Continuous Conventional Tillage Research Articles

Influence of Cropping Sequence and Tillage System on Plant-Parasitic Nematodes and Peanut (Arachis hypogaea) Response to Fluopyram Applied at Planting

Crop sequence and tillage can affect the yield of peanut (Arachis hypogaea L.) and other crops. Research was conducted from 2006 through 2022 to determine the response of peanut to previous crop sequences including corn (Zea mays L.) and cotton (Gossypium hirsutum L.) planted in continuous conventional tillage (e.g., disking, field cultivating, and bedding with in-row sub-soiling) or strip tillage (e.g., tilling a 45 cm section on rows spaced 91 cm apart using fluted coulters, rolling baskets, and in-row sub-soiling). In 2013, 2019, and 2022, the entire test area was planted with peanut. In 2019 and 2022, peanut was planted without or with fluopyram applied in the seed furrow at planting. Decreasing the number of years between peanut planting resulted in lower peanut yields compared with fewer years of peanut planting in the rotation sequence. Continuous conventional tillage and strip tillage resulted in similar peanut yields at one location, while the yield was lower at a second location when peanut was planted in continuous strip tillage. Fluopyram did not affect peanut yield regardless of previous crop rotation sequence, the number of years separating peanut plantings, or the tillage system. However, minor differences in the populations of plant-parasitic nematodes in soil were noted when comparing fluopyram treatment. The results from these experiments indicate that while fluopyram can reduce the populations of some plant-parasitic nematodes in soil, the magnitude of reduction does not translate into increases in peanut yield.

Effects of innovative long-term soil and crop management on topsoil properties of a Mediterranean soil based on detailed water retention curves

Abstract. The effectiveness of conservation agriculture (CA) and other soil management strategies implying a reduction of tillage has been shown to be site-dependent (crop, clime and soil), and thus any new soil and crop management should be rigorously evaluated before its implementation. Moreover, farmers are normally reluctant to abandon conventional practices if this means putting their production at risk. This study evaluates an innovative soil and crop management (including no-tillage, cover crops and organic amendments) as an alternative to conventional management for rainfed cereal cropping in a calcareous soil in a semi-arid Mediterranean climatic zone of Navarra (Spain), based on the analysis of soil water retention curves (SWRCs) and soil structure. The study was carried out in a small agricultural area in the municipality of Garínoain (Navarre, Spain) devoted to rainfed cereal cropping. No other agricultural area in the whole region of Navarre exists where soil and crop management as proposed herein is practiced. Climate is temperate Mediterranean, and the dominant soil is Fluventic Haploxerept. Within the study area there is a subarea devoted to the proposed soil and crop management (OPM treatment), while there is another subarea where the soil and crop management is conventional in the zone (CM treatment). OPM includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Undisturbed soil samples from the topsoil and disturbed samples from the tilled layer were collected for both systems. The undisturbed samples were used to obtain the detailed SWRCs in the low suction range using a HYPROP©device. From the SWRCs, different approaches found in the literature to evaluate soil physical quality were calculated. The pore-size distribution was also estimated from the SWRCs. Disturbed samples were used in the laboratory to assess soil structure by means of an aggregate-size fractionation and to perform complementary analysis from which other indicators related to soil functioning and agricultural sustainability were obtained. The approaches evaluated did not show clear differences between treatments. However, the differences in soil quality between the two forms of management were better observed in the pore size distributions and by the analysis of the size distribution and stability of soil aggregates. There was an overabundance of macropores under CM, while the amount of mesopores (available water) and micropores were similar in both treatments. Likewise, more stable macroaggregates were observed in OPM than in CM, as well as more organic C storage, greater microbial activity, and biomass. The proposed management system is providing good results regarding soil physical quality and contributing also to the enhancement of biodiversity, as well as to the improvement in water-use efficiency. Finally, our findings suggest that the adoption of the proposed practice would not result in a loss in yields compared to conventional management.

