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Yanbian Prefecture in Northeast China is the major apple-pear (Pyrus ussuriensis var ovoidea) producing area in China. The apple-pear orchards in the study were part of the Hualong Fruit Tree Farm, Longjing City, Yanbian, China (42°21′N to 43°24′N, 128°54′E to 129°48′E). The farm has a long history of apple-pear planting. These orchards were situated on the Hosoda Plain at an altitude of 280 m and with slopes that ranged from 0 to 5%. All studied soils were classified as a dark brown soil type (cold leaching soil). The orchards had clean cultivation with fallow between rows, were equipped with no irrigation facilities, and had good management conditions. The apple-pear trees were fertilized annually with urea, diammonium phosphate, and potassium sulfate in the ratio N∶P2O5∶K2O = 1∶0.50∶0.04. The region is characterized by humid and semi-humid continental monsoon climate in the mid-temperate zone with an annual mean temperature of 5.0℃, which varied from −20.9℃ in October 2015 to 23.9℃ in April 2016. The mean annual precipitation is approximately 574 mm, with most falling as snow during winter and as rain between June and August, accounting for 70%–80% of the total. The area is subjected to a distinct seasonal freeze-thaw cycle with freezing beginning at the end of October and thawing occurring in June of the following year. As the ambient temperature fell below 0℃ in late October 2015, soil temperatures decreased accordingly, and the surface soil entered a freeze-thaw cycle because of the changes in day and night ambient temperatures. Then, the soil began to freeze from the topsoil down to the deep layers and entered a frozen state in mid-November, with the ambient temperature continued to decline to the extreme lowest temperatures (−20.0℃). Until the temperature rose above 0℃ in mid-March in 2016, the soil temperature also rose above 0℃, and the upper layers of frozen soil began to thaw, and the soil again entered a freezing and thawing cycle.
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Soil samples were collected from the test apple-pear orchards before the first soil freeze on October 15–17, 2015, and after thawing in the spring from April 29–May 2, 2016, once soils had thawed. Apple-pear trees growing well in orchards with ages of 11, 25, 40, and 63 yr were randomly selected. Twenty-five sample sites avoiding fertilizing sites were set up according to the five-point sampling method for each planting year and then mixed as one soil sample. At the same time, five sample sites in the adjacent uncultivated land were selected as a control. There were 25 sample sites in total. At each sampling point, after the removal of the litter layer, three undisturbed soil samples were collected from the soil layers at depths of 0–20, 20–40, and 40–60 cm and samples collected and mixed into a composite sample, and 150 soil samples were collected in total. The soil was pre-treated and air-dried for determination of the aggregates and other necessary soil parameters.
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Water-stable aggregates were determined according to wet-sieving mechanically stable aggregates using a dry-sieving method according to the modified procedure described by Yi. (2009). Briefly, the air-dried soil samples from each aggregate size group were mixed into a subsample of approximately 50 g in a certain proportion that came from the the ratios of the different aggregate fractions classified by dry-sieving. Next, they were placed on the top of a stack of sieves (20 cm diameter) with decreasing meshes (5.00, 3.00, 2.00, 1.00, 0.50 and 0.25 mm) in a bucket immersed in water for wet-sieved in laboratory. The stack was shaken by hand horizontally for 2 min at a speed of 30 times per min. Consequently, all soil samples were sieved into five size fractions of aggregates: < 0.25, 0.25–0.50, 1.00–0.50, 2.00–1.00, 3.00–2.00, 5.00–3.00, and > 5.00 mm. The soil fractions remaining in each sieve were collected and dried at 60℃ for 48 h to a constant weight and the percentage content of aggregates in each particle size fraction was weighed and calculated. The soil structural stability was assessed by computing the mean weight diameter (MWD) of soil aggregates, the percentage of aggregate destruction (PAD), and the degree of aggregation (DOA). The instability index calculated as the difference of the MWD of the dry sieving minus the MWD of the wet sieving, was taken as a characterization of the stability of the aggregates (Barthès and Roose, 2002).
