A method for regulating water and salt of saline soil by ridge culture combined with ground surface covering

Abstract

This invention relates to the field of agricultural water and soil engineering and ecological environment restoration technology, specifically disclosing a method for water and salt regulation in saline soil using ridge cultivation combined with surface mulching. This invention achieves optimized regulation of soil moisture and salt spatial distribution by constructing a wide-ridge cultivation system and synergistically employing straw mulching. The wide ridges reduce the electrical conductivity of the surface soil in the furrows by 53.89% compared to the ridge tops, creating a low-salt micro-zone conducive to the sowing of salt-tolerant crops. Straw mulching increases the surface moisture content of the ridges by approximately 28% in August, while reducing the surface electrical conductivity by 62.3% in July, effectively alleviating water and salt stress in the ridge root zone. This provides an efficient and operable water and salt synergistic regulation technology solution for coastal saline soil areas.

Description

Technical Field

[0001] This invention relates to the field of agricultural water and soil engineering and ecological environment restoration technology, specifically to a method for water and salt regulation of saline soil using ridge cultivation combined with surface covering. Background Technology

[0002] In coastal saline soil areas such as the Yellow River Delta, ridge tillage has been widely used to regulate soil moisture and salinity. Studies have shown that in coastal areas, ridge tillage (ridge height <15 cm and ridge width <50 cm) can significantly promote salt leaching throughout the soil profile. However, single ridge tillage has limited ability to inhibit soil evaporation. Without long-term auxiliary measures, deep salts tend to rise along capillary tubes and accumulate in the ridges, leading to unstable desalination effects. In addition, its effectiveness is highly dependent on ridge specifications, supporting measures, and local soil and climate conditions. This makes it difficult for existing technologies to form an optimized synergistic regulation strategy for the special conditions of high evaporation and shallow groundwater in coastal saline soils, ultimately resulting in limited salt inhibition in the root zone and low soil water use efficiency. Summary of the Invention

[0003] To address the issues of insufficient salt control capacity and difficulty in coordinated water and salt regulation in coastal saline soils under conditions of high evaporation and shallow groundwater, this invention provides a method for water and salt regulation in saline soils by combining ridge cultivation with surface mulching. By constructing a wide-row ridge cultivation system and coordinating it with straw mulching, the spatial distribution of soil moisture and salt can be optimized, effectively alleviating water and salt stress in the root zone of the ridge bed. This provides an efficient and operable technical solution for coordinated water and salt regulation in coastal saline soil areas.

[0004] This invention provides a method for water and salt regulation in saline soil using a combination of ridge cultivation and surface cover, comprising the following steps: A ridge tillage system is constructed on saline soil, the ridge tillage system comprising adjacent ridges and furrows; Salt management measures are implemented on the surface of the ridges and furrows, and the salt management measures are straw mulching treatment; The ridge top is 55 cm to 65 cm wide, the ridge bottom is 115 cm to 125 cm wide, and the ridge height is 27 cm to 33 cm; the furrow is 55 cm to 65 cm wide.

[0005] This invention addresses the unique conditions of high evaporation and shallow groundwater in coastal saline soils. On one hand, it constructs a ridge-planting structure with specific geometric specifications, utilizing the difference in water potential gradient between the ridges and furrows to drive the directional migration and accumulation of salt from the furrows to the ridge tops, thereby actively creating a significant low-salt planting zone in the furrow area. On the other hand, it introduces straw mulching measures to target the water deficit and salt accumulation problems in the ridge area, effectively improving the water-holding capacity of the ridges by inhibiting evaporation and blocking the upward movement of salt, thus achieving optimized redistribution and synergistic regulation of soil water and salt in different micro-domains.

[0006] Furthermore, the width of the ridge top is 58 cm to 62 cm.

[0007] Furthermore, the width of the ridge bottom is 118 cm to 122 cm.

[0008] Furthermore, the height of the ridge is 29 cm to 31 cm.

[0009] Furthermore, the width of the furrows is 58 cm to 62 cm.

[0010] Furthermore, the straw mulching treatment involves covering the soil surface with straw that is 4.5 cm to 5.5 cm thick.

[0011] Furthermore, the straw mulching treatment lasts for 60 to 90 days.