The lagging movement of soil nitrate in comparison to that of soil water in the 500-cm soil profile

The combination of forage-crop rotation with conservation tillage has long been known to result in proven productivity and sustainability, but less information is available on the influence of long-term conservation tillage practices on the movement of soil water and residual nitrate at deep soil depths in forage-crop rotation systems. In this study, we measured the changes in soil water storage, residual soil nitrate accumulation and their relationship to study the long-term effects of tillage and mulching practices on regional nitrogen management in maize (Zea mays L.)-wheat (Triticum aestivum L.)-common vetch (Vicia sativa L., annual legume forage) rotation system. Soils were collected from the 500-cm soil profile at the harvest stage of the maize and common vetch after 19 years of continuous conventional tillage (T), conventional tillage followed by straw mulching (TS), no tillage (NT), and no tillage followed by straw mulching (NTS) on the Loess Plateau, China. The results showed that the NT practices increased soil water storage by 3.07% compared with the T practices in the maize field, mulching practices increased soil water storage by 3.47% compared with no mulching practices in the common vetch field, and the improvement effect was mainly concentrated in the deep soil layer (150–500 cm). When compared with no mulching, straw mulching practices increased residual soil nitrate accumulation by 51.20 kg ha−1 at shallow soil depths (0–120 cm) but decreased this accumulation by 206.09 kg ha−1 at deep soil depths (120–500 cm) in the maize field; however, straw mulching decreased nitrate accumulation by 16.25 kg ha−1 throughout the whole profile (0–500 cm) in the common vetch field. The NT practices decreased residual soil nitrate accumulation by 131.65 kg ha−1 compared with the T practices in the maize field but had no effects on the common vetch field in the 0–500-cm soil profile. Greater changes in soil residual nitrate accumulation appeared at depths of 200–500 cm than at other depths. Moreover, according to structural equation model, nitrite accumulation was limited by soil water storage. Soil nitrate peaked at deeper soil depths in the NT (90–120 cm) and TS (250–300 cm) treatments than in the T treatment (60–90 cm), whereas the NTS treatment resulted in no nitrate accumulation peak across the whole soil profile. Soil water recharge and depletion were deeper in the NT and TS treatments than in the T treatment, and this effect could limit the further leaching of soil nitrate into deep soil. The depth of soil water recharge was deeper than the depth of nitrate accumulation, and the vertical movement speed of soil residual nitrate was slower than that of soil water. Therefore, the downward movement of soil nitrate lagged behind that of soil water. Together, these results demonstrated that the NTS treatment exerted the strongest effect on maintaining soil water and decreasing residual nitrate accumulation at deep soil depths, which will be favorable for improving regional N management and assessing N budgets in agroecological systems on the Loess Plateau.

Long-term no tillage management impact on soil hydro-physical properties in coffee cultivation

Tillage management in agricultural fields has consequences on the dynamics of the soil structure and soil’s pore functions with far reaching effects on the sustainability of cropping system. The purpose of this study is to investigate changes in both capacity and intensity properties of a very clayey Rhodic Hapludox after 37-year of continuous conventional tillage (CT) and no till (NT) management for weed control under coffee plantations. Undisturbed soil samples were collected at four depths and used for hydro-physical characterization. The tillage treatments modified the capacity and intensity parameters differently depending on the sampled depth. Bulk density was similar at the 0–20 cm layer in both CT and NT treatments, but at the 20–40 cm layer, NT significantly increased the bulk density by (6–8%). Also, NT increased the stability of 8–2 mm macroaggregate fraction in water and significantly increased the geometric mean diameter and the mean weight diameter of the water-stable aggregates in most of the layers relative to CT. Moreover, CT increased hydraulic conductivity by 53% in the surface layer. Generally, the magnitude of the differences in soil properties as a consequence of the 2 tillage treatments was greater for hydraulic conductivity (soil intensity parameters) than the bulk density (soil capacity parameters). In the NT plots, more water was retained within the available water range, while CT presented steeper water retention curves and poorly graded pore-size distributions. The pore-size distribution and hydraulic capacity function curves showed that the impact of CT management was more pronounced at the 10–20 cm layer, while that of NT management was most significant at the 0–10 cm layer (soil surface). This study showed that in addition to soil strength indicators, soil intensity parameters (hydraulic conductivity, hydraulic capacity and soil structure) more succinctly explained differential impact of tillage systems on soils, as compared to the capacity parameters (bulk density, pore size distribution, air capacity and available water capacity).

