No-till Farming Systems Research Articles

The taxonomic structure of southern chernozem at the genus level influenced by microbial preparations and farming systems

The taxonomic structure of the microbiome of southern chernozem compared to virgin soil was studied in the stationary experiment on the use of microbial preparations in the conditions of traditional for the steppe part of the Crimea and each culture of the five-field crop rotation of the farming system and no-till. Among 823 genera it was revealed 7 dominant ones: Candidatus Nitrososphaera, Rubrobacter, Flavisolibacter, Segetibacter, Bacillus, Balneimonas, Skermanella. The low level of cellulose-decomposing bacteria of the genus Cellulomonas was remarked in southern chernozem. The highest proportion of the representatives of this genus was observed in virgin soil (0.55 %), while the farming systems contributed to its decline in 1.3-1.6 times. Microorganisms of the genera Erwinia and Xanthomonas with phytopathogenic properties were found with a minimum proportion in communities from 0.003 % to 0.014 % and 0 – 0.005%, respectively.The complex metagenomic analysis of the taxonomic structure of the soil microbiome allowed us to establish that the use of microbial preparations reduces the negative impact of the no-till farming system on the microbiocenosis of southern chernozem and improves its environmental feasibility in the Crimean steppe.

Organizational and economic approaches to technological updating of agricultural enterprises

Purpose. The aim of the article is the development of theoretical approaches and practical recommendations for substantiation of instruments for improving the reproductive processes of land by agricultural enterprises. Methodology of research. Abstract and logical, computational, constructive and optimization methods are used to solve these problems, in particular in substantiation of directions of improvement of reproductive processes of agricultural lands and formation of rational organizational and economic conditions for reproduction of elements of MTB of agricultural enterprises. Findings. It has been proved that the No-Till farming system is effective in reproducing the fertility of land resources, which is not plowed, and the surface of the earth is covered with a layer of specially crushed plant residues - mulch residues (mulch). The main advantages of using zero tillage include: saving resources - fuel, labour, time, reducing depreciation costs; reducing the complexity of the technological process; restoration and preservation of the fertile soil layer - reduction or complete prevention of soil erosion; moisture accumulation in the soil, which is especially important in the conditions of the Steppe zone, and, accordingly, a noticeable decrease in the dependence of the crop on weather conditions; increasing crop yields due to the above factors. Originality. The scientific approach to the reproduction of land resources in agricultural enterprises is proposed, which is based on a set of organizational and economic instruments of socially responsible conduct of activity, in particular: the motivation of agricultural producers to introduce organic fertilizers, the introduction of the No-till system, the development of organic production, which will enhance the agricultural production. Practical value. The necessity of improvement of the program of state support of organic producers is proved on the basis of forecasting: compensation of costs for development of systems of management of organic production of agricultural production, costs in the transition period to organic production, partial compensation of costs for the use of organic fertilizers, costs for the use of plant protection products, costs for expertise organic products. It is now important to ensure that agro-technical measures are taken to restore the fertility of land resources through co-financing by agricultural enterprises, united territorial communities and the state. An effective factor, although indirectly influencing the increase in fertility of agricultural land, is the dissemination of knowledge about modern resource-saving technologies that can be provided through advisory services. Key words: material and technical base; agricultural enterprise; fertility; organic production; agricultural lands.

Selecting winter cover crop species for northern climatic conditions

ABSTRACTThe use of cover crops in crop rotations provides a wide range of ecosystem services including protection of the soil from nutrient loss. The objective of this study was to determine the suitability of winter cover crop species for Estonian conditions. Field trials with cover crop species winter rye (Secale cereale L), winter turnip rape (Brassica rapa spp. oleifera L.), forage radish (Raphanus sativus L. var. longipinnatus), hairy vetch (Vicia villosa Roth) and berseem clover (Trifolium alexandrinum L.) were carried out during the period 2016–2018 at the Estonian Crop Research Institute. Biomass production, nitrogen (N), phosphorous (P), potassium (K), calcium (Ca) and magnesium (Mg) accumulation were evaluated. The results under northern European conditions indicated that together with winter rye and winter turnip rape, hairy vetch survived the winters. By the spring, hairy vetch had produced the most biomass and accumulated the highest amount of N, compared with the other species. Winter turnip rape showed the greatest uptake of P, K and Ca in the spring. In both years, forage radish presented the highest biomass and nutrient accumulation in the autumn. After winterkill and decomposition in the spring, the forage radish left holes in the ground, which could be a beneficial characteristic, particularly in no-tillage farming systems. Berseem clover did not produce remarkable biomass in the autumn and was killed by the first frosts and was therefore considered unsuitable as an overwintering cover crop for northern latitudes.

