Conventional Soil Tillage Research Articles

Agregação do solo, carbono orgânico e emissão de CO2 em áreas sob diferentes usos no Cerrado, região do Triângulo Mineiro

Soil aggregation and carbon distribution are important indicators of soil quality. Moreover, these attributes are closely related to CO2 fluxes in the soil-atmosphere interface. We sought to evaluate soil aggregation, organic carbon distribution and CO2 evolution in different land uses of Minas Gerais Triangle. Four different land uses were selected: (1) Panicum maximum, (2) Panicum maximum Jacqvr. (Tanzânia), (3) sugarcane, and (4) native Cerrado (control). In each land-use type, soil samples from a 0-10 cm layer were collected. The samples were air-dried and sieved in order to obtain aggregates sized 4-2 mm. The samples were submitted to wet-sieving to evaluate stability and also to obtain aggregates of different sizes: 4-2 mm; 2-1 mm; 1-0.5 mm; and 0.5-0.25 mm. Total organic carbon, humic substances and texture were determined for each aggregate size fraction. The CO2 emission was measured in field and lab conditions, both by the capture in NaOH solution method. The native Cerrado and Panicum maximum Jacqvr. (Tanzânia) areas (mostly clay) showed the highest soil aggregation. The conventional soil tillage adopted in sugarcane areas contributed significantly to aggregate disruption. In all of the areas, the largest aggregates had higher organic carbon and humic substances. Organic carbon content and soil texture seem to be closely associated with CO2 emissions in the areas studied.

No-till surface runoff and soil losses in southern Brazil

No-till is widely used to control soil erosion in agricultural areas in Brazil and is currently practiced on about 30Mha. However, studies have shown that no-till is not as efficient in controlling surface runoff losses as it is in reducing soil loss. The objective of this study is to evaluate soil and surface runoff losses on small and large plots with differing slope lengths, cropping sequences and tillage systems in southern Brazil. Surface runoff and soil losses under natural rainfall erosion plots (3.5×11m, 3.5×22m, 50×100m, and 100×100m) were evaluated in two experiments in a well-drained Oxisol (>60% clay) with 9% and 7% slopes, respectively. The experiment extended over 14 years comparing 4 different soil management systems: (a) bare soil plots with slope length 22m; (b) bare soil plots with slope length 11m; (c) sequence of wheat (Triticum aestivum)/soybean [Glycine max (L.) Merr] with disk plow+lighter off-set disk-harrow (DP+LD); and (d) sequence of wheat/soybean under no-till (NT). In another experiment using large field plots, three soil tillage regimens (DP+LD; heavy off-set disk-harrow+lighter off-set disk-harrow (HD+LD), and NT) were compared over the course of a 5-yr. crop sequence of black oats (Avena estrigosa)/soybean-black oats/corn (Zea mays L.)-wheat/soybean- black oats/soybean -blue lupine (Lupinus angustifolium)/corn. Results for both experiments show that, when compared with conventional soil tillage (DP+LD or HD+LD), soil losses for NT were >70% lower. However, the benefit of reduced surface runoff losses was less evident, suggesting the need to implement additional practices to control surface runoff to avoid transport of pollutants to waterways.

Tillage effects on soil nitrification and the dynamic changes in nitrifying microorganisms in a subtropical rice-based ecosystem: A long-term field study