Soil organic carbon stock and its changes in a typical karst area from 1983 to 2015

Changes in soil organic carbon (SOC) stock have major impacts on global terrestrial carbon cycling. However, their responses to land use conversions are poorly characterized for karst areas with extremely fragile geology and intensive human disturbance. To investigate the effects of soil type and land use on SOC stock in a typical karst region of southwestern China, 0–15 cm topsoil samples were randomly collected in 2015. Furthermore, in the same locations as the sites in 1983, 0–100 cm stratified profile soil samples (0–10, 10–20, 20–30, 30–50, 50–70, and 70–100 cm) were collected to evaluate the changes in SOC stock as affected by land use conversions from 1983 to 2015. The current SOC stock in 0–15 cm differed significantly between Calcisols and Ferralsols, and was highest in the secondary forest, followed by shrubland, grassland, plantation forest, and cropland. Changes in the stratified SOC stock (both recalculated to 0–20, 20–40, 40–60, 60–80, and 80–100 cm intervals in 1983 and 2015) varied among different land use conversions. Average stratified SOC stock decreased after forest degradation and reclamation, except in 80–100 cm. After reforestation, it had decreases in 0–20 and 20–40 cm, whereas it increased in subsoil (40–60, 60–80, and 80–100 cm). However, compared with the cropland in which soil was exposed to continuous conventional tillage, average stratified SOC stock increased in all soil layers after reforestation. The increases in SOC stock after reforestation and re-cultivation (short-term reuse in abandoned croplands) indicated the positive role of agricultural abandonment in increasing terrestrial SOC stock.

Use of solid anaerobic digestate and no-tillage practice for restoring the fertility status of two Mediterranean orchard soils with contrasting properties

Soil structure degradation, declining soil organic matter and nutrient losses are among major drawbacks of continuous conventional tillage with large-scale environmental consequences including decreasing soil productivity, groundwater contamination and greenhouse gases emissions. This becomes especially true in conventionally-tilled Mediterranean croplands which are also affected by severe climatic conditions. In this study, a one-year field experiment was carried out to investigate the impact of different tillage practices on the soil fertility status in two tree orchards (olive, citrus) soils with contrasting texture (clay, sandy loam), carbonate content (non-calcareous, slightly calcareous) and pH (strongly acid, slightly alkaline), located in Southern Italy. Treatments included in this study were conventional tillage, conventional tillage combined with the incorporation of solid anaerobic digestate, and no-tillage. Changes in the aggregate stability and dynamics of various C and N pools were assessed by monitoring a large set of physical (aggregate stability index), chemical (pH, electrical conductivity, total organic C, total N, nitrate-N, ammonium-N, total soluble N, extractable organic N), biochemical (microbial biomass C and N, basal respiration, potentially mineralizable N) and eco-physiological (microbial and metabolic quotients, mineralization coefficient) soil variables. Results showed that the stability of soil aggregates declined under conventional tillage, remained unaltered under no-tillage, improved after digestate amendment. Moreover, following incorporation of digestate large and long-lasting increase of the organic pool, microbial C-use efficiency and release of soluble C and N forms were observed in the fine-textured soil. Whereas opposite responses were found in the moderately coarse alkaline soil, where incorporation of digestate stimulated C resources depletion, microbial respiration and N losses due to ammonia volatilization with less beneficial effects on soil organic pools. On the other hand, no-tillage prevented soil C and N resources from over-exploitation (as observed in conventionally-tilled soils) with greater beneficial effects on microbial C-use efficiency and biomass found in the coarse than in the fine-textured soil. Our findings suggest that improved management practices such as no-tillage or conventional tillage combined with incorporation of solid anaerobic digestate should specifically deal with soil and climate conditions to became effective for restoring the fertility status in Mediterranean orchard soils.

Effects of tillage types on soil aggregate distribution and stability in irrigated sierozem of Gansu Yellow River irrigation area, China

A total of six treatments, including continuous conventional tillage (CT), rotary tillage (RT), subsoiling (ST), no-tillage (NT), conventional-no tillage (CT-NT) and subsoiling-no tillage (ST-NT), were conducted to examine the effects of different tillage types on soil aggregates distribution and stability of irrigated sierozem on continuous 8-year-tillage maize fields in the Gansu Yellow River irrigated area in 2014-2017. The results showed that the aggregation and stability of large aggregates in 0-40 cm soil layer were increased by NT and ST-NT treatments, while the size distribution and stability in plough layer were significantly decreased by CT and RT treatments due to strong soil disturbance. Compared with RT, the mechanical stability of aggregates under dry sieving NT was the best. The contents of >0.25 mm aggregate (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 5.8%, 8.0%, and 13.0%, respectively, and fractal dimension (D) decreased by 3.6%. The water-stable aggregates in ST-NT was the best, with R0.25, MWD and GMD increased by 55.3%, 15.1% and 8.7%, respectively, and D value decreased by 0.8%. The percentage of aggregate destruction (PAD) and unstable aggregate index (ELT) of NT and ST-NT treatments were the lowest. PAD was reduced by 5.9% and 7.7% compared with RT, ELT was reduced by 5.8% and 7.2%, respectively. All the results indicated that the subsoiling-notillage (ST-NT) rotation mode was more conducive to the enhancement of soil aggregate content and stability and consistent with the local farmers operating habits, which would be an ideal tillage method and had certain application value for the sustainable agricultural development in this area.

