No-till Soil Research Articles

Does macropore flow in no-till systems bypass mobile soil nitrogen after harvest?

Reduced tillage practices, including no-till, have been proposed to reduce NO3- leaching in agricultural soils. However, this is not universally supported by experimental data, and the effect of reduced tillage on NO3- leaching is likely connected to the interaction between macropore flow and resident solutes. To investigate this, we carried out infiltration experiments on intact soil cores from conventionally tilled (CT) and no-till (NT) plots, recording resident concentrations and breakthrough curves (BTCs) of three solutes (a tritium pulse, resident Br- tracer and native NO3-). We then fitted a dual porosity model implemented in HYDRUS-1D, to the experimental BTCs. By assuming different initial solute distributions between phases, we investigate possible bypass mechanisms. In the lysimeter experiment, leaching of all solutes initiated and peaked earlier in NT compared to CT, indicating increased macropore flow. However, total leached NO3- was greater in CT, and higher resident NO3- concentrations were found after the experiment in NT, suggesting an overall bypass effect. In the fitted dual porosity model, saturated water contents in the mobile phase were six times smaller in NT than in CT, with smaller horizontal solute transfer rates for NO3- than for Br-. The optimal initial proportion of total resident NO3- in the mobile phase was 7.5% in NT and 65% in CT. Our results suggest a bypass effect of native resident NO3- in NT soils related to a smaller volume of soil involved in macropore flow. Added solutes, however, remain susceptible to quicker leaching in NT compared to CT under intense precipitation.

The Efficiency of Stabilized Fertilizers in Reducing Ammonia Loss Is Influenced by Liming Method

ABSTRACT Urea is the most used nitrogen (N) fertilizer worldwide, but its rapid hydrolysis on the soil surface results in N loss in the form of ammonia (NH3-N). Enzyme inhibitors have been investigated for their ability to reduce NH3-N volatilization, particularly from no-till and surface-limed soils. This study assessed the efficiency of stabilized fertilizers in reducing NH3-N volatilization under different lime rates and application methods. The experiment followed a 2 × 4 × 3 factorial design, with two liming methods (surface application and incorporation), four base saturation levels (50, 60, 70, and 90%), and three urea (45% N) sources: conventional urea, urea + N-(n-butyl)-Thiophosphoric triamide (NBPT), and urea + Boron (B) + Copper (Cu). NH3-N volatilization losses varied from 9.15 to 20.43 kg ha−1, accounting for 11.4 to 25.5% of the applied N rate. Base saturation did not influence NH3-N volatilization. Liming method, however, had a significant effect. Urea + B + Cu was effective in reducing volatilization loss only in soils ameliorated by lime incorporation (23% reduction compared with conventional urea). Urea + NBPT was effective in surface-limed and incorporated soils (up to 55.5% reduction). The results showed that soil management influences the efficiency of stabilized fertilizers and that urea + NBPT provides the best results.

Edaphic Response and Behavior of Agricultural Soils to Mechanical Perturbation in Tillage

Mechanical perturbation constrains edaphic functionality of arable soils in tillage. Seasonal soil tool interactions disrupt the pristine bio-physio-mechanical characteristics of agricultural soils and crop-oriented ecological functions. They interfere with the natural balancing of nutrient cycles, soil carbon, and diverse organic matter that supports soil ecosystem interactions with crop rooting. We review soil working in tillage, associated mechanistic perturbations, and the edaphic response of affected soil properties towards cropping characteristics and behavior as soil working tools evolve. This is to further credit or discredit the global transition to minimum and no-till systems with a more specific characterization to soil properties and edaphic crop-oriented goals of soil tooling. Research has shown that improvement in adoption of conservation tillage is trying to characterize tilled soils with edaphic states of native soil agroecosystems rendering promising strategies to revive overworked soils under the changing climate. Soil can proliferate without disturbance whilst generation of new ecologically rich soil structures develops under more natural conditions. Researchers have argued that crops adapted to the altered physio-mechanical properties of cultivated soils can be developed and domesticated, especially under already impedance induced, mechanically risked, degraded soils. Interestingly edaphic response of soils under no-till soil working appeared less favorable in humid climates and more significant under arid regions. We recommend further studies to elucidate the association between soil health state, soil disturbance, cropping performance, and yield under evolving soil working tools, a perspective that will be useful in guiding the establishment of future soils for future crops.