[0012] Furthermore, the straw is rice straw.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention combines ridge cultivation with surface mulching measures. Through systematic experiments, it verifies the synergistic effect of "ridge cultivation configuration + straw mulching". It solves the problems of insufficient salt control capacity and difficulty in coordinated water and salt regulation in existing technologies when single ridge cultivation is used in coastal saline soil with high evaporation and shallow groundwater conditions. It provides an efficient and operable engineering method for agricultural water and soil management and ecological restoration in coastal saline soil areas.

[0014] This invention, through ridge cultivation configuration (60 cm wide ridge top, 120 cm wide ridge bottom, 30 cm high; 60 cm wide furrow), significantly enhances the spatial redistribution of salt, reducing the surface soil electrical conductivity (EC) in the furrow area by 53.89% compared to the ridge top area, creating a low-salt microenvironment conducive to the sowing and emergence of salt-tolerant crops in the furrow. Ridge cultivation alters the soil moisture distribution pattern, maintaining high moisture content in all soil depths in the furrow, while the surface moisture content of the ridge is relatively low, helping crop roots to obtain water as needed in different micro-topographic units. After applying 5 cm of straw mulch, the soil moisture content in the surface layer (0 cm to 2 cm) of the ridge significantly increased, by approximately 28% in August compared to the uncovered control group. Simultaneously, the surface electrical conductivity of the ridge decreased by 62.3% in July compared to the control group, forming a distinct low-salt zone. This dual regulatory effect significantly improved the inherent water and salt stress in the ridge root zone. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The distribution of soil moisture content at different levels in the profiles in July, August and October under different tillage methods is shown in the figure. In the figure, A is the soil moisture content distribution in July; B is the soil moisture content distribution in August; and C is the soil moisture content distribution in October.

[0017] Figure 2 The spatial distribution of soil moisture content in profiles in July, August, and October is shown for different ridge shapes. In the figure, A represents the spatial distribution of soil moisture content in July for narrow ridges; B represents the spatial distribution of soil moisture content in July for wide ridges; C represents the spatial distribution of soil moisture content in August for narrow ridges; D represents the spatial distribution of soil moisture content in August for wide ridges; E represents the spatial distribution of soil moisture content in October for narrow ridges; and F represents the spatial distribution of soil moisture content in October for wide ridges.

[0018] Figure 3 The distribution of soil electrical conductivity at different levels in the profiles in July, August and October under different tillage methods is shown in the figure. In the figure, A is the soil electrical conductivity distribution in July; B is the soil electrical conductivity distribution in August; and C is the soil electrical conductivity distribution in October.

[0019] Figure 4The spatial distribution of soil electrical conductivity in July, August, and October is shown for different ridge shapes. In the figure, A represents the spatial distribution of soil electrical conductivity in July for narrow ridges; B represents the spatial distribution of soil electrical conductivity in July for wide ridges; C represents the spatial distribution of soil electrical conductivity in August for narrow ridges; D represents the spatial distribution of soil electrical conductivity in August for wide ridges; E represents the spatial distribution of soil electrical conductivity in October for narrow ridges; and F represents the spatial distribution of soil electrical conductivity in October for wide ridges.

[0020] Figure 5 The spatial distribution of soil moisture content in the profile under different salinity management measures is shown in the figure. In the figure, A is the spatial distribution of soil moisture content in the control group in July; B is the spatial distribution of soil moisture content in the surface salt crust removal group in July; C is the spatial distribution of soil moisture content in the rice straw mulch group in July; D is the spatial distribution of soil moisture content in the control group in August; E is the spatial distribution of soil moisture content in the surface salt crust removal group in August; F is the spatial distribution of soil moisture content in the rice straw mulch group in August; G is the spatial distribution of soil moisture content in the control group in October; H is the spatial distribution of soil moisture content in the surface salt crust removal group in October; and I is the spatial distribution of soil moisture content in the rice straw mulch group in October.

[0021] Figure 6 The figures show the spatial distribution of soil electrical conductivity in profiles under different salinity management measures. In the figures, A represents the spatial distribution of soil electrical conductivity in the control group in July; B represents the spatial distribution of soil electrical conductivity in the surface salt crust stripping group in July; C represents the spatial distribution of soil electrical conductivity in the rice straw mulching group in July; D represents the spatial distribution of soil electrical conductivity in the control group in August; E represents the spatial distribution of soil electrical conductivity in the surface salt crust stripping group in August; F represents the spatial distribution of soil electrical conductivity in the rice straw mulching group in August; G represents the spatial distribution of soil electrical conductivity in the control group in October; H represents the spatial distribution of soil electrical conductivity in the surface salt crust stripping group in October; and I represents the spatial distribution of soil electrical conductivity in the rice straw mulching group in October. Detailed Implementation

[0022] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0023] Example 1: A method for water and salt regulation in saline soil using ridge cultivation combined with surface cover.