Soil water use and crop yield increase under different long-term fertilization practices incorporated with two-year tillage rotations

Water shortage and soil nutritionally depleted are the most limiting factors of crop production on the Loess Plateau. Conservation tillage rotation, conserved soil water and enhanced soil fertility effectively, produced high and stable crop yields in a spring maize-winter wheat-fallow rotation over a two-year period (hereafter called maize-wheat-fallow rotation). Corresponding and appropriate fertilization practices should enable the full potential of tillage rotation. Therefore, a long-term two-factor split-plot experiment (2007–2016) was established in Heyang County, Shaanxi Province, China, a typical rainfed dryland agricultural region. Beginning in 2007, three fertilization practices (balanced fertilization (BF), low fertilization (LF) and conventional fertilization (CF)) and four tillage systems (no tillage rotated with subsoiling annually (NS), subsoiling rotated with conventional tillage annually (SC), conventional tillage rotated with no tillage annually (CN), and continuous conventional tillage (CT)) were conducted to assess crop yield and soil water variation. The results showed that CCN (CF + CN, 5440 kg ha−1) and BNS (BF+NS, 8415 kg ha −1) produced the highest crop yield for winter wheat and spring maize, respectively. LNS (LF + NS, 419 mm) had a better soil water condition in fallow periods. NS and CN rotations had a better soil water condition (reserved more soil water for crop growth) than SC and CT during the wheat and maize growth season. However, both the average ET of winter wheat and spring maize under all of the treatments had no significant differences (P > 0.05) in ten years. In ten years, NS and CN rotations had higher water use efficiency (WUEs) than the SC rotation and CT, BNS had the highest WUE (19.0 kg ha −1 mm−1) for the spring maize – winter wheat rotation. Tillage rotation and fertilization had an interactive effect on soil water use and crop growth, and the results might clarify the response of crop yield and soil water variation to fertilization and tillage rotations. For further and sustainable development of crop production, BNS (5133 and 8415 kg ha −1 for wheat and maize yield, respectively; soil water in fallow: 386 mm) and BCN (5221 and 8116 kg ha −1 for wheat and maize yield, respectively; soil water in fallow: 388 mm) are recommended as the optimal fertilization and tillage rotations for rainfed crop production on the Loess Plateau.

Employment of GIS techniques to assess the long-term impact of tillage on the soil organic carbon of agricultural fields under hyper-arid conditions.

A study on six 50 ha agricultural fields was conducted to investigate the effect of conservation tillage practices on the long-term (1990–2016) changes in the soil organic carbon (SOC) content of the topsoil layers (0–10 cm) of agricultural fields. The experimental fields were selected from the 49 fields of the Tawdeehiya Arable Farm (TAF), located 200 kilometers southeast of Riyadh, the capital city of the Kingdom of Saudi Arabia. Data sets from laboratory determined SOC and the corresponding Landsat images generated vegetation indices, namely, the Normalized Difference Vegetation Index (NDVI) and the Bare Soil Index (BSI), were utilized for the prediction of SOC using multivariate regression techniques. Long-term changes in the SOC content of the experimental fields, as a result of different tillage practices, were also studied. The developed SOC prediction models exhibited high accuracy indicated by R2 values ranging from 0.73 to 0.85, RMSE values of 0.34 to 0.85 g kg-1 and P-values of less than 0.0001. The cross-validation results (R2 of 0.61–0.70, RMSE value of 0.34–0.85 g kg-1 and P-values of less than 0.0001) confirmed the high accuracy of the developed SOC prediction models. Results also revealed that the change in the SOC content was clearly associated with soil tillage practices. On the average, 76% of the all agricultural fields in the experimental farm showed a decrease of up to 24 g kg-1 in their SOC content after 10 years (1990–2000) of continuous conventional tillage practices. On the other hand, an average increase of up to 37 g kg-1 in the SOC content was observed in 88% of the studied fields at the end of the study period (2016), where conservation tillage was a continous and consistent practice in the experimental farm.

