NT Treatment Research Articles

The dynamic changes of soil air‐filled porosity associated with soil shrinkage in a Vertisol

AbstractSoil aeration is critical for crop growth, which is generally assessed by air‐filled porosity (AFP). In non‐rigid soils with high shrinkage and swelling, the AFP is not only related to the total porosity and soil moisture, but also to the soil shrinkage behaviour. However, the relationship between AFP and soil shrinkage has not been clarified. The objectives of this study were to (1) establish a mathematical equation to describe the behaviours of AFP associated with soil shrinkage (AFPsh); and (2) to evaluate the influence of tillage practice on the AFPsh. Undisturbed soil core samples were collected from the 0–10 cm to 10–20 cm layers in a Vertisol under four tillage treatments (No tillage, NT; Rotary tillage, RT; Subsoiling, SS; Deep ploughing, DP) to measure the changes in the volumes of soil core, soil water and air at different soil matric potentials. Our results showed that an equation of AFPsh as a function of moisture ratio (ϑ) was well established based on the developed soil shrinkage model (R2 > 0.990, RMSE <0.012). Compared with the AFP under a constant pore assumption (AFPc), the AFPsh was significantly decreased by 10.6% to 60.3% as soil water matric potentials were at <−33 kPa in the 0–10 cm layer or at <−10 kPa in the 10–20 cm layer (p < 0.05). According to the AFPsh curve of the Vertisol, soil moisture content (θ) was approximately 68%–80% of the field capacity when AFPsh reached non‐limiting status (0.10 cm3 cm−3), where the soil matric potential was close to the wilting point (−1500 kPa). Deep tillage treatment (SS and DP) increased AFPsh, showing good performance in decreasing the risk of soil aeration deficit relative to the NT and RT treatment. Our results demonstrate that neglecting the porosity variations during shrinkage may lead to a high bias in the AFP prediction.Highlights An equation of AFP associated with soil shrinkage was established. AFP was significantly decreased when soil shrinkage was considered for a Vertisol. The Vertisol was easily subjected to both water and air stress due to soil shrinkage. Deep tillage practises improved soil aeration in the Vertisol.

Long‐term no‐tillage and rye cover crops affect soil biological indicators on Andosols in a humid, subtropical climate

AbstractThe effects of tillage and cover crop management on the physical and chemical properties of soil are well‐documented. However, the responses of soil microbes to long‐term tillage and crop rotation schemes still need clarification. The objective of this study was to determine the effects of different tillage and cover crop systems on soil biological indicators and their interactions in Andosols in a humid subtropical climate in Japan. This study was conducted during a field trial established in 2002. The main factors were tillage systems (no‐tillage [NT] and mouldboard ploughing [MP]); the subplot was winter cover crop treatments (bare fallow [FA] and rye [RY]) succeeding summer soya bean. Soil microbial biomass, community and structure, and soil organic carbon (SOC) stock were assessed, as well as soil respiration in the past 2.5 years. Overall, the NT and RY systems increased the soil respiration and SOC stocks relative to those detected in the MP and FA systems. After being differentiated for 18 years, the tillage systems showed a greater influence on the soil microbial community and biomass than cover crop treatments. These tillage systems significantly altered the bacterial alpha diversity (NT > MP) and soil microbial biomasses (NT > MP) based on soil Adenosine 5′‐triphosphate content, substrate‐induced respiration and ergosterol content. The NT and RY treatments stimulated soil respiration by positively affecting plant residue retention, SOC stocks, bacterial alpha diversity, soil microbial biomass in summer, and the relative abundance of organic matter decomposers, such as Bacteroidetes‐, Basidiomycota‐ and Ascomycota‐related species. These results suggest that the NT and RY systems helped improve the soil microbial properties of Andosols in a humid subtropical climate in Japan. However, their potential vulnerability to SOC sequestration due to elevated soil respiration needs further clarification, especially in the context of global warming.Highlights Soil microbe responses to agricultural measures on Andosols were studied. No‐tillage and rye cover crops stimulated soil respiration. No‐tillage shifted the soil microbial community more than cover crops. No‐tillage improved the soil organic carbon stock and bacterial alpha diversity.