The dynamics of N mineralization and nitrification may be altered by tillage, which ultimately affects crop growth and yield. This study investigated effects of tillage on soil nitrogen dynamics in a subtropical rice (Oryza sativa L.) soil (Hydragric Anthrosols, WRB classification) under combination ridge with no-tillage (RNT) and conventional tillage (CT) for 22 years in Chongqing, China. Soil mineralization, nitrification and changes in abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were investigated to test the hypothesis that RNT decreases nitrification in the rice-based ecosystem. Soil mineralization and nitrification rates decreased after 22 years of RNT compared with CT. Soil pH decreased about 0.5 units after 22 years of RNT, and this difference may be responsible for the decrease of N mineralization and nitrification rates observed under RNT. The nitrification process was best fitted by a first-order kinetic model for both CT and RNT. While the nitrification rate was significantly lower for RNT (2.96mgNkg−1day−1) than CT (3.40mgNkg−1day−1), AOB and AOA amoA gene copies were significantly higher for RNT than CT. This suggested that the functional expression (i.e., nitrification) may not be closely related to numbers of microorganisms that have the ability to nitrify. The AOA dominated in abundance over the AOB for both CT and RNT paddy soils, with AOA to AOB ratios ranging from 13 to 52, and the AOA abundance showed similar changes with AOB, suggesting that AOA may also play an important role in soil nitrification. Results implied that RNT may increase soil N retention by keeping N longer in the NH4+ state, thus decreasing the potential for N loss from leaching.

Corn and Soybean Responses to Two Tillage Systems in a Cool Growing Season

A field study in 2014 documented corn and soybean biomass and nutrient responses between conventional-till and no-till tillage systems at Beresford, SD during cooler than normal weather conditions with adequate soil moisture. The overall study was established in 1992. Each treatment plot was monitored weekly from June to August for soil moisture, temperature, and plant growth stages. Biomass was harvested during and at the end of the growing season for yield and nutrient content. Soil moisture measured throughout the early and middle part of the growing season was determined to be sufficient for crop growth, since precipitation was much greater than normal in June (33.2 cm). However, air temperature was below normal early in the growing season and lowered Growing Degree Days (939°C) compared to the 30-year average (139°C). Soil temperatures (5 cm depth) were not significant between tillage treatments in the corn plots during the growing season for 12 observation dates (range 16.3°C - 28.0°C). Plant growth was not significantly different between tillage treatments, reflecting the lack of soil temperature differences (5 cm depth) between tillage treatments. The mid-season plant tissue and crop residue at harvest nutrient content (P, K, and Zn) were not significant between tillage treatments. Corn grain yields were 10.3 T·ha-1 and 10.1 T·ha-1 for conventional tillage and no-till, respectively. Soybean grain yields were 3.9 T·ha-1 and 3.3 T·ha-1 for conventional tillage and no-till, respectively. These results would more than likely have been much different in a warmer growing season, when soil temperature and moisture differences between tillage treatments would likely stimulate crop growth in the conventional-tilled soil. This would have also increased nutrient uptake and grain yield levels to greater degree than observed in this study.

Temporal variation in soil physical properties improves the water dynamics modeling in a conventionally-tilled soil

Temporal variations in soil physical properties are rarely recorded in field experiments or considered when modeling water and solute dynamics in agricultural soils. This study aimed at (a) quantifying the temporal variations in soil physical properties, such as the saturated hydraulic conductivity (Ks), bulk density (ρb) and soil water retention during the growing season of an irrigated maize crop conventionally tilled with a moldboard plow, and (b) modeling the observed water dynamics. For modeling, the effect of temporal variations of soil properties was explored and compared to results with constant values of soil properties during the simulation period and with results after an optimization of soil parameters by inverse modeling. Field and laboratory experiments were performed to measure the soil physical properties of five soil compartments (defined according to the position relative to crop row and the depth) at three dates during the maize season (sowing, flowering and just before harvest). During the maize season, ρb values ranged from 1.21 to 1.56gcm−3 and increased with time (by 15–25% of the initial value). Ks values, ranging from 2.9 to 56.3mmh−1, significantly decreased with time (by a factor of 3 to 6) according to the soil compartment, and were negatively correlated with ρb. In the first step to model water dynamics, the initial values of soil physical properties (measured at maize sowing) were used as constant input parameters for the model HYDRUS-2D during the maize season. This simulation led to a poor description of soil water potentials and water content dynamics, without any drainage at 100cm depth during the maize season. After an optimization of soil physical parameters, the description of the water dynamics was significantly improved, but optimized parameters, especially Ks and θs, were not within the range of field measurements. In a last modeling step, the simulation period was divided into three periods with a specific parameterization of soil physical properties for each period. The description of the water dynamics was improved compared to the simulation with constant values for soil physical properties. Such results argue for taking into account time-variable soil physical properties in modeling to correctly assess the water and solute dynamics in soils.