Effect of tractor forward speed on field performance of zero till seed-cum-fertilizer drill in tilth and un-tilth sandy loam soil

The zero till seed-cum-ferti-drill was assessed for field performance in sandy loam soil under tillage and no-tillage soil conditions at variable forward speed of tractor. With increase in forward speed of tractor, field capacity of the machine was in increasing order in all treatments, in tilth and un-tilth soil. Field efficiency of machine in tilth soil was initially increasing with tractor speed with maximum value 94.71% at 3.39 km/h. However, in un-tilth soil, it was highest (94.17%) at slowest speed i.e. 1.73 km/h and remained almost constant around 92% upon increase in tractor speed up to 4.32 km/h. The tractor wheel slip percentage started decreasing with increase in tractor speed and was in minimum range between 6.35-7.59% in tilth soil and between 16.03-15.55% in un-tilth soil in treatments at rated speed of the tractor between 3.62-4.77 km/h. Drive wheel skid in no-tillage condition of soil was found minimum at 5.69 km/h forward speed of tractor for zero till-seed-cum-ferti-drill and 188 the same was observed to be in decreasing order with increase in tractor forward speed. However, in tilth soil, drive wheel skid was remained in between 14.94%-19.05% with increase in tractor forward speed. Seeding efficiency of zero till-seed-cum-ferti-drill was observed to have been influenced by the drive wheel skid, and had direct as well as inverse co-relation with increase in tractor forward speed in un-tilth and tilth soil, respectively. Obviously, design characteristic of zero till-seed-cum-ferti-drill is better suited for its use in no-tillage soil condition to achieve higher seeding efficiency, field capacity and field efficiency.

No-till farming and greenhouse gas fluxes: Insights from literature and experimental data

Tillage intensity may differently impact gaseous losses of C and N to the atmosphere, but data from long-term experiments are relatively few. Yet, this information is needed to better understand C and N losses and gains in agricultural systems. The objective of this study was to determine how tillage intensity affects soil greenhouse gas (GHG) fluxes (CO2, N2O, and CH4) by comparing experimental data from moldboard plow (MP), chisel plow (CP), double disk (DD), and no-till (NT) soils after 38–40 yr of management in a rainfed corn (Zea mays L.)- soybean (Glycine max (L.) Merr) cropping system. We also reviewed global literature to evaluate the impacts of tillage on soil GHG emissions. After 38–40 yr of management, CO2 fluxes decreased in this order: MP > CP ≈ DD > NT, indicating that as tillage intensity decreased, CO2 fluxes decreased. Indeed, daily CO2 fluxes were typically lower under NT than under MP and CP. Similarly, the overall cumulative CO2 fluxes across 26-mo of measurement were 1.4–1.8 times lower with NT than MP, CP, and DD soils. Also, MP soils had 1.3 times higher CO2 fluxes than CP and DD soils. These results are similar to those from our global literature review of 60 studies on CO2 fluxes. The reduction in CO2 fluxes in NT was likely due to a combination of increased residue cover, reduced soil temperature (r = 0.71; n = 12; p < 0.001), and increased water content (r = −0.75; n = 12; p < 0.001). Daily N2O and CH4 fluxes were highly variable; and cumulative fluxes across the 26-mo study were unaffected by tillage, mirroring findings of our literature review of 37 papers on N2O fluxes and 24 on CH4 fluxes. Overall, based on the data from both the long-term experiment and literature review, NT appears to be the best option to reduce losses of CO2 followed by reduced till (DD), but N2O and CH4 fluxes do not generally differ with tillage intensity.