Low soil carbon saturation deficit limits the abundance of cbbL-carrying bacteria under long-term no-tillage maize cultivation in northern China

The responses of cbbL-carrying bacteria to different levels of soil carbon saturation deficits (SCSD) under tillage managements are largely unknown. We assessed the influence of SCSD on the abundance and diversity of cbbL-carrying bacteria under long-term no-tillage with residue retention (NT) and conventional tillage without residue retention (CT) cultivation systems in maize. We found SCSD was smaller under NT than under CT in the 0–15 cm soil layer. The abundance and the Shannon diversity of cbbL-carrying bacteria in the NT treatment were lower than in the CT treatment. Soil carbon saturation and cbbL gene abundance showed a significant positive correlation, but there was no correlation between soil carbon saturation and cbbL gene diversity. However, the long-term NT practice decreased cbbL-carrying bacteria diversity and altered the community structure of the cbbL-carrying bacteria. Our results indicated that low SCSD limited the abundance of cbbL-carrying bacteria, but there was no relationship between low SCSD and diversity of cbbL-carrying bacteria. We suggest that further studies of cbbL-carrying bacteria carbon sequestration rates and capacity should be based on the effect of management practices on cbbL-carrying bacteria abundance and diversity. Our study has important implications for the relationship between the biological and physicochemical mechanisms in CO2 fixation.

Interactive effects of conservation tillage on the aggregate stability and soil organic carbon

AbstractBackgroundSoil carbon sequestration is of great significance to achieve carbon neutralization at an early date.AimsThe present study was conducted in order to explore the interactive effects of conservation tillage on soil organic carbon (SOC) and aggregate stability, and to understand the response of soil organic carbon to aggregate structure and distribution characteristics.MethodsUndisturbed soil from varying depths was collected from the conservation tillage demonstration base under differential tillage practices (NT, no‐tillage mulch; DT, deep‐tillage mulch; CT, conventional‐tillage mulch). SOC and stable‐aggregates of different particle sizes, their number, and structures were analyzed and the relationship between the stability of soil aggregates and SOC was presented.ResultsThe SOC content was the highest under CT treatment (1.67 g kg–1) and the lowest under NT treatment (1.31 g kg–1). In surface soil, the number of macroaggregates (>0.25 mm, M) under NT treatment was the largest (89.1%), the mean weight diameter (MWD) and geometric mean diameter (GMD) of water stability and mechanical aggregates were the highest, and the fractal dimension (D) was the lowest. This indicated that the NT treatment could maintain the aggregate structure of surface soil well. In the short term, DT and CT could increase SOC content, while NT could decrease SOC content. There was a significant correlation between SOC content and MWD (R2 = 0.40), GMD (R2 = 0.38), and D (R2 = 0.44). The more stable the aggregate structure, the higher the soil fixation and maintenance of SOC.ConclusionsSOC content and aggregate stability have a synergistic effect, and NT can promote the formation of soil aggregates, improve their stability, and balance the distribution of carbon in soil aggregates with different particle sizes.

Maize response to localized mineral or organic NP starter fertilization under different soil tillage methods

An early maize (Zea mays L.) sowing date plays a key role in increasing the grain yield, especially in a temperate climate. The adoption of reduced tillage techniques, such as strip tillage (ST), can decrease cultivation costs, compared to plowing (PLOW), but might also reduce the crop early development rate as a result of lower soil temperatures. Therefore, farmers often adopt starter fertilizations when sowing maize, in order to improve the early-season nutrient uptake, nutrient use efficiency and plant development. The aims of this study were to assess the effects of the adoption of ST, compared to PLOW, and a starter fertilization with deep-injected digestate (DIG) or sub-surface placed diammonium phosphate (DAP), compared to an unfertilized treatment (NT) on the early growth, grain yield and grain qualitative and sanitary traits of maize. Field experiments were carried out in NW Italy over the 2019 and 2020 growing seasons on two different soils. ST determined cooler soil conditions at both sites, compared to PLOW, thus resulting in lower NDVI values due to both slower plant development and lower final crop density. The starter fertilization with DAP recorded the best early vigor and canopy development, expressed as plant height in both sites and for both tillage techniques, while the DIG values were intermediate between the DAP and NT treatments. Although the effects on the early vigor of maize differed between the experimental sites, displaying more pronounced differences in the finer-textured soil, ST on average delayed the flowering (+2.2 days) and consequently delayed the moisture dry down process (+1.2% grain moisture content at harvest), compared to PLOW. The starter fertilization with DIG or DAP led to an earlier flowering, compared to NT (−2.6 and −4.6 days, respectively). The grain yield was not affected by the tillage system, as the plants in ST compensated for the lower plant density with an increased ear length (+1.5%). Instead, DIG and DAP recorded similar and higher grain yields (+1.8 and +1.6 Mg ha−1) than NT. DIG application led to a higher grain protein content and lower level of fumonisin contamination than the other treatments, while ST determined higher deoxynivalenol values than PLOW. The combination of ST and DIG as a starter fertilization can help maintain the production level and the grain quality, compared to conventional techniques that involve the use of mineral fertilizers and plowing, thereby leading to a higher sustainability of the maize cropping system.