MWD was calculated by (Zhang and Horn, 2001):
$$ MWD=\sum {W}_{i}\times {X}_{i} $$ (1) where Wi is the mean diameter of aggregate size i, and Xi is the proportion of aggregates size i in the total sample weight.
PAD was determined as following (Zhang and Horn, 2001):
$$ {{PAD}}= \frac{{{W_{\rm{a}}} - {W_{\rm{b}}}}}{{{W_{\rm{a}}}}}\times 100\% $$ (2) where Wa is the mass fraction of aggregates > 0.25 mm from wet sieving and Wb is the mass fraction of aggregates > 0.25 mm from dry sieving.
DOA can be used to evaluate particle aggregation in the soil, and is defined
$$ {{ DOA = }}\dfrac{{{M_{\rm{a}}}}}{{{M_{\rm{b}}}}} \times 100\% $$ (3) where Ma is the total amount of water-stable aggregates at all sizes > 0.25 mm minus the mass of sand grains < 0.25 mm, and Mb is the total amount of mechanical composition < 0.25 mm (obtained from mechanical composition analysis).
The mechanical composition was determined by the hydrometer method; The free iron oxide content was determined by the dithionite sodium-citrate sodium-bicarbonate method; the amorphous iron oxide content was determined by Tamm method; the organic matter content was determined by the using an oil bath-K2Cr2O7 titration method; and the pH was measured by the potentiometric method in laboratory (Lu, 2000). The general soil properties of apple-pear orchards are shown in Table 1.
Land uses Planting years /
yrSoil layers /
cmParticle size distribution pH Organic matter /
(g/kg)Total N /
(g/kg)Total P /
(g/kg)Total K /
(g/kg)2–0.02 mm / % 0.02–0.002 mm / % <0.002 mm / % Apple-pear orchards 11 0–20 37.15 24.51 5.69 5.69 24.51 1.90 17.89 0.18 20–40 37.86 21.17 6.13 6.13 21.17 0.99 19.09 0.13 40–60 38.90 21.68 6.38 6.38 21.68 1.10 19.71 0.11 25 0–20 40.35 25.21 5.01 5.01 25.21 1.45 24.59 0.33 20–40 37.83 22.43 5.17 5.17 22.43 1.22 25.91 0.15 40–60 35.95 22.74 5.73 5.73 22.74 1.19 25.52 0.10 40 0–20 37.93 24.57 5.12 5.12 24.57 2.18 17.88 0.35 20–40 36.51 20.72 5.15 5.15 20.72 2.01 18.92 0.22 40–60 35.99 20.58 5.05 5.05 20.58 1.92 18.13 0.16 63 0–20 41.90 20.55 5.50 5.50 20.55 2.18 20.02 0.23 20–40 42.67 19.86 5.01 5.01 19.86 1.47 20.08 0.19 40–60 39.89 18.98 5.48 5.48 18.98 1.20 19.26 0.16 Uncultivated land — 0–20 46.98 23.50 5.85 5.85 23.50 1.95 20.61 0.17 20–40 44.82 22.23 5.64 5.64 22.23 1.53 21.47 0.13 40–60 45.41 20.91 6.11 6.11 20.91 1.38 20.27 0.11 Table 1. General soil properties in the apple-pear orchard of Longjing City, Northeast China
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The paired sample tests were used to detect the significant effects of SFC on soil variables before and after freezing-thawing. The results are presented as the means ±standard error in the figures in this paper. All statistical analyses were performed using SPSS 20.0 for Windows (SPSS Inc., Chicago, IL, USA).
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Paired-samples t-tests were performed on the instability index before freezing and after thawing in the three soil layers in the orchards and uncultivated lands (Table 2). In the 0–20 cm layer, the instability index had significant differences (P < 0.05) undergoing SFT. however, there were no significant differences in the other soil layers.
