Tillage Intensity Research Articles

Transition to conservation agriculture: how tillage intensity and covering affect soil physical parameters

Abstract. Conservation agriculture (CA) relies on the following three key practices to improve agricultural sustainability: crop rotation, reduced tillage, and cover crop usage. Despite known soil physical benefits (reduced soil compaction and strength, enhanced soil porosity, and permeability), inconsistent reports on short-term CA results have limited its adoption in the European agroecosystems. To elucidate the short-term effects, a 3-year field experiment was undertaken in the low-lying Venetian plain (northern Italy). Bulk density (BD), penetration resistance (PR), soil hydraulic saturated conductivity, and sorptivity were used to evaluate soil quality obtained by combining three tillage intensities (conventional tillage – CT; minimum tillage – MT; no tillage – NT) with three winter soil coverings (bare soil – BS; tillage radish cover crop – TR; winter wheat cover crop – WW). Among the tillage methods, CT, on average, reduced BD by 4 % (from 1.48 to 1.42 g cm−3) and PR by 3.1 % (from 1.69 to 1.64 MPa) in the 0–30 cm tilled layer. Across the soil profile, reduced tillage coupled with WW improved soil physical properties even below the tilled layer, as evidenced by root-growth-limiting condition reductions (−11 % in BD values, with BD >1.55 g cm−3, and −7 % in PR values, with PR >2.5 MPa). Soil hydraulic measurements confirmed this positive behaviour; NT combined with either BS or WW produced a soil saturated conductivity of 2.12×10-4 m s−1 (4 times that of all other treatments). Likewise, sorptivity increased in NT combined with BS vs. other treatments (3.64×10-4 m s−1 vs. an all-treatment average of 7.98×10-5 m s−1). Our results suggest that, despite the increase in BD and PR due to reduced tillage, the strategy improved soil functioning and particularly soil hydraulic conductivity. In the short term, the WW cover crop moderately increased physical soil parameters, whereas TR had negligible effects. This study demonstrates that, to quantify CA, several soil physical parameters should be monitored.

Alternative combinations of tillage practices and crop rotations can foster earthworm density and bioturbation

Earthworms, which contribute to important soil functions, suffer from intensive agriculture. Their response depends among other things on the earthworm ecological group (anecic, endogeic, epigeic) and the combination of the applied farming practices. To advice on methodological adaptations that enhance earthworm-mediated soil functions, effects of different practices on earthworms need to be studied in concert. We investigated the effects of tillage intensity (conventional, reduced, no tillage) and crop rotation diversity (simple = wheat, barley; diverse = wheat, peas, oil seed rape) on earthworm density and community composition in a Swedish long-term experiment. Furthermore, we calculated annual earthworm bioturbation to quantify the effects of farming practices on earthworm functions. Total earthworm densities did not vary between the different tillage intensities, but were on average 58% higher in the diverse than in the simple crop rotation. The pattern was mainly due to the response of the most abundant endogeic earthworms, which were not affected by tillage intensity, but were nearly two times more abundant in the diverse than in the simple crop rotation. Densities of anecic earthworms were 17 times higher under no tillage than conventional tillage. Anecic earthworms also benefitted from a diversified crop rotation, but the response depended on tillage intensity. The level of bioturbation reflected the response of anecic earthworms, and was more than four times higher under no tillage, 549 g dw m−2 year−1, than under conventional tillage. We conclude that highest earthworm bioturbation is best achieved with no tillage. However, earthworm densities and potentially bioturbation can be increased also by a diversified crop rotation, when reducing tillage intensity is not feasible.

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.

