No-till Fields Research Articles

Description of two new genera, three new species, and redescription of two species of Pronematinae (Acari: Iolinidae)

Duoparus n. gen. with its type species Duoparus hyeresensis n. gen. n. sp. from Rubus in France are described. Duoparus is the first genus within the Pronematinae with two ag setae. In the genus Pseudopronematulus, two new species, P. duffelensis n. sp. from sweet pepper leaf litter in Belgium and Pseudopronematulus tocantinsensis n. sp. from leaf/soil litter from a no-tillage field in Brazil are described. Pseudopronematulus tenuisetosus, recently transferred from the genus Pronematus, from cotton in Mozambique is redescribed. Pseudopronematulus duffelensis n. sp. and P. tocantinsensis n. sp. are the fourth and fifth species in this genus and the first to be described in detail, including nymphal stages for P. duffelensis n. sp. Dasilcoferla n. gen. is described with Pseudopronematulus nadirae n. comb. as type species, which is transferred from Pseudopronematulus to Dasilcoferla and redescribed. A taxonomic key is provided for the separation of the species presently placed in Pseudopronematulus Fan and Li, 1992. Molecular analysis and morphological differences, mostly the chaetotaxy, of P. duffelensis n. sp. are compared with those of Pronematus ubiquitus (McGregor, 1932) and Homeopronematus anconai (Baker, 1943). The molecular results underpin the morphological difference between the species that belong to different genera. Relative distance of the genera are discussed.

Bio-fertilizer applications from poultry slaughterhouses in subtropical agriculture – Interactions between soil structure and nitrate dynamics

The No-till system and organic fertilization combined can be a potential strategy to avoid nutrient leaching, as the soil structure plays a crucial role in retaining them. In this study, we evaluated the influence of different rates of a bio-fertilizer made of industrial organic waste (IOW) from a poultry slaughterhouse on the percolation and stocks of nitrate in disturbed and undisturbed soil samples collected from a subtropical no-till field in southern Brazil. In an incubation experiment, we performed a percolation experiment using lysimeters and simulated rainfall for 180 days and evaluated the remaining soil nitrate stock after the incubation period. We set up a completely randomized experiment with three replicates using four IOW rates (equivalent to 0, 2, 4, and 8 Mg ha−1) and two sample types: disturbed and undisturbed soils. Using the bio-fertilizer increased nitrate mineralization from 0.77 to 1.55 kg ha−1 day−1. Overall, the IOW application increased the amount of percolated nitrate, significantly influenced by the simulated rainfall (p < 0.01). The amount of water flushed through the lysimeters was significantly higher for the disturbed soils (p < 0.05, LSD test), suggesting that the loosened structure promoted a higher water flux. No differences were observed between undisturbed and disturbed samples for nitrate percolation, implying that the amount of nitrate in the liquid soil phase may be a more critical factor in determining nitrate leaching than the water flux. The disturbed samples presented significantly higher nitrate percolation with increasing IOW rates, regardless of precipitation. Stocks in the 0–5 cm depth were 6.6 kg ha−1 higher for undisturbed samples (p < 0.05, LSD test). This result suggests preserving the soil structure can significantly increase the nitrate stocks upon IOW application.

Effects of occasional tillage on soil physical and chemical properties and weed infestation in a 10-year no-till system