Fungi determine increased soil organic carbon more than bacteria through their necromass inputs in conservation tillage croplands

Stover mulching over no-till soil is regarded as a promising practice to increase soil organic carbon (SOC) in croplands against climate change. Microbial necromass is a significant source of SOC stock and unequivocally controlled by the microbial community. Yet, a complete link that spans from agricultural practices to microbial community features, to soil necromass C, and eventually to SOC is poorly understood. Here, we conducted a 10-y corn field experiment with five treatments, which included conventional tillage (CT), no-tillage without stover (NT–0), and no-tillage with low, medium, and high amounts of stover mulching (NT–low, NT–medium, and NT–high) in a Molisol of northeastern China. We investigated the stocks and changes in total SOC and its microbial necromass C along a soil depth down to 40 cm, and we evaluated how SOC dynamics and stabilization processes were associated with microbial community features. We characterized microbial community diversity and structure using 16S rRNA and internal transcribed spacer (ITS) sequencing, and we characterized microbial biomass and necromass using phospholipid fatty acid and amino sugar biomarkers. Compared with conventional tillage, no-tillage with medium and high amounts of stover mulching increased SOC stocks in the upper 0–40 cm of soil by > 0.4% per year. No-tillage treatments (without and with stover) had almost no effect on the proportion of total microbial necromass C to SOC, but greatly modified the ratio of fungal necromass C to bacterial necromass C, which increased in top layers (0–5 cm) and decreased in deep layers (10–40 cm). SOC was governed mainly by fungal necromass C, which was correlated positively with fungal biomass. Fungal necromass C, not bacterial necromass C, was more closely associated with microbial community composition. Our results suggested that no-tillage with medium stover mulching was the optimal treatment to achieve the best trade-off between stover input and SOC storage. Differentiating microbial C pools from total SOC and, notably, separating fungal and bacterial necromass C pools can refine our mechanistic understanding of SOC storage as well as its association with microbial biota.

Long-Term Effects of Animal Manures on Nutrient Recovery and Soil Quality in Acid Typic Hapludalf under No-Till Conditions

No-till farming and manure application are means of storing carbon in soil and increasing soil quality. However, the organic fertilization of no-till soils may sustain subtropical agroecosystems for only a limited period until the soil quality declines. The C, N, P, and other nutrient cycles are perturbed due to the nutrient imbalance in manures and their application on the soil surface, which poses a risk for nutrient dispersion into the environment. Long-term N-based manure application also impacts the apparent nutrient recovery (ANR) by crops and, hence, the crop quality. Our objective was to monitor changes in soil quality and to measure nutrient recovery from N-based organic fertilization in a Brazilian agroecosystem. A long-term experiment was established in May 2004 on Typic Hapludalf soil in Southern Brazil. The experiment comprised two periods: 2004–2009 and 2009–2020. The treatments were unfertilized (control), pig slurry, pig deep litter (swine manure and rice husk), cattle slurry, and mineral fertilizer (urea, triple superphosphate, and K chloride). Grain and cover crops were grown. The maize grain yield and oat biomass were used as indicators of productivity. The application of cattle slurry, pig deep litter, and pig slurry increased the grain production by 20% on average compared to mineral fertilization. Organic manuring increased the soil pH by up to one unit, while urea acidified the soil. The highest crop yields were obtained with pig deep litter, which increased the levels of P, K, Ca, Mg, and C in the soil test. Pig deep litter showed the highest N-ANR for the aboveground part of the plants. The ANRs for P, K, Ca, and Mg were also highest when pig slurry had been applied. The ANR values for the micronutrients varied widely among the organic sources but indicated large marginal offtake gains compared to mineral fertilization. The N-based fertilization with animal manures increased the rate of nutrient uptake by plants but led to an accumulation of nutrients in the soil, threatening the sustainability of the system. Manure applications must be monitored regularly to avoid the accumulation of nutrients that could impair the soil quality and become an environmental problem in the future.