Agricultural intensification reduces microbial network complexity and the abundance of keystone taxa in roots

Root-associated microbes play a key role in plant performance and productivity, making them important players in agroecosystems. So far, very few studies have assessed the impact of different farming systems on the root microbiota and it is still unclear whether agricultural intensification influences the structure and complexity of microbial communities. We investigated the impact of conventional, no-till, and organic farming on wheat root fungal communities using PacBio SMRT sequencing on samples collected from 60 farmlands in Switzerland. Organic farming harbored a much more complex fungal network with significantly higher connectivity than conventional and no-till farming systems. The abundance of keystone taxa was the highest under organic farming where agricultural intensification was the lowest. We also found a strong negative association (R2 = 0.366; P < 0.0001) between agricultural intensification and root fungal network connectivity. The occurrence of keystone taxa was best explained by soil phosphorus levels, bulk density, pH, and mycorrhizal colonization. The majority of keystone taxa are known to form arbuscular mycorrhizal associations with plants and belong to the orders Glomerales, Paraglomerales, and Diversisporales. Supporting this, the abundance of mycorrhizal fungi in roots and soils was also significantly higher under organic farming. To our knowledge, this is the first study to report mycorrhizal keystone taxa for agroecosystems, and we demonstrate that agricultural intensification reduces network complexity and the abundance of keystone taxa in the root microbiome.

Rainfall affects leaching of pre-emergent herbicide from wheat residue into the soil

No-tillage with stubble retention is a widely used cropping system for its conservation and yield benefits. The no-tillage farming system in southern Australia relies heavily on herbicides for weed management, but heavy crop residues may have a negative impact on the activity of pre-emergent herbicides applied. Any herbicide intercepted by the crop residue may not reach the soil surface without timely rainfall and may dissipate due to volatilisation, photo-degradation and/or microbial activity. Two experiments were carried out to investigate the interception of prosulfocarb, pyroxasulfone, and trifluralin herbicides by wheat residue and retention following simulated rainfall. For the first experiment, there were four simulated rainfall amounts (0, 5, 10, and 20 mm), three intensities (5, 10, and 20 mm h–1) and five application times (immediately after spraying herbicide, 6 h, 1, 7, and 14 days after spraying). In the second experiment, 20 mm of rainfall was applied at 10 mm h–1 in either 4 × 5 mm rainfall events over two days, 2 × 10 mm rainfall events over one day, or a single 20 mm rainfall event, with a no-rainfall control treatment. Bioassays were used to assess the herbicide activity/availability in the soil and remaining on the residue, using cucumber (Cucumis sativus L.) and Italian ryegrass (Lolium multiflorum Lam.) as indicator plants. At higher rainfall amounts, most of the herbicide leached from the stubble into the soil soon after application; more so with rain in one event rather than multiple events. However, the intensity of rainfall had no effect. Pyroxasulfone leached easily from the residue to the soil to potentially offer good weed control, prosulfocarb had an intermediary leaching effect, while only a small amount of trifluralin leached from stubble after rain. Therefore, in no-tillage situations with large amounts of crop residue present on the soil surface, herbicides that leach easily from the residue should be considered, like pyroxasulfone.

Microwave Soil Treatment Increases Soil Nitrogen Supply for Sustained Wheat Productivity

Abstract. Herbicide-resistant weeds have prompted the development and adoption of new non-chemical weed management technologies for sustainable food production. Considering this, pre-sowing microwave (MW) soil treatment has potential to reduce weed pressure in no-till farming systems. However, the effects of this transient heat disturbance on the soil nutrient profile and on the uptake and accumulation of nutrients in plant biomass warrant further study. In this study, we examined the effect of MW soil treatment on the recovery and accumulation of nitrogen (N) in wheat dry biomass using a 15N pool dilution technique over two years. Further, temporal changes in wheat yields were assessed by running sequential residual trials. The pre-sowing MW treatment achieved a temperature of 75°C to 85°C. MW soil heating increased the dry biomass and grain yields of the wheat crop over two years of study regardless of the initial N application. Furthermore, MW soil treatment did not significantly increase the N derived from fertilizer (Ndff, %). The maximum Ndff achieved for the untreated control soils at the higher N dose was 13%, while it was only 8% for the MW-treated soil. Despite this, the total N accumulation in the dry biomass increased by 17% because of MW soil heating, compared to the untreated control soils, revealing the uptake of N from indigenous sources. Consequently, the grain yield supported by indigenous soil N was significantly higher with MW soil treatment at 160, 440, and 740 days after heating. In summary, MW soil treatment appeared to be effective for sustaining the soil fertility over the long term, regardless of initial labeled N application. Keywords: Long-lasting effect, Microwave energy, Nitrogen accumulation, Soil temperature, Wheat yields.