Few studies have investigated how one-time targeted tillage of long-term no-till fields impacts topsoil properties and weed dynamics. An on-farm trial was implemented in 2020 to test the effects of occasional tillage (OT) in Morocco with a long-term no-tillage (NT) system and rainfed field crops: durum wheat (Triticum durum), faba bean (Vicia faba minor), and chickpea (Cicer arietinum). Four treatments were established, namely, continuous NT with crop residues maintained (“NT + residue”); continuous NT with crop residues not maintained (“NT-residue”); shallow inversion tillage (“shallow OT”); and deep non-inversion tillage (“deep OT”). We assessed the effect of these treatments on soil physical and chemical properties in 0–10 and 10–20 cm soil depths after crop harvest of the 2020–2021 (year 1) and 2021–2022 (year 2) growing seasons corresponding to 1 and 2 years after OT, respectively. In addition, we evaluated the effect of the treatments on weed populations and the effect of the legume crop rotated with wheat on soil nitrogen (N) and weed density. In year 1, deep OT reduced the water content at field capacity and available water capacity at 0–10 cm compared to continuous NT; the cation-exchange capacity (CEC) under deep OT was lower than in NT-residue and NT + residue at 0–10 cm and 10–20 cm, respectively. Furthermore, deep OT increased ammonium-N (NH4-N) at 0–10 and 10–20 cm compared to NT + residue but reduced exchangeable potassium (K) at 10–20 cm depth compared to NT-residue. In year 2, shallow OT had lower total porosity at 10–20 cm than NT + residue, while shallow and deep OT recorded higher water-stable aggregates at 0–10 cm than NT + residue; at 10–20 cm, deep OT recorded lower CEC than NT + residue. However, deep OT had higher nitrate-N (NO3-N) and available sulfur (S) than NT-residue at 10–20 cm. Occasional tillage did not significantly affect 10 out of 19 of the soil properties evaluated, including soil organic matter (SOM), in all the years and did not help reduce the stratification of soil nutrients in NT. In year 1, 50 days after OT, deep OT reduced the weed density by 46% compared to NT + residue, while in year 2, 406 days after OT, shallow OT reduced weed density by 53% compared to NT-residue. Regarding the effect of the legume rotated with wheat, faba bean appeared to be the better preceding or following wheat crop as it resulted in higher residual soil mineral N and lower weed infestation than chickpea.

Tillage and land use management effects on soil organic matter and soil microbial biomass in a field network of practical farms in France, Romania, and Sweden

A reduction in tillage intensity, organic farming, and introduction of ley-grass periods into the crop rotation are means to improve the sustainable use of arable soils. The current study uses an on-farm approach to investigate soils from different practical farms in Northern France, Central Sweden, and Romania in comparison with previously published results from randomized field-experiments nearby. No-tillage generally increased the mean SOC and total N contents of arable fields in comparison with ploughing. However, this increase was only significant for the 70 % increase at 0–10 cm depth in France. No-tillage had no general effects on MBC or MBN and increased the ergosterol content at 0–10 cm depth in France and Sweden but not in Romania. Averaging depths and tillage systems, median MBC significantly increased in the order France (220 μg g−1 soil), Romania (324 μg g−1 soil), and Sweden (384 μg g−1 soil), whereas the median MB-C/N ratios followed the order France (5.6), Sweden (8.3), and Romania (10.4). The study region-specific changes in soil pH significantly affected covariate MBC and MBN in the regression equations for equal slopes ANCOVA models. In Northern France, organic farming and ley-grass implementation into the crop rotation increased SOC and total N contents to the level of the no-tillage fields. On-farm research gives similar results to long-term field experiments in France, Romania, and Sweden. For this reason, on-farm research on practical fields is an important, less expensive alternative to randomized field experiments, with a high potential for investigating actual and relevant research objectives. This will intensify exchange in knowledge between scientists and farmers.

Influence of cover crops on soil aggregate stability, size distribution and related factors in a no-till field

Soil aggregation plays an essential role in maintaining soil structure. A three-year field experiment was undertaken to explore the effects of cover crops on soil aggregate stability indices (mean weight diameter, water-stable aggregates greater than 0.25 mm, and soil erodibility factor), size distribution and their correlations with nine soil physical and chemical properties (soil bulk density, pH, organic carbon, total nitrogen, C/N, calcium, phosphorus, potassium, and cation exchange capacity) at 0–5 and 5–10 cm depths in a Marietta silt loam soil in a no-till field, Northeastern Mississippi. The cover crop treatments included elbon rye (Secale cereale L.), daikon radish (Raphanus sativus ssp. acanthiformis), Austrian winter field peas (Lathyrus hirsutus), and their mixture. The samples were wet-sieved to five size classes of aggregates (> 2, 2–1, 1–0.5, 0.5–0.25, and < 0.25 mm). Results showed that the < 0.25 mm aggregates dominated (50.95–78.02 %) soil aggregate size distribution at 0–5 and 5–10 cm depths. The rye plot soil displayed the greatest values for mean weight diameter (0.58 mm) in the two soil depths. Soil water-stable aggregates greater than 0.25 mm value under peas was significantly higher by 68.61 % compared to the no cover crop treatment at 0–5 cm depth, while soil erodibility factor did not change significantly. Mean weight diameter, water-stable aggregates greater than 0.25 mm, soil erodibility factor, 1–0.5 mm aggregates, and < 0.25 mm aggregates were significantly correlated with soil organic carbon, pH, bulk density, phosphorus, and potassium. The dominant factors driving changes in three aggregate stability indices and size fractions (excluding 2–1 mm aggregates) were bulk density and pH. Furthermore, high pH restricted soil aggregate stability and size distribution. This study demonstrated the positive impact of cover crops, specifically peas and rye, on soil aggregate stability and size distribution. This study will provide valuable information for future research on soil stabilization in crop production management systems.