Carbon sequestration capacity in no-till soil decreases in the long-term due to saturation of fine silt plus clay-size fraction

The capacity of soils to stabilize carbon (C) may decrease over time, limiting the potential of no-till soil to act as a C sink in the long-term. Our objectives were to evaluate the effects of long-term no-till cropping systems on (i) C storage in soil, (ii) C stabilization in the fine silt plus clay-size (<20 μm) fraction and its relationship with the decrease of C saturation deficit (CSD) in this fraction, and (iii) on C accumulation in labile fractions of soil organic matter (SOM) in 0–2.5, 2.5–5, 5–10 and 10–20 cm layers of a subtropical Acrisol. The study was based on a long-term (36 years) no-till experiment where five cropping systems, with variable annual C inputs, were assessed: [i] bare-soil, [ii] black oat/maize, [iii] black oat + vetch/maize + cowpea, [iv] lablab + maize and [v] pigeon pea + maize. Cropping systems including maize and tropical legumes (lablab, pigeon pea and cowpea) with high C input led to the highest C storage in the top layers (up to 10 cm depth) of this no-till soil. Also, a decrease of CSD in fine silt plus clay-size fraction was observed in all soil layers to 20 cm depth, but the most expressive impact on CSD occurred in the topsoil (0–2.5 cm), where the capacity to further stabilize more carbon decreased by 90–97% when compared to bare soil. Considering the full C saturation level of the silt plus clay-size fraction and the current C contents in the soil, the remaining capacity of C sequestration up to 20 cm was estimated as ranging from 22.5 to 32.8 Mg C ha−1, and much of it (58–75%) was in the 10–20 cm layer. Our results highlight the importance of diversified cropping systems with high input (quantity and quality) crop residues to C sequestration in soil. Moreover, although the mineral-associated SOM of the top layer reached a C stabilization limit, C accumulation continues in non-saturated labile fractions, and in non-saturated fine silt plus clay-size fraction in deeper layers of subtropical no-till soils.

Greenhouse gas emissions from the wheat-maize cropping system under different tillage and crop residue management practices in the North China Plain

With increasing attention being placed on mitigating global warming and achieving agricultural sustainable intensification, conservation agriculture practices have gradually been implemented in the North China Plain (NCP). However, there are still knowledge gaps on the effects of conservation practices on greenhouse gas (GHG) emissions in this area. In this study, a four-year field experiment was conducted from 2014 to 2018 to assess the effects of tillage and crop residue management practices on the emissions of nitrous oxide (N2O) and methane (CH4). Subsequently, crop yields, area-scaled and yield-scaled total non-carbon dioxide (CO2) GHG emissions were assessed. Our research found that no-till (NT) decreased N2O emissions by 22.6% compared with conventional tillage (CT) in winter wheat (Triticum aestivum L.) seasons, but there was no difference between tillage practices in summer maize (Zea mays L.) seasons. Crop residue retention practice (+R) increased N2O emissions by 28.1% and 26.7% compared with residue removal practice (−R) in winter wheat and summer maize seasons, respectively. The NT soils took up more CH4 compared with the CT soils in summer maize seasons. Area-scaled total non-CO2 GHG emissions showed trends similar to those of N2O emission. Since crop residue retention improved the maize yield compared with the residue removal treatments, yield-scaled total non-CO2 GHGs emission did not differ between residue management practices in summer maize seasons. Our four-year field measurements indicated that no-till practice could be more useful as an option to mitigate non-CO2 GHG emissions in the wheat – maize cropping system.

Critical limits of soil physical attributes for corn and black oat in a Xanthic Hapludox

Soil compaction can decrease potential crop yield and is frequently found in no-till cultivation systems, but there is little information on the critical limits of soil physical properties in these conditions, especially in subtropical soils. The objectives of this study were to evaluate the infl uence of tractor traffi c on soil physical properties and identifi es critical limits of soil bulk density, soil compaction degree, macro, and microporosity on crop yield of corn and black oat assessed in situ in a Xanthic Hapludox in Southern Brazil. Tractor machine traffi c (0, 2, 5 and 20 passes) was established in no-till soil to create different soil compaction levels. Undisturbed soil samples were collected at depths of 0.00-0.05, 0.07-0.12 and 0.17-0.22 m just after tractor traffi c in two moments: before corn cultivation, and then before black oat cultivation. Under the conditions of this experiment, the 10% higher yields of corn and black oats were obtained with macroporosity above 0.10 m3m-3 and 0.13 m3 m-3, respectively. Similarly, the soil compactness degrees of 90% and 86% were considered critical for the corn and black oat, respectively. In addition, soil compaction by machine traffi c reduced maize yield up to 33% and black oat biomass yield up to 44%. Our results demonstrate that growers should be aware of the consequences of machine traffi c on soil properties, as it can severely compromise crop yields, especially of corn and black oats cultivated in very clayey soil like the one evaluated in this study.