Soil layers /cm The instability index Organic matter PAD DOA Free iron oxide Amorphous iron oxide Crystalline iron oxide Clay content 0–20 0.042* 0.000** 0.116ns 0.409 0.114ns 0.116ns 0.310ns 0.002* 20–40 0.513ns 0.000** 0.512ns 0.540 0.533ns 0.512ns 0.358ns 0.213ns 40–60 0.065ns 0.000** 0.024* 0.356 0.027* 0.024* 0.061ns 0.893ns Note: PAD, the percentage of aggregate destruction; DOA, the degree of aggregation; *, a significant difference at P < 0.05; **, a very significant difference at P < 0.01; ns, no significant difference Table 2. Paired samples test result (P value) for the instability index undergoing freezing and thawing in the apple-pear orchard in Longjing City, Northeast China
The instability indices in different soil layers in orchard of different ages before freezing and after thawing are shown in Fig. 1. Undergoing SFT, the instability index increased significantly in the 0–20 cm topsoil layer, except for a small decline in the soils of the 63-year-old orchard and uncultivated area. Notably, the largest variations in the instability index were in the uncultivated land, and the index was significantly higher than those of the orchard soils (P < 0.05). Most importantly, there were significant differences before soil freezing and after thawing in the 11- and 25-year-old orchards and the uncultivated land (P < 0.05). In 20–40 cm layer, the soil instability index of the 25-year-old orchard decreased, but the index increased to different degrees in the orchards of other ages. In 40–60 cm layer, the index generally increased after SFT, except in the 25-year-old orchard. However, the increases at this depth were not as large as those in the 20–40 cm depth. None of the changes were significant (P > 0.05).
Figure 1. The instability index against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; *, a significant difference at P < 0.05; **, a very significant difference at P < 0.01; ns, no significant difference; U, uncultivated land
The instability index in the uncultivated land was higher than that in the orchard soils in all soil layers, indicating that the stability of orchard soils was better than that of uncultivated land. In the 20–40 cm and 40–60 cm layers, the index in the 25-year-old orchard decreased slightly after freezing and thawing, whereas it increased by varying degrees in the other aging orchards, with the largest increase in the 63-year-old orchard. As expected, SFT had a greater effect on older orchards than that on younger orchards, indicating that the structure of water-stable aggregates declined more in elder orchards. The lower soil layers were more affected by freezing and thawing than the top soil layer. In addition, in the two seasons, the same trend was observed in all orchards. The variable amplitude decreased with increasing soil depth.
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The PAD in orchards against planting years before freezing and after thawing is shown in Fig. 2. According to paired-samples t-tests (Table 2), there were no significant differences in the PAD before freezing and after thawing in the three soil layers between the orchards and uncultivated lands (P > 0.05).
Figure 2. The percentage of aggregate destruction (PAD) against the planting years in responses to seasonal freezing and thawing in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
Undergoing SFT, the PAD values in 0–20 cm layer decreased in the 11- and 25-year-old orchards, but increased in the 40- and 63-year-old orchards and the uncultivated land. The PAD values were most variable in the 11-year-old orchard, and there was a significant difference in the PAD in the 63-year-old orchard (P < 0.05, Fig. 2). In 20–40 cm layer, the PAD values decreased in the 11- and 25-year-old orchards, but increased significantly in the other orchard ages. The PAD was the largest and increased by 7.37% in the 40-year-old orchard, followed by the 63-year-old orchard, in which the PAD increased by 5.64%. The PAD was significantly different in the uncultivated land, 25- and 63-year-old orchards (P < 0.05) before freezing and after thawing. In 40–60 cm layer, the trend in the PAD before freezing and after thawing was consistent with that in the other two soil layers.
The maximum PAD value in the three soil layers was 32.88%. The PAD values in the 11- and 25-year-old orchards decreased undergoing SFT, but they increased in the other orchard ages, which showed that SFT had a greater destructive effect on water-stable aggregates in the older orchards than that in the younger orchards. After freezing and thawing, the PAD values in uncultivated land increased by 4.72%, 5.53%, and 8.39% in 0–20 cm, 20–40 cm and 40–60 cm soil depth, respectively, which had a larger increase than those in the orchard soils. Thus, the decline in the stability of water-stable aggregates was more substantial in the uncultivated land than in the orchard soils. Furthermore, the amplitude of PAD changes gradually increased with depth.