No tillage and leguminous cover crop improve soil quality in a typical rainfed Mediterranean system

Soil and crop management influence soil organic carbon (SOC), chemical composition, and overall soil quality. In a Mediterranean region, a study initiated in 1994 examined the long-term effects of conventional tillage (CT) versus no-tillage (NT) practices. Initially focusing on continuous durum wheat cultivation until 2009, the experiment later introduced a 2-year rotation of durum wheat and Vicia faba L. cover crops in half of the CT and NT fields. SOC was monitored from 2008 to 2018, while microbial biomass (as dsDNA), soluble nitrogen (N), and enzyme activities (EAs) were monitored from 2011 to 2014 to evaluate the rotation’s impact. Between 2009 and 2018, CT yields were on average 15% higher than NT, especially during high rainfall years. NT significantly increased SOC content in the 0–30 cm soil layer, along with higher levels of soluble N, dsDNA, and EAs at 0–10 cm depth. NT led to a 23% and 10% increase in SOC stock and SOC stock per equivalent soil mass compared to CT. EAs increased by over 50% under NT, indicating enhanced biological activity. The SOC increase due to NT was limited to the top 10 cm, with a decrease at deeper depths (up to 50 cm). Introducing cover crops over 4 years did not yield significant impacts, suggesting the need for a longer period to observe noticeable effects. Overall, adopting NT practices resulted in higher SOC concentration, enhanced soil biological activity, and improved biogeochemical cycles, emphasizing the positive impact of NT on soil health and sustainability.

Automated Crop Residue Estimation via Unsupervised Techniques Using High-Resolution UAS RGB Imagery

Crop Residue Cover (CRC) is crucial for enhancing soil quality and mitigating erosion in agricultural fields. Accurately estimating CRC in near real-time presents challenges due to the limitations of traditional and remote sensing methods. This study addresses the challenge of accurately estimating CRC using unsupervised algorithms on high-resolution Unmanned Aerial System (UAS) imagery. We employ two methods to perform CRC estimation: (1) K-means unsupervised algorithm and (2) Principal Component Analysis (PCA) along with the Otsu thresholding technique. The advantages of these methods lie in their independence from human intervention for any supervised training stage. Additionally, these methods are rapid and suitable for near real-time estimation of CRC as a decision-making support in agricultural management. Our analysis reveals that the K-means method, with an R2=0.79, achieves superior accuracy in CRC estimation over the PCA-Otsu method with an R2=0.46. The accuracy of CRC estimation for both corn and soybean crops is significantly higher in winter than in spring, attributable to the more weathered state of crop residue. Furthermore, CRC estimations in corn fields exhibit a stronger correlation, likely due to the larger size of corn residue which enhances detectability in images. Nevertheless, the variance in CRC estimation accuracy between corn and soybean fields is minimal. Furthermore, CRC estimation achieves the highest correlation in no-till fields, while the lowest correlation is observed in conventionally tilled fields, a difference likely due to the soil disturbance during plowing in conventional tillage practices.

Reduction of Nitrate Leaching and Threats to Surface Water Under Conservation Tillage