Practical aspects of the implementation of the resource conservation system at various stages of soil cultivation and sowing in the difficult soil and climatic conditions of Central Ukraine

Purpose. Justification of constructions of agricultural machines intended for the implementation of systems of soil protection and energy-saving technologies in the soil and climatic conditions of Central Ukraine. Methods. Analytical and monographic. Results. The results of multi-year field studies of the implementation of traditional and resource-saving technologies in the conditions of the Forest-Steppe zone of Ukraine are analyzed. It was determined that the system of soil cultivation in a specific farm should be chosen in accordance with the structure of crops, taking into account the biological requirements of cultivated crops, the topography of the fields, the physical and mechanical properties of the soil, the presence and depth of the layer of high compaction. It is also necessary to evaluate the economic expediency of farm expenses for different tillage options for each field for crop rotation. The work proves the necessity of introducing into production the following tillage and seeding machines developed by scientists of the National Technical University: a roller-shredder of harvest residues with optimized parameters of a cylindrical drum, a family of multi-layer soil looseners, chisel tools for high-quality no-till soil cultivation with various physical and mechanical properties, elastic supports of cultivator paws with adjustment of vibration characteristics depending on the type and condition of the soil, optimal design of the section for direct sowing of grain crops with local application of liquid fertilizers. The implementation of the proposed technique in the technological processes of growing agricultural crops should become the basis for the introduction of soil protection and energy-saving. Conclusions. The proposed technique for the technological processes of growing agricultural crops for the introduction of soil protection and energy-saving technologies allows you to reduce fuel consumption by more than half, from 79.5 l/ha under traditional technologies to 39 l/ha under the developed improved farming system built on the principles of No-Till, and the device for applying liquid fertilizers as part of the modernized section of the Terra Nova 1714 planter allows this operation to be carried out simultaneously with sowing to a depth that is 10–20 mm greater than the depth of the seed placement. Keywords: resource conservation system, tillage, shredder roller, soil loosener, chisel tool, elastic rack.

APPLICATION OF FRACTAL THEORY IN QUANTIFYING SOIL AGGREGATE STABILITY AS INFLUENCED BY VARYING TILLAGE PRACTICES AND COVER CROPS IN NORTHERN GUINEA SAVANNA, NIGERIA

