Construction effect of fertile cultivated layer in albic soil. Ⅱ. Effects of deep tillage with organic materials on nutrient contents and pH in tillage layer of albic soil.

We examined the effects of fertile soil layer construction technology on soil fertility and maize yield with a 3-year field experiment in Albic soil in Fujin, Heilongjiang Province. There were five treatments, including conventional tillage (T15, without organic matter return) and fertile soil layer construction methods [deep tillage (0-35 cm) with straw return, T35+S; deep tillage with organic manure, T35+M; deep tillage with straw and organic manure return, T35+S+M; deep tillage with straw, organic manure return and chemical fertilizer, T35+S+M+F]. The results showed that: 1) compared with the T15 treatment, maize yield was significantly increased by 15.4%-50.9% under fertile layer construction treatments. 2) There was no significant difference of soil pH among all treatments in the first two years, but fertile soil layer construction treatments significantly increased soil pH of topsoil (0-15 cm soil layer) in the third year. The pH of subsoil (15-35 cm soil layer) significantly increased under T35+S+M+F, T35+S+M, and T35+M treatments, while no significant difference was observed for T35+S treatment, compared with T15 treatment. 3) The fertile soil layer construction treatments could improve the nutrient contents of the topsoil and subsoil layer, especially in the subsoil layer, with the contents of organic matter, total nitrogen, available phosphorus, alkali-hydrolyzed nitrogen and available potassium being increased by 3.2%-46.6%, 9.1%-51.8%, 17.5%-130.1%, 4.4%-62.8%, 22.2%-68.7% under the subsoil layer, respectively. The fertility richness indices were increased in the subsoil layer, and nutrient contents of the subsoil layer were close to those of topsoil layer, indicating that 0-35 cm fertile soil layer had been constructed. 4) Soil organic matter contents in the 0-35 cm layer were increased by 8.8%-23.2% and 13.2%-30.1% in the second and third years of fertile soil layer construction, respectively. Soil organic carbon storage was also gradually increased under fertile soil layer construction treatments. 5) The carbon conversion rate of organic matter was 9.3%-20.9% under T35+S treatment, and 10.6%-24.6% under T35+M, T35+S+M, and T35+S+M+F treatments. The carbon sequestration rate was 815.7-3066.4 kg·hm-2·a-1 in fertile soil layer construction treatments. The carbon sequestration rate of T35+S treatment increased with experimental periods, and soil carbon content under T35+M, T35+S+M and T35+S+M+F treatments reached saturation point in the experimental second year. Construction of fertile soil layers could improve the fertility of topsoil and subsoil and maize yield. In term of economic benefits, combination application of maize straw, organic material and chemical fertilizer within 0-35 cm soil, cooperating with conservation tillage, is recommended for the Albic soil fertility improvement.

Effects of the combined application of organic and chemical nitrogen fertilizer on soil aggregate carbon and nitrogen: A 30-year study

Impacts of straw return coupled with tillage practices on soil organic carbon stock in upland wheat and maize croplands in China: A meta-analysis

衡阳紫色土丘陵坡地植被恢复阶段土壤特性的演变

Fertilization is an important agricultural practice for increasing crop yields and influencing soil properties. A field experiment was conducted in the period of 2006-2011 in southeastern China, to investigate the effects of fertilization regimes on tea (Camellia sinensis [L.] Kuntze) yields, soil chemical properties, and soil bacterial and fungal communities. The field experiment included six treatments: (1) unfertilized control (CON); (2) chemical fertilizers (NPK); (3) half-chemical fertilizers plus half-organic manure (1/2NPKOM); (4) organic manure fertilizers (OM); (5) half-chemical fertilizers plus half-organic manure plus legume stover returned (1/2NPKOM+L), and (6) chemical fertilizers plus legume stover returned (NPKL). Results showed that, compared to the control, NPK treatment showed no significant effect on soil organic matter (SOM), total N (TN), total P (TP), total K (TK), available N (AN), available K (AK) and tea yields, but showed the lowest bacterial Shannon index of 1.714 and the lowest value of 2.002 for fungal Shannon index. Organic manure treatment had the richest diversity of soil bacterial community with Shannon index of 2.542, and the highest levels of soil essential nutrients, including SOM (30.03%), TN (2.90 g kg-1), TP (1.35 g kg-1), AN (245.30 mg kg-1), AP (57.00 mg kg-1), and AK (271.80 mg kg-1), followed by 1/2NPKOM+L, which appeared the maximal tea yields of 6772 kg ha-1. Organic manure amendment was a key factor in determining soil properties and productivity. Base on soil quality and tea yields, both OM and 1/2NPKOM+L treatments were recommended as better choices of fertilization practices for tea soils in southeastern China. These findings provided a better understanding of the importance of fertilizations in promoting soil fertility, crop yields, and altering soil microbial diversity, leading to selection of scientific fertilization practices for sustainable development of agroecosystems.