Highlights Conservation agriculture practice (NT) improved soil organic matter, a principal indicator of soil health, soil health score (SHS) and CO2 respiration, and other soil physical and chemical properties vs. conventional till (CT) practice. Conservation agriculture practice (NT) promoted soil health functions under sufficient precipitation distribution and ample temperature conditions and aided the soil's retention ability to resist nitrate leaching and loads in subsurface drainage discharge systems. Uneven weather conditions, drought, and other variable agronomic practices rendered soil conditions unfavorable to retain nitrate and induced adverse effects by increasing the nitrate leaching and loads in NT vs. CT. The limited experiment period presented significant challenges for the evaluation and synthesizing of soil health motivations and barriers in the NT vs. CT. Abstract. An edge-of-field subsurface drainage discharge system removes excess subsurface water from agricultural fields to improve the conditions of the soil system making them favorable for plant growth. Conversely, edge-of-fields can increase the nitrate (NO3 -) offsite movement to surface water bodies, which ultimately impacts water quality. In St. Johns, MI. Two on-farm large areas were initiated in 2013 for conservation (NT) and conventional till (CT) practices, of which two microscale fields, an area of 4 acres for each, were delineated in 2019 for NT and CT practices under a corn/soybean crop rotation. NT and CT fields were monitored and evaluated through full water years (WYs) 2019-2022. The objective was to use an innovative approach in coupling edge-of-field with soil health assessments to learn how improved soil health functions are influencing nitrate leaching and loads. NT practice enhanced SOM, other physical properties, and soil health parameters, promoting soil health functions compared to CT practice under conditions of adequate precipitation and favorable temperatures. Additionally, it improved the soil's ability to retain and resist nitrate loads in the 2020 water year, with reductions of 9.6 and 18.3 kg/ha, respectively. In 2021, WY nitrate loads reported nearly an equal value in NT vs. CT (4.8 and 4.4 kg/ha, respectively). Factors of uneven weather conditions and drought, variable agronomic practices, and residual nitrogen after corn, rendered soil conditions unfavorable to retain nitrate and induced adverse effects by increasing the nitrate leaching and loads in NT vs CT in 2022 WY (8.1 and 5.8 kg/h, respectively). Therefore, the limited evaluation period (2019-2022 WYs) presented significant challenges and revealed no affirmative evidence that the improved soil health functions under NT reduced the nitrate leaching loads in all WYs of this research. Further research is needed to prove the impact of NT on improving soil health functions to sustainably reduce nitrate leaching and loads in edge-of-fields. Keywords: Conservation no-till (NT), Conventional till (CT), Nitrate load, Soil health functions, Subsurface drainage discharge, Water quality.

Cover crop impacts water quality in a tile-terraced no-till field with corn-soybean rotation

Cover crops (CCs) are a recognized best management practice to reduce surface water runoff and nutrient loss from agroecosystems. This 4-yr study was conducted in a tile-terraced field to assess the effects of CCs on nutrient loss compared to without CC (no CC) in a corn (Zea mays L.)-soybean (Glycine max L.) rotation. The 3xCCmix (wheat (Triticum aestivum L.), radish (Raphanus raphanistrum subsp. Sativus), and turnip (Brassica rapa subsp. Rapa)) was aerial seeded in soybean at R6 in 2018 and 2020. Cereal rye (Secale cereale) was drill seeded after the corn harvest in 2019 and 2021 (corn-cereal rye-soybean-3xCCmix). Water samples from individual flumes were collected using automated samplers and analyzed for concentrations and loads of nitrate-N (NO3-N), total phosphorus (TP), dissolved phosphorus (PO4-P), and total suspended solids (TSS). The 3xCCmix and cereal rye had 16% and 12% lower discharge, respectively, than no CC. The 3xCCmix reduced TSS load 50% compared to CC, while cereal rye had no effect. Cover crops reduced NO3-N load 20%, 54%, and 68% during the corn, cereal rye, and soybean growing periods, respectively. Over the full rotations, cumulative discharge and nutrient loads were greater during the 2018–20 crop rotation year because of increased precipitation in 2019. The variability in effectiveness of CCs in reducing nutrient losses was likely affected by different climatic and management factors including CC planting and termination dates. This study highlights the benefits of CCs for reducing sediment and nutrient loss over crop rotation, as well as the continued need for enhanced fertilizer management systems to reduce nutrient loss.

Assessing the watershed-scale effects of tillage management on surface runoff and sediment loss using a Curve Number-precipitation relationship based approach

Poor soil management limits the soil functions of water infiltration and storage and enhances water and soil losses. Adoption of improved soil management practices is thus vital to protecting agricultural soils amid recurring droughts and declining water availability. Although the benefits of adopting soil health promoting practices such as no-tillage (NT) have been extensively investigated at field scale, studies quantifying the watershed-scale impacts of such practices are lacking. This study aims to address this gap by quantifying soil and water conservation benefits of adopting NT over conventional tillage (CT) on all croplands in the Brushy Creek Watershed in the Texas Blackland Prairies using the Agricultural Policy/Environmental eXtender (APEX) model. Most hydrologic and water quality models often fall short in accurately simulating the effects of management practices since they are not capable of simulating changes in soil and hydrologic properties that result from changes in soil management. This study proposed a novel framework to translate field-scale rainfall and runoff relationships into a watershed-scale parameterization tool that can be used for any agricultural watershed where measured rainfall and runoff data are available. Curve Number–Precipitation (CN-P) relationships were first defined based on field observations of rainfall and runoff from paired CT and NT fields. The CT and NT APEX models were then trained to follow the defined CN-P relationships to reflect the associated changes in hydrologic properties. Changing management from CT to NT on all croplands in the study watershed (i.e., in 35% of the watershed area) resulted in a 25% (38 mm year−1) reduction in average annual runoff and a 57% (1.13 t ha -1year−1) reduction in average annual sediment loss at the outlet of the watershed. The reduction in sediment loss from individual subareas with NT management was found to be sensitive to subarea physical properties such as slope and channel depth to width ratio, but the reduction in runoff was not sensitive to those properties. Results from this study are useful to natural resource conservationists and watershed managers in effectively implementing improved soil management practices.