Short-term carbon dioxide emission under contrasting soil disturbance levels and organic amendments

Agriculture can be either a source or sink of atmospheric CO2 depending on soil management. The application of swine slurry in conventional tilled soils could enhance soil CO2 emission depleting soil organic C stocks. However, the use of recalcitrant C-rich organic fertilizers in no-till soils can offset soil CO2 emission promoting soil C sequestration. This hypothesis was tested by evaluating short-term CO2-C emissions from a Rhodic Nitisol under contrasting soil disturbance levels (disturbed (DS) and undisturbed soil (US)) top-dressed with mineral or organic fertilizers (urea (UR), raw swine slurry (RS), anaerobically digested swine slurry (ADS), and composted swine slurry (CS)). Soil CO2 emission was evaluated for 64 days using static chambers where gas samples were collected and analysed by photoacoustic infrared spectroscopy. Soil water-filled pore space (WFPS), temperature and meteorological data were concomitantly registered and a first-order exponential decay model was used to assess the decomposition of organic fertilizers and CO2 emissions induced by soil disturbance. Soil CO2-C emission was correlated with soil temperature, while limiting soil aeration impaired CO2-C efflux when WFPS >0.6cm3cm−3. Disturbance increased soil CO2-C efflux (36.3±2.2kg CO2-Cha−1 day−1) in relation to US (33.3±1.6kg CO2-Cha−1 day−1). Extra labile C input through RS amendment induced an increased soil CO2-C efflux for a longer period (t1/2=16.9 and 9.6 days in DS and US treatments, respectively), resulting in higher CO2-C emissions than soil amended with other fertilizers. The recalcitrant C input by ADS and CS had limited effect on soil CO2-C emissions. CS presented a genuine potential for substantial soil organic C accumulation while offsetting increased CO2-C emissions in comparison to RS amended soils.

English

Ethiopian soils, formed from old weathered rocks, are naturally low in fertility. Moreover, crop production is constrained by non-sustainable cropping practices, particularly repeated plowing and hoeing, which enhances loss of soil organic matter. Field trials were therefore conducted to determine the integrated effects of tillage system and nitrogen fertilization on organic matter content of Nitisols at five sites using maize as test crop during 2000 to 2004 in Western Ethiopia. Three tillage systems [minimum tillage with residue retention (MTRR), minimum tillage with residue removal (MTRV) and conventional tillage (CT)] and three N levels (the recommended rate and 25% less and 25% more than this rate) were combined in factorial arrangement with three replications. After 5 years, the two measured indices of organic matter, viz. the organic carbon (C) and total nitrogen (N) content were both significantly higher in the MTRR soil compared to the CT and MTRV soils. However, the influence of tillage systems on organic C and total N was confined to the upper 0 to 7.5 cm soil layer. On average, organic C and total N in this layer were 17 and 25%, and 20 and 29% higher with MTRR than with CT and MTRV, respectively. Application of N fertilization for 5 consecutive years showed profound effects on organic C and total N. Increasing levels of N application led to higher organic C and total N irrespective of tillage system. Both organic C and total N showed however a steady (115 kg ha-1 N level) to declining (69 and 92 kg ha-1 N levels) trend over time. Based on these results, replacement of CT with MTRR should be beneficial and sustainable to soil quality in the study area. However, MTRV is not an option at all to replace CT from a soil quality point of view.  This study’s findings may be applicable to other highland regions in Africa where cropping on Nitisols is common.   Key words: Conventional tillage (CT), crop residues, minimum tillage, organic carbon, total nitrogen.

Agricultural practices indirectly influence plant productivity and ecosystem services through effects on soil biota.