Root disease and fungal populations in organic crops under different tillage–cropping systems

AbstractThere has been a steady expansion in organic production in the Canadian Prairies because of higher consumer demand. Thus, increasing the sustainability of organic systems would be important. An organic trial was conducted in the semi‐arid Prairies (2010–2015) with two tillage intensities (low vs. high) in a simplified [spring wheat (Triticum aestivum L.)–forage pea (Pisum sativum L.) green manure (GM)] and a diversified (spring wheat–oilseed–pulse–GM) rotation. In 2013–2015, the impact of these systems on root rot was examined on spring wheat, pulses, and GM crops. Several Fusarium spp. were more abundant in GM and pulses than spring wheat, suggesting that they could be a source of inoculum, especially of F. avenaceum (Fr.:Fr.) Sacc. (teleomorph Gibberella avenacea Cook), for Fusarium diseases in cereals including Fusarium head blight. Under different environments, tillage–rotation systems had an impact on root disease and fungal populations, some of which have biocontrol capabilities. There was no difference among systems for root rot in forage pea, while the low tillage‐diversified rotation had the lowest root rot in spring wheat but was associated with more Fusarium spp. For all crops, most Fusaria were not associated with root rot severity. Cochliobolus sativus (Ito &amp; Kurib.) Drechs. ex Dast. [anamorph Bipolaris sorokiniana (Sacc.) Shoemaker] accounted the most for root rot in spring wheat and was favored by intensive tillage and simplified rotations. The Shannon diversity index (H') of fungal species in spring wheat was higher in the diversified rotation under both tillage intensities than when spring wheat alternated with GM in the simplified rotation, especially under high tillage. In forage pea, H' was higher than in spring wheat, but did not differ among tillage–rotation systems.

Emerging Issues and Potential Opportunities in the Rice-Wheat Cropping System of North-Western India.

The rice–wheat cropping system (RWCS) is the backbone of Indian farming, especially in the north-western region. But continuous adoption of the RWCS in northwest India has resulted in major challenges and stagnation in the productivity of this system. Additionally, the Indo-Gangetic Plains of Pakistan, Nepal, and Bangladesh are also facing similar challenges for sustainable production of the RWCS. Several emerging problems, such as the exhausting nutrient pool in soil, deteriorating soil health, groundwater depletion, escalating production cost, labor scarcity, environmental pollution due to crop residue burning and enhanced greenhouse gas emissions, climatic vulnerabilities, and herbicide resistance in weed species, are a few major threats to its sustainability. To address these challenges, a wide range of sustainable intensification technologies have been developed to reduce the irrigation and labor requirements, tillage intensity, and straw burning. Awareness and capacity building of the stakeholders and policy matching/advocacy need to be prioritized to adopt time- and need-based strategies at the ground level to combat these challenges. This review summarizes the current status and challenges of the RWCS in the northwest region of the country and also focuses on the precision management options for achieving high productivity, profitability, and sustainability.

Can Regenerative Agriculture increase national soil carbon stocks? Simulated country-scale adoption of reduced tillage, cover cropping, and ley-arable integration using RothC

Adopting Regenerative Agriculture (RA) practices on temperate arable land can increase soil organic carbon (SOC) concentration without reducing crop yields. RA is therefore receiving much attention as a climate change mitigation strategy. However, estimating the potential change in national soil carbon stocks following adoption of RA practices is required to determine its suitability for this. Here, we use a well-validated model of soil carbon turnover (RothC) to simulate adoption of three regenerative practices (cover cropping, reduced tillage intensity and incorporation of a grass-based ley phase into arable rotations) across arable land in Great Britain (GB). We develop a modelling framework which calibrates RothC using studies of these measures from a recent systematic review, estimating the proportional increase in carbon inputs to the soil compared to conventional practice, before simulating adoption across GB. We find that cover cropping would on average increase SOC stocks by 10 t·ha−1 within 30 years of adoption across GB, potentially sequestering 6.5 megatonnes of carbon dioxide per year (MtCO2·y−1). Ley-arable systems could increase SOC stocks by 3 or 16 t·ha−1, potentially providing 2.2 or 10.6 MtCO2·y−1 of sequestration over 30 years, depending on the length of the ley-phase (one and four years, respectively, in these scenarios). In contrast, our modelling approach finds little change in soil carbon stocks when practising reduced tillage intensity. Our results indicate that adopting RA practices could make a meaningful contribution to GB agriculture reaching net zero greenhouse gas emissions despite practical constraints to their uptake.

