Short-term Tillage Research Articles

Effects of Short-Term Tillage on Rhizosphere Soil Nitrogen Mineralization and Microbial Community Composition in Double-Cropping Rice Field.

Soil extracellular enzyme plays a vital role in changing soil nitrogen (N) mineralization of rice field. However, the effects of soil extracellular enzyme activities (EEA) and microbial community composition response to N mineralization of rice field under short-term tillage treatment needed to be further explored. In this study, we investigated the impact of short-term (8-year) tillage practices on rhizosphere soil N transformation rate, soil enzyme activities, soil microbial community structure, and the N mineralization function gene abundances in double-cropping rice field in southern China. The experiment consisted of four tillage treatments: rotary tillage with crop straw input (RT), conventional tillage with crop straw input (CT), no-tillage with crop straw retention (NT), and rotary tillage with all crop straw removed as a control (RTO). The results indicated that the rhizosphere soil N transformation rate in paddy field under the NT and RTO treatments was significantly decreased compared to RT and CT treatments. In comparison to the NT and RTO treatments, soil protease, urease, β-glucosaminidase, and arginase activities were significantly improved by the CT treatment, as were abundances of soil sub, npr, and chiA with CT and RT treatments. Moreover, the overall diversity of soil bacterial communities in NT and RTO treatments was significantly lower than that in RT and CT treatments. Soil chitinolytic and bacterial ureolytic communities were also obviously changed under a combination of tillage and crop straw input practices.

The Influence of Short-Term Tillage, Compost, and Beneficial Microbes on Soil Properties and the Productivity of Wheat and Cowpea Crops

Tillage systems comprise physical, chemical, and biological modification processes that influence soil properties. Soil cultivation aims to create favorable conditions for the development and growth of crops, as evident in their yields. Three growing seasons (winter 2019/2020 (wheat), summer 2020 (cowpea), and winter 2020/2021 (wheat)) were studied in field experiments in Sidi Salem, Kafr El-Sheikh, Egypt, to investigate the effects of soil tillage and the application of organic and beneficial microbes on various biological, chemical, and physical properties of soil and its productivity. Three replicates of the experimental treatments were set up in a split-plot design, in which there were four main plots: conventional soil tillage (ST) treatment for all three seasons (ST1); tillage in the first and second seasons (ST2); tillage only in the first season (ST3); and no tillage for all three seasons (ST4). However, the subplots (soil additives) were conditioned as follows: without treatment (control, T1); compost (C, T2); beneficial microorganisms (BM, T3); and combination (C + BM, T4). The biological property results showed that ST4T4 treatment produced high levels of microbial communities (bacteria, fungi, and actinomycetes), as well as high levels of soil enzyme activity (dehydrogenase, urease, and phosphatase), during the three growing seasons. However, the second season produced high numbers and dry weights of cowpea plants’ nodules. Additionally, changes in the chemical and physical properties showed that the application of various soil tillage treatments during the examined seasons led to significant increases in electrical conductivity (ECe, dSm−1), bulk density (BD, kg m−3), and soil infiltration rate (IR, cm h−1), following the trend of ST4 > ST3 > ST2 > ST1. In contrast, the results revealed decreases in the exchangeable sodium percentage (ESP, %), porosity (PO, %), soil aggregates (stable aggregates and optimal-sized aggregates, %), and soil penetration resistance (SPRa, Mpa). The combination treatment (ST4T4) provided the best yields, with grain yields of 4.991 and 5.325 tons ha−1 and straw yields of 5.214 and 5.338 tons ha−1 in the first and third seasons (wheat), respectively. Cowpea plants showed the same pattern in the second season. Therefore, improvements in soil properties and enhancements in biological activity help maintain its productivity and fertility through simplified tillage processes that reduce interference with the soil surface layer.