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The DOA was plotted against the orchard ages in different soil layers undergoing SFT (Fig. 3). According to paired-samples tests, there were no significant differences in the DOA before freezing and after thawing in the three soil layers in the orchards and uncultivated land (P > 0.05, Table 2).
Figure 3. Degree of aggregation (DOA) against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
As shown in Fig. 3, after SFT, in 0–20 cm topsoil layer, the DOA declined to different degrees, except for some slight increases in the 11- and 25-year-old orchards. The greatest DOA occurred in uncultivated land, but none of the differences with orchards ages were significant; In 20 –40 cm layer, small changes occurred in DOA between the two seasons, but no differences in the orchard soils were significant (P < 0.05). However, the change in DOA in the uncultivated land was significant (P < 0.05). The DOA in all soils exceeded 58%, with the highest values in the 25-year-old orchard in the spring of 2016 where DOA reached as high as 78.63%. The DOA in the three soil depths of 11-year-old and 25-year-old orchards increased, with a maximum increase of 10.6% in the latter. In the uncultivated soil and orchards of other ages, the DOA declined by 5.75% to 6.78%. In 40–60 cm layer in the uncultivated land, the DOA decreased significantly undergoing SFT (P < 0.05), and the decrease was the largest, reaching 10.42%. In addition, at this depth, no significant changes in DOA before freezing and after thawing were detected in orchard soils (P > 0.05).
Overall, the DOA in the three soil layers ranged from 58.06% to 79.80%. A similar trend in the DOA was observed in the different soil layers with the increase in orchard age, which all showed that the DOA increased after SFT in the 11- and 25-year-old orchards but decreased in the older orchards. In the uncultivated land, the DOA declined more sharply in comparison with that observed in the orchard soils. In addition, the change in DOA gradually increased with increasing soil depth.
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Fig. 4 provides a comparison of the free iron oxide content in the different layers of orchard soils before freezing with that after thawing. According to paired-samples tests on the free iron oxide content in the three soil layers in the orchards and uncultivated land (Table 2), in 40–60 cm layer, the free iron oxide content was significantly different (P < 0.05) before freezing and thawing, whereas there were no significant differences in the other soil layers.
Figure 4. Free iron oxide against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
As shown in Fig. 4, in 0–20 cm topsoil layer, the free iron oxide content decreased by different degrees in the orchards of different ages, with an exception in the 25-year-old orchard in which the free iron oxide content increased undergoing SFT, which indicated that the older the orchard were, the larger free iron oxide decrease. For example, in the 63-year-old orchard the free iron oxide content decreased significantly (P < 0.05), decreasing by 3.29 g/kg. In 20–40 cm and 40–60 cm depths, the free iron oxide content followed a similar pattern in the different aged orchards undergoing SFT. Specifically, SFT significantly changed the free iron oxide content (P = 0.001). The largest decrease in the free iron oxide content was found in 40–60 cm layer of the 63-year-old orchard, with a decrease of 11.13 g/kg. In addition, the free iron oxide content in soil at this depth in the 25-year-old orchard was also significantly different (P < 0.05) undergoing SFT. In the uncultivated land, the free iron oxide content also decreased in each soil layer after freezing and thawing.
Overall, SFT had a greater effect on the free iron oxide content in the older orchards than in the younger orchards, which had sharper declines. A decrease in the free iron oxide content was not conducive to the formation of water-stable aggregates. Furthermore, the declines in free iron oxide content increased with increasing soil depth. These results suggested that SFT substantially influenced the free iron oxide content in the deep soil layers of the older orchards. These changes were consistent with those in the instability index, which indicated that the changes in soil free iron oxide might explain the changes in water-stable aggregates.
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The amorphous iron oxide content was plotted against orchard ages in the different soil layers undergoing SFT (Fig. 5). According to the paired-samples tests on the amorphous iron oxide content in the three soil layers in the orchards and uncultivated land (Table 2), there were no significant differences in the three soil layers before freezing and after thawing (P > 0.05).