Long-term effects of pig slurry application on selected soil quality parameters and tissue composition of maize in a subhumid subtropical environment

Effects of long-term application of pig slurry (PS) on soil organic carbon (SOC) pools, nutrients and maize tissue composition under continuous conventional tillage in a maize–soyabean rotation system in subhumid subtropical environments are unclear. The soil and plant parameters have important implications for PS management under intensive agriculture. Soil (0–20 cm depth) and maize tissue were sampled from lands treated with PS for 0, 10 and 20 years and analysed for soil chemical properties and plant nutrients. Soil available phosphorus, potassium, copper and zinc and tissue concentrations increased due to PS application. Total nitrogen and SOC declined, whereas soil microbial biomass carbon (MBC), hot-water-soluble carbon (HWSC) and microbial quotient (MB/SOC) increased with PS application period. The SOC was negatively correlated to MBC and HWSC (r = −0.472 and −0.663, respectively). Increase in MBC, MBC/SOC and HWSC indicated presence of an untenable soil organic matter with limited possibility of carbon sequestration. The findings imply that long-term PS application, with conventional tillage, not only increased most plant nutrients but also vulnerability of SOC.

Comprehensive assessment of soil fertility characteristics under different long-term conservation tillages of wheat field in Weibei Highland, China.

Soil fertility properties described by four physical indices and seven chemical indices in the 10-year long-term experiment of wheat fields in Weibei Highland were used to investigate the cumulative effect of 11 soil indices under six long-term conservation tillage treatments. The principal component analysis was performed to comprehensively evaluate the cumulative effect of soil fertility under different tillage treatments, so as to provide scientific basis for soil sustainable utilization and management in Weibei Highland. The results showed that, compared with continuous conventional tillage (CT/CT), soil bulk density by no-tillage/subsoiling rotational tillage (NT/ST), subsoiling/conventional tillage rotational tillage (ST/CT) and conventional tillage/no-tillage rotational tillage (CT/NT) decreased by 6.6%, 5.9% and 6.6%, respectively, and no significant difference was found between continuous no-tillage (NT/NT) and CT/CT. NT/NT had the highest content of >0.25 mm mechanical stable aggregate, and no-tillage/subsoiling rotational tillage (NT/ST) had the highest content of >0.25 mm water stable aggregate. Compared with CT/CT, the mechanical stable aggregate contents under other five tillage treatments increased by 1.7%-10.1%, soil organic matter increased by 0.6%-11.2%, and the contents of nitrogen, phosphorus, and potassium contents also increased. By principal component analysis, 11 soil indices were divided into two principal components to comprehensively characterize soil quality. The contribution rate of the first principal component was 75.5%, where the major contributors were soil organic matter, water stable aggregate, total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, available phosphorus, available potassium, bulk density and soil porosity. The contribution rate of the second principal component was 13.2%, where the major contributor was mechanical stable aggregate. Together, those two principal components accounted for 88.6% of the original variables. The soil fertility performance was in the sequence of NT/ST>ST/CT>CT/NT>NT/NT>ST/ST>CT/CT after gradually accumulating the effects of long-term conservation tillage. NT/ST was the most appropriate tillage patterns for the wheat fields in Weibei Highland, due to the resulting balanced and high-quality soil environment.

Farming systems’ productivity and soil organic carbon stocks following fertilisers, no-tillage or legumes on a fertility-depleted soil in a semi-arid subtropical region

Depleted soil nitrogen supplies in long-term continuously cultivated soil for cereal grain cropping have resulted in reduced cereal yields, low grain proteins and hence low economic returns. This has necessitated the development of alternative management practices to sustain crop yields, as well as to restore and maintain soil fertility. In the present study we examined the comparative performance of several management options over a 12-year period, including: a 4-year rotation of grass + legume pasture followed by wheat (GL–wheat); 2-year rotations of lucerne–wheat, annual medic–wheat and chickpea–wheat; and continuous conventional tillage (CT) or no-tillage (NT), without or with fertiliser N application (0, 25 and 75 kg N ha–1 for each crop). Average wheat grain yields were highest in the chickpea–wheat rotation, followed by the NT wheat with 75 kg N ha–1; the lowest grain yields were in the CT or NT wheat treatment without fertiliser N application. Crop water use and gross margin were strongly correlated. However, there was an increasing potential for the deep leaching of nitrate-N at 75 kg N ha–1 application, as well as from the GL pasture initiated in 1987, but not from that initiated in 1986, emphasising the effect of variability in growing seasons. Soil organic C stocks increased under the 4-year GL pasture in the 0–0.1 m depth only, then decreased steadily following the cropping phase. The rotation of 4-year GL pasture followed by wheat cropping for 4–6 years may maintain initial soil organic C stock, but a shorter cropping phase is required to increase soil organic C and N stocks and soil fertility in the long term. Partial economic analysis of the treatments suggested that restoring or maintaining soil N fertility, either through legume-based pastures, grain legume and/or N fertiliser, provides long-term positive economic return.