Effects of Conventional Tillage and No-Tillage Systems on Maize (Zea mays L.) Growth and Yield, Soil Structure, and Water in Loess Plateau of China: Field Experiment and Modeling Studies

Cropping system models can be useful tools for assessing tillage systems, which are both economically and environmentally viable. The objectives of this study were to evaluate the decision support system for agrotechnology transfer (DSSAT) CERES-Maize model’s ability to predict maize growth and yield, as well as soil water dynamics, and to apply the evaluated model to predict evapotranspiration processes under conventional tillage (CT) and no-tillage (NT) systems in a semi-arid loess plateau area of China from 2014 to 2016. The field experiment results showed that NT increased the surface soil bulk density and water-holding capacity but decreased the total porosity for the surface soil and the maize grain yield. Model calibration for maize cultivar was achieved using grain yield measurements from 2014 to 2016 for CT, and model evaluation was achieved using soil and crop measurements from both CT and NT for the same 3 yr period. Good agreement was reached for CT grain yields for model calibration (nRMSE = 4.02%; d = 0.87), indicating that the model was successfully calibrated. Overall, the results of model evaluation were acceptable, with good agreement for NT grain yields (nRMSE = 4.26%; d = 0.86); the agreement for LAI ranged from good to moderate (RMSE = 0.30‒0.31; d = 0.84‒0.85); the agreement for soil water content was good for NT (RMSE = 0.03‒0.08; d = 0.81‒0.95), but ranged from good to poor for CT (RMSE = 0.06‒0.09; d = 0.42‒0.88); the overall agreement between measured and simulated soil water varied from poor to good depending on soil depth and tillage. It was concluded that the DSSAT CERES-Maize model provided generally good-to-moderate simulations of continuous maize production (yield and LAI) for a short-term tillage experiment in the loess plateau, China, but generally good-to-poor simulations of soil water content.

Soil Bacteria Mediate Soil Organic Carbon Sequestration under Different Tillage and Straw Management in Rice-Wheat Cropping Systems

Soil organic carbon (SOC) largely influences soil quality and sustainability. The effects of no-till (NT) and crop straw return practices (SR) on soil organic carbon sequestration have been well documented. However, the mechanism of soil bacterial community in regulating soil organic carbon under NT and SR remains unclear. In this study, we investigated the impacts of tillage (conventional tillage (CT) and NT) and crop straw return practices (crop straw removal (NS) and SR) on topsoil layer (0–5 cm) bacterial community, CH4 and CO2 emissions and SOC fractions in rice-wheat cropping system. Overall, in the wheat season following the annual rice-wheat rotation in two cycles, NT significantly increased SOC by 4.4% for 1–2 mm aggregates in the 0–5 cm soil layer, but decreased CO2 emissions by 7.4%. Compared with NS, SR notably increased the contents of SOC in the topsoil layer by 6.5% and in macro-aggregate by 17.4% in 0–5 cm soil layer, and promoted CH4 emissions (by 22.3%) and CO2 emissions (by 22.4%). The combination of NT and NS resulted in relatively high SOC and low CH4 emissions along with high bacterial community abundance. The most abundant genus under different treatments was Gp6, which significant impacted SOC and MBC. Bacterial communities like Subdivision3 had the most impact on CH4 emissions. Structural equation modeling further suggested that the soil bacterial community indirectly mediated the SOC through balancing SOC in 1–2 mm aggregates and CH4 emissions. This study provides a new idea to reveal the mechanism of short-term tillage and straw return on SOC.

Short-term Tillage and Soil Nutrient Management on Soil Water Movement in a Lixisol in a Tropical Climate