Evaluation of promising varieties of winter barley in order to obtain high-quality raw materials for the production of bulky feed

The influence of the use of fertilizer doses at different intensity of tillage on the yield and quality of green feed based on winter barley varieties Romance, Kondrat, Dobrynya, Carioca was studied. The research was carried out in 2018-2020 in the Republic of Adygea on low-humus heavy-duty heavy-clay merged leached chernozems according to the method of field experience of B.A. Dospekhov. It was revealed that disking reduced the productivity of the green mass of various varieties of winter barley by 14,0–41,0%; the average yield for both processing methods varied from 5,75 to 11,2 t/ha. It was found that the most effective method of cultivation was the introduction of 60 kg of d.v. N by background, by both methods of processing, but plowing options are preferable in terms of yield. The use of this method of cultivation allowed to obtain the highest level of yield on these options for all studied varieties: Romance 15,3 t/ha, Dobrynya 14,6 t/ha, Kondrat 14,2 t/ha, Carioca 7,4 t/ha (on average for both methods of processing). The nutrient content in 1 kg of dry matter of feed varied from 8,02 to 11,0% crude protein; 11,1–11,74 MJ of exchange energy; 1,04–1,14 KE. The green mass of the Kondrat, Carioca, Romance varieties is classified as low- and medium-protein feeds, however, in terms of the content of feed units and exchange energy, all varieties are Class I feeds. The studied varieties contain an average of 0,42 to 0,605 EQ of cattle (energy feed units) in 1 kg of natural feed. According to the qualitative indicators in 1 kg of dry matter of feed, as well as the content of EKE in 1 kg of natural feed, the advantage belongs to the Dobrynya variety. The best variety in terms of yield, as well as nutritional and energy value for harvesting from 1 ha is the Romance variety.

The integration of nematode communities into the soil biological health framework by factor analysis

A critique of the soil health framework is that biological indicators currently lag behind chemical and physical indicators of soil health. Incorporating nematode communities into the soil health framework could help to better reflect key aspects of soil food web structure and function and significantly contribute to ecosystem processes. However, little is understood regarding how nematode communities relate to soil biological health indicators such as permanganate oxidizable carbon (POXC), soil protein, mineralizable C, and enzyme activities in agroecosystems. Here, we use an exploratory factor analysis (EFA) to quantitatively explore which set of soil health indicators best explain a given factor (i.e. soil health trait) using data from two long term experimental trials and 44 farm fields across Ohio. Specifically, this paper aims to 1) integrate our understanding of nematode structure and function with other soil biological health indicators to describe soil health traits; and 2) determine how management practices alter soil health traits. We found that soil biological health indicators represented four underlying soil health traits: fungal organic matter processing pathway, the rate of nutrient cycling, trophic complexity, and cumulative disturbance. Results indicated that soil biological health indicators, such as enzyme activities, POXC, mineralizable C and soil protein were more integrated with nematode feeding groups than with nematode indices. Additionally, tillage intensity had a significant effect on the fungal organic matter processing pathway and the rate of nutrient cycling. This study indicates that nematode feeding groups can be readily incorporated into the soil health framework and future soil health assessments.

