Affect Soil Functioning Research Articles

Long-term tillage and synthetic fertilization affect soil functioning and crop yields in a corn–soybean rotation in eastern Canada

Ziadi, N., Angers, D. A., Gagnon, B., Lalande, R., Morel, C., Rochette, P. and Chantigny, M. H. 2014. Long-term tillage and synthetic fertilization affect soil functioning and crop yields in a corn–soybean rotation in eastern Canada. Can. J. Soil Sci. 94: 365–376. Adoption of conservation practices can induce beneficial changes to soil properties and related crop yields in which magnitude varies according to soil and climatic conditions but usually increases with time. A long-term field experiment was initiated in 1992 at L'Acadie in southern Quebec on a clay loam soil to evaluate the effect of tillage [mouldboard plow (MP) vs. conservation (CT)], synthetic N fertilization (0, 80, and 160 kg N ha−1) and synthetic P fertilization (0, 17.5, and 35 kg P ha−1) on soil functioning and grain yields of a corn–soybean rotation. Soil tillage was performed every year while synthetic fertilizers were applied only to the corn. Results obtained 12 to 20 yr after initiation of the study indicated that CT enhanced organic C accumulation, NO3-N, P and K availability, microbial biomass and activity, and microbial community structure in the upper soil layer, likely due to leaving crop residues at the soil surface. The MP practice resulted in greater organic C content deeper, near the bottom of the plow layer, which promoted soil microbial activity at that depth. However, soil N2O emissions were not affected by tillage. The N and P fertilization increased the availability of these nutrients, but had no significant effect on the soil microbial biomass, activity, and structure. Linear relationships were established between soil available P and cumulative P budgets obtained under MP or 0 kg P ha−1 under CT. Crop yields varied by year in this study but on average, MP yielded 10% more corn and 13% more soybeans than CT. Corn yield increased linearly with added synthetic N each year, whereas soybean yield was little affected by residual N, and both crops did not respond to fertilizer P. Response to N fertilization did not differ due to tillage or P. Despite higher costs associated with plowing, the profitability of MP was greater than CT on this clay loam soil due to greater yields. Specialized management practices (e.g., delayed planting, better herbicide selection, fall cover crop, in-row tillage) might help to improve CT performance on these cool, humid fine-textured soils.

Pb, Cu and Zn geochemistry in reclaimed soils (Technosols) of Bulgaria

The content and availability of Pb, Cu and Zn were determined by the methods of soil extractions with aqua regia, 1M NH4NO3 and 1M NH4Ac. Reclaimed soils, which differ in land use, the duration of post reclamation development, geological and geographical characteristics were included in the study. In most pedons trace element total contents are irregular along depth and close to the background values in Bulgarian soils (Pb — 26μg/g, Cu — 34μg/g and Zn — 88μg/g). The copper content greatly varies between the minimum of 8.5μg/g and the maximum of 500μg/g. The latter is defined as an intervention concentration by the Bulgarian legislation, and is accepted as a toxic threshold which affects soil functions, the environment and human health.Mobile concentrations of Pb, Cu and Zn are non-toxic assuming 8μg/g for Cu, 4μg/g for Pb and 43μg/g for Zn as acceptable limits of available heavy metals in Technosols with slightly alkaline pH (7.0 - 8.0). The acidic pH (<6.0) increases the solubility and desorption of zinc and copper, but diversely influences the bioavailability of lead. In acidic Technosols Pb and Cu mobile contents could exceed the Prüeß critical level of 1μg/g and may provoke independent and joint toxic effects. The lithogenic origin of Cu toxicity which amounted to 47.7μg available Cu/g soil shows the most serious risk of environmental pollution.Intensive weathering of soil surface layers does not accelerate the trace element bioavailability. Pb, Cu and Zn mobility mostly depends on pH, the content and mineralogy of fine earth fractions (<0.01mm) and organic carbon pools in studied soils.

Indicators of soil ecosystem services in conventional and organic arable fields along a gradient of landscape heterogeneity in southern Sweden

Agricultural intensification has been vital for meeting global food demand but has caused environmental degradation. This has disrupted the ability of soil to provide vital ecosystem services. Organic farming is often thought to conserve and utilise soil ecosystem services, and thus be a more sustainable method of food production than conventional farming. However, evidence for this is equivocal, and little is known of the potential trade-offs between soil functions, which can be classified as supporting and provisioning ecosystem services, in conventional and organic systems. In addition, few studies have simultaneously examined how surrounding landscape heterogeneity affects soil functions in agriculture. In this study we investigated the effects of farming method (conventional versus organic) and landscape heterogeneity (100m, 500m and 1000m radius) on indicators of soil ecosystem services: soil organic carbon (SOC), total nitrogen (TN), water holding capacity (WHC) and plant-available phosphorous (P) (measures of carbon storage and nutrient retention); net N mineralisation and microbial community composition and biomass (nutrient cycling); and crop yield. We found no effect of landscape heterogeneity, and no differences in any of the measured soil and microbial variables between conventional and organic farms, apart from net N mineralisation, which was higher in organic farms. However, conventional farms had significantly greater yield than organic farms, and there was no apparent trade-off between increasing yield and the level of supporting ecosystem services. The organic farms in this study appear to have been intensively managed, with a straight substitution of organic inputs for chemicals, but little other effort to enhance soil fertility. For example, the organic farms applied large quantities of manure compared with conventional farms but conducted mechanical weeding (harrowing), whereas conventional farms applied herbicides. This repeated soil disturbance may cause rapid organic matter mineralisation and undermine the ability of these organic farms to retain carbon and nitrogen. The terms ‘organic’ and ‘conventional’ agriculture both cover a wide variety of farming methods, some of which enhance or deplete ecosystem services more than others. To develop truly sustainable methods of agriculture, research should focus on the effects of specific farming practices, rather than the labels ‘conventional’ and ‘organic’.