Aims: The study was conducted to assess the effects of different soil tillage practices and soil amendments on soil hydraulic characteristics.
 Study Design: The study was a 3 × 4 split-plot experiment arranged in randomized complete block design (RCBD) with 3 replications.
 Methodology: The treatments comprised 12 main plots, namely no till (NT), plough-plant (PP) and plough-harrow-plant (PHP) and 36 sub-plots, namely no amendment (NA), NPK 60:40:40 (100% NPK), 4 tons/ha poultry manure (100% PM) and 2 tons/ha PM + NPK 30:20:20 [½(NPK + PM)]. Soil bulk density (BD), volumetric moisture content (VMC), total porosity (TP), aggregate stability (ASt), and infiltration parameters were measured under the different treatments.
 Results: Among the different tillage operations, the NT plot had the lowest BD, but highest TP, VMC and ASt. With regard to the soil amendments, TP was highest under the ½(NPK + PM) treatment. The cumulative infiltration amount (F) and infiltration capacity (K0) were highest in the NT plots. However, sorptivity (S\(\theta\)) was highest and lowest in the PP and NT plots, respectively. The infiltration parameters were highest in the ½(NPK + PM) plots. Further, the combined application of NT + ½(NPK + PM) resulted in the highest F, S\(\theta\) and K0.
 Conclusion: The, NT, ½(NPK + PM) and NT + ½(NPK + PM) improved the soil hydro-physical properties.

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.

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.

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.

Long-term nitrogen fertilization, but not short-term tillage reversal, affects bacterial community structure and function in a no-till soil

Long-term nitrogen fertilization, but not short-term tillage reversal, affects bacterial community structure and function in a no-till soil

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.

Functional soil organic matter fraction in response to short-term tillage management under the double-cropping rice paddy field in southern of China.

Soil organic matter (SOM) and its fraction play an important role in maintaining and improving soil fertility of paddy field. However, there is still limited information about how SOM fraction response to carbon (C) sequestration with different short-term tillage practices under the double-cropping rice paddy field in southern of China. Therefore, the effects of 5-year short-term tillage treatments on different SOM fractions (physically protected, physico-chemically protected, physico-biochemically protected, chemically protected, biochemically protected, and unprotected) under the double-cropping rice paddy field in southern of China were studied in this paper. The field experiment included four different tillage treatments: rotary tillage with crop residue 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 soil unprotected (cPOM), biochemically (NH-dSilt), physically-biochemically (NH-μSilt), and chemically protected (H-dSilt) fractions with different tillage treatments were the mainly C storage fraction in paddy field. The soil organic carbon (SOC) content in unprotected (cPOM and fPOM), physically protected (iPOM), and physico-chemically protected (H-μClay) fractions with CT treatment was increased by 1.45, 2.13, 1.91, and 1.42 times higher than that of RTO treatment, respectively. The results showed that largest proportion of fraction to SOC content was biochemically protected, followed by unprotected and physically-biochemically protected, and physically protected was the lowest. These results indicated that soil physically protected, physically-chemically protected, and physically-biochemically protected fractions with CT and RT treatments were higher than that of NT and RTO treatments. In summary, it was a benefit practice for increasing SOM fraction under the double-cropping rice paddy field in southern of China by combined application of conventional tillage and rotary tillage with crop residue incorporation management.

Effect of different short-term tillage management on nitrogen-fixing bacteria community in a double-cropping paddy field of southern China.

Soil nitrogen (N)-fixing bacteria community plays an important role in the N cycling process in soil, but there is still limited information about how the soil microbes that drive this process to respond to combined application of tillage and crop residue management under the double-cropping rice (Oryza sativa L.) paddy field in southern of China. Therefore, the effects of 6-years short-term tillage treatment on soil N-fixing bacteria community under the double-cropping rice paddy field in southern China were studied by using the polymerase chain reaction-denaturing gradient gel electrophoresis method. The field experimentincluded four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), rotary tillage with crop residue removed as control (RTO). The results showed that the diversity index and richness index of cbbLR and nifH genes with CT, RT, and NT treatments were increased, compared with RTO treatment. Compared with RTO treatment, the abundance of cbbLR gene with CT, RT, and NT treatments were increased by 6.54, 4.73, and 2.78 times, respectively. Meanwhile, the abundance of nifH gene with CT, RT, and NT treatments were 5.32, 3.71, and 2.45 times higher than that of RTO treatment. The results also indicated that soil autotrophic Azotobacter and nitrogenase activity with CT and RT treatments were significantly higher (p < .05) than that of RTO treatment. There was an obvious difference in characteristic of soil N-fixing bacteria community between the application of crop residue and without crop residue input treatments. In summary, the results indicated that the abundance of N-fixing bacteria community in the double-cropping rice paddy field increased with conventional tillage and rotary tillage practice.