Response of Fungal Sub-Communities in a Maize-Wheat Rotation Field Subjected to Long-Term Conservation Tillage Management.

Conservation tillage is an advanced agricultural technology that seeks to minimize soil disturbance by reducing, or even eliminating tillage. Straw or stubble mulching in conservation tillage systems help to increase crop yield, maintain biodiversity and increase levels of exogenous nutrients, all of which may influence the structure of fungal communities in the soil. Currently, however, the assembly processes and co-occurrence patterns of fungal sub-communities remain unknown. In this paper, we investigated the effects of no-tillage and straw mulching on the composition, assembly process, and co-occurrence patterns of soil fungal sub-communities in a long-term experimental plot (15 years). The results revealed that combine straw mulching with no-tillage significantly increased the richness of fungi but not their diversity. Differential abundance analysis and principal component analysis (PCA) indicated that tillage management had a greater effect on the fungal communities of abundant and intermediate taxa than on the rare taxa. Available phosphorus (AP) and total nitrogen (TN) were the major determinants of fungal sub-communities in NT treatment. The abundant fungal sub-communities were assembled by deterministic processes under medium strength selection, while strong conservation tillage strength shifts the abundant sub-community assembly process from deterministic to stochastic. Overall, the investigation of the ecological network indicated that no-tillage and straw mulching practices decreased the complexity of the abundant and intermediate fungal networks, while not significantly influencing rare fungal networks. These findings refine our knowledge of the response of fungal sub-communities to conservation tillage management techniques and provide new insights into understanding fungal sub-community assembly.

Effects of short‐term tillage managements on rhizosphere soil‐labile organic carbon fractions and their hydrolytic enzyme activity under a double‐cropping rice field regime in Southern China

AbstractThe soil‐labile organic carbon (C) fractions and their hydrolytic enzyme activity play an important role in maintaining or increasing soil quality and soil fertility, which are affected by adopting various tillage managements. But there is still limited information about how rhizosphere soil‐labile organic C fractions and their hydrolytic enzyme activity respond to different tillage managements under a double‐cropping rice (Oryza sativa L.) (early rice and late rice) in a field in Southern China. We hypothesized that rhizosphere soil‐labile organic C fractions and their hydrolytic enzyme activity in the double‐cropping rice field were modified by combined application of tillage with crop residue incorporation. Therefore, the main objectives of this study were to explore change in rhizosphere SOC content, soil‐labile organic C fractions [mineralizable C (Cmin), microbial biomass C (MBC), dissolved organic C (DOC), particulate organic C (POC), light fraction organic C (LFOC), permanganate oxidizable C (KMnO4‐C)] and their hydrolytic enzyme activity during 6‐years tillage management in a double‐cropping rice system in Southern China by using the fluorometric method. The relationship between proportion of each labile organic C fraction to SOC content were analysis using the redundancy analysis (RDA) method. The experiments included four tillage treatments: rotary tillage with all crop residues removed as a control (RTO), conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), and no‐tillage with crop residue retention (NT). The results showed that combined application of tillage with crop residue incorporation managements significantly increases rhizosphere SOC content and soil‐labile organic C fractions compared without crop residue input treatment. Compared with RTO treatment, rhizosphere soil Cmin, KMnO4‐C, POC, DOC, LFOC, and MBC contents with CT treatment increased by 170.97%, 37.22%, 52.53%, 14.46%, 20.29%, and 27.35%, respectively. The proportion of labile C with CT, RT, and NT treatments was higher than that of RTO treatment. This results demonstrated that rhizosphere soil hydrolytic enzyme activity with CT, RT, and NT treatments were higher than that of RTO treatment. Compared with RTO treatment, rhizosphere soil polyphenol oxidase and peroxidase activities with NT treatment increased by 75.80% and 40.90%, respectively. They had significantly positive correlation between rhizosphere soil hydrolytic enzyme activity and SOC content and its labile organic C fractions. Rhizosphere soil polyphenol oxidase and peroxidase activities had significantly positive correlation with labile organic C fractions. The RDA results indicated that CT and RT treatments were significantly different from NT and RTO treatments, and all of them were clearly separated from each other. As a result, combined application of tillage with crop residue incorporation is a beneficial nutrient management for improving rhizosphere soil‐labile organic C fractions and their hydrolytic enzyme activity in the double‐cropping rice fields of Southern China.