Impacts of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on maize yields, nutrient use efficiency, and soil nutrient balance: Insights from a long-term diverse NPK omission experiment in the North China Plain

The turnover of soil organic carbon (SOC) in cropland plays an important role in terrestrial carbon cycling, but little is known about the temperature sensitivity (Q10) of SOC decomposition below the topsoil layer of arable soil. Here, samples of topsoil (0–20 cm) and subsoil (20–40 cm) layers were obtained from paddy fields and upland croplands in two regions of China. Using a sequential temperature changing method, soil respiration rates were calculated at different temperatures (8 °C to 28 °C) and fitted to an exponential equation to estimate Q10 values. The average SOC decomposition rate was 59% to 282% higher in the topsoil than in the subsoil layer because of higher labile carbon levels in the topsoil. However, Q10 values in the topsoil layer (5.29 ± 1.47) were significantly lower than those in the subsoil layer (7.52 ± 1.84). The pattern of Q10 values between the topsoil and subsoil was significantly negative to labile carbon content, which is consistent with the carbon quality-temperature hypothesis. These results suggest that the high temperature sensitivity of SOC decomposition in the subsoil layer needs to be considered in soil C models to better predict the responses of agricultural SOC pools to global warming.

We examined the effects of different tillage practices on plough layer soil structure and organic carbon stabilization in black soil farmland with a long-term positioning platform. The wet-sieving method and infrared spectroscopy method were used to investigate the impacts of conventional tillage (CT), no-tillage (NT), sub-soiling tillage (ST), and moldboard plowing tillage (MP) on soil aggregates distribution and organic carbon characteristics in 0-40 cm soil layers. Compared to CT, both NT and ST treatments significantly increased the proportion of large macroaggregates (>2 mm) in the topsoil layer (0-20 cm)and that of small macroaggregates (0.25-2 mm) in the subsoil layer (20-40 cm) for NT, ST, and MP. NT, ST, and MP treatments resulted in higher mean weight dia-meter (MWD) and mean geometric diameter (GMD) of soil aggregates in both the topsoil and subsoil layers. NT treatment improved organic carbon contents in bulk soil and large macroaggregates in the topsoil layer, while ST and MP enhanced organic carbon contents in bulk soil and large macroaggregates in the subsoil layer. The contribution rate of small macroaggregates organic carbon content to the total was between 68.9% and 83.4%. Furthermore, the organic carbon chemical stabilization of soil body and aggregates increased in the topsoil and subsoil layers under NT treatment compared to others. The MWD had a positive correlation with the organic carbon content and chemical stability of soil body and small macroaggregates. These findings offered a theoretical basis for understanding the impacts of different tillage practices on the stability of soil aggregate and organic carbon in black soil region.

Hydraulic properties of soil aggregates as influenced by compaction

Growth of Rhodes grass and leaching of ions from seawater neutralized bauxite residues after amendment with gypsum and organic wastes

The age of vegetation restoration has significant influences on near-surface hydrological function and soil quality in mining areas. This study analyzed the effects of restoration age and tree species on water conservation function (reflected by the water-holding characteristics of litter and soil) and soil fertility quality [reflected by soil bulk density (BD), soil organic carbon (SOC), total N (TN), available N (AN), available P (AP), and available K (AK)] of restored woodlands in phosphate mined-out areas. A primary forest (the control) and six woodlands restored for 4–25 years were selected as test sites. The results showed that total litter storage capacity, litter water-holding capacity, soil effective water-holding capacity, SOC, TN, AN, AP, and the comprehensive soil fertility index (SFI) increased with the restoration age, while small changes were also observed in soil total water-holding capacity, BD, and AK with restoration age. Compared to the control, the litter-modified interception amount, soil total water-holding capacity, and SFI in woodlands restored for 25 years were restored on average by 78%, 77%, and 92%, respectively. Furthermore, the litter water-holding capacities, soil capillary water-holding capacity, and AN in the Eucalyptus robusta woodlands restored for 10 years were significantly lower than those in woodlands of Alnus nepalensis restored for < 10 years. Our findings highlight that the restoration age has positive impacts on improving the water conservation function and soil fertility quality of restored woodlands, and the influence of tree species on the water conservation function should be specifically considered while carrying out vegetation restoration in phosphate mined-out areas.