Effects of Short-Term Soil Tillage Management on Activity and Community Structure of Denitrifiers under Double- Cropping Rice Field.

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. 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 retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH4+-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

Cotton Growth and Yield Response to Short-Term Tillage Systems and Planting Date in North Carolina

Tillage practices, cover crops, and planting dates can influence soil moisture and temperature conditions at planting and cotton (Gossypium hirsutum L.) stand establishment and yield. A study was conducted in North Carolina at two locations from 2014 through 2016. Treatments included six tillage systems of fall and spring conventional raised beds and flat strip tillage planted in early and late May, with and without a wheat (Triticum aestivum L.) cover crop. Tillage treatments include conventional spring raised beds, fall strip till, stale seedbed, at-plant strip till, pre-plant strip till, and stale seedbed with at-plant strip till. Except for fall strip tillage, no tillage systems reduced plant populations compared to conventionally tilled cotton in any environment. Crop growth rates were similar in conventional and spring strip-till systems and were lower in four planting date environments with stale seedbeds. In 2016, in-row soil resistance was measured from 0- to 30-cm depth using a conical penetrometer both at planting and post-harvest. Plots without any spring tillage had the greatest soil resistance for all measurements and depths. All plots with spring tillage had similar soil resistance to at least the 15-cm depth from which point the conventional spring beds had the least soil resistance through the 30-cm profile. Late planted cotton in 2014 showed inconsistent yield differences among tillage systems between locations. When pooled over location and year for 2015 and 2016, however, tillage system did not influence cotton yield. These data indicate that cotton yields in reduced-till systems are comparable to cotton grown in conventional systems in North Carolina soils.

Soil management effect on soil properties in traditional and mechanized vineyards under a semiarid Mediterranean environment

The aim of this study was to investigate the effects of short-term tillage on soil bulk density (BD), penetration resistance (PR), soil temperature (ST), electrical conductivity (EC), pH and oxygen diffusion rate (ODR) in both the topsoil and subsoil of vineyards in an area with the same soil type in Bozcaada. Mechanized tillage practices consisting of using tractor-driven rotary tiller (TDR) and field cultivator (TDC) were tested against hand driven rotary tiller (HDR) in two vineyards (wired-wide row spacing) for two growing periods. These practices involved mechanical weeding by frequent tilling and cultivating in late winter and early spring, and rotary-tilling in early summer in rainfed vineyard soils. The BD was sampled six times in two years of growing period for each tillage at 20 cm intervals between 0–60 cm in two row positions (between and in-row) while PR, ST and ODR were at the same depths of BD in the second growing period. BD in both TDR and HDR showed similarity in terms of soil depths and row positions in two growing periods, but it is lower in TDC. The highest values of the PR (1.65–2.61 MPa) were found below the depth of tilling (20 cm) regardless of tillage systems. PR was higher under HDR at subsoil in between-row than in in-row compared to TDR and TDC. However, TDC had the lowest PR in both between and in-row, especially at the subsoil, compared to HDR and TDR. The differences in BD and PR with respect to row position and soil depth were more pronounced in both TDR and HDR than in TDC. ODR was higher at topsoil than subsoil in both row positions for three tillage systems, but the highest ODR was in TDC throughout the soil profile.

Soil physical properties response to tillage practices during summer fallow of dryland winter wheat field on the Loess Plateau.

