Impact of long‐term sub‐soiling tillage on soil porosity and soil physical properties in the soil profile

Abstract

Long‐term conventional tillage leads to soil compaction and formation of a plough layer, which affects soil physical properties, transport of water, and growth of crop roots toward deeper soil, resulting in soil degradation and a decline in crop productivity. Long‐term sub‐soiling tillage has proven to be an effective measure for remediating the plough layer and improving the structure and physical properties of the soil. In this study, we experimentally investigated the effects of long‐term sub‐soiling tillage in an arid region of Henan Province, China, along a deep soil (0–100 cm) profile over 8 years of sub‐soiling tillage at a depth of 30 cm and compared the results against conventional tillage at a depth of 15 cm. We measured soil pore distributions of macropores (> 1 mm in diameter), mesopores (0.16–1.0 mm), and total pores (> 0.16 mm) measured by X‐ray computed tomography (CT), soil total porosity (ϕ) and > 0.16 mm equivalent porosity measured by conventional methods, soil bulk density (ρs), soil organic carbon content (SOC), the proportion of macroaggregates (> 0.25 mm) (PMA), soil field moisture capacity (fc), available moisture content, and saturated hydraulic conductivity (Ksat). The results indicate that long‐term sub‐soiling tillage increased soil pore numbers at 0–35 cm depth (macropores, mesopores, and total pores), improved pore shape, and significantly increased porosity at 0–20 cm depth (macropores, mesopores, and total pores; p < 0.05) compared to conventional tillage. In addition, ϕ and > 0.16 mm equivalent porosity were increased by 10.4 and 87.1% at depths of 0–60 cm under sub‐soiling tillage, respectively. SOC (0–55 cm depth), fc (0–45 cm depth), available moisture content (0–40 cm depth), Ksat (0–40 cm depth), and PMA (0–50 cm depth) were increased by 16.7, 14.3, 23.8, 471.5, and 98.3%, respectively, and ρs (0–60 cm depth) was reduced by 8.6%. Observed correlations between SOC, soil pore parameters, and soil physical properties suggest that soil pore parameters and soil physical properties can be improved by increasing SOC. These correlations are stronger under sub‐soiling than that under conventional tillage. Therefore, sub‐soiling is an effective technique for improving soil pore characteristics and physical properties while preventing soil degradation.

Impact of Combining Long-Term Subsoiling and Organic Fertilizer on Soil Microbial Biomass Carbon and Nitrogen, Soil Enzyme Activity, and Water Use of Winter Wheat

“…We found that S, OF and S+OF treatments increased the proportion of >0.5 mm aggregates significantly. Among these, S+OF treatment was most beneficial for increasing the proportion of >0.25 mm aggregates because of the synergistic effects of the combination of S+OF: subsoiling provides loose soil conditions ( Yang et al, 2021b ) and leads to increased water availability in the root zone, which promotes crop root growth and increases soil organic carbon ( Yang et al, 2021b ), while organic fertilizers provide nutrients to the crop and soil microorganisms ( Spedding et al, 2004 ; Wang et al, 2015 ) and thereby promote microbial activity ( Piovanelli et al, 2006 ; Kuzyakov and Xu, 2013 ) and increase soil organic carbon ( Yang et al, 2021a ). These factors in turn increased soil structure stability, increased soil water retention, and improved crop growth.…”

Long‐term combined subsoiling and straw mulching conserves water and improves agricultural soil properties

“…Straw mulching may contribute toward the mitigation of these adverse outcomes (Yang et al, 2018). It has also been reported that long‐term subsoiling tillage increases the soil hydraulic conductivity, available moisture, and field moisture capacity in the top 40 cm of soil, which provides favorable conditions for crop growth (Yang et al, 2021). In this study, we have shown that when subsoiling tillage with straw mulching are combined, all of the aforementioned benefits to the soil are obtained.…”

Long-term intensive management reduced the soil quality of a Carya dabieshanensis forest

“…All sample processing and testing work was completed in a laboratory at Anhui Agricultural University, where the samples were divided into two portions. Fresh soil samples were used for the detection of total protease (T-Pro), sucrase (S-SC), acid phosphatase (S-ACP), β-glucosidase (S-β-GC), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), and soil microbial biomass phosphorus (SMBP) within 48 h. Used the ring knife method, the remaining portion was used to collect samples to measure the soil bulk density (BD) and soil moisture content (MC), while the determination of total soil porosity (TPO) was achieved by specific gravity 30 . Following air drying, the soil urease (S-UE), pH value, conductivity value (EC), soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali hydrolyzed nitrogen (AN), available phosphorus (AP), and available potassium (AK) content were quantified.…”