[0024] I. Experimental Methods 1. Test site In 2023, a field experiment was conducted at the Ludong University Industry-University-Research Integration Modern Agriculture High-Quality Development Base (Dongying Base) in the Yellow River Delta region (37°39′40″~37°39′42″N, 118°55′33″~118°55′35″E). The soil texture in the study area was sandy loam, and both soil salinity and electrical conductivity decreased with increasing depth. The salinity in the surface layer (0 cm to 2 cm) was 30.45±21.54 g / kg, and the electrical conductivity was 9.44±5.90 mS / cm; while in the bottom layer (30 cm to 50 cm), the salinity was 7.02±3.78 g / kg and the electrical conductivity was 2.65±1.34 mS / cm, respectively.

[0025] 2. Experimental Design Two sets of experiments were conducted: one set was used to investigate different ridge (trapezoidal) specifications, and the other set was used to evaluate ridge-based salt management measures.

[0026] Ridge configuration experiment: Three treatment schemes were tested: flat planting (control group, CK), narrow ridge (ridge top width: 30 cm, ridge bottom width: 90 cm, ridge height: 30 cm; furrow width: 30 cm), and wide ridge (ridge top width: 60 cm, ridge bottom width: 120 cm, ridge height: 30 cm; furrow width: 60 cm). Three replicate plots (6 m × 5 m) were set up for each treatment, and standardized agronomic practices were used to reduce confounding variables. Soil samples were collected in July, August, and October 2023 to determine soil salinity and moisture content. Under flat planting conditions, three sampling points were randomly set up in each plot; under ridge planting conditions, three sampling points were set up at the ridge top and two furrows on each side of each plot. The sampling depths were 0 cm–2 cm, 2 cm–10 cm, 10 cm–20 cm, 20 cm–30 cm, 30 cm–50 cm, 50 cm–70 cm, and 70 cm–90 cm, respectively. In addition, topsoil samples of 0 cm to 2 cm were collected along the transverse cross section. The sampling route started from one side of the furrow, passed through the ridge slope and ridge top to the other side of the furrow, in order to analyze the transverse salt distribution pattern of the ridge (i.e., furrow → ridge slope → ridge top → opposite ridge slope → furrow).

[0027] Ridge Cultivation and Salt Management Experiment: Ridge cultivation was implemented using a traditional ridge configuration (ridge top width 30 cm, ridge bottom width 90 cm, ridge height 30 cm). Two surface treatments were implemented under this system: surface salt crust removal (removal of the top 0 cm to 3 cm of salt crust) and rice straw mulching (covering the soil surface with 5 cm thick rice straw). An untreated ridge control group (CK) was also included. All treatments were replicated three times. Salt crust removal was carried out in May, and rice straw mulching was carried out in May and removed in July (simulating farmers removing the mulch themselves before the hottest season). Soil samples were collected in July, August, and October 2023 to determine moisture and salt content. Sampling points during ridge cultivation were located at the ridge top and furrow, with the sampling depth and method as described above. Additionally, surface samples (0 cm–2 cm) were collected at the junction of the ridge slope and furrow to study the distribution characteristics of salt along the ridge profile.

[0028] 3. Measurement and Statistical Analysis Soil moisture content was determined using the oven drying method, and soil salinity was measured using a DDS-12A conductivity meter on a 1:5 soil-water extract. Spatial distribution maps of soil salinity and moisture content were generated using Surfer25 software. Statistical analyses (including analysis of variance) were performed using SPSS 26.0 software.

[0029] II. Test Results 1. Spatiotemporal distribution characteristics of soil moisture and salinity under different farming methods 1.1 Spatiotemporal Variation of Soil Moisture Soil moisture content varied significantly across the three sampling months depending on tillage method, ridge location, and soil depth. In the 0-2 cm soil layer, the ridges under narrow and wide ridges consistently exhibited the lowest moisture content (7.17% and 5.73% in July, respectively), significantly lower than that under flat tillage (16.39% in July) and the corresponding furrow tillage (23.77% and 19.83% in July) (Table 1). This ridge-top drying effect was most pronounced in the top 0-10 cm layer and persisted into August and October. In contrast, furrows typically maintained higher and more stable moisture content, especially in the top and subsurface soils, often exceeding the levels observed under flat tillage.