Soil physical properties are a greatly important part of the soil and indicator of soil quality, which can directly affect soil nutrient turnover and crop yields in dryland. This study was carried out with three tillage practices during the summer fallow season since 2011, including no tillage (NT), plow tillage (PT), and subsoiling (ST) in dryland winter wheat fields of the Loess Plateau. Results showed that soil tillage during the summer fallow had a small effect on soil bulk density (ρ b) in the 0-50-cm soil profile before sowing and after harvesting of winter wheat. Soil ρ b under NT at a depth of 20-30cm was significantly greater than those under PT in both seasons. Both soil gravimetric water content (θ g) and volumetric moisture content (θ v) after harvesting increased by 28.8-78.6% and 37.5-87.3%, respectively, compared with those before sowing. Adoption of PT significantly increased soil θ g and θ v in the entire 0-50-cm profile before sowing compared with NT and ST (P<0.05). In addition, there was a small effect on soil porosity (e.g., total porosity, air-filled porosity, and capillary porosity) in the profile of 0-50cm both before sowing and after harvesting. Overall, short-term tillage during summer fallow mainly affected soil water content in the 0-50-cm soil profile, and it had a slight effect on other physical soil properties.

Tillage and nitrogen fertilization enhanced belowground carbon allocation and plant nitrogen uptake in a semi-arid canola crop\u2013soil system

Carbon (C) and nitrogen (N) allocation and assimilation are coupled processes, likely influencing C accumulation, N use efficiency and plant productivity in agro-ecosystems. However, dynamics and responses of these processes to management practices in semi-arid agro-ecosystems are poorly understood. A field-based 13CO2 and urea-15N pulse labelling experiment was conducted to track how C and N allocation and assimilation during canola growth from flowering to maturity were affected by short-term (2-year) tillage (T) and no-till (NT) with or without 100 kg urea-N ha−1 (T-0, T-100, NT-0, NT-100) on a Luvisol in an Australian semi-arid region. The T-100 caused greater (P < 0.05) belowground C allocation and higher (P < 0.05) translocation of soil N to shoots and seeds, compared to other treatments. Microbial N uptake was rapid and greatest in the fertilized (cf. non-fertilized) treatments, followed by a rapid release of microbial immobilized N, thus increasing N availability for plant uptake. In contrast, management practices had insignificant impact on soil C and N stocks, aggregate stability, microbial biomass, and 13C retention in aggregate-size fractions. In conclusion, tillage and N fertilization increased belowground C allocation and crop N uptake and yield, possibly via enhancing root–microbial interactions, with minimal impact on soil properties.

Soil Quality Evaluation Using the Soil Management Assessment Framework (SMAF) in Brazilian Oxisols with Contrasting Texture

The Soil Management Assessment Framework (SMAF) was developed in the U.S.A. and has been used as a tool for assessing and quantifying changes in soil quality/health (SQ) induced by land uses and agricultural practices in that region and elsewhere throughout the world. An initial study using SMAF in Brazil was recently published, but additional research for a variety of soils and management systems is still needed. Our objective was to use data from five studies in southern Brazil to evaluate the potential of SMAF for assessing diverse land-use and management practices on SQ. The studies examined were: (i) horizontal and vertical distribution of soil properties in a long-term orange orchard; (ii) impacts of long-term land-use change from native vegetation to agricultural crops on soil properties; (iii) effects of short-term tillage on soil properties in a cassava production area; (iv) changes in soil properties due to mineral fertilizer and pig slurry application coupled with soil tillage practices; and (v) row and inter-row sowing effects on soil properties in a long-term no-tillage area. The soils were classified as Oxisols, with clay content ranging from 180 to 800 g kg-1. Six SQ indicators [pH(H2O), P, K, bulk density, organic C, and microbial biomass] were individually scored using SMAF curves and integrated into an overall Soil Quality Index (SQI) focusing on chemical, physical, and biological sectors. The SMAF was sensitive for detecting SQ changes induced by different land uses and management practices within this wide textural range of Brazilian Oxisols. The SMAF scoring curve algorithms properly transformed the indicator values expressed in different units into unitless scores ranging from 0-1, thus enabling the individual indicators to be combined into an overall index for evaluating land-use and management effects on soil functions. Soil sector scores (i.e., chemical, physical, and biological) identify the principal soil limitations and can therefore be used to establish priorities for specific management actions. The SMAF can be used as a tool for assessing SQ in Brazilian soils, thus helping farmers, land managers, and politicians make better decisions regarding sustainable land-use and management practices.