Comparing soil physical properties from continuous conventional tillage with long‐term reduced tillage affected by one‐time inversion

AbstractIn addition to various positive aspects, long‐term reduced tillage may cause disadvantages such as increased weed pressure and soil compaction. Thus, single inversion tillage is customarily used for overcoming these drawbacks; however, the effects on the enhanced soil functions are unknown. The main objective of this study was therefore to assess whether improved soil physical properties following long‐term reduced tillage remain after one‐time inversion tillage by mouldboard plough. The study was undertaken on a silt loam field in Lower Saxony, Germany. Since 1996, this field has been subdivided into three treatments; one was managed conventionally using a mouldboard plough (CT), while on the others a chisel plough (RT1) and a disc harrow (RT2) were employed. In October 2014, the entire field was mouldboard ploughed. The following year, four field campaigns were conducted to compare the soil physical properties of the continuously conventional tilled plot with those affected by one‐time inversion tillage (RT1 and RT2). Dry bulk density (DBD), saturated hydraulic conductivity (Ks) and infiltration rate [K(h)] were analysed in untrafficked and trafficked areas in each plot. There were clear differences between CT and RT. At all sampling dates, both RT plots had higher Ks and K(h) compared with CT. These differences also occurred to some extent on the trafficked areas. This suggests that improved soil hydraulic properties remained after one‐time inversion tillage of a long‐term reduced tilled field. Thus, one‐time inversion tillage may offer a suitable measure for overcoming some of the main disadvantages associated with long‐term reduced tillage, while preserving the positive effects on soil physical properties.

Tillage and establishment system effects on annual ryegrass seed crops

Annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] seed crops have been produced on some Oregon farms continuously for decades without rotation of crops or farming practices. The objective of the study was to determine the effects of tillage and establishment systems on ‘Gulf’ annual ryegrass seed crops over a 9-year period. Six systems were employed: (i) continuous conventional tillage (CT), (ii) continuous no-till (NT), (iii) NT/CT cycle alternate year tillage (NT/CT), (iv) volunteer/CT cycle alternate year tillage (Vol/CT), (v) burn and NT/CT cycle alternate year tillage (Burn+NT/CT), and (vi) volunteer/NT/CT cycle with tillage every 3rd year (Vol/NT/CT). Environment×system interaction effects governed seed production characteristics. Three seed yield environments were observed during the 9 years: high, intermediate, and low. High yield environments had higher temperatures (+1.2°C) and lower precipitation (−48mm) in April–June than in low yield environments. Across environments, yields were greatest with Burn+NT/CT, CT, and Vol/NT/CT and lowest with NT. Stability analysis revealed that Burn+NT/CT, CT, and Vol/NT/CT systems produced up to 40% greater yields than the mean of all systems in low yield environments. Yield variation among systems was high in low yield environments. Increasing tillage frequency from zero in NT to once every other year in NT/CT boosted yields so that they were equivalent to CT. Yield differences among systems were attributable to seed number. Moderate tillage frequency and occasional residue removal are required to produce the best long-term seed yields in annual ryegrass.

Sediment-bound total organic carbon and total organic nitrogen losses from conventional and strip tillage cropping systems