Biochar derived from papermill factories improves soil physical and hydraulic properties in no-till cotton fields

Whether biochar produced as a by-product of energy generation from the papermill industry, and often disposed in landfills, can be gainfully applied to commercial croplands has not been investigated. The objective of this study was to investigate the physical and hydraulic properties of soils in commercial cotton fields managed as no-till systems following repeated applications of biochar generated as a waste of a papermill plant. Undisturbed cores and disturbed soil samples were collected from 0–5 and 5–10 cm layers from five commercial no-till fields in Mississippi, USA that received 6.7 Mg ha−1 year−1 biochar for 0, 2, 3, 5 or 10 years. A number of physical, hydraulic, and chemical properties of these samples were measured in the lab. The results showed that biochar reduced the degree of soil compactness and increased soil aggregation and structural stability index. The findings were particularly apparent for the 10 years of consecutive application, which increased soil aggregate stability by up to 67%, reduced bulk density from 1.40 to 1.26 g cm−3, and reduced degree of compactness from 73.2% to 62.8%. Biochar increased soil porosity but much of this increase (55%) occurred for small pores (< 0.5 μm) with little effect on storage pores (0.5–50 μm) or transmission pores (> 50 μm). Consequently, biochar increased soil field capacity by up to 26%, but PAW increased by only 17%. Biochar significantly increased soil physical quality index score in the 0–5 cm layer from 0.16 to 0.26 and the increase was positively correlated with the number of years of application. The results suggest biochar generated as a byproduct of papermill could be land-applied in real-world crop production systems to improve soil health as an alternative to disposal in landfills.Graphical

Earthworm richness in no-tillage farming systems and riparian forests in Southern and Southeastern Brazil

No-tillage (NT) is a soil conservation management practice that can sustain important earthworm populations due the maintenance of soil cover and absence of soil disturbance. Sites with NT can also support native earthworm species, but few studies have identified the earthworms collected under NT. Therefore, the present study evaluated earthworm diversity in 14 sites under NT and seven with riparian forest (RF) in Atlantic Forest located in Rolândia, Cambé, Toledo (Paraná), Coxilha, Sarandi (Rio Grande do Sul) and Itaí (São Paulo). The earthworms were collected by handsorting using quantitative and qualitative methods. The 1471 individuals collected were classified into 23 species belonging to five families: Glossoscolex sp.71, sp.72, sp.73 and sp.74, Fimoscolex sp.23 sp.24 and sp.25 (Glossoscolecidae); Pontoscolex corethrurus, Urobenus brasiliensis (Rhinodrilidae); Haplodrilus sp.1 and sp.2, Ocnerodrilidae sp.1, sp.15, sp.16, sp.48, sp.49 and sp.50 (Ocnerodrilidae); Amynthas gracilis, Metaphire californica (Megascolecidae); Dichogaster affinis, D. gracilis, D. bolaui and D. saliens (Benhamiidae). Of the total, 15 were native and eight were exotic species. In general NT sites had higher species richness than the forest sites (except at Itaí), mainly due to the invasion of NT fields by exotic species, particularly Ocnerodrilidae sp.1 and Dichogaster spp. Six of the seven forests had native species, but only four NT fields had native earthworms, and these were generally found in low abundance.