Estimating fractional coverage of crop, crop residue, and bare soil using shortwave infrared angle index and Sentinel-2 MSI

ABSTRACT Accurate estimations of soil cover parameters (fractional coverage of crop residue [f cr], crop [f c], and bare soil [f bs]) in croplands can assist in decision-making for agricultural management organisations and are important for understanding the interrelations between global changes and terrestrial ecosystems. In recent decades, optical remote sensing has been widely used for mapping f c, f cr, and f bs. The crop residue and soil spectra decrease rapidly with increasing cropland moisture primarily because of water absorption in the near-infrared and shortwave infrared bands. This leads to a decrease in the denominator of current normalized crop residue spectral indices (shortwave infrared [SWIR] band 1 + band 2), thereby causing them to increase with increasing cropland moisture. This study revealed that the slopes of the soil and crop residue spectra between SWIR1 and SWIR2 were less affected by cropland moisture changes. Based on this feature, we propose a shortwave infrared angle (SWIRA) index and jointly use it with normalized difference vegetation index (NDVI) to estimate and produce multi-temporal maps of f c, f cr, and f bs using broadband Sentinel-2 MSI images. The proposed SWIRA is the slope of the spectrum between SWIR1 and SWIR2. This study (i) uses laboratory-based spectral reflectance to evaluate the performance of the SWIRA and (ii) further evaluates the performance of the SWIRA–NDVI method using multi-temporal Sentinel-2 MSI images. Our results indicate that (i) cropland moisture has a considerably smaller effect on SWIRA than it does on current broadband normalized crop residue spectral indices, and (ii) maps of the estimated f c, f cr, and f bs values can be used to improve crop growth and decision-making, for example, by providing harvest maps and soil tillage intensity maps.

Using arable units with tractors of traction class 1.4 of different power

The article presents the results of analytical studies of the traction characteristics of wheeled tractors with a power of 50-75 kW located in the same traction class 1.4. Empirical expressions are obtained for the dependence of the tractive effort of the Case IH Farmall JX 1090U, Challenger MT 425, Massey Ferguson 4225, New Holland TD 5030 MTZ-80, MTZ-82 tractors on the travel speed. The dependence of the traction resistance of a three-body plow PLN-3-35 on the speed of movement, aggregated with tractors of traction class 1.4, has been determined. As a result of the graphic-analytical analysis, the optimal loading mode for each tractor was established when working with a PLN-35 plow, 1.05 m wide at a depth of 0.30 m. The hourly productivity of arable units and the energy intensity of the main moldboard tillage are determined. A comparison of the obtained operational indicators is given.

Long-term impact of zero-till residue management in post-rainy seasons after puddled rice and cropping intensification on weed seedbank, above-ground weed flora and crop productivity

Regulation in weed seed recruitment to soil and its emergence is an ecological approach of weed management for sustainable cropping intensification and land restoration. Intensive tillage operations in rice (Oryza sativa L.) - wheat (Triticum aestivum L.) system is a predominant practice in the South East Asian countries. This practice has emerged as an unsustainable crop management options. Consequently, zero tillage (ZT) in post–rainy seasons after conventional tilled (CT) puddled transplanted rice is being adopted to minimize tillage intensity in system in these regions. However, long–term impact of continuous CT in all seasons versus seasonal ZT (in post–rainy seasons) after puddled transplanted rice with crop residues in cropping system mode on above– and below– ground weed density and diversity is not adequately studied. Hence, we examined four tillage based residue management: (i) conventional tillage in each crop of rotation without residue (CT–CT), (ii) conventional tillage in each crop with incorporated residue (CT–CT + R), (iii) conventional tilled puddled transplanted rice – zero tillage in post–rainy season crops without residue (CT–ZT), (iv) conventional tilled puddled transplanted rice – zero tillage in post–rainy season crops with surface residue mulch (CT–ZT + R) each with three levels of crop rotation: (i) rice – wheat (R–W), (ii) rice – chickpea (Cicer arietinum L.) (R–C), (iii) rice – chickpea – mungbean (Vigna radiata (L.) (R–C–Mb) in split–plot design in Kanpur, India. Zero tillage in post–rainy seasons after conventional tilled rice resulted in 11%, 23%, and 13% lower (P < 0.05) weed seed density than CT–CT at 0–7.5, 7.5–15, and 0–15 cm depth, respectively. However, zero-tilled residue management had 15–19% and 10–14% (P < 0.05) higher above–ground weed density compared with CT–CT. Rice-chickpea-mungbean rotation reduced weed seed density by 6–11%, 4–11%, and 6–8% (P < 0.05) than those of rice-wheat and rice-chickpea across depth. In contrast, rice-chickpea-mungbean had 30–38% higher total above–ground weed density than rest of the crop rotations. Post–rainy seasons zero tillage with and without residues attributed higher weed diversity indices (Shannon and Simpson) compared with conventional tillage in seedbank. Importantly, CT–ZT + R with R–C–Mb (interaction) reduced 24% total viable seed density at 0–15 cm depth than CT–CT with R–W. Further, this system brought about 15% and 62% higher rice seed yield and system productivity over CT–CT with R–W, respectively. Conventional tilled puddled transplanted rice – zero tillage with added residues increased 16% and 33% seed yield of wheat and chickpea compared with CT–CT (P < 0.05), respectively. Thus, it can be concluded that zero tillage in post-rainy seasons after puddled transplanted rice and intensive pulse based cropping (rice-chickpea-mungbean) can minimize viable weed seeds in soil vis–a–vis above–ground weed density over time than conventional tillage and rice-wheat system. The reduced weed density could reduce soil fertility degradation, enhance crop/system productivity, restore soil health and provides opportunity for sustainable cropping intensification in rice ecologies of the Indo-Gangetic plains.