Global carbon (C) and nitrogen (N) cycles are closely linked to erosion and hydrologic processes. By reducing tillage erosion and runoff, sediment-bound C and N losses can be reduced. Published studies represent only a few soil types and regions and rarely directly compare tillage practices. The objective of this study was to quantify concentrations and sediment-bound total organic carbon (TOC) and nitrogen (TON) loads and enrichment ratios in runoff from 0.2-ha fields in rotational cotton (Gossypium hirsutum L.)-peanut (Arachis hypogea L.) production during a 7-yr study within a southeastern USA coastal plain landscape. The Ultisoils at the study site have loamy sand to sandy loam texture surface horizons. The fields were in either continuous conventional tillage (CT) or strip tillage (ST) and were at upper, middle, and lower landscape positions. Sediment-bound TON and TOC concentrations were significantly greater from ST than CT fields as were the TOC and TON enrichment ratios. However, due to greater surface runoff and sediment loss, TON and TOC loads were significantly greater from CT than ST fields. The CT and ST loads were significantly different at the upper and middle but not at the lower landscape position. Enrichment ratios, 14 to 19 for TON and 8 to 12 for TOC, were several-fold greater than reported in the limited available literature, where studies focused on finer textured surface soils. Our findings have highlighted the site-specific nature of erosion processes, how they affect sediment-bound C and N loss in agricultural landscapes, and how reducing tillage may impact sediment C and N dynamics. The observed enrichment ratios can be used to modify or adjust values used in current erosion models and improve their suitability for use in the region and elsewhere where surface soils have sandy texture and when practices like ST are implemented.

PM10 emissions from aggregate fractions of an Entic Haplustoll under two contrasting tillage systems

Abstract Tillage systems affect physical and chemical properties of soils modifying its aggregation. How changes of the aggregate size distribution affect the capacity of the soil to emit fine particulate matter (PM10) to the atmosphere during wind erosion processes, is a less investigated issue. In order to answer this question, PM10 emissions from an Entic Haplustoll submitted to 25 years of continuous conventional tillage (LC) and no-till (NT) were analyzed. Soil samples were sieved with a rotary sieve in order to determine the aggregate size distribution (fractions : 19.2 mm), the dry aggregate stability (DAS) and the erodible fraction (EF). The organic matter contents (OM), the particle size composition and the PM10 emission of each aggregate fraction were also measured. Results showed that NT promoted OM accumulations in all aggregate fractions which favored DAS and soil aggregation. The 19.2 mm (41.7%) in NT, while the proportion of the other aggregate fractions was similar in both tillage systems. As a consequence of the smaller proportion of the

Corn, Cotton, and Peanut Response to Tillage and Subsurface Drip Irrigation in North Carolina

Determining response of agronomic crops to subsurface drip irrigation (SDI) in conventional and reduced tillage systems is important in defining utility of SDI. Therefore, the objectives of this research were to define interactions of SDI and tillage with respect to yield and economic return of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and peanut (Arachis hypogaea L.) planted in rotation. Research was conducted in two 4‐yr periods (2007–2010 and 2008–2011) in North Carolina using continuous strip tillage vs. continuous conventional tillage without irrigation or with SDI using a crop sequence of 1 yr of cotton, 2 yr of corn, followed by 1 yr of peanut. Corn, cotton, and peanut yields increased with SDI compared with no irrigation regardless of tillage system. Cotton and peanut yields were not affected by tillage system or the interaction of tillage and irrigation; corn yield was affected by this interaction. In the second year of corn, yield and economic return were higher in conventional tillage with SDI than strip tillage with SDI. Economic return for the sum of crops in the rotation was affected by the interaction of irrigation and tillage. Economic return was higher in both periods during each year corn was grown under SDI compared with non‐irrigated corn while higher economic returns for cotton and peanut under SDI were noted in one of two periods. When pooled over periods, crops, and tillage, economic return for SDI was US$1,552 ha−1 higher than non‐irrigated production over 4 yr.

Effect of Rotational Tillage on Soil Aggregates, Organic Carbon and Nitrogen in the Loess Plateau Area of China

In rain-fed semi-arid agroecosystems, continuous conventional tillage can cause serious problems in soil quality and crop production, whereas rotational tillage (no-tillage and subsoiling) could decrease soil bulk density, and increase soil aggregates and organic carbon in the 0–40 cm soil layer. A 3-year field study was conducted to determine the effect of tillage practices on soil organic carbon (SOC), total nitrogen (TN), water-stable aggregate size distribution and aggregate C and N sequestration from 0 to 40 cm soil in semi-arid areas of southern Ningxia. Three tillage treatments were tested: no-tillage in year 1, subsoiling in year 2, and no-tillage in year 3 (NT-ST-NT); subsoiling in year 1, no-tillage in year 2, and subsoiling in year 3 (ST-NT-ST); and conventional tillage over years 1–3 (CT). Mean values of soil bulk density in 0–40 cm under NT-ST-NT and ST-NT-ST were significantly decreased by 3.3% and 6.5%, respectively, compared with CT, while soil total porosity was greatly improved. Rotational tillage increased SOC, TN, and water-stable aggregates in the 0–40 cm soil, with the greatest effect under ST-NT-ST. In 0–20 and 20–40 cm soils, the tillage effect was confined to the 2–0.25 mm size fraction of soil aggregates, and rotational tillage treatments obtained significantly higher SOC and TN contents than conventional tillage. No significant differences were detected in SOC and TN contents in the > 2 mm and > 0.25 mm aggregates among all treatments. In conclusion, rotational tillage practices could significantly increase SOC and TN levels, due to a fundamental change in soil structure, and maintain agroecosystem sustainability in the Loess Plateau area of China.