Weed Seed Bank Density in Seven-Year-Old Conservation in No-Till System

Weed management remains a challenge when introducing new cropping systems. In Lebanon, farmers are increasingly adopting conservation agriculture (No-till) because it saves energy and reduces water and nutrient erosion. However, introducing a new system will cause a significant shift in production and management practices and is expected to produce novel weed management challenges. Thus, knowledge of soil seed banks of weeds in such systems is vital in designing effective weed management strategies. The objective of this research was to assess the size of the weed seed bank in seven-year-old conservation no-till fields. Soil samples were collected from established till and no-till fields at a depth of 0-5 cm. Transient and persistent weed seeds banks were evaluated. Results provide tangible evidence that the weed seed bank at a depth between 0-5cm in no-till system is greater than in till system. The no-till fields contained almost seven times the density of monocot and dicot weed seeds than in the conventional tilled fields. Ongoing work that builds on present results will help gain knowledge pertaining to weed seed bank dynamics in no-till system compared with conventionally tilled system.

Mechanical Intervention in Compacted No-Till Soil in Southern Brazil: Soil Physical Quality and Maize Yield

The intense and successive use of mechanization in modern cropping systems has increased soil compaction under no-till areas. In this study, we aimed to assess the performance of a fixed shank coupled with a seeder for the mitigation of soil compaction induced by machinery traffic as an efficient alternative to replacing the chiseling and subsoiling operations in no-till areas. We evaluated a long-term experiment conducted in clay loam (Rhodic Haplustox) soil in southern Brazil. The experiment was conducted under a randomized block design, whose treatments consisted of three wheel-traffic intensities: 0 wheel-traffic (0 WT), 14 wheel-traffic (14 WT), and 28 wheel-traffic (28 WT), combined with four soil tillage mechanical interventions under a no-till field: no-till (NT), no-till with a fixed shank (NT + FS), soil chiseling (SC), and soil subsoiling (SS). The soil physical attributes evaluated were the soil penetration resistance (SPR), macroporosity (MaP), microporosity (MiP), total porosity (TP), bulk density (BD), field-saturated hydraulic conductivity (Kfs), S index, and plant-available water capacity (PAWC). In addition, three critical soil physical functions were evaluated by using a soil physical quality index (SPQI). The results showed that SPR was sensitive to soil compaction and captured differences among the mechanical intervention methods. Machinery traffic caused soil compaction, increasing SPR and reducing PAWC. Soil chiseling and subsoiling promoted lower BD, a higher TP, MaP, Kfs, and higher S index at the 0.05–0.15 m soil layer. Based on the SPQI, no changes were detected in the soil physical functions between NT and NT + FS. On the other hand, SC and SS enhanced soil physical functioning by 10%. We concluded that a 15-cm deep fixed shank could not mitigate the soil compaction induced by machinery traffic at the seeder operation. Therefore, this method is less effective in improving the soil’s physical environment than chiseling and subsoiling operations. Finally, we encourage monitoring the persistence of these benefits on the soil over the subsequent crop seasons and in years with an intense water deficit along with the crop cycle.

&lt;i&gt;Corrigendum to&lt;/i&gt;: A method for soil management assessment in an unreplicated commercial field

&lt;sec&gt; &lt;b&gt;Context&lt;/b&gt;: Unreplicated trials are common in agriculture. However, statistical inferences differ from those of traditional experiments based on small, replicated plots. &lt;/sec&gt; &lt;sec&gt; &lt;b&gt;Aims&lt;/b&gt;: To present a method to assess management effects on soil carbon (C) storage from unreplicated, side-by-side field trials. &lt;/sec&gt; &lt;sec&gt; &lt;b&gt;Methods&lt;/b&gt;: Two estimates of means with spatially correlated errors are compared using a corrected &lt;i&gt;t&lt;/i&gt;-statistic. Then causal inference is made by analysing a significant difference between the means (&lt;i&gt;P&lt;/i&gt;&lt;0.05) and its changes over time. The use of the method is described in comparing yield and organic C stocks between two large fields. Yield was measured during 1997&amp;#x2013;2005 with a commercial yield monitor, and soil organic C stocks during 2003&amp;#x2013;2005. The fields experienced the same tillage practice until autumn 2003 and then with different tillage intensity. &lt;/sec&gt; &lt;sec&gt; &lt;b&gt;Key results&lt;/b&gt;: The results show that crop C yield did not differ between the fields when using the same tillage practice but was greater in the tilled than the no-till field. The results also suggest that total and particulate organic matter-C contents depend on tillage history. For comparative purposes, the data were also analysed using standard mixed model analysis with a semivariogram model for spatial autocorrelation among the residuals. The mixed model results were generally similar to those of the corrected &lt;i&gt;t&lt;/i&gt;-statistic method. The mixed model was often, but not always, less conservative than the corrected &lt;i&gt;t&lt;/i&gt;-statistic model. &lt;/sec&gt; &lt;sec&gt; &lt;b&gt;Conclusions&lt;/b&gt;: The method allows analysis of whole-field data and improves our understanding of soil C processes in commercial fields, where agricultural assessment cannot involve replication due to agronomic and economic constraints. &lt;/sec&gt; &lt;sec&gt; &lt;b&gt;Implications&lt;/b&gt;: The method complements observational data analyses and can offer a direction towards whole-field management. &lt;/sec&gt;

