Conservation agriculture (CA) is advocated as a sustainable farming method to improve soil health, increase crop yields and food security, while reducing input costs. In South Africa, a country with ...low rainfall, limited agricultural lands and a large smallholder farming community, implementing CA is imperative. To investigate the research status of CA in South Africa, a systematic review of available literature was conducted. Conservation agriculture initiatives as captured in the form of peer-reviewed publications, reports, dissertations, proceedings and projects were collected. Relevant data, such as location, type of research, CA treatments implemented, duration of interventions, main results, limitations and challenges were recorded. Most literature were in the form of peer-reviewed publications (45%). The CA interventions mostly occurred as researcher-managed field trials (60%), followed by farmer-led trials. While the interventions were fairly scattered throughout the country, there was a poor correlation between major crop-producing areas and research focus. Conservation agriculture interventions generally had a positive effect on soil properties and crop yield. Important limitations include poor reporting, short trial periods and insufficient data collection. Local research involving farmers is needed to support best-management practices for different agro-ecological zones.
•The ecological agriculture intensification improves SOC, POC, AS, and MA stability.•Crop-pasture rotations are an excellent tool to improve/maintain soil health.•No tillage does not improve SOC as ...compared to CT, but does increase MA stability.•Cropping periods under NT could be longer without compromising soil physical health.
Soil physical health is strongly dependent on aggregate stability (AS) given it determines most soil physical properties. Aggregate stability is associated with total (SOC) and particulate (POC) soil organic carbon and all of them are very sensitive to management practices. Crop-pasture rotations and tillage systems could be combined pursuing ecological agriculture intensification (EAI) to manage soil manipulation and carbon input to improve or maintain AS and SOC and POC. We hypothesized that 1) EAI through rotating pasture periods with cropping improves AS through macroaggregate (MA) formation and stabilization regardless of the tillage system, and 2) reduced disturbance due to no-tillage (NT) during cropping periods allow reducing pasture period frequency without affecting MA formation and stabilization. The aim of this work was to evaluate the effect of different crop-pasture rotations and tillage systems (NT and conventional tillage (CT)) on soil AS and MA proportion and stability, and SOC and POC content of a mollisol of the Southeastern Argentinean Pampas (37° 45' 09’’ S, 58° 18' 48’’ W). Soil samples were taken at 0–5 and 5–20 cm in a long-term experiment (since 1976) to determine aggregate size distribution and stability and SOC and POC content. The sequence intensification index on a monthly basis (SIIm) was calculated and carbon input through crops and pastures was estimated. The increase of SIIm due to crop-pasture rotations led to higher AS and MA stability in the arable layer and especially in the surface 5 cm. This was due to the greater aboveground and root carbon input and lower frequency of tillage associated with pastures respect to cash crops. Cropping systems under NT failed to sequester organic carbon as compared to CT except for the uppermost soil layer, but they successfully improved AS and MA stability. Anyway, regardless of the tillage system, two years of pasture after a cropping period were not enough to take AS up to the level shown by permanent pasture, except under NT at 0–5 cm. The results suggest that despite carbon sequestration failure, cropping periods under NT could be extended (<SIIm) without compromising soil physical health. Contrarily, under CT soil health decreases sharply with the decrease of SIIm. Therefore, the only way to grant better soil functioning under CT is through increasing SIIm with more frequent or longer pasture periods and/or introducing other crops between cash crops. Evidence collected in this loam high-organic-matter soil was not enough to reject the hypotheses.
Intensive tillage will continuously reduce soil quality, characterized by decreased soil organic-C. Low soil organic-C indicates the disturbance of soil fertility. More conservative soil management ...experiments have been done for seven years to restore the soil quality for sugarcane (Saccharum officinarum L.) productivity. This research aimed to study the effect of the tillage system, bagasse mulch, and their interactions on soil chemical properties and sugarcane agronomic response. The research was conducted on a Split Plot of five groups. The main plot was the tillage system consisting of intensive tillage and no-tillage, while the subplot was the bagasse mulch consisting of bagasse mulch and no-bagasse mulch. This study found that in sugarcane cultivation, no-tillage system was beneficial for soil P-available, sugarcane length, and sugarcane ripening; bagasse mulch was beneficial for soil organic-C and also soil P-available. The no-tillage system to increase P-available can be combined with bagasse mulch or no-bagasse mulch, but the no-tillage system combined with no-bagasse mulch increases the percentage of gap in sugarcane cultivation.