Seed-germination ecology of glyphosate-resistant and glyphosate-susceptible biotypes of Echinochloa colona in Australia

Echinochloa colona L. (Link) (awnless barnyard grass) is one of the top three most problematic weeds of summer crops in Australia. This weed has evolved resistance to glyphosate. A study was conducted to evaluate the effect of environmental factors on the germination and seedling emergence of a glyphosate-resistant (GR) and a glyphosate-susceptible (GS) biotype of E. colona. The two biotypes had similar germination and emergence responses to light and temperature conditions, water stress, solution pH, sorghum residue cover and seed burial depth. Light stimulated germination more than dark conditions, and seeds germinated at a wide range of alternating day/night temperatures, from 20°C/10°C to 35°C/25°C, whereas no seeds germinated at 15°C/5°C. These results suggest that E. colona can emerge in spring, summer and autumn in Queensland. The sodium chloride concentration required to inhibit 50% germination was greater for the GR biotype (209 mm) than the GS biotype (174 mm). Seed germination was not affected by pH in the range 4–10. Water stress reduced germination by 50% at an osmotic potential of –0.44 MPa. In a shade-house study, retention of sorghum residue cover on the soil surface reduced the seedling emergence of E. colona. Emergence was 70% in the absence of crop residue, whereas a residue amount of 8 t ha–1 reduced emergence to 47%. Emergence was greatest for seeds placed on the soil surface and declined linearly with increasing burial depth; no seedlings emerged from 8 cm depth. The GR biotype had higher germination than the GS biotype under high sodium chloride concentrations; therefore, this biotype may be highly competitive with crops under highly saline conditions. Because germination was high on the soil surface and was stimulated by light, this weed will remain problematic under no-till farming systems in Australia.

The Influence of Tillage Frequency on Crop Productivity in Sub-Tropical to Semi-Arid Climates

Strategic tillage (ST), an occasional tillage in a continuous no-till (NT) farming system, is already being utilized by many landholders in the Northern Grains Region (NGR) of Australia to control weeds. But the impact on productivity (yield), both short- and long-term, has been largely under investigated. This study focused on yield data from 14 on-farm ST in NT experiments from 2012 to 2014 (3 years/4 seasons) and the comparison of the re-interpreted results of a long-term (27 years) tillage experiment. This study explored production impacts of tillage on long-term NT systems over the short and longer term. Results from tillage-frequency studies across the NGR demonstrated that overall grain yield was not significantly impacted. A long-term tillage trial at Biloela showed wheat (Triticum aestivum) and sorghum (Sorghum bicolor) grain yields were similar across no till, stubble mulch and reduced tillage treatments, these in turn were all significantly higher than aggressive tillage without stubble retention treatments. Dealing with increased herbicide resistance often associated with reduced tillage and no-till systems poses a real time issue with landholders in the NGR. This analysis of historical yield data together with the more recent strategic tillage data can aid in selecting the appropriate soil management option by providing tillage impacts on yield.

Dinitroaniline herbicide resistance in a multiple-resistant Lolium rigidum population.