Lime and calcium-magnesium silicate cause chemical attributes stratification in no-till fields

The stratification of soil chemical properties under long-term no-till (NT) where different soil pH regimes are used and at different cropping-systems (CS) has yet to be studied. We aimed to evaluate the effect of the surface application of soil pH amendments on soil chemical attributes of stratified soil samples and their relationship with the subsequent yield of the soybean crop. The effect of the surface application of lime and calcium-magnesium silicate (CMS) on the chemical attributes of soil samples with increment depth (0–5, 5–10, 10–20, 20–40, and 40–60 cm) was evaluated. Also, their relationships with the subsequent soybean (Glycine max) yield on a tropical acidic soil under NT with four CS (SB: soybean─Brachiaria brizantha; SC: soybean─Crotalaria spectabilis; SF: soybean─fallow; and SW: soybean─ Triticum aestivum) were compared. The NT operations caused the stratification of all soil chemical attributes studied regardless of the CS and soil pH amendment. Application of lime or CMS significantly decreased exchangeable aluminum (Al) and potential acidity (H+Al), and increased pH, calcium (Ca), magnesium (Mg), silicon (Si), the sum of base (SB), and base saturation (BS%) in the upper soil layers (up to 10 cm) for most CS studied. Soil acidity parameters from 0 to 5 cm were related to soybean yield, and the stratification of H+Al led to a difference of 2-ton ha-1 soil amendment needed (p < 0.001) when soil is sampled from 0 to 5 cm in comparison to the 0–20 cm sampling.

Synergistic effects of straw and earthworm addition on microbial diversity and microbial nutrient limitation in a subtropical conservation farming system

Conservation farming systems with straw return and no-tillage are recommended as effective methods for soil quality improvement, and they are often accompanied by increases in soil fauna populations. Recently, attempts have been made to improve the soil fertility in conservation agriculture through enhanced bioturbation by adding earthworms to no-till fields. However, the mechanisms associated with the responses in terms of soil functions, such as microbial diversity and microbial nutrient metabolism, to the synergistic effects of biotic and abiotic factors remain unclear. In this study, plow layer and plow pan soils were collected from subtropic cropland, and a full factorial microcosm experiment was conducted to quantify the effects of straw mulching and adding earthworms on the soil nutrient contents, microbial diversity, and extracellular enzymatic activities. The results showed that the single application of straw significantly increased the soil organic carbon (C), the ratio of C to nitrogen (N), and the ratio of C to phosphorus (P) in the plow layer soil (p < 0.05). The combined addition of straw and earthworms significantly increased the microbial diversity (Observed species, Chao 1 and Shannon), C/N/P-acquiring enzymatic activities, and microbial C limitation (p < 0.05), but decreased the microbial P limitation (p < 0.05) in the plow pan soil. Adding straw or earthworms did not affect the soil nutrient content in the plow pan soil (p > 0.05), microbial diversity, C-acquiring enzymatic activities, and microbial C and P limitations in the plow layer soil (p > 0.05). Structural equation models indicated that straw mulching indirectly affected the soil microbial diversity and microbial nutrient limitation through the buffering effects of aggregate stability and the C/P ratio in the plow layer soil. By contrast, the soil microbial activities were directly influenced by straw and earthworm addition in the plow pan soil. These findings indicate that earthworms enhanced soil microbial metabolism when straw was added by improving the substrate availability, and the soil physicochemical properties determined the asynchronous responses of the soil functions to land management. We suggest that the combined addition of organic matter and earthworms can improve the quality of soil in infertile land.