Effects of Short-Term Tillage Managements on CH4 and N2O Emissions from a Double-Cropping Rice Field in Southern of China

Soil carbon (C) content plays an important role in maintaining or increasing soil quality and soil fertility. However, the impacts of different tillage and crop residue incorporation managements on greenhouse gas (GHG) emissions from paddy fields under the double-cropping rice (Oryza sativa L.) system in southern China still need further study. Therefore, a field experiment was conducted to determine the impacts of different short-term (5-years) tillage and crop residue incorporation managements on soil organic carbon (SOC) content, SOC stock, and GHG emissions from paddy fields under the double-cropping rice system in southern China. The field experiment included four tillage treatments: rotary tillage with all crop residues removed as a control (RTO), conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), and no-tillage with crop residue retention (NT). These results indicated that SOC stock in paddy fields with CT, RT, and NT treatments increased by 4.64, 3.60, 3.50 Mg ha−1 and 4.68, 4.21, and 4.04 Mg ha−1 in 2019 and 2020, respectively, compared with RTO treatment. The results showed that early rice and late rice yield with CT treatment increased by 7.22% and 19.99% in 2019 and 6.19% and 6.40% in 2020, respectively, compared with RTO treatment. A two-year (2019–2020) investigation of GHG results indicated that methane emissions from paddy fields with NT treatment were decreased, but nitrous oxide emissions from paddy fields were increased. The lowest mean global warming potential (GWP) and per yield GWP carbon dioxide were found with NT treatment, compared to RT and CT treatments. Therefore, it was a beneficial practice for maintaining SOC stock and decreasing GHG mitigation under the double-cropping rice system in southern China by applying no-tillage with crop residue retention management.

Effect of Ensiling Density and Storage Temperature on Fermentation Quality, Bacterial Community, and Nitrate Concentration of Sorghum-Sudangrass Silage.

This study aimed to evaluate the fermentation quality, bacterial community, and nitrate content of sorghum-sudangrass silage with two ensiling densities [550 kg fresh weight (FW)/m3 (low density, LD) and 650 kg FW/m3 (high density, HD)] stored at two temperatures [10°C (low temperature, LT) and 25°C (normal temperature, NT)] for 60 days. The fermentation parameters, microbial counts, bacterial community, nutritional composition, and nitrate and nitrite levels were assessed. The pH and ammonia nitrogen (N) in all silages were below 4.0 and 80 g/kg total N, respectively. Compared with LT treatments, NT treatments had lower pH and lactic acid (LA) bacteria and yeasts counts and contained higher LA and LA/acetic acid (LA/AA) (p < 0.05). The LT-LD contained more ammonia–N than LT-HD (p < 0.05) and had higher nitrate and lower nitrate degradation than other treatments (p < 0.05). Lactobacillus was the most dominant genus with all treatments (57.2–66.9%). The LA, LA/AA, and abundances of Pantoea, Pseudomonas, and Enterobacter in the silage negatively correlated with nitrate concentration and positively correlated with nitrate degradation (p < 0.05). Moreover, pH and ammonia–N were positively correlated with nitrate concentration and negatively correlated with nitrate degradation (p < 0.05). Overall, all silage had satisfactory fermentation quality, and the silage with HD and NT had better fermentation quality and higher nitrate degradation. The bacterial communities in all silages were dominated by Lactobacillus. The nitrate degradation during the fermentation process might be related to the fermentation quality and the activity of Pantoea, Pseudomonas, and Enterobacter in silage.

Impacts of short-term tillage and crop residue incorporation managements on soil microbial community in a double-cropping rice field