[0030] Table 1. Soil moisture content of different soil layers under different tillage methods (unit: %) Note: Different lowercase letters indicate significant differences at the α=0.05 level.

[0031] As soil depth increased, the differences in moisture content among different treatment groups gradually decreased (Table 1). Figure 1(A~C). Within a depth of less than 20 cm, soil moisture content in all treatment groups showed a convergent trend, but in the middle soil layer (20 cm~50 cm), ridges were generally still slightly lower than furrows or flat fields. Seasonal variation characteristics were also significant. Figure 2 (A~F): Compared with July and October, the moisture profile in August was generally higher across most depths and treatment groups, reflecting the impact of mid-season rainfall or irrigation replenishment.

[0032] 1.2 Spatiotemporal Variation of Soil Salinity Soil electrical conductivity (EC) under different tillage methods exhibited significant spatial and temporal variations. Spatially, the EC value in the topsoil (0 cm–2 cm) remained the highest across all treatment groups and observation months (Table 2). Figure 3 (A~C).

[0033] Table 2. Soil electrical conductivity (EC) of different soil layers under different tillage methods (unit: mS / cm) Note: Different lowercase letters indicate significant differences at the α=0.05 level.

[0034] Significant horizontal gradient differences were observed under ridge cultivation conditions: the EC value at the ridge top was significantly higher than that at the corresponding furrow, and the difference was more significant in wide ridges than in narrow ridges. July observation data showed that the EC value at the surface of the ridge top in wide ridges (21.98 mS / cm) was significantly higher than that in the furrow (14.56 mS / cm), while the difference was relatively smaller in narrow ridges (ridge top: 17.87 mS / cm, furrow: 10.23 mS / cm) (Table 2). Regarding vertical distribution (… Figure 3 (A~C) The EC value showed a sharp decreasing trend with increasing depth. The EC value decreased significantly below 10 cm, and the differences between most treatment groups were no longer statistically significant in the 20 cm~30 cm depth range, indicating that the salt redistribution caused by tillage was mainly limited to the topsoil profile.

[0035] From the perspective of time distribution ( Figure 4 The surface electrical conductivity (EC) of all treatment groups (A-F) peaked in October, followed by a sustained increase in July and August. This seasonal pattern indicates that surface salt accumulation gradually increases as the growing season progresses. Notably, the surface EC of wide ridges reached its maximum in October (26.77 mS / cm), further confirming its role as a major area for salt enrichment.

[0036] 2. Research on the response of water-salt ratio to salt crust stripping and straw mulching in ridge cultivation Compared to the control group (CK), straw mulching significantly altered soil moisture distribution characteristics. The most significant effect was a substantial increase in ridge moisture content, particularly in the critical topsoil (0 cm–2 cm) (Table 3). In August, the ridge moisture content under straw mulching reached 22.87%, significantly higher than the control group's 17.87%. This moisture enhancement effectively alleviated the problem of soil moisture deficit in the ridges compared to the furrows. In contrast, salt crust stripping had a negligible effect on moisture improvement; ridge moisture values ​​under this treatment remained essentially the same as the control group across most soil depths and sampling months (e.g., surface moisture content in August was 18.68% and 17.87%, respectively). The effects of both management measures were primarily concentrated in the topsoil; once the depth exceeded 30 cm to 50 cm, the differences between treatment groups relative to the control group significantly decreased.

[0037] In the horizontal direction, the furrows of the untreated control group remained the wetter areas, while the ridge areas had relatively lower moisture content. Figure 5 (A~I). Straw mulching effectively reduced the moisture gradient between the ridges and furrows by retaining more moisture on the ridges; while salt crust stripping treatment did not significantly change the original "wet furrows, dry ridges" spatial pattern. Vertically, the differences between the different treatments gradually weakened below 30 cm, indicating that the effects of management measures were mainly concentrated in the topsoil and subsoil.

[0038] Combined with the spatial distribution map of soil electrical conductivity ( Figure 6 The A~I) and profile data (Table 4) reveal that different salt management measures significantly altered the spatial distribution pattern of soil salinity. Straw mulching created a distinct low-salinity zone on the ridge surface (especially in the top 0-2 cm layer). In July, the soil electrical conductivity of the straw-mulched ridges was only 6.11 mS / cm, far lower than the untreated control group (16.19 mS / cm) and the salt crust removal treatment group (14.63 mS / cm) (Table 4). This low-salinity zone persisted from July to October, indicating that straw effectively inhibited salt accumulation on the ridge surface. In contrast, although the salt crust removal treatment reduced the soil electrical conductivity of the ridges to some extent, its low-salinity zone was smaller in spatial distribution and less distinctive.