Tillage Management Impacts on Soil Phosphorus Variability under Maize–Soybean Rotation in Eastern Canada

Conservation tillage, including no-tillage (NT), is being used increasingly with respect to conventional tillage (CT) to mitigate soil erosion, improve water conservation and prevent land degradation. However, NT increases soil phosphorus (P) stratification, causing P runoff and eutrophication. For sustainable P management, fertilization must be balanced between P sources and actual crop demand. To reduce P losses to the environment, it is important to better understand P spatial variability in NT fields. Little is known about tillage impacts on field-scale P spatial variabi-lity in precision agriculture. This study examines tillage impacts on spatial variability of soil-avai-lable P in a maize–soybean rotation, in two commercial fields, denoted CT (10.8 ha) and NT (9.5 ha), with the aim of improving P fertilizer recommendations in Eastern Canada. NPK fertilizers were applied to the soils (Humic Gleysols) following local recommendations. Soil samples were collected in fall 2014 in regular 35 m by 35 m grids, at 0–5 and 5–20 cm depths, providing 141 and 134 geore-ferenced points for CT and NT fields, respectively. Available P and other elements were analyzed by Mehlich-3 extraction (M3), and the P saturation index (P/Al)M3 was calculated. Variability of soil-available P in both fields ranged from moderate to very high (32% to 60%). A mean (P/Al)M3 of 3% was found in both layers under CT, compared to 8% in the 0–5 cm layer and 6% in the 5–20 cm layer under NT. Relationships between P indices and other elements differed between tillage practices. This study highlights the need to improve P fertilizer recommendations in Eastern Canada.

Proposed revision to Canadian System of Soil Classification: broaden taxonomic criteria for applying LFH horizons to include nonforest soils

In the first edition (1974) of Canadian System of Soil Classification (CSSC), the taxonomic criteria for LFH organic horizons allowed application to any soil and land use developed under imperfectly to well-drained conditions. However, in the third edition (1998) of CSSC, the narrower taxonomic criteria for LFH horizons restricted application to only forest soils. A limited survey was conducted of some soil scientists across Canada to ask them if they had observed LFH horizons in nonforest soils. Distinct LFH horizons were observed across Canada under agriculture such as in no-till fields, tame and native pastures, and in reclaimed soils. They have also been observed in urban areas such as golf courses and grass-recreation fields. LFH horizons could also potentially develop under other nonforest land uses across Canada. Since no-till and native and tame pastures are most dominant in the prairies, the potential for LFH horizons is greatest in this region than elsewhere. However, they may occur anywhere in Canada where accumulation exceeds decomposition of organic material and they contain more than 17% organic carbon by weight or 30% organic matter. Therefore, we propose that the taxonomic criteria for applying LFH horizons be revised and broadened to include nonforest soils and be applicable to any soil order (where relevant) within Canada, and be at the discretion of the field pedologist. It is critical to identify and monitor LFH horizons over time because they are important for soil health, climate change, greenhouse gases, carbon sequestration, nutrient cycling, soil erosion, and hydrology.

Alteration in surface energy balance fluxes induced from long-term disk-tilled versus no-till management in maize production

Impacts of tillage-induced surface conditions on modification of the soil-crop-atmospheric interface have not been adequately studied. There is poor quantitative understanding at the intersection of tillage and surface energy balance (SEB), especially for the complete growing season. This research measured and evaluated SEB fluxes, i.e., net radiation (Rn), latent heat (LE), sensible heat (H), and ground heat flux (G) for three growing seasons (2011–2013) in a concurrent fashion in two similarly-managed maize (Zea mays L.) fields, which were under disk-till (DT) and no-till (NT) management for 17 years. To this end, each field was equipped with an identical Bowen Ratio Energy Balance System (BREBS) that collected 30-minute SEB data throughout the growing season. G was the most impacted SEB component, followed by H, LE, and Rn on an average basis, although these comparisons were subject to change during different times in the growing season. Seasonal mean interpretations masked within-season heterogeneity in DT vs. NT SEB dynamics and thus, daily differences for all SEB components, albedo (α), surface soil moisture (θv), and Bowen Ratio (β) were quantified. Greater α in NT field (0.16) was maintained throughout the growing season than DT field (0.14). All SEB components demonstrated greater differences between DT and NT in the early and late growing season. Nevertheless, SEB observations show that tillage impacts during significant crop canopy cover should not be ignored. NT surface (0–0.30 m) θv was as much as 22% greater than that of DT, and held critical importance for regional NT crop production during the extreme 2012 drought. θv also exerted control on albedo, with wetter soils having a lower albedo, which consequently translated into altered Rn across DT and NT fields. The research findings shown here underscore the particular importance of accounting for within-season behavior of albedo and G along with other components of SEB for evaluating soil management-related applications.