rendering them hazardous for human consumption.

Advocating for the mitigation of brick kiln emissions and their impact on agricultural lands, especially during the peak brick production period from November to May, is imperative due to the heightened intensity of emissions during this time. This period witnessed a surge in brick production to meet the escalating demand for construction materials, exacerbating the environmental and agricultural implications. It is crucial to address this issue now to safeguard Nepal's agricultural landscape and ensure the well-being of its farming communities amidst this crucial production phase. In the context of Nepal, scant research has delved into the impact of brick kiln emissions on agricultural soil quality, and none have scrutinized the impact on crops. Most studies have concentrated solely on the environmental impact of brick kiln emissions, primarily within the Kathmandu Valley, thereby leaving a conspicuous void. Assessing the current hazardous levels in soil quality and heavy metal concentrations in surface soil, assessing their deleterious impacts on crops, and formulating a comprehensive mitigation strategy are areas to dwell upon in future. Acknowledging the far-reaching impact of brick kiln emissions, strict regulation, meticulous monitoring, and further research are imperative to quantify their impact on agricultural crops and soils. Policymakers must act decisively to regulate the establishment of brick kiln industries for conservation of agricultural lands. The need for policy-level development cannot be overstated in ensuring the protection and sustenance of Nepal’s agricultural landscape.