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Soil aggregate stability varies with management practices like tillage and soil organic matter management. &lt;strong&gt;Objective.&lt;/strong&gt; The objectives of this study were to (i) Explore a fractal theory to investigate the extent of soil fragmentation in soil of Samaru, Northern Nigeria, subjected to different tillage practices and covers crops for the purpose of improving soil aggregate stability (ii) Establish a relationship between fractal dimension (D) and mean weight diameter (MWD). &lt;strong&gt;Methodology.&lt;/strong&gt; A three years field trials was conducted with three tillage practices (no-till, reduced till and conventional till) as main treatments and four cover crops (&lt;em&gt;Centrosema pascuorum, Macrotyloma uniflorum, Cucurbita maxima&lt;/em&gt; and &lt;em&gt;Glyine max&lt;/em&gt;), and a bare/control (no cover crop) as sub treatments. The trial was laid out in randomized complete block design, split plot arrangement and replicated three times. Soil samples were collected at 0-15 cm prior to trial establishment for routine soil physical and chemical properties and at depths 0-5, 5-10, 10-15 and 15-20 cm at the end of each cropping season each year for soil aggregate stability test. &lt;strong&gt;Results. &lt;/strong&gt;No-till soils had 12.58% better soil aggregate stability than soils under reduced and conventional tillage systems. Also, no-till soils had 2.40 % less fragmented soil aggregates than Reduced and Conventional till soil as indicated by the fractal dimension of soil aggregates. Soils under &lt;em&gt;Macrotyloma uniflorum&lt;/em&gt; cover crop, were on the average 2.33% less fragmented than soils under &lt;em&gt;Centrosema pascuorum, Glycine max &lt;/em&gt;and&lt;em&gt; Cucurbita maxima&lt;/em&gt; but 4.56% less fragmented than soils with no cover crops. &lt;strong&gt;Implication, &lt;/strong&gt;No-till and reduced till systems; and cover cropping better enhanced soil aggregate stability due to better accumulation of organic matter emanating from crop residues return to soil in these practices. &lt;strong&gt;Conclusion.&lt;/strong&gt; Conservation tillage and the use of cover crops lowered soil aggregate fragmentation relative to conventionally tilled system and bare soil with no cover crop. The strong linear relationship established between MWD and fractal dimension showed over 80% dependency, suggesting that fractal dimension is another useful index for evaluating soil aggregate stability.&lt;/p&gt;&lt;p&gt;.&lt;/p&gt;

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

Mulch and no-till impacts on nitrogen and phosphorus leaching in a maize field under sub-tropic monsoon climate

Mulching and no-till are recommended practices to conserve soil water and soil health, but their effects on nutrient leaching in maize fields under monsoon rainfall need to be assessed. Soil water, soil temperature, and root and shoot growth of maize under plastic mulch, straw mulch, and no-till treatments were observed. Nitrogen (N) and phosphorus (P) leaching below a 110-cm deep lysimeter after heavy rainfall events were determined. The mulching and no-till treatments increased soil water content by 0.022–0.025 cm3/cm3 and reduced daytime soil temperature by 0.5–2.6 °C. Average leaching concentrations of total N and available P at 63 and 93 DAS (days after sowing) were 2.4 and 4.9 mg N/L and 0.12 and 0.08 mg P/L, respectively. For the control condition, the leaching concentrations of N and P decreased between 63 and 93 DAS. The mulching treatments did not influence nutrient leaching load at 63 DAS, but at 93 DAS the N leaching load increased by 181–248 g/ha and P load by 3.1–4.9 g/ha compared with the control treatment. The mulch treatments had taller shoots (5.1–18.3 cm) and a higher root-shoot ratio. The higher soil water content in the mulched treatments facilitated nutrient redistribution, plant growth, nutrient transport, and leaching. No-till increased N leaching by 103 g N/ha per leaching event but not P leaching. The no-till treatment had shorter shoots but longer roots than the conventional tillage treatment due to poor nutrient redistribution in the no-till soil. A modification in the nutrient management plan is needed to better control nutrient redistribution and minimize leaching.

Effect of Tillage on Agro-morphological Parameters and Yield of Cassava (Manihot esculenta crantz) in Abongoua, East-Central Côte d'Ivoire

The objective of this work is to improve the production and yield of cassava cultivated by tillage. The experiment was conducted in the field for 13 months (June 2019-july 2020) in Abongoua in the department of Bongouanou (East-central Côte d'Ivoire). After the cleaning of a 900 m2 surface of a fallow of more than 5 years, and cleared of all plant debris, soil samples were taken with an auger in the 40 cm surface in each corner and in the center of the experimental plot to constitute the composite sample for laboratory analysis. The trials were conducted in a randomized complete block design with four replicates in which four elementary plots were distributed. Three treatments T1 (tilled soil), T2 (mounded soil) and T3 (ridged soil) compared to a control treatment T0 (no-till soil) were applied in each microplot. The cuttings were directly sown at a rate of 12 cuttings per treatment. The data of the different parameters collected underwent an analysis of variance (ANOVA) performed with SAS software version 9.4 and the means were separated using the Newman and Keuls test at the 5% probability threshold. The results showed an acidic soil with a sandy texture and a good supply of nutrients, particularly major elements, trace elements and clay-humus complex. Good growth and development of agro-morphological parameters as well as yield were obtained with treatments T3 (ridged soil), T2 (mounded soil) and T1 (tilled soil) in decreasing order of importance compared to the control treatment (T0). In conclusion, the study clearly showed that the type of tillage, particularly the ridged tillage technique, improves the agro morphological parameters, productivity and yield of cassava. What we recommend to farmers for a good yield of cassava in the area.