Soil microbial community were usually reconsidered as a sensitive indicator in soil quality and soil environment change of paddy field. However, the effects of different tillage and crop residue incorporation managements on soil bacterial community under the double-cropping rice cropping system were still need to further investigated. Therefore, the impacts of different tillage and crop residue incorporation managements on soil bacterial community under the double-cropping rice cropping system in southern of China were studied by using phospholipid fatty acids (PLFAs) profile method in the present paper. The experiment included four different tillage treatments: rotary tillage without crop residue input as a control (RTO), no-tillage with crop residue retention (NT), rotary tillage with crop residue incorporation (RT), and conventional tillage with crop residue incorporation (CT). Compared with RTO treatment, grain yield of rice with NT, RT and CT treatments increased by 1.21%, 3.13% and 6.40%, respectively. This results showed that soil aC15:0, C16:0, iC17:0, C19:0c9, 10 fatty acids with CT and RT treatments were higher than that of RTO treatment, while soil C16:1ω6c and C18:1ω9t fatty acids with NT treatment were higher than that of RTO treatment, respectively. Soil G+ and G− bacteria PLFAs contents with CT treatment were higher than that of NT, RT and RTO treatments, while the value of soil G+/G− bacteria PLFAs with NT treatment were higher than that of CT, RT and RTO treatments. This results indicated that Richness and McIntosh indices with CT treatment were significantly higher than that of RTO treatment. Principal component analysis (PCA) results showed that the first and second principal components (PC1 and PC2) were explained 93.2% of total variance with all tillage treatments. Except C12:0, C14:0 2OH and C18:2ω6, all unsaturated and cyclopropyl PLFAs contents were belong to PC1. PC1 and PC2 were explained 88.4% of total variance with all tillage treatments. There had significantly positive correlation between soil Richness, Shannon indices and soil PLFAs, G+ bacteria, G− bacteria, fungi contents. As a result, it were benefit practices for increasing soil bacterial community structure in the double-cropping rice field of southern China by combined application of rotary, conventional tillage with crop residue incorporation managements.

Efficacy of authentic bio-nematicides against the root-knot nematode, Meloidogyne javanica infecting tomato under greenhouse conditions

The root-knot nematode (RKN), Meloidogyne javanica is considered one of the most widely distributed and economically damaging plant-parasitic nematodes worldwide. Given the exacerbation of the environmental pollution problem with chemical nematicides, the use of biological nematicides is one of the most acceptable alternative methods in nematode management by the farming community. Four bio-nematicides namely: NT (Steinernema feltiae), MM (Ascophyllum nodosum and Bacillus amyloliquefaciens), GA sol+ (A. nodosum, B. amyloliquefaciens, and Trichoderma harzianum), and Ortie-Prele (aqueous extract of nettle and horsetail (Equisetum arvense)) were evaluated for their efficacy against M. javanica infecting tomato plants under greenhouse conditions. Their efficiencies were compared to a positive control and NemGuard Granules (garlic granule extract) as a standard nematicide. Treatment effects on the growth parameters were also examined. All tested treatments gave high nematicidal effect, except for the Ortie-Prele. The highest reductions in root galling (63%), as well as the number of egg masses (98%), eggs (96%), second-stage juveniles (J2s) (93%), and the reproduction factor (RF = 2.36) were obtained by the NT treatment, which was superior to the efficacy of the standard nematicide 52.63%, 91.58%, 88.30%, and 92.07%, respectively. The Ortie-Prele treatment gave the lowest reduction for the previous nematode criteria 0%, 53.96%, 12.39%, and 11.84%, respectively. On the other hand, all treatments, significantly improved tomato growth parameters; plant length, shoot fresh weight and, root systems when compared to the standard nematicide (Nemguard Granules), and the positive control. The highest increase in shoot length (30.90%), root length (58.13%) and shoot weight (30.98%) were obtained by GA sol+, while Ortie-Prele recorded the highest increase in root weight systems (91.89%). Therefore, our results indicated that NT, MM, and GA sol + proved to be crucial components for an integrated management of M. javanica in tomato crops.

Effects of different short-term tillage managements on rhizosphere soil autotrophic CO2 -fixing bacteria in a double-cropping rice paddy field.

Soil autotrophic bacteria community plays an important role in carbon (C) cycling process in soil, but there is still limited information about how the rhizosphere soil microbe that drives this process respond to combined application of tillage with crop residue incorporation managements under a double-cropping rice (Oryza sativa L.) paddy field in southern China. Therefore, the 6-years short-term tillage treatment on rhizosphere soil autotrophic bacteria community [RubisCO gene (cbbL)] under the double-cropping rice paddy field in southern China was studied using the high-throughput sequencing method in the present article. The field experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT) and rotary tillage with all crop residues removed as a control (RTO). The results showed that abundance, composition and activity of rhizosphere soil cbbL-carrying bacteria were obviously influenced by application of different tillage treatments. The rhizosphere soil abundant cbbL and 16S rRNA genes as well as RubisCO activity with CT, RT and NT treatments were higher than that of RTO treatment. The cbbL sequences in rhizosphere soil with CT, RT andNTtreatments mainly included Azoarcus_sp._KH33C,Ralstonia_pickettii, Thermomonospora_curvata, Variovorax_paradoxus and uncultured_proteobacterium. Meanwhile, the results indicated that cbbL-carrying bacterial composition was significantly affected by soil organic carbon, microbial biomass carbon, dissolved organic carbon contents and soil bulk density. There had an obvious difference in characteristics of rhizosphere soil autotrophic bacteria community between CT, RT, NT treatments and RTO treatment. Therefore, it was a beneficial practice for improving rhizosphere soil autotrophic bacteria community in the double-cropping rice paddy field in southern China by combined application of tillage with crop residue incorporation practices.