The relationship between farmer demographics, social identity and tillage behavior: Evidence from Michigan soybean producers

Effectively promoting sustainable agricultural practices like conservation tillage (CT) is of critical importance for developing more efficient and sustainable value chains. While many studies have considered what factors might lead to tillage reduction, few have considered the role of social and structural determinants in farmer decision-making. Fewer still have considered tillage intensity as existing on a continuous spectrum that ranges from no-till to conventional tillage. Using primary data collected from Michigan soybean growers and an adapted Theory of Planned Behavior model, this article identifies key relationships between growers' demographics, social connections and their tillage practices. Results indicate that farmers with lower household income, more farming experience and weaker social network connectivity may be more likely to adopt CT technologies in Michigan soybean production. In addition to these factors, accounting for farmers’ subjective perspectives on the efficacy of CT, particularly its ability to save labor and conserve soil, may increase the success of future outreach encouraging CT in this context. These results have important implications for ongoing extension programs, as they suggest that adoption of sustainable agricultural practices such as CT is not only a function of individual level farm or farmer characteristics, but also of farmer perceptions of the opinions and practices of their unique social networks.

A method for soil management assessment in an unreplicated commercial field

Context Unreplicated trials are common in agriculture. However, statistical inferences differ from those of traditional experiments based on small, replicated plots. Aims To present a method to assess management effects on soil carbon (C) storage from unreplicated, side-by-side field trials. Methods Two estimates of means with spatially correlated errors are compared using a corrected t-statistic. Then causal inference is made by analysing a significant difference between the means (P &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 1997–2005 with a commercial yield monitor, and soil organic C stocks during 2003–2005. The fields experienced the same tillage practice until autumn 2003 and then with different tillage intensity. Key results 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 t-statistic method. The mixed model was often, but not always, less conservative than the corrected t-statistic model. Conclusions 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. Implications The method complements observational data analyses and can offer a direction towards whole-field management.

Influence of Tillage Intensity and Weed Control Practices on Mesopore Hysteresis Loop of Soil Moisture Retention Curves in Southwest Nigeria

Influence of Tillage Intensity and Weed Control Practices on Mesopore Hysteresis Loop of Soil Moisture Retention Curves in Southwest Nigeria