It is well established that agricultural practices alter the composition and diversity of soil microbial communities. However, the impact of changing soil microbial communities on the functioning of the agroecosystems is still poorly understood. Earlier work showed that soil tillage drastically altered microbial community composition. Here we tested, using an experimental grassland (Lolium, Trifolium, Plantago) as a model system, whether soil microbial communities from conventionally tilled (CT) and non-tilled (NT) soils have different influences on plant productivity and nutrient acquisition. We specifically focus on arbuscular mycorrhizal fungi (AMF), as they are a group of beneficial soil fungi that can promote plant productivity and ecosystem functioning and are also strongly affected by tillage management. Soil microbial communities from CT and NT soils varied greatly in their effects on the grassland communities. Communities from CT soil increased overall biomass production more than soil communities from NT soil. This effect was mainly due to a significant growth promotion of Trifolium by CT microorganisms. In contrast to CT soil inoculum, NT soil inoculum increased plant phosphorus concentration and total plant P content, demonstrating that the soil microbial communities from NT fields enhance P uptake. Differences in AM fungal community composition resulting, for instance, in twofold greater hyphal length in NT soil communities when compared to CT, are the most likely explanation for the different plant responses to CT and NT soil inocula. A range of field studies have shown that plant P uptake increases when farmers change to conservation tillage or direct seeding. Our results indicate that this enhanced P uptake results from enhanced hyphal length and an altered AM fungal community. Our results further demonstrate that agricultural management practices indirectly influence ecosystem services and plant community structure through effects on soil biota.

Response of Arbuscular Mycorrhizal Fungi in Different Soil Tillage Systems to Long‐Term Swine Slurry Application

AbstractSwine slurry is a common agricultural fertilizer in many countries. However, its long‐term use in large amounts can cause excess nutrient accumulation, alter soil compounds, and potentially influence critical microbial populations such as arbuscular mycorrhizal fungi, which have important roles in plant nutrition and soil sustainability. This work determined if arbuscular mycorrhizal status, external mycelium, and glomalin‐related soil protein content were affected by long‐term swine slurry application to different soil tillage systems. The experiment was conducted on a clayey oxisol, in southern Brazil. Swine slurry (0, 30, 60, 90, and 120 m3 ha−1 y−1) was applied for 15 years to conventional tillage and no tillage soil prior to the summer (soybean or maize) and winter (wheat or oats) crop seasons. Swine slurry decreased mycorrhizal root colonization, spore number, and total external mycelium. Swine slurry increased active external mycelium and both easily extractable and total glomalin‐related soil protein. No‐tillage soil had more glomalin‐related soil protein than conventional tillage soil. The most significant response variables were root colonization, easily extractable glomalin‐related soil protein, and total external arbuscular mycorrhizal mycelia. Long‐term application of swine slurry in this environment, even at high rates, did not adversely affect crop yield but did influence arbuscular mycorrhizae fungi and their products in the soil environment. Benefits of swine slurry application for crop nutrition must be weighed against potential adverse consequences for the size, activity, and benefits of the mycorrhizal community to subsequent annual crops. Copyright © 2014 John Wiley & Sons, Ltd.

Soil fauna community in the black soil of Northeast China under different tillage systems

Soil fauna is an important component in soil ecosystems. This study tested whether conservation tillage or conventional tillage of a black soil (Udic Mollisol) field in Northeast China could affect its soil fauna communities. Two different conservation tillage systems, no-tillage (NT) and reduced tillage (RT), as well as a conventional rotary tillage system (CT), were chosen for this study. There were 4562 individuals isolated from this study, which included two orders and 35 families. Acariformes was the most abundant family and represented 91.56% of the total faunal abundance. The abundance and the number of faunal families were higher in conservation tillage systems than in the CT. The RT system had the highest individual number of soil fauna among three tillage methods. The faunal accumulation in the soil surface also was significantly higher in the two conservation tillage systems than in the CT. Our results indicate that the conservation tillage systems could protect the soil fauna in the soil ecosystem better than the CT.