The pre-emergence dinitroaniline herbicides (such as trifluralin and pendimethalin) are vital to Australian no-till farming systems. A Lolium rigidum population collected from the Western Australian grain belt with a 12-year trifluralin use history was characterised for resistance to dinitroaniline, acetyl CoA carboxylase (ACCase)- and acetolactate synthase (ALS)-inhibiting herbicides. Target-site resistance mechanisms were investigated. This L. rigidum population exhibited 32-fold resistance to trifluralin, as compared with the susceptible population. It also displayed 12- to 30-fold cross-resistance to other dinitroaniline herbicides (pendimethalin, ethalfluralin and oryzalin). In addition, this population showed multiple resistance to commonly used post-emergence ACCase- and ALS-inhibiting herbicides. Two target-site α-tubulin gene mutations (Val-202-Phe and Thr-239-Ile) previously documented in other dinitroaniline-resistant weed species were identified, and some known target-site mutations in ACCase (Ile-1781-Leu, Asp-2078-Gly and Cys-2088-Arg) and ALS (Pro-197-Gln/Ser) were found in the same population. An agar-based Petri dish screening method was established for the rapid diagnosis of resistance to dinitroaniline herbicides. Evolution of target-site resistance to both pre- and post-emergence herbicides was confirmed in a single L. rigidum population. The α-tubulin mutations Val-202-Phe and Thr-239-Ile, documented here for the first time in L. rigidum, are likely to be responsible for dinitroaniline resistance in this population. Early detection of dinitroaniline herbicide resistance and integrated weed management strategies are needed to maintain the effectiveness of dinitroaniline herbicides. © 2017 Society of Chemical Industry.

Microwave Soil Treatment Improves Weed Management in Australian Dryland Wheat

Abstract. Herbicide resistance has prompted the development of a chemical-free weed management practice in no-till farming systems. In this study, we examined the effect of pre-emergence microwave (MW) soil treatment for weed management in a no-till wheat production system in Australia. One-time MW soil treatment (2.45 GHz, 600 W, 120 s) was applied to plots that were arranged in a randomized complete block design with five replicates. The MW energy was projected through a horn antenna with aperture dimensions of 5.5 cm × 11 cm into the topsoil (0 to 6 cm) horizon. The applied MW energy density in the treated plots (2.6 m2), which was calculated by Simpson’s numerical surface integral approximation, was approximately 560 J cm-2. This achieved an increase in soil temperature of about 75°C to 80°C. This temperature induced a 65% to 80% reduction in weed establishment through thermal devitalization of the weed seedbank, compared to the untreated control plots. In addition, a substantial increase in wheat grain yield of 39.2% was achieved through MW energy application (7.8 t ha-1) compared to non-MW conditions (5.6 t ha-1). In summary, this non-chemical weed management strategy promises to effectively control herbicide-resistant weeds and sustain dryland wheat yields. Keywords: Microwave energy, Soil, Weed Suppression, Wheat.

Transgene escape and persistence in an agroecosystem: the case of glyphosate-resistant Brassica rapa L. in central Argentina.

Brassica rapa L. is an annual Brassicaceae species cultivated for oil and food production, whose wild form is a weed of crops worldwide. In temperate regions of South America and especially in the Argentine Pampas region, this species is widely distributed. During 2014, wild B. rapa populations that escaped control with glyphosate applications by farmers were found in this area. These plants were characterized by morphology and seed acidic profile, and all the characters agreed with B. rapa description. The dose-response assays showed that the biotypes were highly resistant to glyphosate. It was also shown that they had multiple resistance to AHAS-inhibiting herbicides. The transgenic origin of the glyphosate resistance in B. rapa biotypes was verified by an immunological test which confirmed the presence of the CP4 EPSPS protein and by an event-specific GT73molecular marker. The persistence of the transgene in nature was confirmed for at least 4years, in ruderal and agrestal habitats. This finding suggests that glyphosate resistance might come from GM oilseed rape crops illegally cultivated in the country or as a seed contaminant, and it implies gene flow and introgression between feral populations of GM B. napus and wild B. rapa. The persistence and spread of the resistance in agricultural environments was promoted by the high selection pressure imposed by intensive herbicide usage in the prevalent no-till farming systems.

Agricultural management of an Oxisol affects accumulation of heavy metals

Soil contamination may result from the inadequate disposal of substances with polluting potential or prolonged agricultural use. Therefore, cadmium (Cd), chromium (Cr) and nickel (Ni) concentrations were assessed in a Eutroferric Red Oxisol under a no-tillage farming system with mineral fertilizer applications, a conventional tillage system with mineral fertilizer application and a conventional tillage system with sewage sludge application in an area used for agriculture for more than 80 years. We evaluated the spatial distributions of these elements in the experimental area and the effect of the different management practices on the soil retention of these metals. The concentrations of metals extracted from 422 soil samples by open-system digestion with HNO3, H2O2 and HCl were assessed by flame atomic absorption spectroscopy. The pH and soil organic matter were also assessed, and spatial distribution maps were designed. The mean concentrations of Cd, Cr and Ni (1.0, 50 and 14 mg kg−1, respectively) in the native forest were higher than the reference values (100, 25 and 8% greater, respectively) in Brazilian legislation, indicating that the source material was the determining factor of the high metal concentrations in the study soils. Soil management with sewage sludge was the major contributor to the accumulation of Cd and Ni, whereas Cr concentration did not vary with management type. Approximately 0.3, 12 and 16% of the experimental area is contaminated with Ni, Cd and Cr, respectively, because their concentrations exceeded the values for alertness or prevention in Brazilian legislation.