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

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

Cropping system diversification does not always beget weed diversity

Cropping system (CS) diversification appears as a promising solution to increase CS sustainability. However, weed community response to different options of CS diversification remains poorly documented. Moreover, these effects are expected to be more pronounced in experimental than commercial farms because experimental farms explore more diverse combinations of farming practices. We hypothesized that (i) CS diversification would increase weed diversity at multiple spatio-temporal scales but that (ii) different options of CS diversification would select different weed communities and that (iii) responses could differ between experimental and commercial farms. Hence, weed density per species was measured over a 6-year time period in a CS experiment and in a farmers’ network (both resorting to diverse CSs that were numerically summarized to allow their comparison, i.e. different positions along gradients of tillage intensity, herbicide use, crop rotation length etc.). Weed density measures were used to compute weed diversity indices (taxonomic and functional, at annual and plurennial scales) and community weighted means on key response traits for each CS. All experimented alternative CSs (diversified crop sequences with coherent but different combinations of weed management tools) showed that diverse combinations of agronomic tools are available to increase weed diversity, as highlighted by a 3 and 2-fold increase in species richness at the annual and plurennial scales, respectively. In contrast, only one farmer CS (3-year rotation, low tillage intensity, intermediate herbicide reliance) showed significantly higher levels of weed diversity, possibly because the reduced tillage intensity was not compensated by other agronomic levers (e.g. increase of herbicide use and/or crop rotation diversity). Such outcomes were attributed to (i) reduced CS complexity in commercial compared to experimental farms and (ii) high herbicide reliance in commercial farms, irrespectively of CS complexity. Across both experimental and commercial farms, tillage, weed management and crop type appeared as the main factors structuring weed communities. Systems with reduced tillage were associated with a higher percentage of grasses and perennials. Systems with spring/summer crops and/or mechanical weeding were associated with a higher proportion of spring/summer and perennial species. These results suggest that solutions are readily available for farmers to implement sustainable weed management, but supports are required to address the factors hindering the adoption of these experimented CS in commercial conditions.

Global variation in soil carbon sequestration potential through improved cropland management.

Widespread adoption of improved cropland management measures is advocated to increase soil organic carbon (SOC) levels, thereby improving soil fertility and mitigating climate change. However, spatially explicit insight on management impacts is limited, which is crucial for region‐specific and climate‐smart practices. To overcome these limitations, we combined global meta‐analytical results on improved management practices on SOC sequestration with spatially explicit data on current management practices and potential areas for the adoption of these measures. We included (a) fertilization practices, i.e., use of organic fertilizer compared to inorganic fertilizer or no fertilizer, (b) soil tillage practices, i.e., no‐tillage relative to high or intermediate intensity tillage, and (c) crop management practices, i.e., use of cover crops and enhanced crop residue incorporation. We show that the estimated global C sequestration potential varies between 0.44 and 0.68 Gt C yr−1, assuming maximum complementarity among all measures taken. A more realistic estimate, not assuming maximum complementarity, is from 0.28 to 0.43 Gt C yr−1, being on the lower end of the current range of 0.1–2 Gt C yr−1 found in the literature. One reason for the lower estimate is the limited availability of manure that has not yet been recycled. Another reason is the limited area for the adoption of improved measures, considering their current application and application limitations. We found large regional differences in carbon sequestration potential due to differences in yield gaps, SOC levels, and current practices applied. The highest potential is found in regions with low crop production, low initial SOC levels, and in regions where livestock manure and crop residues are only partially recycled. Supporting previous findings, we highlight that to encourage both soil fertility and SOC sequestration, it is best to focus on agricultural soils with large yield gaps and/or where SOC values are below levels that may limit crop production.

Belowground Dynamics Influence Nitrogen Cycling and Crop Productivity in Diversified Corn Systems