Responses of Cereal Yields and Soil Carbon Sequestration to Four Long-Term Tillage Practices in the North China Plain

Current tillage practices in the important winter wheat–summer maize double cropping system of the North China Plain are under debate because of negative effects on soil quality and crop yield. Therefore, a long-term experiment was conducted from 2001 to 2018 to determine the effects of soil conservation practices on crop yield and soil quality. The treatments were imposed following maize harvest and prior wheat seeding, and were defined as follows: (1) moldboard ploughing (0–20 cm) following maize straw removal (CK); (2) moldboard ploughing (0–20 cm) following maize straw return (CT); (3) rotary tillage following maize straw return (RT); and (4) no tillage with maize straw covering the soil surface (NT). Wheat straw was chopped and spread on the soil in all treatments and maize seeded without prior tillage. Wheat yields were higher in CT than RT and NT treatments (p &lt; 0.05); NT had 18% lower wheat yields than CT. No significant differences were found between treatments in summer maize yields. The soil organic carbon (SOC) content in the surface layer (0–5 cm) was higher in NT and RT compared to CT and CK. However, SOC content in the 10–20 cm and 20–30 cm layers was lower in NT and RT compared to CT and CK. Similarly, available phosphorus in the surface soil was higher in NT and RT than in CT and CK. but the opposite was true for the lower soil layers. SOC stocks (0–30 cm) increased in all treatments, and were initially faster in NT and RT than in CT and CK. However, SOC stocks were higher in CT than in other treatments at the end of the experiment. This finding indicates that no tillage and reduced tillage decreased both wheat yields and soil C sequestration over time; it also indicates that CT was the most robust in terms of crop yields and soil C sequestration.

Effects of crop residue managements and tillage practices on variations of soil penetration resistance in sloping farmland of Mollisols

Soil penetration resistance (SPR) is one of the major indicators of soil physical properties. Crop residue managements, tillage practices and their interactions exert significant effects on the SPR. However, rare information is available in the sloping farmland of Mollisols. Field experiments were conducted to investigate the variations of the SPR as affected by crop residue managements and tillage practices on the sloping land in Northeast China from 2015 to 2019. The split-plot experiment was arranged with two crop residue managements (removed, REM and retained, RET), and three tillage practices (no tillage, NT; rotary tillage, RT; plow tillage, PT). SPR data in 0-80 cm soil depth was measured at the end of harvest of maize monoculture. Results showed that the two crop residue managements induced significant variations in the SPR at 0-15 cm, 15-30 cm and 0-80 cm soil depths under NT, RT, and PT treatments, respectively. In comparison with RET treatment, the average values of the SPR under REM treatment were 10.9% and 8.9% higher in 45-60 cm and 60-80 cm soil depths, respectively. The average values of the SPR under PT treatment were 12.4% and 14.1% lower in 0-15 cm soil depth, and 23.9% and 10.4% lower in 15-30 cm soil depth than those under NT and RT treatments. However, the average value of the SPR under PT treatment was 11.2% and 22.0% higher in 60-80 cm soil depth than those under NT and RT treatments, respectively. The SPR generally decreased with the slope position declined in the deeper soil depth (except for the NT+RET treatment). The findings from this research can provide a scientific reference for the establishment of rational cultivation and the sustainable development of productivity on the sloping land of Mollisols in cold regions. Keywords: soil penetration resistance, crop residue management, tillage practice, slope position, soil depth, Mollisols DOI: 10.25165/j.ijabe.20221501.6526 Citation: Wang Y J, Qiao J Y, Ji W Y, Sun J, Huo D X, Liu Y P, et al. Effects of crop residue managements and tillage practices on variations of soil penetration resistance in sloping farmland of Mollisols. Int J Agric & Biol Eng, 2022; 15(1): 164–171.