Effects of Short-term Tillage of a Long-term No-Till Land on Crop Yield and Nutrient Uptake in Two Contrasting Soil Types

&lt;p&gt;Pre-seeding tillage of long-term no-till (NT) land may alter crop production by changing the availability of some nutrients in soil. Effects of short-term (4 years) tillage (hereafter called reverse tillage [RT]) of land previously under long-term (29 or 30 years) NT, with straw management (straw removed [SRem] and straw retained [SRet]) and N fertilizer rate (0, 50 and 100 kg N ha&lt;sup&gt;-1&lt;/sup&gt; in SRet, and 0 kg N ha&lt;sup&gt;-1&lt;/sup&gt; in SRem plots), were determined on plant yield (seed + straw, or harvested as forage/silage at soft dough stage), and N and P uptake in growing seasons from 2010 to 2013 at Breton (Gray Luvisol [Typic Cryoboralf] loam) and from 2009 to 2012 at Ellerslie (Black Chernozem [Albic Argicryoll] loam), Alberta, Canada. Plant yield, N uptake and P uptake tended to be greater with RT compared to NT in most cases at both sites, although significant in a few cases only at Ellerslie. On average over both sites, RT produced greater plant yield by 560 kg ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;, N uptake by 5.8 kg N ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;, and P uptake by 1.8 kg P ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; than NT. There was no consistent beneficial effect of straw retention on plant yield, N uptake and P uptake in different years. Plant yield, N uptake and P uptake increased with N fertilization at both sites, with up to the maximum rate of applied N at 100 kg N ha&lt;sup&gt;-1&lt;/sup&gt; in 3 of 4 years at Breton and in 2 of 4 years at Ellerslie. In conclusion, our findings suggested some beneficial impact of occasional tillage of long-term NT soil on crop yield and nutrient uptake.&lt;/p&gt;

Effects of Short-term Tillage of a Long-term No-Till Land on Quantity and Quality of Organic C and N in Two Contrasting Soil Types