Effects of different sub-soiling frequencies incorporated into no-tillage systems on soil properties and crop yield in dryland wheat-maize rotation system

No-tillage has become a universal management system to conserve soil water and sustain soil productivity in dryland agriculture. However, no-tillage in a long-term may produce some undesirable soil characteristics. An occasional tillage operation has been used as a mean to manage some of the defects that have emerged in NT farming systems. This study was to explore the effect of sub-soiling at different frequencies in a no-tillage farming system of an annual cropping system of winter wheat-spring maize rotation on Loess Plateau. The study consisted of three tillage practices: NT (no-tillage were applied every year), NT/ST (no-tillage were applied in first year and rotated with sub-soiling in second year), NT/NT/ST (no-tillage were applied in first two year and rotated with sub-soiling in third year). The study began in 2007 on a former spring maize field with conventional tillage and lasted for three-year rotation cycles by 2016. In ten years, for the soil physical properties, NT/ST rotation significantly decreased soil bulk density, and increased soil porosity and amount of macroaggregates (>0.25mm) when compared to NT (P<0.05). For water storage, NT with ST rotations (NT/ST & NT/NT/ST) increased the soil water storage in the fallow periods. Moreover, NT/ST rotation produced higher average grain yields, WUE and economic profit in the winter wheat-spring maize cropping system when compared to NT over the ten years. However, the soil organic matter (SOM) and total N under NT with ST rotations (NT/ST & NT/NT/ST) were lower than it for NT. For this long-term experiment, NT provided a better soil nutrient condition, NT/NT/ST and NT/ST rotation showed a better effect on soil water storage in fallow. For the comprehensive productivity, NT/ST rotation showed a balanced soil properties and crop production effect among three tillage treatments. In the winter wheat-spring maize cropping system, NT/ST rotation enhanced soil physical and chemical properties and increased yield and water holding capacity of soil. We predict that the NT/ST rotation will be of great significance in promoting the development of rain-fed conservation farming in the Loess Plateau of China.

Occasional tillage has no effect on soil microbial biomass, activity and composition in Vertisols under long-term no-till

Heavy rains in recent years have triggered an increase in herbicide-resistant weeds and crop diseases in long-term no-till (NT) farming systems in Queensland, Australia. As a possible solution, occasional or strategic tillage (ST) has been applied during summer fallow in two farms located near Jimbour and Biloela, Queensland, Australia. We investigated the impact of different frequencies (one to three passes) and timings (December, January and March) of tillage imposition on microbial indicators of soil health. Tillage implements included chisel plow sweeps at the Biloela site and narrow chisel point and offset disc at the Jimbour site. Seven soil samples were collected from each plot in April 2013 at 17, 10 and 2 weeks post-ST from 0 to 0.1 and 0.1 to 0.2 m depths and composited separately for each soil depth. Samples were analysed for microbial biomass C, enzyme activity, community-level physiological profiling (CLPP) via microrespirometry method and bacterial genetic fingerprinting. Overall, there were no significant differences for any of these parameters between NT and ST at both sites. However, irrespective of tillage treatments, significant differences between soil depths were found for enzyme activity (Biloela), substrate utilisation (Jimbour and Biloela) and bacterial genetic fingerprinting (Jimbour). There were no major effects of ST on the microbial indicators used either under different timings, frequencies or type of tillage implement. Therefore, ST with chisel plow sweeps, narrow chisel point and offset disc may be undertaken with minimal impact on soil microbial communities to combat problems associated with long-term NT Vertisols, such as weed and soil-borne disease outbreak in Queensland, Australia.