Studies on how the alteration in the soil pore architecture can influence the permeability of small soil aggregates are still scarce. These aggregates affect the water dynamics mainly at the ...intra-aggregate pore scale. Thus, investigating the intra-aggregate pore space properties becomes crucial for comprehending the matter and energy transported into the soil. This paper focuses on analyzing the permeability and hydraulic conductivity of small soil aggregates from contrasting tillage systems (no-tillage – NT, minimum tillage – MT, conventional tillage – CT, and secondary forest – F) through synchrotron-based X-ray Computed Tomography. The 3D image segmentation was performed using machine and deep learning strategies. Permeability was measured based on the image-based parametrization of the Kozeny-Carman equation, which is dependent on porosity, hydraulic radius, and tortuosity. The porosity, hydraulic radius, and pore connectivity were not affected by the soil tillage systems at the scale of analysis (aggregates of a few millimeters). Conventional tillage had higher pore tortuosity relative to NT, demonstrating less favorable fluid transport at the aggregate scale. However, only the aggregates under F had significantly higher permeability and hydraulic conductivity relative to NT, MT, and CT. Our results brought new insights into the effects of different tillage systems on the soil structure and their possible impact on water dynamics at the microscale.
•Porosity, hydraulic radius, and connectivity were not affected by tillage systems.•Aggregates from conventional tillage had more tortuous pores than from no-tillage.•Aggregates from forest are more permeable and conductive than from tilled soils.•Image segmentation was performed using machine and deep learning strategies.
Liu, X., Burras, C. L., Kravchenko, Y. S., Duran, A., Huffman, T., Morras, H., Studdert, G., Zhang, X., Cruse, R. M. and Yuan, X. 2012. Overview of Mollisols in the world: Distribution, land use and ...management. Can. J. Soil Sci. 92: 383–402. Mollisols – a.k.a., Black Soils or Prairie Soils – make up about 916 million ha, which is 7% of the world's ice-free land surface. Their distribution strongly correlates with native prairie ecosystems, but is not limited to them. They are most prevalent in the mid-latitudes of North America, Eurasia, and South America. In North America, they cover 200 million ha of the United States, more than 40 million ha of Canada and 50 million ha of Mexico. Across Eurasia they cover around 450 million ha, extending from the western 148 million ha in southern Russia and 34 million ha in Ukraine to the eastern 35 million ha in northeast China. They are common to South America's Argentina and Uruguay, covering about 89 million and 13 million ha, respectively. Mollisols are often recognized as inherently productive and fertile soils. They are extensively and intensively farmed, and increasingly dedicated to cereals production, which needs significant inputs of fertilizers and tillage. Mollisols are also important soils in pasture, range and forage systems. Thus, it is not surprising that these soils are prone to soil erosion, dehumification (loss of stable aggregates and organic matter) and are suffering from anthropogenic soil acidity. Therefore, soil scientists from all of the world's Mollisols regions are concerned about the sustainability of some of current trends in land use and agricultural practices. These same scientists recommend increasing the acreage under minimum or restricted tillage, returning plant residues and adding organic amendments such as animal manure to maintain or increase soil organic matter content, and more systematic use of chemical amendments such as agricultural limestone to replenish soil calcium reserves.
In agricultural soils, fungi constitute most of the total microbial biomass in the environment contributing with more than 50% of the soil biomass. The fungi should be considered as a link in the ...production not only by their attributes but also for their potential pathogenicity on crops chains. We aim to determine in what extent the combination of management styles and tillage systems control specific cultivable soil fungal community structure in temperate fertile Petrocalcic Argiudoll soil in a field experiment. We measured soil fungal richness, abundance and diversity along a one-year experiment (2009–2010). The plots were subjected to different tillage systems (conventional vs. zero) combined with different agricultural management histories (pasture/agriculture rotation vs. intensive agriculture). The measures were performed every three months along a year in three replicated plots. Rotation with pastures and zero tillage stimulated the saprophytic soil fungi community in detriment of pathogens. The clearest dissimilarity was given by the seasons. The results obtained from assay suggested that the seasons effect was strongest that the management or tillage on the soil fungal community.
•An increase in the fertilizer N rate increased N2O emissions in irrigated corn.•No-tillage significantly increased soil N2O emission at the highest N-fertilizer rate.•Denitrification was the main ...pathway under no-tillage for N2O emission.•The use 200 kg N ha−1 reduced the yield-scaled N2O emissions in the first out of three years.•The emission factor was much lower than 1% proposed by IPCC.