Quantifying influence of tillage practices on soil aggregate microstructure using synchrotron‐based micro‐computed tomography

AbstractStudying the internal structure of soil aggregates is an insightful way to improve the understanding of soil aggregation process. However, it is still not clear how the macroaggregate pore structure is influenced by the application of long‐term tillage practices. In this study, we aimed to determine the differences in macroaggregate pore structure among long‐term tillage practices using micro‐computed tomography (SR‐μCT). Soil samples were collected from no tillage (NT) and ridge tillage (RT) plots and surrounding fields under conventional tillage (CT) and uncultivated soils (CK). The results showed that the diameters of most pores were greater than 30 μm, but &gt;100 μm pores had the greatest percentage of total macroaggregate porosities in all four soils, that is NT, RT, CT and CK. The CK soil had a higher aggregate porosity of &lt;30 μm and 30–60 μm, as well as a lower porosity of &gt;100 μm than the NT, RT and CT soils. Total porosities within soil macroaggregates in both CK and CT were significantly lower than those in RT and NT, but the porosities of 30–60 μm and 60–100 μm within soil macroaggregates in both CK and RT were no significance. There were no significant differences in pore parameters between CK and RT. The CK and RT had higher mean weight diameter (MWD) and aggregate‐associated SOC contents than CT. Therefore, the pore structure of RT was similar to CK with good soil structure. Overall, RT was more appropriate tillage system to protect soil aggregate structure in black soils of Northeast China.

The biodiversity effect of reduced tillage on soil microbiota.

The conversion of natural habitats into farmland has been a leading cause of species loss worldwide. Here, we investigated to what extent less intensive soil disturbance can mitigate this loss. Specifically, we examined whether reduced soil disturbance by tillage in agricultural fields could contribute to soil microbial biodiversity by providing a habitat for species that are limited by conventional tillage. To do so, we studied the diversity of soil biotas from three agricultural practices representing conventional tillage, reduced tillage and no tillage. Study fields were sampled by taking a bulk soil sample at the centre and edge of each field. The soil communities were recorded with environmental DNA metabarcoding using three molecular markers targeting bacteria, fungi and eukaryotes. While these three markers represent the vast majority of biotic variation in the soil, they will inevitably be dominated by the megadiverse microbiota of bacteria, microfungi and protists. We found a significant differentiation in community composition related to the intensity of tillage. Richness was weakly correlated to tillage, and more influenced by whether the sample was taken in the center or the edge of the field. Despite the significant effect of tillage on composition, comparisons with natural ecosystems revealed that all 30 study fields were much more similar in composition to other rotational fields than to more natural habitats, oldfields and leys. Despite a slightly higher similarity to oldfields and semi-natural grasslands, the contribution of no-till soil communities to biodiversity conservation is negligible, and our results indicate that restoration on set aside land may contribute more to conservation.

Intensification of no‐till agricultural systems: An opportunity for carbon sequestration