Ecological nutrient management is a strategy that can help create resilient cropping systems and reduce the negative impact that agricultural systems have on the environment. Ecological nutrient management enhances plant-soil-microbial interactions and optimizes crop production while providing key ecosystem services. Incorporating perennial legumes into crop rotations and implementing no-till to enhance organic nitrogen (N) soil pools could reduce the need for inorganic N fertilizer inputs and lead to improved soil health. Plant and soil N pools need to be further quantified to understand how to enhance soil health across a range of agroecosystems. This paper aims to quantify plant and soil N pools in systems contrasting in crop perenniality (corn–corn, corn–soy, and corn–forage–forage) and tillage intensity (chisel till vs. no-till). Key plant, soil, and organismal metrics of N cycling were measured including fine root production, N-Acetyl-B-Gulcosaminidase (NAG) enzyme activity, and soil protein, nematode enrichment opportunist (fungal and bacterial feeding nematodes) and the nematode Enrichment Index. Fine root production was determined using in-growth mesh cores. Findings reveal that monoculture cropping systems with reduced tillage intensity and rotations with perennial legumes had significantly greater fine root N (FRN), soil protein and NAG enzyme activity (p &amp;lt; 0.05) relative to corn-soy. Additionally, nematode bacterivore enrichment opportunists (b1) were significantly reduced in corn-corn systems when compared to all other crop rotation systems. Correlation analyses indicated positive and significant relationships between FRN and soil protein (p &amp;lt; 0.05). These results demonstrate that lengthening crop rotations with perennial legumes and incorporating no-till management can increase organic N inputs, N mineralization rates, and organic N storage. Such ecological approaches to management have the potential to reduce the need for inorganic N inputs, while increasing long-term soil health and crop productivity.

Soil Disturbance Impact on Crop Ergothioneine Content Connects Soil and Human Health

Ergothioneine (ERGO) is a potent antioxidant and anti-inflammatory amino acid that is produced in nature mainly by non-yeast fungi, cyanobacteria, and mycobacteria. Mounting evidence suggests that ERGO can be considered a longevity vitamin that can mitigate chronic diseases of aging and thereby increase life expectancy. Humans must obtain ERGO from their diet, and it is therefore important to know which foods contain it. Although ERGO is not produced by plants it is found in plant products such as grain, apparently because detrital or symbiotic soil fungi pass on ERGO to plants through their roots. Besides differences between plant species in their ability to accumulate ERGO, how they are managed might also affect its concentration. Soil tillage has been shown to reduce soil fungal biomass, and therefore ERGO contents in maize, soybeans, and oats grown in soil managed with annual moldboard plowing (most intensive), chisel/disking (less intensive), or no-tillage (least intensive) in crop rotation were compared. ERGO concentrations declined in all three crops as tillage intensity increased, with reductions from no till to moldboard plow of approximately 30% in all three crops. Because crop yield was also negatively impacted by intensive tillage, ERGO yield per hectare was reduced even more due to increasing tillage intensity. This study is one of the first to show that soil health improving practices that minimize soil disturbance can directly enhance a key dietary factor associated with long-term human health.

Alternative methods for terminating green manures in organic grain systems

AbstractLegume green manures (GM) are a vital source of nitrogen (N) for many organic grain systems. A common practice among organic growers is to undersow clover into a small grain, harvest the grain crop and terminate the clover stand in late fall by moldboard plowing in preparation for a cash crop the following spring. While fall plowing offers excellent clover kill, growers increasingly seek an alternative termination method that reduces tillage intensity and bare winter soil. This study, performed at two sites in Maine, evaluates three clover termination methods for kill efficacy, winter soil cover, spring soil conditions and N uptake and grain yield and protein of a subsequent test crop of hard red spring wheat (Triticum aestivum L., var. Glenn). Red clover (Trifolium pratense L.) was intercropped with spring barley (Hordeum vulgare L.) and terminated in late fall by moldboard plowing (PL), skim plowing (SK) or undercutting (UC). A control treatment received no clover and was fall plowed. An additional treatment, winterkilled field peas (WK), was evaluated at one site. SK, UC and WK increased soil cover relative to PL, though UC resulted in low clover kill efficacy in a wet spring and is in need of improved design. Grain yield was higher following red clover compared to the no-clover control at one site, but was unaffected by termination method. At one site, grain crude protein was higher following PL than the other treatments, indicating the possibility for more favorable timing of N availability associated with PL.