Soil and Groundwater Investigation for Sustainable Agricultural Development: A Case Study from Brunei Darussalam

Siti Lieyana Azffri,Salwana Md Jaafar,Md Faizan Ibrahim,Mario Schirmer,Stefan Herwig Gödeke,Azimatul Azaman,Rahayu Sukmaria Sukri

doi:10.3390/su14031388

Abstract

Brunei has made significant progress in agricultural development over the past four decades. However, crop production, such as rice, is still insufficient to meet the demands of the growing population, mainly due to the scarcity of water resources, acidic soils, and advancing environmental deterioration. This study conducted soil and groundwater investigations at three selected rice cultivation sites in Brunei Darussalam. The geoelectrical resistivity method using the vertical electrical sounding (VES) technique delineated subsurface stratigraphy with resistivities ranging from 1 to 180 Ωm in the investigated area. A potential aquifer zone was inferred in one of the surveyed areas with resistivities ranging from 10 to 150 Ωm at depths of about 40 to 60 m below ground level. Groundwater levels were also shallower in irrigated sites compared to non-irrigated sites. Groundwater physicochemical properties revealed high alkalinity and mineralisation, as evident from high magnesium, bicarbonate, ammoniacal nitrogen, and iron, as well as pH values in the water samples, believed to be the effects of leaching of salt ions into the shallow aquifer through infiltration recharge. In addition, soil physicochemical properties showed that the soils near a pumping well were more acidic, had lower moisture, and total nutrients, likely due to the effects of groundwater pumping. Our results demonstrate that future irrigation activities need to consider local aquifer characteristics, groundwater flow paths, and nutrient transport to ensure sustainable development in agricultural areas.

Highlights

IntroductionThe agricultural sector is responsible for more than 70% of water withdrawal from rivers, lakes, and groundwater, significantly for irrigation purposes [1]
A potential aquifer zone was detected at site-3 at depths of about 40 to 60 m from the surface, with resistivities ranging from 10 to
Groundwater levels were shallower in irrigated fields compared to non-irrigated fields, suggesting that surface irrigation may be a significant source of recharge to the nearby groundwater, especially during the irrigation seasons

Summary

Introduction

The agricultural sector is responsible for more than 70% of water withdrawal from rivers, lakes, and groundwater, significantly for irrigation purposes [1]. Groundwater, in particular, is a vital source of freshwater, especially when surface water sources have been depleted or rainfall is insufficient. Countries such as the USA, China, India, Iran, and Pakistan account for more than 60% of groundwater abstracted each year worldwide [2]. Groundwater can provide a renewable source of water that farmers can use to the extent permitted by its quality and quantity. In many food-producing regions, excessive groundwater abstraction and climate change have led to a significant decline in groundwater levels, depletion of

Methods

Results

Discussion

Conclusion