Figure 5. Amorphous iron oxide against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
As indicated in Fig. 5, in 0–20 cm layer, SFT increased the amorphous iron oxide content in the 11-and 25-year-old orchard soils, whereas it decreased the amorphous iron oxide content in the other aged orchards and the uncultivated land. The greatest decrease (0.48 g/kg) was in the 63-year-old orchard. Significant differences were found in the 11- and 63-year-old orchards (P < 0.05). The change in amorphous iron oxide in 20–40 cm layer was similar to that in the 0 to 20 cm layer. The highest amorphous iron oxide content occurred in the 40-year-old orchard, although no significant differences were found between before freezing and after thawing (P > 0.05). In 40–60 cm layer, SFT decreased the amorphous iron oxide content in the orchards of different ages. With increasing orchard age, the decrease was greater, and the effects of SFT on amorphous iron oxide content were highly significant in the 63-year-old orchard (P = 0.001). The amorphous iron oxide content in the 40-year-old orchard was significantly higher than that in the orchard ages (P < 0.05). The amorphous iron oxide content in soil from the uncultivated control group in each soil layer also decreased after SFT. Additionally, the amorphous iron oxide content also declined undergoing SFT.
Overall, SFT led to slight increases in the amorphous iron oxide content in the 11-and 25-year-old orchards but to decreases in orchards of the other ages. However, the content decreased in 40–60 cm depth in all orchards.
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The crystalline iron oxide content was plotted against orchard ages in different soil layers undergoing SFT (Fig. 6). According to the paired-samples tests on crystalline iron oxide content in the three soil layers of the orchard and uncultivated land (Table 2), in 40–60 cm layer, there were significant differences in crystalline iron oxide content before freezing and after thawing (P < 0.05), but there were no significant differences in the other soil layers (P > 0.05).
Figure 6. Crystal iron oxide against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
In the 0–20 cm topsoil layer, the crystalline iron oxide content decreased in the different orchards, except for an increase in the 25-year-old orchard undergoing SFT, which shows that the older was the orchard, the larger the crystalline iron oxide decrease (Fig. 6). Specifically, SFT have a significant influence on the crystalline iron oxide content in the 63-year-old orchard, with a decrease of 2.82 g/kg (P < 0.05). In 20–40 cm layer, the crystalline iron oxide content followed a similar trend to that in the 0 to 20 cm layer, with significant effects of SFT on it in the 25-year-old orchard (P < 0.05). In 40–60 cm layer, SFT significantly decreased the content in the 63-year-old orchard, which had the lowest value of 10.66 g/kg (P = 0.002). Additionally, SFT significantly decreased the crystalline iron oxide content in the 35-year-old orchard (P < 0.05).
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Across all soil depths in the orchards and uncultivated lands, SFT had a highly significant effect on organic matter content (P < 0.01, Table 2).
SFT significantly decreased the organic matter content, with the trend being 25 yr > 11 yr > 40 yr > 63 yr (Fig. 7). The differences were highly significant in the 11- and 25-year-old orchards (P < 0.01), with a substantial decline in the 25-year-old orchard. There was also a decrease of 2.30 g/kg in the uncultivated land after thawing. In the 20–40 cm layer, the same trend was observed in the 25-year-old orchard, which had the most obvious decline (5.53 g/kg). In addition, some significant differences were detected between before freezing and after thawing in the 11-, 25-, and 40-year-old orchards, as well as in the uncultivated soil (P < 0.05). In the 40–60 cm layer, the organic matter content decreased with increasing orchard ages, with decreases of 4.16 g/kg, 5.45 g/kg, 2.56 g/kg, and 1.35 g/kg, respectively. In the uncultivated land, the organic matter content decreased by 2.96 g/kg. At this depth, SFT significantly affected the organic matter content (P < 0.05) across orchards and in the uncultivated soil, except in the 63-year-old orchard.
Figure 7. The soil organic matter against the orchard ages for the before soil freezing and after thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
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According to paired-samples tests on clay content in the three soil layers in the orchards and uncultivated land (Table 2), in the 0–20 cm layer, clay content was significantly different (P < 0.01) undergoing SFT, but there were no significant differences in the other soil layers (P > 0.05 ).