A Multivariate Approach to Evaluate Reduced Tillage Systems and Cover Crop Sustainability

The evaluation of the effects of conservation agriculture during the transition from conventional tillage to no-tillage requires numerous indicators to be considered. For this purpose, we monitored changes in a multi-parameter dataset during a three-year experiment that combined three tillage intensities (conventional tillage—CT; minimum tillage—MT; and no tillage—NT) with three soil covering managements (tillage radish cover crop, winter wheat cover crop and bare soil). Using a multivariate analysis, we developed a Relative Sustainability Index (RSI) based on 11 physical (e.g., bulk density and penetration resistance), chemical (e.g., soil organic carbon and pH) and biological soil properties (e.g., earthworm density) to evaluate cropping systems sustainability. The RSI was most affected by tillage intensity showing higher RSI values (i.e., better performances) in reduced tillage systems. Specifically, the RSI under NT was 42% greater than that of CT and 13% greater than that of MT. Soil covering had little impact on the RSI. Among the tested parameters, the RSI was increased most by saturated hydraulic conductivity (+193%) and earthworm density (+339%) across CT and NT treatments. Our results suggest that conservation agriculture and, particularly, reduced tillage systems, have the potential to increase farm environmental and agronomic sustainability.

One-time omission of puddling improves soil structure and post-rice soybean yield in clay-rich fields within paddy–soybean rotation systems in central Hokkaido, Japan

A one-time omission of puddling was noted to increase post-rice soybean yields within the paddy–soybean rotation systems in central Hokkaido, Japan. We analyzed the physical, chemical, and biological properties of soil via an onsite survey in 47 farmers’ soybean fields where either puddled transplanted rice (PT), nonpuddled transplanted rice (NT), or dry direct-seeded rice (DS) was cultivated in the previous year (referred to as one-time PT, NT, and DS treatments, respectively). The objective of the study was to determine the key soil parameters that could explain the higher post-rice soybean yield following the one-time omission of puddling (NT and DS treatments). In addition, soybean yield and soil properties were surveyed in an experimental field experiment where PT and NT treatments were applied for 3 consecutive years with the expectation that the increases in post-rice soybean yield caused by the omission of puddling (NT treatment) would be more pronounced. In the survey of farmers’ field, soybean yields were comparable among the one-time PT, NT, and DS treatments when the clay content was < 40%. However, soybean yield decreased as the clay content increased only under the one-time PT treatment. The adverse effects of puddling (PT treatment) on clay-rich soil appeared in a few soil physical parameters but not on any soil chemical and biological parameters. In the 34 selected clay-rich farmers’ fields (clay content >40%), narrow macropore and mesopore volumes, which indicate total available water capacity, were significantly (P < 0.05) lower under the one-time PT treatment than under the other two treatments. At the same time, the narrow macropore volume was significantly (P < 0.05) correlated with soybean yield. The one-time omission of puddling (NT and DS treatments) adopted in the surveyed farmers’ fields did not affect the wide macropore volume. Three consecutive years of NT treatment improved several soil physical properties as well as soybean root development in the experimental field. However, these improvements did not significantly increase soybean yield in the experimental field where the clay content was < 40%. These findings suggest that the one-time omission of puddling (NT and DS treatments) prevents the decreasing in the yields of post-rice soybean in clay-rich soils in central Hokkaido. The stable soybean yield, irrespective of the clay content, after the one-time omission of puddling (NT and DS treatments) in fields was attributed to the increased plant-available water capacity owing to the increased narrow macropore and mesopore volumes without clear changes in the wide macropore volume. By contrast, the effects of the one-time and three-time omission of puddling (NT and DS treatments) were not obvious in non–clay-rich field conditions in central Hokkaido.

Impact of land use and tillage practice on soil macropore characteristics inferred from X-ray computed tomography

Quantification of soil macropores is important to enhance our understanding of preferential flow behavior in soils. However, knowledge of 3D soil architecture for different land uses in a continental climate region is limited. X-ray computed tomography is a novel technique that can provide valuable information about the 3D features of the soil, such as connectivity, length density, and tortuosity, that largely control water flow through the macropores. In this study, X-ray computed tomography and image analysis were employed to quantify the soil macropore characteristics from four combinations of different land uses and soil tillage practices - native grassland (Nat), alfalfa (Alf), conventional till-corn (CT), and no-till corn (NT) systems. A total of 15 undisturbed soil columns, 150 mm in diameter and 500 mm in length, were collected from different fields. The macropore characteristics were distinctively different for different land use and tillage treatments, especially near the surface depth (top 100 mm). The soil macropores under CT were highly connected and concentrated mostly in the surface soil layer. In contrast, macropores under NT were larger and had well-developed pore networks. The Alf field had relatively larger and more vertically oriented macropores as compared to the Nat field. Relatively larger macroporosity and a higher number of macropores were observed in the surface of soils collected from Nat field. Macropore characteristics were mostly similar between Alf and NT treatments. The results of this study facilitate quantitative evaluation of 3D soil macropore features with significant implications for non-equilibrium flow prediction and contaminant transport modeling in soils.