&lt;p&gt;Pre-seeding tillage of long-term no-till soil may alter soil quality by changing some properties, but the magnitude of change depends on soil type and climatic conditions. Effects of short-term (2 or 3 years) tillage (hereafter called reverse tillage [RT]) of land previously under long-term no-till (NT, 29 or 30 years), with straw management (straw removed [S&lt;sub&gt;Rem&lt;/sub&gt;] and straw retained [S&lt;sub&gt;Ret&lt;/sub&gt;]) and N fertilizer rate (0, 50 and 100 kg N ha&lt;sup&gt;-1 &lt;/sup&gt;in S&lt;sub&gt;Ret&lt;/sub&gt;, and 0 kg N ha&lt;sup&gt;-1 &lt;/sup&gt;in S&lt;sub&gt;Rem&lt;/sub&gt; plots) were determined in autumn 2011 on total organic C (TOC) and N (TON), light fraction organic C (LFOC) and N (LFON), and mineralizable N (N&lt;sub&gt;min&lt;/sub&gt;) in the 0-7.5, 7.5-15, or 15-20 cm soil layers at Breton (Gray Luvisol [Typic Cryoboralf] loam) and Ellerslie (Black Chernozem [Albic Argicryoll] loam), Alberta, Canada. Short-term RT following long-term NT had no significant negative effect on TOC and TON in soil at both sites, although these parameters tended to be slightly lower in the 0-7.5 cm soil layer with RT compared to NT. For the zero-N treatment, S&lt;sub&gt;Ret&lt;/sub&gt; had greater TOC and TON compared to S&lt;sub&gt;Rem&lt;/sub&gt; in both soil layers at both sites. On average, over both sites, TOC and TON in the 0-15 cm soil increased by 2.08 Mg C ha&lt;sup&gt;-1&lt;/sup&gt; and 0.216 Mg N ha&lt;sup&gt;-1&lt;/sup&gt;, respectively. Application of N fertilizer increased TOC and TON in both soil layers, up to the 50 kg N ha&lt;sup&gt;-1&lt;/sup&gt; rate at Breton (by 7.96 Mg C ha&lt;sup&gt;-1&lt;/sup&gt; and 0.702 Mg N ha&lt;sup&gt;-1&lt;/sup&gt; in the 0-15 cm soil) and up to the 100 kg N ha&lt;sup&gt;-1&lt;/sup&gt; rate at Ellerslie (by 5.11 Mg C ha&lt;sup&gt;-1&lt;/sup&gt; and 0.439 Mg N ha&lt;sup&gt;-1&lt;/sup&gt; in the 0-15 cm soil). In both RT and NT treatments, the effects of N rate on TOC and TON were similar for S&lt;sub&gt;Ret&lt;/sub&gt; and S&lt;sub&gt;Rem. &lt;/sub&gt;There was greater LFOC and LFON in the 7.5-15 cm soil layer with RT than NT at both sites. In the 0-15 cm soil layer, averaged over both sites, RT increased LFOC by 66 kg C ha&lt;sup&gt;-1&lt;/sup&gt; and LFON by 4.0 kg N ha&lt;sup&gt;-1&lt;/sup&gt;. In both 0-7.5 and 7.5-15 cm soil layers, LFOC and LFON increased with S&lt;sub&gt;Ret&lt;/sub&gt; compared to S&lt;sub&gt;Rem.&lt;/sub&gt; Averaged over both sites, the increase in LFOC and LFON in the 0-15 cm soil was 97 kg C ha&lt;sup&gt;-1&lt;/sup&gt; and 3.5 kg N ha&lt;sup&gt;-1&lt;/sup&gt;, respectively. Mass of LFOC and LFON increased dramatically in both soil layers with application of N fertilizer up to the 100 kg N ha&lt;sup&gt;-1&lt;/sup&gt; rate at both sites, with an average increase of 866 kg C ha&lt;sup&gt;-1&lt;/sup&gt; and 45.5 kg N ha&lt;sup&gt;-1&lt;/sup&gt;. In the zero-N treatment, LFOC and LFON increased with S&lt;sub&gt;Ret&lt;/sub&gt; compared to S&lt;sub&gt;Rem&lt;/sub&gt; under RT at Breton and under NT at Ellerslie. On average, tillage had no effect on N&lt;sub&gt;min&lt;/sub&gt; in soil, but S&lt;sub&gt;Ret&lt;/sub&gt; increased N&lt;sub&gt;min &lt;/sub&gt;in soil in both RT and NT, with an average increase of 4.8 kg N ha&lt;sup&gt;-1&lt;/sup&gt;. Application of N fertilizer increased N&lt;sub&gt;min&lt;/sub&gt; in the 0-20 cm soil up to 50 kg N ha&lt;sup&gt;-1&lt;/sup&gt; rate at Breton (by 13.7 kg N ha&lt;sup&gt;-1&lt;/sup&gt;) and up to 100 kg N ha&lt;sup&gt;-1&lt;/sup&gt; rate at Ellerslie (by 18.6 kg N ha&lt;sup&gt;-1&lt;/sup&gt;). In conclusion, RT had no effect on TOC, TON and N&lt;sub&gt;min&lt;/sub&gt; in soil, but LFOC and LFON increased with RT compared to NT in the 7.5-15 cm layer at one site. S&lt;sub&gt;Ret&lt;/sub&gt; and N fertilization usually had dramatic positive effects on TOC, TON, LFOC, LFON and N&lt;sub&gt;min&lt;/sub&gt; in soil compared to the corresponding treatments.&lt;/p&gt;