AbstractThe “4 per 1,000” initiative was launched at the 21st Conference of the Parties (COP21) stimulating a long‐standing debate on the potential of no‐till (NT) to promote soil C sequestration. Previous reviews found little or no soil organic C (SOC) accrual in NT soils as compared with full inversion tillage when soils are sampled deeper than 30 cm. Here, we present the results of a global meta‐analysis of studies assessing SOC and total N (TN) storage and dynamics in NT and tilled soils from the most important agricultural regions of the world. Overall, our results show that NT soils stored 6.7 ± 1.9 Mg C ha–1 and 1.1 ± 0.4 Mg N ha–1 more than tilled soils (0‐to‐100‐cm depth) with an average of 16 yr of NT, in contrast with previous findings. However, C sequestration (+4.7 ± 1.9 Mg C ha–1 in the 0‐to‐60‐cm depth with an average of 11 yr of NT) depended on the association of NT with increased crop frequency and the inclusion of legumes cover crops. Single‐cropping systems lack the necessary C inputs to offset SOC losses in the soil profile (below 30‐cm depth). However, double‐cropping systems decreased soil TN that may constrain future C sequestration. The use of legumes alleviated TN loss and supported soil C sequestration. Briefly, our findings indicate that NT can avoid SOC losses from tilled soils, partially offsetting CO2 emissions from agriculture. Moreover, NT with agricultural intensification can promote soil C sequestration, thus contributing to soil quality, food security, and adaptation to climate change.

Sustainable Conservation Tillage Technique for Improving Soil Health by Enhancing Soil Physicochemical Quality Indicators under Wheat Mono-Cropping System Conditions

An improved understanding of the effect of conservation tillage on soil physicochemical quality indicators is obligatory to manage and conserve soil in a climate change scenario. Tillage strategies change soil physicochemical characteristics, consequently modifying crop yields. Conservation tillage is generally used to improve the soil physicochemical characteristics globally. However, the impact of conservation tillage on different soil depths under wheat cultivation is not well documented. A 3-year study was conducted using a randomized complete block design (RCDB). The objective of this research was to specifically study soil physicochemical indicators (soil bulk density, porosity, hydraulic conductivity, water content, temperature, nitrogen, phosphorous, potassium, C:N ratio, pH) and (crop yield) in conventional tillage (CT), straw incorporation into the conventionally tilled soil (CTS), no-tillage (NT), and stubble-retention to the no-tilled soil (NTS) measures under wheat monocropping system across different soil layers. Averaged over 0–40 cm soil layer, the results depicted scarce differences among the tillage practices regarding soil bulk density, porosity, water content and hydraulic conductivity. CT increased soil temperature over conservation tillage systems. Overall, conservation tillage improved soil total nitrogen, available phosphorous, total potassium, C:N ratio and yield than CT, whilst it decreased soil pH. We conclude that NTS and CTS are the best strategies to enhance soil health under wheat mono-cropping system conditions.

Importance of short-term temporal variability in soil physical properties for soil water modelling under different tillage practices

Soil properties are often assumed to be static over time in hydrological studies, especially in hydrological modelling. Although it is well appreciated that soil structure and its impact on hydraulic properties are time-variable, particularly on cultivated land, very few studies have focused on quantifying the influence of such changes on soil hydrology, especially at the short term (i.e. seasonal). This study explored the value of incorporating such short-term time-variable soil properties in hydrological models. It is based on soil hydraulic properties from temporal field data under no-till done by direct seeding and under conventional cultivation done by ploughing to 0.2 m and harrowing. It uses a controlled tillage experiment in Scotland, on a soil with very good structural stability that experiences gentle rainfall in a temperate oceanic climate (Köppen Cfb). Water retention data were collected from intact soil cores sampled at 0.025, 0.095 and 0.275 m depth at three times between April and August 2013; (i) immediately following tillage, (ii) at barley crop establishment 1 month later and (iii) after harvest. Soil structure varied over time, with no-till soils gaining porosity and ploughed soils losing porosity. We hypothesised that no-till soils would have less seasonal temporal variability, but found it to be comparable to ploughed soils, albeit with pore structure changes following different trends. These changes were reflected in Van Genuchten fitting parameters, which if accounted for in 1-D HYDRUS modelling, had a marked impact on modelled soil water content over time if contrasted to predictions assuming a static pore structure. Using data from multiple sampling events, as opposed to one sampling event, resulted in up to a 44 % difference in soil water content predictions and increased the temporal variability by a factor of 1.5. Hence, our results have demonstrated that it is important to account for short-term temporal variability in soil physical properties in soil water modelling studies, and should not be ignored as a default, particularly on cultivated agricultural soils.