The Role of Trees and Pastures in Organic Agriculture

&lt;p&gt;Environmental concerns associated with annual row crop grain production – including soil erosion, soil carbon loss, intensive use of chemicals and petroleum, limited arable land, among others – could be addressed by converting conventional livestock production to an organic pasture based system. The inclusion of tree crops would further enhance the opportunity for feeding pasture- raised livestock by providing shelter and alternative feed sources. Biodiversity is an essential aspect of an organic farm plan. The idea of including tree crops and other perennials into the vision of an organic farm as a “living system” is very much compatible with the goals and philosophy of organic farming. Before modern no-till farming systems were developed, tree crops and pasture systems were found to provide similar benefits for controlling soil erosion and conserving soil carbon. For example, J. Russell Smith’s &lt;em&gt;Tree Crops: A Permanent Agriculture&lt;/em&gt; (Smith, 1950) and pioneered tree crop agriculture as the alternative to annual row crops for protecting soils from erosion while producing livestock feed such as acorns, nuts, and fodder. A survey of Mid-Atlantic USA soils under pasture found 60% higher soil organic matter content than cultivated fields. Because United States Department of Agriculture’s National Organic Program (USDA-NOP) standards require dairy cattle consume pasture forage and limited grain (7 C.F.R. pt. 206), organic milk contains higher concentrations of omega-3 and fewer omega-6 fatty acids than conventional milk. Organic standards also state “the producer must not use lumber treated with arsenate or other prohibited materials for new [fence posts] installations or replacement purposes in contact with soil or livestock.” Black locust (&lt;em&gt;Robinia pseudoacacia&lt;/em&gt;) is a fast growing renewable alternative to treated lumber with many attributes compatible with organic farming. This versatile tree fixes nitrogen (N), provides flowers for honey bees and other pollinators, and produces a highly durable dense wood ideal for fence posts useable for up to 50 year.&lt;/p&gt;

Correlation of the least limiting water range with soil physical attributes, nutrient levels and soybean yield.

In soils that are compacted or undergoing compaction, the interval of water available to the plants can decline to zero, which according to the least limiting water range (LLWR) method is called the critical soil bulk density (Bdcritical), when LLWR = 0. The aim of this study was to determine the LLWR of a highly clayey typic dystrophic Red Latosol (Oxisol) and to correlate it with the soil physical attributes, nutrient levels and soybean yield, because hypothetically if there is a negative correlation, the use of the LLWR associated with spatial variability maps can help reach decisions regarding intervention or modification of soil management. We observed that in no-till farming, limitation of plant development can occur as the soil dries out, mainly due to the higher resistance to mechanical penetration. Besides this, we found that the LLWR0- 0.10m and LLWR0.10- 0.20m values were correlated in greater numbers with macronutrients and micronutrients analyzed, and also with the land slope, compared the correlation with the soybean yield data. Therefore, nutritional analysis of the grains complemented by physical analysis of the soil can be used to identify nutritional imbalances that are not otherwise observable and thus, the LLWR can be useful for planning corrective actions regarding soil and crop management, based on measurement of the Bdcritical. Key words: No-tillage system, no-till farming system, soil physical quality indicator, spatial variability of soil water content.

No-till strip row farming using yearly maize-soybean rotation increases yield of maize by 75 %

Development of agronomic practices that maximize the use of natural resources to improve soil health and crop productivity is critical for long-term sustainability of agricultural technologies. In Ontario, Canada, the most conventional maize production practice follows a 3-year rotation with soybeans and ploughing of the land before planting and after harvesting. This technology yields 8–10 t ha−1 of maize. We became aware of a long-term no-till strip row farming system developed by an Ontario grower where maize yields are double that of the average for the province. This study set out to identify what factors contribute to such a massive yield increase and the basis for this superior method of maize production. In a 2-year field study, we compared a variety of biotic and abiotic factors associated with yields at this highly productive site with those of two average yielding sites. The no-till strip row farming system grew maize and soybeans in alternate strips rotated yearly and had higher plant populations, better root architecture, higher plant biomass, and 75 % greater (18.35 t ha−1) grain yield compared to a nearby farm that used conventional production practices. About 21 % of the yield increase resulted from early planting, greater number of seeds planted, and healthier ears/seeds. The remaining 54 % increase was linked to larger ears, which we tentatively attribute to beneficial effects conferred by the microorganisms that develop in this unique agro-ecosystem. The average net return at the no-till site was estimated to be CDN (Canadian) $2000 ha−1, which was 400 % higher than the net returns of the conventional sites. The study concludes that no-till management where soil remains undisturbed when combined with yearly rotations of an appropriate legume crop, growing crops exactly on the same cropping rows every year, and optimization of plant density creates a sustainable technology for maximizing maize yields.