Effects of different tillage management on rhizosphere soil nitrogen mineralization and its extracellular enzyme activity in a double‐cropping rice paddy field of southern China

AbstractSoil extracellular enzyme activity plays an important role in regulating the process of nitrogen (N) mineralization in the paddy field. However, there is still limited information about how rhizosphere N mineralization and its extracellular enzyme activities respond to different tillage treatments in a double‐cropping rice paddy fields of southern China. Therefore, the effects of 6‐year (short‐term) tillage management on rhizosphere soil acid hydrolysable N and its fractions, N mineralization, and its extracellular enzyme activities in a double‐cropping rice paddy fields of southern China were studied and reported in this article. The field experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no‐tillage with crop residue retention (NT), and rotary tillage with crop residue removed as a control (RTO). The results showed that rhizosphere soil total acid hydrolysable N and its fractions with CT, RT and NT treatments were higher than those with RTO treatment. Compared to RTO treatment, the rhizosphere soil total acid hydrolysable N content with CT and RT treatments was increased by 19.17% and 17.74%, respectively. Compared to RTO treatment, the rhizosphere soil aerobic and anaerobic N mineralization rates with CT and RT treatments were increased by 100.00% and 80.65%, and 43.02% and 33.72%, respectively. Rhizosphere soil extracellular enzyme activities with CT and RT treatments were higher than those with NT and RTO treatments. There was a positive correlation between rhizosphere soil amino sugar N, amino acid N, total acid hydrolysable N contents, L‐glutaminase activity and N mineralization rate. The principal component analysis results indicated that rhizosphere soil organic carbon, amino sugar N, amino acid N and total acid hydrolysable N contents, soil β‐glucosaminidase, β‐glucosidase and L‐glutaminase activities were the main factors affecting rhizosphere soil aerobic and anaerobic N mineralization rates. As a result, rhizosphere soil acid hydrolysable N and its fractions, N mineralization, and its extracellular enzyme activities were significantly increased under the combined application of conventional tillage and rotary tillage with the crop residue incorporation condition.

Effects of short-term soil tillage practice on activity and community structure of ammonia-oxidizing bacteria and archaea under the double-cropping rice field.

The potential nitrification activity (PNA), population size and community composition of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in paddy soil from a short-term (5years) tillage field experiment conducted at tillering stage of late rice were investigated using the shaken slurry method and quantitative real-time polymerase chain reaction. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue returning (NT) and rotary tillage with all crop residues removed as a control (RTO). The results showed that PNA in paddy soil of CT, RT and NT treatments was higher than that of RTO treatment, and the abundance of AOA and AOB was much higher in paddy soil of CT, RT and NT treatments than RTO treatment. Meanwhile, PNA and the abundance of AOB and AOA in paddy soil were greatly enhanced by combined application of tillage and crop residue, whereas PNA and the abundance of AOB and AOA in paddy soil were decreased by combined application of no-tillage and crop residue. Moreover, PNA was closely correlated with the abundance and community structure of AOB rather than AOA. The results also showed that PNA and the population sizes of AOB and AOA in crop incorporation treatments were higher than that of crop residue removed treatment. Cluster and redundancy analyses indicated that crop residue effect played a more important role in shaping AOA community structure compared to short-term tillage management. The results indicated that AOB rather than AOA functionally dominated ammonia oxidation in the double-cropping rice paddy soil, the activities of AOB and AOA were increased and the community structure was also changed under the combination of conventional tillage, rotary tillage and crop residue condition. The activity and community structure of AOB and AOA, which were affected by the combination of tillage and crop residue managements, play an important role in cycling of nitrogen.

The Effects of NT and Adjuvant Treatments on Anastomotic Leakage in Rectal Cancer

The Effects of NT and Adjuvant Treatments on Anastomotic Leakage in Rectal Cancer