[0039] Table 3 Soil moisture content of each soil layer under ridge-cropping salinity management measures (unit: %) Note: Different lowercase letters indicate significant differences at the α=0.05 level.

[0040] In the untreated control group, salt gradually accumulated on the ridge surface, forming a high-salinity area, while the salt content in the furrows remained at a relatively low level. Figure 6(A~I). The application of straw mulch effectively reduced the salt gradient between ridges and furrows, resulting in a more uniform horizontal distribution of salt. Salt crust stripping treatment did not fundamentally change the spatial pattern of salt accumulation towards the ridges. Vertically, the electrical conductivity (EC) of all treatment groups decreased sharply with depth, and the differences between treatments gradually weakened below a depth of 40-60 cm. The results confirm that both measures can precisely target the topsoil—the main site of evaporation-driven salt accumulation—effectively alleviating surface salinization and creating a low-salinity rhizosphere environment.

[0041] Throughout the sampling period, the overall EC value peaked in October, reflecting increased surface salinity accumulation at the end of the growing season. However, throughout all sampling months, the straw mulch layer maintained a low salinity on the ridges, and the soil electrical conductivity in the furrows dropped to an extremely low level (0.53 mS / cm) in August, highlighting its significant inhibitory effect on salinity during the critical growth period.

[0042] Table 4. Soil electrical conductivity of each soil layer under ridge-cropping salinity management measures (unit: mS / cm) Note: Different lowercase letters indicate significant differences at the α=0.05 level.

[0043] In summary, compared with narrow ridges, wide ridges exhibit superior hydrological regulation and salt redistribution capabilities. Specifically, under wide ridge conditions, the surface soil salinity at the furrow level is reduced by 53.9% compared to the ridge top area, forming a significant low-salt zone, which is beneficial for seed sowing. The effectiveness of this spatial partitioning effect increases with increasing ridge size.

[0044] Straw mulching is an effective agricultural measure to enhance water retention and inhibit salt accumulation. Compared to the control group (CK) using ridge cultivation alone, straw mulching significantly increased the surface soil moisture of the ridges (e.g., an increase of approximately 28% in August) and created a distinct low-salinity zone. Notably, compared to the control group (CK), this measure reduced the surface soil electrical conductivity (EC) of the ridges by 62.3% in July. This dual effect of increasing soil moisture content and significantly reducing salt concentration effectively alleviates soil moisture deficit and salinization pressure in the ridge area.

[0045] Salt crust stripping technology has limited effectiveness in altering soil water and salt distribution patterns. Compared to the untreated control group (CK), this measure slightly reduced surface salinity (approximately 9.6% reduction in ridge salinity in July), but the effect was weak and short-lived. This technology failed to significantly improve ridge soil moisture or persistently alter the spatial gradient of water and salt, indicating that simply removing the surface salt crust without addressing the underlying evaporation drivers is insufficient to achieve sustained improvements.

[0046] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for regulating water and salt content in saline soil using a combination of ridge cultivation and surface cover, characterized in that, Includes the following steps: A ridge tillage system is constructed on saline soil, the ridge tillage system comprising adjacent ridges and furrows; Salt management measures are implemented on the surface of the ridges and furrows, and the salt management measures are straw mulching treatment; The ridge top is 55 cm to 65 cm wide, the ridge bottom is 115 cm to 125 cm wide, and the ridge height is 27 cm to 33 cm; the furrow is 55 cm to 65 cm wide.

2. The method according to claim 1, characterized in that, The width of the ridge top is 58 cm to 62 cm.

3. The method according to claim 1, characterized in that, The width of the ridge bottom is 118 cm to 122 cm.

4. The method according to claim 1, characterized in that, The height of the raised platform is 29 cm to 31 cm.

5. The method according to claim 1, characterized in that, The furrows are 58 cm to 62 cm wide.

6. The method according to claim 1, characterized in that, The straw mulching treatment involves covering the soil surface with straw that is 4.5 cm to 5.5 cm thick.

7. The method according to claim 1, characterized in that, The straw mulching treatment period is 60 to 90 days.

8. The method according to claim 7, characterized in that, The straw in question is rice straw.

Images