Changes in the soil quality attributes of continuous no-till farming systems following a strategic tillage

The adoption of no-till farming systems has greatly reduced energy and machinery inputs while significantly improving soil health and productivity. However, the control of crop weeds and diseases in no-till (NT) systems has become increasingly difficult for landholders in Australia’s northern grains regions, with occasional strategic tillage (ST) being considered as a potential management option. This study investigated the effects of occasional ST on physical, chemical and biological soil properties, productivity, and weed control on five long-term (7–44 years) NT-managed soils. The study area extended from Biloela (Vertosol, 666 mm annual rainfall), Condamine (Sodosol, 624 mm annual rainfall), Moonie (Dermosol, 636 mm annual rainfall) and Warwick (Vertosol, 675 mm annual rainfall) in Queensland to Wee Waa (Vertosol, 582 mm annual rainfall) in New South Wales. Tillage treatments included chisel, offset disc and prickle–disc chain with various timings and frequencies. Soil samples (0–0.3 m) obtained 3 and 12 months after occasional ST were analysed for total and particulate organic carbon (TOC, POC), available phosphorus (P), bulk density, soil water, and microbial enzymatic activity. In-crop weed density was also recorded. One-time tillage, with chisel tines, offset disc or chain harrows, in long-term NT helped to control winter weeds in the first year, with variable results in the second year. Grain yield overall showed no significant impact in either year, except on the Brown Sodosol (P = 0.08) in the first year. The initial impacts of strategic tillage on soil water were largely restricted to the 0–0.1 m depth range, with slight, non-significant decreases occurring. Available P, TOC, POC and total microbial enzymatic activity were not significantly impacted by either cultivation frequency or implement type. The use of an occasional ST for the purpose of weed control could be utilised as a viable management option for NT systems in the region without impacting on long-term productivity.

Nutrient removal effectiveness by riparian buffer zones in rural temperate watersheds: The impact of no-till crops practices

Riparian buffer zones have the potential to capture chemical contaminants and to mitigate detrimental side-effects in aquatic ecosystems derived from excess fertilizers used in agro-food production. No-till farming systems are well known agricultural practices and are widely used in temperate areas. In that regard, different settings and widths of riparian buffer zones (12, 24, 36, 48 and 60m) with woody vegetation, shrubs or grasses were assessed. The methodology was comprised of the evaluation of a large number of experimental sites and the sampling was conducted after the first rain period and respective fertilizer applications. The results point to the fact that effectiveness is largely controlled by buffer zone width and vegetation type. Indeed, buffer zones with 60m width composed of woody soils were more effective in phosphorus (99.9%) and nitrogen (99.9%) removal when compared to shrub (66.4% and 83.9%, respectively) or grass vegetation (52.9% and 61.6%, respectively) areas. Woody vegetation has deep rooting systems and woody soils have a higher content of organic matter when compared to grass and shrubs areas.

Improving Soybean Performance in the Northern Great Plains through the Use of Cover Crops

Cover crops are capable of providing multiple benefits for improving soil quality and enhancing annual crop growth. Maintaining continuous plant cover on agricultural fields with cover crop is of great interest to improve nutrient cycling, prevent soil degradation, and promote further adoption of no-till farming systems. A field study was conducted in eastern South Dakota, USA, in 2007, 2008, and 2009 to evaluate four cover crop combinations [(1) no cover; (2) buckwheat (BUCK) (Fagopyrum esculentum Moench) + slender wheatgrass (Agropyron caninum L.) (SLD WHT); (3) oilseed radish (Raphanus sativus L.) (RAD) + SLD WHT; and (4) purple top turnips (Brassica rapa L.) (TURN + SLD WHT)] sown after oat (Avena sativa L.) on soybean [Glycine max (L.) Merr.] performance. The impacts of no tillage (NT) and conventional tillage (CT) were evaluated at two different planting populations. Soybean plant biomass, seed harvest index, yield, total nitrogen (N), oil concentration, and test weight were measured. Cover crops preceding soybean did not negatively impact most measured plant parameters. Seed yield was increased by the RAD + SLD WHT and TURN + SLD WHT in 2008, whereas in 2007 and 2009 no yield increase or slight yield decrease was shown by the cover crops. Soil tillage practice and planting population had a strong influence on seed yield and seed quality in all three study years.