In irrigated Mediterranean conditions there is a lack of knowledge about the best combination of tillage and N fertilization practices to reduce soil nitrous oxide (N2O) emissions while maintaining maize productivity. The aim of this work was to investigate the effects of different soil management practices and synthetic N fertilization rates on soil N2O emissions and their relationship with maize grain yield to determine the best management system to reduce yield-scaled N2O emissions (YSNE) in a semiarid area recently converted to irrigation under Mediterranean conditions. A long-term tillage and N rate field experiment established in 1996 under barley (Hordeum vulgare L.) rainfed conditions, was converted to irrigated maize (Zea mays L.) in 2015. After the transformation to irrigation, the field experiment maintained the same tillage treatments and N fertilization rates. Three types of tillage (conventional tillage, CT; reduced tillage, RT; no-tillage, NT) and three mineral N fertilization rates (0, 200, 400 kg N ha−1) were compared during three years (2015–2017) in a randomized block design with three replications. Soil N2O emissions, water-filled pore space, soil temperature, mineral N content (as NH4+ and NO3−), denitrification potential and maize grain yield and above-ground N uptake were quantified. Moreover, the emission factor (EF) and YSNE were calculated. The results showed that the combination of NT and the highest rate of N fertilization led to greater N2O emissions. Furthermore, the lowest N2O fluxes were observed in CT when WFPS was below 40% and the highest N2O fluxes were seen in NT when WFPS was above 60% coinciding with the greatest denitrification potential. Cumulative N2O emissions in 2017 and 2015 followed the order 400 > 200 > 0 kg N ha−1, while in 2016, rate of 400 and 200 kg N ha−1 showed greater cumulative N2O emission compared to the control. Only RT showed differences between growing seasons on cumulative N2O emissions, with greater values in 2017 compared to 2015, and intermediate values in 2016. In all treatments, the N2O EF was much lower than the default IPCC emission factor (1%). NT and RT increased the grain production compared to CT which was affected by severe soil crusting causing water deficit. Likewise, N fertilizer treatments significantly affected the YSNE, increasing with increasing fertilizer N application rate in the first year of study. Our data show that the use of NT or RT does not lead to more yield-scaled N2O emissions than CT in Mediterranean agroecosystems recently converted to irrigation.
Soil pore space can change over time due to tillage, frost, wetting and drying cycles, plant roots, and compaction. However, a soil water retention curve (SWRC) is usually considered to be static and ...is determinedin a laboratory on a limited number of small soil samples. Field SWRCs were determined at a depth of 20 cm on Mollic Gleysol. Measurements were made in two growing seasons at different spatial locations on plots with different tillage systems: no-tillage (NT) and conventional tillage (CT). The unimodal van Genuchten retention function (VG) was fitted to each SWRC and model parameters were estimated. We evaluated the variability of the curves within growing seasons, predicted soilwater contents at field capacity, and evaluated the differences in the estimated parameters of the VG model between different growing seasons and tillage systems considering intraseasonal and spatial variability. The shape of the curves depended more on the environmental conditions during the growing season than on the tillage system. In the wetter and cooler growing season of 2020, when soybeans were grown, the soil retained water in a narrower range. In the drier growing season of 2021, when maize was grown, intraseasonal variability in SWRCs was greater than in 2020. Regardless of the growing season, estimated α values were more intraseasonally variable under the CT than under the NT. Based on the SWRCs, predicted water contents at field capacity varied intraseasonally, seasonally, and spatially. Accounting for spatial and intraseasonal variability, the estimated VG parameter θr differed between years, regardless of tillage system. In 2020, the parameter α was higher under the NT system than under the CT system. Under the CT, α differed between years, while under NT it did not. For the parameter n, there were no significant differences between tillage systems or growing seasons. Seasonal, intraseasonal, and spatial variability in soil hydraulic properties should be considered in soil water modelling studies.
•Soil water retention curves were constructed from continuous field measurements.•The SWRCs were determined under different tillage systems and environmental conditions.•The retention curves change intraseasonally, seasonally, and spatially.•The tillage systems and growing season affect the parameters of the van Genuchten model.•Under conventional tillage, the retention curves are more variable within season.