As shown in Fig. 8, the clay contents were significantly lower after thawing than those before freezing in the 0–20 cm layer in orchards, which had declines of 1.73%, 3.34%, 3.92%, and 1.05%, respectively, with increasing orchards age. The largest decrease occurred in the 40-year-old orchard, but no differences were significant (P > 0.05). In the 2–40 cm and 40–60 cm layers, the clay content decreased across all orchards undergoing SFT, except for an increase in the 25-year-old orchard under SFT. There was a significant increase in the clay content in the 20–60 cm layer in the 25-year-old orchard (P < 0.05). The 63-year-old orchard had the smallest change in clay content, and the uncultivated land had some declines in clay content across all soil layers undergoing SFT. These results suggest that the agglomeration by clay particles generally decreased, and therefore, the cementing effect of clay was weakened after SFT.
Figure 8. Clay content against the planting years in responses to seasonal freezing and thawing situations in the (a) 0–20, (b) 20–40, and (c) 40–60 cm depth in apple-pear orchard in Longjing City, Northeast China; * indicates a significant difference between treatments (P < 0.05), ** indicates a very significant difference (P < 0.01), ns indicates no significant difference; U, uncultivated land
Influences of Seasonal Freezing and Thawing on Soil Water-stable Aggregates in Orchard in High Cold Region, Northeast China
doi: 10.1007/s11769-021-1187-7
- Received Date: 2020-05-20
- Accepted Date: 2020-08-31
- Publish Date: 2021-03-01
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Key words:
- water-stable aggregates /
- orchard age /
- apple-pear orchard /
- soil seasonal freezing and thawing /
- soil degradation /
- high cold region
Abstract: Soil aggregate stability, as an important indicator of soil functions, may be affected by seasonal freezing and thawing (SFT) and land use in high cold and wet regions. Therefore, comprehensive understanding the effects of SFT on aggregate stability in orchards during winter and spring is crucial to develop appropriate management strategies that can effectively alleviate the degradation of soil quality to ensure sustainable development of orchard ecosystems. To determine the mechanism of degradation in orchard soil quality, the effects of SFT on the stability of water-stable aggregates were examined in apple-pear orchards (Pyrus ussuriensis var. ovoidea) of four different ages (11, 25, 40, and 63 yr) on 0 to 5% slopes before freezing and after thawing from October 2015 to June 2016 in Longjing City, Yanbian Prefecture, Northeast China, involving a comparison of planted versus adjacent uncultivated lands (control). Soil samples were collected to investigate water-stable aggregate stability in three incremental soil layers (0–20, 20–40 and 40–60 cm). In the same samples, iron oxide, organic matter, and clay contents of the soil were also determined. Results showed that the destructive influences of SFT on water-stable aggregates were more pronounced with the increased orchards ages, and SFT exerted severe effects on water-stable aggregates of older orchards (40 and 63 yr) than juvenile orchards. Undergoing SFT, the soil instability index and the percentage of aggregate destruction increased by mean 0.15 mm and 1.86%, the degree of aggregation decreased by mean 1.32%, and the erosion resistance weakened, which consequently led to aggregate stability decreased. In addition, soil free, amorphous, and crystalline iron oxide as well as soil organic matter and clay contents are all important factors affecting the stability of water-stable aggregates, and their changes in their contents were consistent with those in the stability of water-stable aggregates. The results of this study suggest that long-term planting fruit trees can exacerbate the damaging effects of SFT on aggregate stability and further soil erosion increases and nutrient losses in an orchard, which hider sustainable use of soil and the productivity orchards.
Citation: | LIANG Yunjiang, DENG Xu, SONG Tao, CHEN Guoshuang, WANG Yuemei, ZHANG Qing, LU Xinrui, 2021. Influences of Seasonal Freezing and Thawing on Soil Water-stable Aggregates in Orchard in High Cold Region, Northeast China. Chinese Geographical Science, 31(2): 234−247 doi: 10.1007/s11769-021-1187-7 |