Least limiting water range and soil pore-size distribution related to soil organic carbon dynamics following zero and conventional tillage of a black soil in Northeast China

SUMMARYThe present work built on a previous study of tillage trials, which found the effectiveness of least limiting water range (LLWR) as an indicator of soil organic carbon (SOC) mineralization under different tillage practices in a black soil of Northeast China in 2009. To improve the understanding of soil structure controls over SOC dynamics, a study was conducted to explore the relationship between LLWR, which was calculated based on soil bulk density and soil pore-size distribution, and the effects of LLWR, which was calculated based on soil bulk density and soil pore-size distribution on SOC mineralization following no tillage (NT) and mouldboard ploughing (MP). In contrast to MP, NT had a significantly greater volume of large macropores (>100 μm) at depths of 0–0·05 and 0·2–0·3 m, but a significantly lower volume of small macropores (30–100 μm) at depths of 0–0·05, 0·05–0·1, 0·1–0·2 and 0·2–0·3 m. The volume of meso- (0·2–30 μm) and micro-pores (<0·2 μm) at different depths under the two tillage practices were similar. Tillage-induced changes in soil bulk density and pore-size volumes affected the ability of soil to fulfil essential soil functions in relation to organic matter turnover. Soil pore-size distribution, especially small macropores greatly affected LLWR and there was a significant correlation between LLWR, which was calculated based on soil bulk density, and the proportion of small macropores. The proportion of small macropores were used to calculate LLWR instead of soil bulk density and the values for NT and MP soils ranged from 0·073 to 0·148 m3water/m3soil. Using the proportion of small macropores rather than bulk density in the calculation of LLWR resulted in more sensitive indications of SOC mineralization. Variation in the proportion of small macropores can help characterize the impacts of tillage practices on dynamics of LLWR and SOC sequestration.

No-till and conservation agriculture in the United States: An example from the David Brandt farm, Carroll, Ohio

No-till (NT) farming (conservation agriculture) began in the US in the 1960s. The state of Ohio has a university research location that began no-till research in 1962. A few innovative Ohio farmers, including NT pioneers David Brandt and Bill Richards, were early adopters of the new conservation practice. Initially, no-till was most successful on sloping, well drained soils, then with improvements to the system, including cover crops, it became more widely adopted on all soil types. David Brandt was an enthusiastic learner and teacher of no-till practices, working with chemical company representatives and Cooperative Extension Specialists to demonstrate the system.David Brandt's cooperation with Ohio State University researchers continues to provide a valuable site for studying the long term changes in soil health and ecosystem services. Results showed that total microbial biomass as one of the soil biological health indicators significantly increased with an associated decrease in carbon (C) loss under NT compared with conventional tilled soil (CT). Under NT, there was significantly higher total C and total N compared to CT. Active C, as a composite measure of soil health, significantly increased with NT. When cover crops, especially cover crop cocktail mixes, were used, NT substantially improved soil health. Long-term NT with cover crop cocktail mixes significantly increased the soil aggregate stability, compared with CT. The overall rate of C sequestration by NT suggested that the soils on the Brandt farm act as a consistent sink of atmospheric CO2 although this tends to level off after about 20 years. The Brandt farm showed that crop yields are increased under long-term NT with cover crops mixes. Results suggested that starting with a cover crop when switching from CT to NT, is more likely to ensure success and to maintain economic crop yields.Another early adopter, Bill Richards, from Circleville, Ohio, also became a national leader and promoter of no-till farming. He served as head of the United States Department of Agriculture's Natural Resources Conservation Service in the early 1990s and instituted a program that led to rapid expansion of no-till. He advises that farmers who follow conservation agriculture principles need to be more proactive, from local level to national levels, to influence policy decisions that can lead to robust improvement in soil health.

