Ma Yao, Cao Bin, Wang Xiaojia, Chen Weijun
School of Forestry and Pratacultural, Ningxia University, China.
Ningxia Technical College of Wine and Desertification Prevention, Yinchuan, Ningxia, China.
PeerJ. 2025 Feb 7;13:e18710. doi: 10.7717/peerj.18710. eCollection 2025.
The cultivation of Lingwu jujube traditionally employs clean tillage, leaving substantial gaps between rows and exposing almost 60% of the orchard to the elements. This method promotes rapid soil moisture evaporation, exacerbates soil erosion, and deteriorates the soil's physicochemical properties. Consequently, there is a critical need for a more sustainable planting approach that optimally utilizes land resources. A pertinent question is whether varying densities of ryegrass intercropping can improve the uptake of nutrients and water by the jujube tree, the primary species in this ecosystem. In this context, a 2-year field experiment was conducted with three densities of perennial ryegrass intercropped with Lingwu jujube. The experiment assessed the impact on soil's physical and chemical attributes beneath the jujube canopy, with a focus on correlating soil moisture, enzyme activity, and physical properties. The findings reveal that intercropping at a medium density most effectively enhanced the soil's physical characteristics. Relative to monoculture, this approach increased the proportion of water-stable aggregates (0.5-0.25 mm) by 4.16%, decreased the soil's fractal dimension by 0.46%, augmented the field water holding capacity by 14.78%, and significantly boosted soil enzyme activity. Furthermore, high-density ryegrass intercropping elevated the soil's organic matter content by 36.09% and ameliorated both the pH and cation exchange capacity. Conversely, low-density intercropping raised soil moisture levels by 40.18% in the top 20 cm of the soil. Collectively, these results suggest that an optimal density of ryegrass in intercropping not only bolsters the moisture retention capabilities of soil in Lingwu jujube orchards but also enhances overall soil fertility. Therefore, the adoption of ryegrass and jujube tree intercropping is highly advisable in the ecologically sensitive and resource-constrained arid sandy regions of northern China, offering substantial practical benefits.
灵武长枣的传统种植方式采用清耕法，行距之间存在较大间隙，近60%的果园暴露在外。这种方法促进了土壤水分的快速蒸发，加剧了土壤侵蚀，并使土壤的理化性质恶化。因此，迫切需要一种更可持续的种植方法，以优化土地资源的利用。一个相关的问题是，不同密度的黑麦草间作是否能提高枣（该生态系统中的主要物种）对养分和水分的吸收。在此背景下，进行了一项为期两年的田间试验，将三种密度的多年生黑麦草与灵武长枣间作。该试验评估了对枣树冠层下土壤物理和化学属性的影响，重点是关联土壤水分、酶活性和物理性质。研究结果表明，中等密度间作最有效地改善了土壤的物理特性。与单作相比，这种方法使水稳性团聚体（0.5 - 0.25毫米）的比例提高了4.16%，土壤分形维数降低了0.46%，田间持水量提高了14.78%，并显著提高了土壤酶活性。此外，高密度黑麦草间作使土壤有机质含量提高了36.09%，并改善了土壤pH值和阳离子交换容量。相反，低密度间作使土壤表层20厘米处的土壤水分含量提高了40.18%。总体而言，这些结果表明，间作中黑麦草的最佳密度不仅增强了灵武长枣果园土壤的保水能力，还提高了整体土壤肥力。因此，在中国北方生态敏感和资源有限的干旱沙区，采用黑麦草与枣树间作非常可取，具有显著的实际效益。