Soil organic carbon storage in a no-tillage chronosequence under Mediterranean conditions

The duration of soil organic carbon (SOC) sequestration in agricultural soils varies according to soil management, land-use history and soil and climate conditions. Despite several experiments have reported SOC sequestration with the adoption of no-tillage (NT) in Mediterranean dryland agroecosystems scarce information exists about the duration and magnitude of the sequestration process. For this reason, 20 years ago we established in northeast Spain a NT chronosequence experiment to evaluate SOC sequestration duration under Mediterranean dryland conditions. In July 2010 we sampled five chronosequence phases with different years under NT (i.e., 1, 4, 11, and 20 years) and a continuous conventional tillage (CT) field, in which management prevailed unchanged during decades. Soil samples were taken at four depths: 0–5, 5–10, 10–20 and 20–30 cm. The SOC stocks were calculated from the SOC concentration and soil bulk density. Furthermore, we applied the Century ecosystem model to the different stages of the chronosequence to better understand the factors controlling SOC sequestration with NT adoption. Differences in SOC stocks were only found in the upper 5 cm soil layer in which 4, 11 and 20 years under NT showed greater SOC stocks compared with 1 year under NT and the CT phase. Despite no significant differences were found in the total SOC stock (0–30 cm soil layer) there was a noteworthy difference of 5.7 Mg ha−1 between the phase with the longest NT duration and the phase under conventional tillage. The maximum annual SOC sequestration occurred after 5 years of NT adoption with almost 50% change in the annual rate of SOC sequestration. NT sequestered SOC over the 20 years following the change in management. However, more than 75% of the total SOC sequestered was gained during the first 11 years after NT adoption. The Century model predicted reasonably well SOC stocks over the NT chronosequence. In Mediterranean agroecosystems, despite the continuous use of NT has limited capacity for SOC sequestration, other environmental and agronomic benefits associated to this technique may justify the maintenance of NT over the long-term.

Effects of rotational tillage practices on soil properties, winter wheat yields and water-use efficiency in semi-arid areas of north-west China

Soil degradation caused by continuous conventional tillage and long-term minimum and no-tillage in rain-fed areas of north-west China is known to reduce water-use efficiency and crop yield, because of the reduced soil porosity and decreased availability of soil water and nutrients. A 3-year field study was conducted to determine the effects of interval with no-tillage and subsoiling to overcome some of the tillage after crop harvesting on soil properties, crop yields and water-use efficiency in semi-arid areas of southern Ningxia. Three tillage treatments were tested: conventional tillage (CT) for 3 years as the control; no-tillage in year 1, subsoiling in year 2, and no-tillage in year 3 (NT/ST/NT); subsoiling in year 1, no-tillage in year 2, and subsoiling in year 3 (ST/NT/ST). The mean soil bulk density of tilth soil (0–40cm) was significantly decreased by 3.5% and 6.2% compared with CT under NT/ST/NT and ST/NT/ST, respectively, and both treatments greatly improved total soil porosity. Rotational tillage could increase water-stable aggregates, soil organic matter and the available N and P content. Rotational tillage significantly in the 0–40cm soil layers, with a higher effect under ST/NT/ST. Rotational tillage significantly improved soil water status, increased the amount of soil water stored during the summer fallow and wheat growing season compared with conventional tillage. Higher yield improvements coupled with greater water-use efficiency were achieved with NT/ST/NT and ST/NT/ST compared with CT, and these treatments increased wheat yields by 9.6% and 10.7%, along with water-use efficiency improvements of 7.2% and 7.7%, respectively. The results showed that the interval of no-tillage and subsoiling (rotational tillage) could improve soil physical and chemical properties, and thus significantly increase crop yields and water-use efficiency. This method could have important applications in the semi-arid areas of north-west China.