Soil mapping to assess workability in central Italy as climate change adaptation technique

<div> <p><span style="font-family:arial,helvetica,sans-serif;">In this paper soil conventional tillage (CT) in two adiacent on-farm sites, hilly and plain fields, was carried out in comparison with direct-seeding + fertilizing at very low water content. The quality and quantity of work were evaluated through machine performance, fossil-fuel energy requirements and carbon dioxide emissions from agricultural machinery. The fields were previously sampled and mapped to investigate spatial variability of soil properties, to find soil quality indicators and to asses soil workability. The results revealed good traction performance during CT operations (slip values were lower than 15%). During plowing, time efficiency of the wheeled tractor was 40% lower with respect to the tracked tractor. Global energy employed was of the same magnitude for the tracked and wheeled tractor (220 kWh ha<sup>-1</sup>) while was significantly lower (52 kWh ha<sup>-1</sup>) for direct-seeding+fertilizing. The degree of crushing of the soil caused by CT required further energy employed (98 kWh ha<sup>-1</sup>) to seedbed preparation. Fossil-fuel energy requirements from agricultural machinery were significantly lower during direct-seeding+fertilizing (0.52 GJ ha<sup>-1</sup>) with respect to the conventional soil tillage (2.30 GJ ha<sup>-1</sup>). Wheat yield of direct seeded field and the total cost of the crop cycle (€/ha) were 9% and 16% lower respectively than the values recorded on fields under conventional tillage.</span></p> </div> <p> </p>

土壤质地对连续免耕稻田土壤理化性质变化的影响

As one of soil conservation tillage methods,no tillage( NT) has been widely applied in farmlands worldwide. Due to the combined effect of soil type,cropland ecological condition and cropping system type,there is still ongoing debate concerning the positive versus negative effect of NT on paddy soil properties. Although soil texture has been recognized as one of important factors in characterizing soil property variation in response to different management practices,few attempts have been performed to address effects of tillage method on soil property considering the difference in soil textures. Such effort will be beneficial to explain the ongoing debate and improve our knowledge on the effect of NT on soil property. In this study,effects of soil texture( i. e.,loam and clay) on the variations of soil physical and chemical properties in response to continuous NT were addressed for the single cropping paddy field in Shaoxing area in southern China. Studied paddy fields were commonly and continuously used for rice cultivation by local farmers,which would be significant to reveal effects of NT on soil property under practical production. To avoid the disturbances from other factors,all soil samples were collected in the paddy fields with same field management measures in rice seeding,fertilization,and irrigation. Soil sampling efforts were finished during 5—10 days after rice harvesting at November,2008. According to local practices,rice straws were all removed from paddy fields. Results indicated that although soil compactions at 0—20 cm layers were increased with increasing NT applied years in both the loam and clay paddy soil,its increased intensity was higher in the clay soil than that in the loam soil,resulting in shallower plough layer occurring in the NT clay soil. Compare to the conventional tillage soil,the penetration resistance was increased by 32% and 90% in the loam and clay soil after 6 years of continuous NT,respectively. The clay soil also presented greater soil bulk densities than the loam soil after same years of continuous NT. Furthermore,soil organic matter and available nitrogen contents were both increased with NT applied years in the loam soil,while they were both significantly decreased in the clay soil. Although soil available phosphorus contents at the plough layer( 0—20 cm) in both the loam and clay soils were increased after 6 years of continuous NT,their soil available potassium contents were both decreased. After 1—6 years of continuous NT,the loam paddy soil presented more positive consequences than the clay ones in terms of soil physical and chemical properties. When assessing the feasibility of applying NT method in paddy fields,the role of soil texture should be further considered in study,as it is an important factor in regulating variation of soil property under continuous NT. Rice straw mulching is an economic and effective way to mitigate soil degradation under continuous NT in practice. Considering the tillage cost and soil quality maintenance,overall ploughing is suggested to be performed once after every 3—4 years of continuous NT for clay paddy soils but for loam paddy soils it can be applied after a bit longer years of continuous NT in southern China.