We compared patterns of soil bacterial community diversity and structure in six secondary forests (JM, Juglans mandshurica; QM, Quercus mongolica; MB, mixed Broadleaf forest; BE, Betula ermanii; CB, conifer-broadleaf forest; PT, Pinus tabuliformis) and two plantation forests (LG, Larix gmelinii; PK, Pinus koraiensis) of the Baishilazi Nature Reserve, China, based on the 16S rRNA high-throughput Illumina sequencing data. The correlations between the bacterial community and soil environmental factors were also examined. The results showed that the broadleaf forests (JM, QM, MB) had higher levels of total C (TC), total N (TN), available N (AN), and available K (AK) compared to the coniferous forests (PT, LG, PK) and conifer-broadleaf forest (CB). Different revegetation pathways had different effects on the soil bacterial community diversity and structure. For the α-diversity, the highest Shannon index and Simpson index were found in JM. The Simpson index was significantly positively correlated with the available P (AP) (P < 0.05), and the Shannon index was significantly positively correlated with AK (P < 0.05). Compared with others, the increased ACE index and Chao1 index were observed in the CB and MB, and both of these α-diversity were significantly negative with AK (P < 0.05). The relative abundances of bacterial phyla and genera differed among different revegetation types. At the phylum level, the dominant phylum groups in all soils were Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, Chloroflexi, Bacteroidetes, Gemmatimonadetes, and Planctomycetes. Significant differences in relative abundance of bacteria phyla were found for Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, and Proteobacteria. Correlation analysis showed that Soil pH, TC, TN, AP, and AK were the main abiotic factors structuring the bacterial communities. As revealed by the clear differentiation of bacterial communities and the clustering in the heatmap and in the PCA plots, broadleaf forests and coniferous forests harbored distinct bacterial communities, indicating a significant impact of the respective reforestation pathway on soil bacterial communities in the Baishilazi Nature Reserve.

A simple assessment on spatial variability of rice yield and selected soil chemical properties of paddy fields in South China

Stumps are a significant component of coarse woody debris in plantations, but their effect on microsite soil organic carbon (C) and enzyme activities remains understudied. Soil (Alfisol) samples were collected at varying distances from larch (Larix olgensis Henry) stumps and at different soil depths (0–20 cm and 20–40 cm) to analyze soil total organic C (TOC), particulate organic C (POC), easily oxidizable C (EOC), microbial biomass C (MBC), and enzyme activities. Results indicated that stumps significantly affected TOC and POC contents, with the greatest horizontal range of impact reaching up to 15 cm in both the topsoil and subsoil layers. Stumps also significantly affected MBC content, with the greatest horizontal range of impact reaching up to 55 cm in the subsoil layer. EOC content was the most affected, with the stumps’ impact extending to 55 cm in both soil layers. Additionally, the study showed that stumps had a significant impact on the activities of β-glucosidase and β-cellobiohydrolase, with the greatest horizontal range of impact reaching up to 15 cm for glucosidase and 35 cm for cellobiohydrolase in the topsoil layer. Stumps also significantly affected the activities of phenol oxidase and peroxidase, with the maximum horizontal range of stump impact extending up to 35 cm for phenol oxidase and 55 cm for peroxidase in the topsoil layer. This study enhances our understanding of the role of stumps in plantation ecosystems and offers valuable insights for future management strategies to maintain soil fertility and improve site productivity.

This study investigates the effects of surface liming on soil attenuation radiation properties. For this, measurements of soil chemical attributes (pH, organic carbon, H+Al, Al3+, Ca2+, and Mg2+) and attenuation radiation parameters (mass attenuation coefficient, μm, atomic and electronic cross sections, σa and σe, effective atomic number and electron density, Zeff and Nel) were carried out. This aim was motivated by the fact that possible μm variation might cause as well variation in the determination of soil physical properties. The studied soil, classified as a Dystrudept sity-clay, is located in South Brazil. The trial consisted of five stripes, one of them under pasture and the remaining under no-till system (NTS). Lime rates of 0, 10, 15, and 20 t ha−1 were broadcast on the NTS soil surface. Disturbed soil samples were collected 30 months after liming at the top (0–10 cm) and subsoil (10–20 cm) layers. Soil chemical attributes were characterized following standard experimental procedures. The soil oxide composition, obtained by EDXRF analysis, was used to calculate μm for 241Am and 137Cs photon energies with XCOM computer code. μm values were employed to calculate σa, σe, Zeff, and Nel and to predict variations in soil bulk density (ρ) and total porosity (φ). Surface liming notably increased contents of soil pH, Ca2+, and Mg2+ while reduced H+Al and Al3+ at the top soil layer, where μm, σa, σe, and Zeff were also increased with the lime rates. However, at the subsoil layer, liming neither lessened soil acidity nor induced remarkable changes in the attenuation parameters. When using 137Cs photon energy, incoherent scattering totally dominated over the radiation interaction processes whereas photoelectric absorption and coherent scattering substantially contributed when 241Am photon energy was used. Therefore, the increasing in soil attenuation parameters at the top soil layer was more accentuated considering 241Am than 137Cs photon energy. Variation in μm caused considerable variation in ρ and φ only for 241Am photon energy. The findings regarding the effect of μm variation induced by liming on the determination of soil physical properties are extremely relevant because traditionally, in the soil science area, μm values are calculated without considering any chemical modification to which the soil can be submitted. Bearing in mind that ρ and φ are important parameters from the agricultural and environmental points of view, not representative measurements of μm can lead to biased values of ρ and φ.