Evaluation of new cultivars for the agronomic performance under actual on-farm conditions is a highly recommended method for assessing the performance and stability of new cultivars in variable ...environments and under different management practices. The main purpose of this study was to evaluate the performance and agronomic characteristics of new wheat cultivars in on-farm conditions using different tillage systems to provide suggestions to help the improvement programs and increase the farmers' crop productivity from cropping systems and new cultivars. Seven wheat cultivars, including three bread wheat and four durum wheat cultivars, were evaluated under three tillage systems, including conventional tillage (CT), reduced tillage (RT), and no-tillage (NT) in farmers' fields conditions across two locations and three cropping seasons (2018–21). The results indicated that some of the traits were mainly explained by the genotype effect (thousand kernel weight, heading date and NDVI), while some others by the management practices (grain yield), some by the location (grain yield, spike density, heading date) and year (grain yield, TKW, NDVI, spike density, heading date) effects. Across years and locations, the highest productivity was recorded under CT (2603 kg/ha) followed by RT (2378 kg/ha) and NT (2295 kg/ha), indicating about 13% and 10% superiority production under CT compared with NT and RT, respectively. The wheat cultivars showed different responses to tillage systems, showing the performance of genotypes varied between tillage systems. The Shalan and Eminbey varieties did not interact with tillage systems, but other genotypes significantly differed in their adaptation to tillage systems. The highest mean yield was recorded for the Saji cultivar (durum wheat) under RT (2310 kg/ha), while the Shalan cultivar (bread wheat) performed well in NT (2058 kg/ha), and Saji, Imren, Zahab (durum wheat), and Rijaw and Paraw (bread wheat) had the highest yield under CT. According to GGE biplot analysis, the Shalan and Eminbey varieties had superior performance across on-farm trials, suggesting that they have a broad adaptation to diverse environments. The results identified genotypes with both specific and general adaptions to tillage systems in farmers' fields, that could be explored for increasing productivity and stability under rainfed conditions. Conservation agriculture principles must be incorporated into current wheat breeding program under CT system, to use wheat genetic diversity for conservation agriculture conditions to keep pace food insecurity.
•The grain yield mainly affected by year followed by location, and tillage systems.•Genotypes well performed under conventional tillage system.•Genotypes with adaptation to no-tillage system were identified.•Under no-tillage system, variation in grain yield, 1000-kernel weight, and spike density showed low variability.•Wheat breeding under no-tillage system must be considered from preliminary yield trials.
•Tillage systems impacts on soil properties were confined near the soil surface.•No-till and double disk increased surface SOC relative to chisel and plow tillage.•No-till increased POM near the ...surface compared to all other tillage treatments.•No difference in soil pH was observed near the surface among tillage treatments.•No-till improved soil properties compared to plow till near the soil surface.
Soil organic matter affects a number of soil processes and properties. A better understanding of soil-profile distribution of organic matter components and related soil properties under long-term tillage systems is thus needed. The objective of this study was to evaluate the impacts of 33 years no-till (NT), double disk (DD), chisel (CH), and plow tillage (PT) under corn (Zea mays L.)–soybean (Glycine max L.) rotation on soil organic C (SOC), particulate organic matter (POM), pH, and wet aggregate stability to 100cm soil depth on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) in eastern NE. After 33 years, NT and DD management increased SOC by 1.2 times and mean weight diameter (MWD) of aggregates by 2 times compared with CH and PT at the 0–10cm depth. At the 0–20cm, NT had 1.1 times higher SOC concentration than CH and PT. When compared with data collected 24 years prior to this study, SOC at the 0–20cm increased by 12.5% across NT, DD, and CH and by 2.7% for PT. No-till had 5 times higher total POM concentration than PT, 4.7 times higher than CH, and 2.4 times higher than DD at the 0–10cm depth. However, at the 10–20cm, PT had higher POM than other tillage systems, which is most probably due to mixing and burial of residues at the bottom of the plow layer. Soil pH did not differ among tillage treatments at the 0–10cm, but it differed in this order: PT>CH>DD>NT at the 10–20cm and PT=CH=DD>NT at the 20–40cm depth. The lower pH under NT, DD, and CH in deeper soil depths may be due to the limited or no lime mixing in these systems compared with PT. When compared with data (pH 5) collected 33 years prior to this study, soil pH increased by 0.9 in NT, 1.4 in DD, 1.5 in CH, and 1.9 units in PT at 0–20cm depth, probably due to surface application and incorporation of lime. Overall, 33 years of NT increased near-surface soil organic matter components and soil aggregation compared with the PT.
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