Soil Science Faculty, Can Tho University, Can Tho City, Vietnam.
United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan.
PeerJ. 2023 Sep 29;11:e16178. doi: 10.7717/peerj.16178. eCollection 2023.
To grow fruit plants, farmers in the Vietnamese Mekong Delta (VMD) must use raised bed constructions to avoid waterlogging during the rainy season. This study aimed to evaluate the effects of the age of the raised beds on the soil physicochemical properties of longan orchards located in the VMD. Two raised bed systems were evaluated: a young bed constructed 10 years ago and an old bed constructed 42 years ago. Soil samples were collected from five different soil layers (0-20, 20-40, 40-60, 60-80, and 80-100 cm) with four replicates per layer. Soil samples were tested for pH, electrical conductivity (EC), available phosphorus (AP), total nitrogen (TN), soil organic matter (SOM), exchangeable cations (Ca, K, Mg, and Na), cation exchange capacity (CEC), bulk density (BD), soil porosity, available water-holding capacity (AWC), particle composition (sand, silt, and clay), and size. The soil pH was approximately 1.0 units lower in the old bed compared to the young bed at depths of 0-20 and 20-40 cm. The BD was higher in the old bed (0.15 g cm) than in the young bed at a soil depth of 0.4 m. SOM, AP, exchangeable cations (Ca, Na, and Mg), AWC, and soil porosity were significantly lower in both the topsoil (0-20 cm) and subsoil (20-40 cm) layers in the old bed than in the young bed. In particular, the SOM, AP, AWC, and soil porosity contents in the old bed decreased by 18%, 20%, 15%, and 17%, respectively, compared with those in the young bed at soil depths of 0-40 cm. Therefore, cultivating raised bed soil for a longer period significantly reduced the soil exchangeable cations, porosity, and fertility of the surface and subsurface soils. Based on these results, farmers should use soil conservation practices, such as cover crops, rice straw mulching, and soil amendments in their orchards to mitigate topsoil degradation.
为了种植水果植物，越南湄公河三角洲（VMD）的农民必须使用抬高床结构来避免雨季积水。本研究旨在评估抬高床的年龄对 VMD 地区龙眼果园土壤物理化学性质的影响。评估了两种抬高床系统：一个 10 年前建造的年轻床和一个 42 年前建造的旧床。从五个不同土层（0-20、20-40、40-60、60-80 和 80-100 cm）采集土壤样本，每个土层采集四个重复样本。对土壤样本进行 pH 值、电导率（EC）、有效磷（AP）、总氮（TN）、土壤有机质（SOM）、可交换阳离子（Ca、K、Mg 和 Na）、阳离子交换容量（CEC）、体密度（BD）、土壤孔隙度、有效持水量（AWC）、颗粒组成（砂、粉砂和粘土）和粒径进行测试。在 0-20 和 20-40 cm 深度处，旧床的土壤 pH 值比年轻床低约 1.0 个单位。在 0.4 m 深的土壤中，旧床的 BD（0.15 g cm）高于年轻床。在表土（0-20 cm）和底土（20-40 cm）中，旧床的 SOM、AP、可交换阳离子（Ca、Na 和 Mg）、AWC 和土壤孔隙度均明显低于年轻床。特别是在 0-40 cm 深的土壤中，旧床的 SOM、AP、AWC 和土壤孔隙度分别比年轻床低 18%、20%、15%和 17%。因此，较长时间的抬高床土壤栽培显著降低了表层和次表层土壤的可交换阳离子、孔隙度和肥力。根据这些结果，农民应在果园中采用土壤保持措施，如覆盖作物、稻秸覆盖和土壤改良剂，以减轻表土退化。