Winter wheat crown and root rot are affected by soil tillage and crop rotation in Latvia

Reduced soil tillage and wheat monoculture have become increasingly widespread technologies in Latvia. The aim of this study was to estimate the development of winter wheat crown and root rot, depending on soil tillage and crop rotation. Two-factor experiments were carried out from 2009 to 2012: (1) crop rotation and (2) soil management. The incidence of the complex of stem-base diseases (root and crown rot) was determined after wheat harvesting. Causal agents were determined microscopically; species of Fusarium were identified by sequencing the Transcription Elongation Factor (TEF) region and subsequent phylogenetic clustering of acquired DNA sequences. The most important factor influencing the progression of crown and root rot was year (p < 0.05). The disease incidence among years fluctuated between 13 and 72%. Crop rotation (p < 0.05) and soil tillage method (p < 0.1) also affected the level of crown and root rot development. Conventional soil tillage slightly decreased disease development. The disease incidence in continuous wheat cropping was 10% higher compared to that in winter wheat fields following oilseed rape. The spectrum of pathogens and other fungi did not differ depending on soil tillage and crop rotation. The most common pathogens were fungi of the Fusarium genus: on average, 36% of isolates were identified as Fusarium spp: F. culmorum and F. avenaceum were the dominant species, but F. sporotrichioides and F. trinctum were also identified. The problem of wheat stem base and root rot is complex; different circumstances and unknown factors influence the spectrum of causal agents and the total disease level. Further investigations are necessary to research changes in disease development during a longer time period, as well as to clarify the occurrence of different pathogens, depending on different factors.

Long-term effects of no-tillage management practice on soil organic carbon and its fractions in the northern China

The influence of different tillage practices on soil organic carbon levels is more significant under long-term tillage compared to short-term tillage. Despite the great interest in the effect of no-tillage (NT) management practice on carbon sequestration, the long-term effect of NT practice on soil organic carbon and its fractions in northern China remain unclear. We evaluated the long-term effects (after 17years) of NT and conventional tillage (CT) practices on soil organic carbon and its fractions at different depths ranging from 0 to 60cm using a cinnamon soil in Shanxi, China. A randomised block design with three replications was used to evaluate both the tillage and its effects on the yield performance of winter wheat (Triticum aestivum L.). After 17years, the soil organic carbon (SOC) concentration in the NT soil was greater than that of the CT soil, but only in the layer that was located between 0 and 10cm. There was a significant accumulation of SOC (0–60cm) in the NT soil (50.2MgCha−1) compared to that observed in the CT soil (46.3MgCha−1). The particulate organic matter C (POM-C), dissolved organic C (DOC), and microbial biomass C (MBC) levels in the 0–5cm layer under NT treatment were 155%, 232%, and 63% greater, respectively, compared to the CT treatment. The POM-C, DOC, and MBC in the 5–10cm layer under NT treatment were 67%, 123%, and 63% greater, respectively, compared to the CT treatment. Below 10cm, the labile carbon observed in the NT treatment did not differ from that of the CT treatment. Significantly positive correlations were observed between the SOC and the labile organic C fractions. Moreover, the winter wheat (T. aestivum L.) yield increased 28.9% in the NT treatment compared to the CT treatment. The data show that NT is an effective and sustainable management practice that improves carbon sequestration and increases soil fertility, resulting in higher winter wheat yields in the rainfed dryland farming areas of northern China.

A wide view of no-tillage practices and soil organic carbon sequestration

Many believe that conservation tillage practices could increase the sequestration of atmospheric carbon dioxide into agricultural soils and this sequestered carbon may partially offset the greenhouse gas effect and thus reduce the impact of global warming. Recent advances in soil carbon (C) and greenhouse gas analysis have made it possible to evaluate the impacts of conservation tillage on C sequestration from various perspectives. Although conservation tillage favors soil and water conservation, there are biased estimates of C sequestration associated with conservation tillage, and it is particularly an issue for a “pure” no-tillage (NT) system. Accordingly, this paper presents an overview of the progress achieved in evaluating C sequestration in no-till (the extreme type of conservation tillage) and conventional tillage production systems. In addition to extended discussion of how soil sampling and calculations could influence the estimates of C gains or losses in no-till versus conventional tilled soil, this review will also focus on following aspects, including (1) the impact of NT on crop yields which governs organic C inputs to soil from crop residue, (2) the impact of NT on soil organic C mineralization which is a major pathway of soil C output, and (3) the roles of the initial levels of C stocks and soil erosion rates which are crucial for estimating soil C sequestration under different tillage systems. Many soil C studies have indicated that the impacts of NT on soil C sequestration are compounded by many factors and should not be generalized.

Prototyping the visualization of geographic and sensor data for agriculture

The effectiveness of decision-making processes in the agricultural domain can be improved by integrating current local environmental and agromonitoring with the Geographic Information System (GIS) and wireless sensor networks (WSNs). The presented paper describes conceptual approaches to context-based cartographic visualization methods for agricultural and metrological data acquired by WSN and a portal prototype for integrated visualization.Each sensor used for agricultural applications has a location and can be placed within a broader spatial context. In our study, sensor characteristics (soil temperature and moisture, atmospheric temperature and moisture) were automatically monitored at frequent intervals and these readings were aggregated with geospatial data from both local and remote (Web Map Service) sources. An experimental portal for the integration and visualization of sensor data and geospatial data was designed and prototyped on the basis of an open source interoperable platform. Conceptual approaches were successfully implemented on four experimental small-plot fields planted with different crop species and operated using different soil tillage practices. Experimental fields were situated in the southeast of the Czech Republic. Very Long range Identification Tag (VLIT) technology was used for wireless communication. Sensor observations verified differences in agrometeorological variables for the conventional tillage of soil and the no-tillage variant. Contextual cartographic visualization was successfully deployed for map view, dynamic cartographic symbology, and the dynamic measurement chart.

Consequences on macroporosity and bacterial diversity of adopting a no-tillage farming system in a clayish soil of Central Italy

Conservation agricultural practices, such as no-tillage, crops rotation and balanced fertilization are increasingly adopted for maintaining soil fertility, improving crops health and reducing soil erosion.The aim of this study was to evaluate the effects of the long-term adoption of contrasting tillage (no-tillage or conventional tillage) and N-fertilization (0 or 90 kg/ha N) practices on soil porosity and active bacterial communities in cropping system plots (sunflower–wheat or maize–wheat rotation) established on a clayish soil and under Mediterranean climate. Soil porosity was evaluated by micromorphological observations of soil thin sections. The composition and structure of the active bacterial communities were estimated by a culture-independent approach (reverse transcription – polymerase chain reaction – denaturing gradient gel electrophoresis, RT-PCR-DGGE) exploiting the 16S rRNA of bacteria and nirK, nirS and nosZ transcripts of denitrifiers. Finally, canonical correspondence analysis (CCA) was used to correlate microbial data with soil physical and chemical characteristics.When repeated for a long period, no-tillage has significantly increased soil compaction compared to the conventional tilled soil. Soil compaction was likely responsible for creating a selective environment for active bacterial species. On the other hand, tillage favoured the richness and diversity of active soil bacteria by increasing the rate of diffusion of O2 and the energy sources availability. A wide variability of active nirK denitrifiers was found in each soil management, while nirS denitrifiers were more closely related to lower porosity conditions. N fertilizer management seemed to affect mainly the active nosZ denitrifiers.Our results suggested that conservation tillage practices on heavy clayish soils are not free of relevant side effects on soil porosity and bacterial soil communities.

Weed management in winter wheat ( Triticum aestivum L.) influenced by different soil tillage systems

In this study, weed management in winter wheat influenced by different soil tillage systems was investigated. The experiment was carried out under Mediterranean conditions on a Luvisol, during two growing seasons (1996/1997 and 1999/2000). Two factors (different soil tillage systems and post-emergence weed control) were studied, with two levels each: Two soil tillage systems and two levels of post-emergence weed control. The conventional soil tillage system, performed for seedbed preparation after the emergence of a high percentage of weeds, increases the appearance of monocotyledons, especially Lolium rigidum Gaud. in wheat crops, when compared to their establishment in no-till system. As a consequence of the higher number of monocotyledons there is an increase in weed-crop competition. Without post-emergence herbicide treatment, the wheat crop yield is lower in the treatments with the conventional soil tillage system and yield reduction is less under no-till system compared to the respective treatments with post-emergence herbicide application. Key words: No-till system, weeds, wheat, herbicides.