Emission of CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O and dynamics of mineral N in soils amended with castor bean (Ricinus communis L.) and piñón (Jatropha curcas L.) seed cake

Extraction of oils from castor bean (Ricinus communis L.) and Jatropha curcas L. to produce biofuel is set to increase. The produced seed cake could be applied to soil as it is nutrient rich, but might affect soil functioning. Seven soils from Chiapas, M&amp;eacute;xico, were amended with seed cake of both plants while CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O emissions and mineral N concentrations were monitored in an aerobic incubation. The concentration of phorbol esters in the J. curcas seed cake (JSC) was 0.993 mg/g while no ricin was detected in the R. communis seed cake (RSC). Application of JSC increased CO&lt;sub&gt;2&lt;/sub&gt; emission 2.5-times, N&lt;sub&gt;2&lt;/sub&gt;O 12.6-times and CH&lt;sub&gt;4&lt;/sub&gt; 18.4-times compared to the unamended soil, while RSC CO&lt;sub&gt;2&lt;/sub&gt; emission 2.1-times, N&lt;sub&gt;2&lt;/sub&gt;O 21.3-times and CH&lt;sub&gt;4&lt;/sub&gt; 2.3-times. On average, 66% of the 88 mg organic N added with JSC was mineralized and 83% of the 101 mg organic N of the RSC within 56 days. It was found that J. curcas and castor bean seed cake increased CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O emission and mineral N in soil, without inhibiting soil microbial activity.

An appraisal of soil organic C content in Mediterranean agricultural soils

AbstractLow soil organic carbon (SOC) levels in dry areas can affect soil functions and may thus indicate soil degradation. This study assesses the significance of SOC content in Mediterranean arable soils based on the analysis of a broad data set of 2613 soils sampled from Mediterranean grasslands and agricultural land. The distribution in values of SOC, pH, clay and carbonates was analysed according to different climatic areas (semi‐arid, Mediterranean temperate, Mediterranean continental and Atlantic) and with respect to six different land uses (grassland, cereal crops, olives and nuts, vineyards, fruit trees and vegetable gardens). The general trend was for low SOC in arable land and decreased with aridity. In wet areas (Atlantic and Mediterranean continental), acidic soils had a higher SOC content than did calcareous soils, whereas in the Mediterranean temperate area SOC had little relationship to soil pH. In low SOC arable soils, the SOC content was related to clay content. In calcareous arable soils of the Mediterranean temperate zone, SOC content was more closely related to carbonates than to clay. In contrast to the Atlantic area, Mediterranean grassland soils had much lower amounts of SOC than forest soils. Mediterranean calcareous and temperate acidic soils under grassland had SOC‐to‐clay ratios similar to or only slightly greater than that under a crop regime. In contrast, Mediterranean continental acidic soils under grassland had a much higher SOC‐to‐clay ratio than arable soils. This suggests a low resilience of the Mediterranean temperate and calcareous arable soils in terms of SOC recovery after the secession of ploughing, which may be a result of intensive use of these soils over many centuries. Consequently, we hypothesize that the Mediterranean calcareous soils have undergone significant changes that are not readily reversed after ploughing ceases. Such changes may be related to alterations in soil aggregation and porosity which, in turn, are associated with soil carbonate dynamics. Decarbonation processes (the depletion of active carbonates) may therefore be relevant to the reclamation of highly calcareous arable soils through fostering soil re‐aggregation. The article concludes by discussing the suitability of zero tillage, manuring or the introduction of woody species to increase SOC in calcareous arable soils that are highly depleted of organic matter.

Visualization, modelling and prediction in soil microbiology

The introduction of new approaches for characterizing microbial communities and imaging soil environments has benefited soil microbiology by providing new ways of detecting and locating microorganisms. Consequently, soil microbiology is poised to progress from simply cataloguing microbial complexity to becoming a systems science. A systems approach will enable the structures of microbial communities to be characterized and will inform how microbial communities affect soil function. Systems approaches require accurate analyses of the spatio-temporal properties of the different microenvironments present in soil. In this Review we advocate the need for the convergence of the experimental and theoretical approaches that are used to characterize and model the development of microbial communities in soils.

Great Plains cropping system studies for soil quality assessment

AbstractInteractions between environmental conditions and management practices can significantly affect soil function. Soil quality assessments may improve our understanding of how soils interact with the hydrosphere and atmosphere. This information can then be used to develop management practices that improve the capacity of the soil to perform its various functions and help identify physical, chemical, and biological soil attributes to quantify the present state of a soil and detect changes resulting from management. In protocols established by the Great Plains cropping system network, sampling and testing procedures were selected to identify physical, chemical, and biological soil attributes responsive to management that may serve as useful indicators in assessing the effects of management on the soil resource. Eight existing long-term studies from throughout the Great Plains in the central USA were used to make these assessments because, (1) many years are required for certain soil properties to change measurably; (2) annual weather causes variation in system performance; and (3) the soil pools of interest are spatially variable. This paper includes detailed descriptions of the treatments and sites, and both long-term and short-term (1999–2002) data on precipitation, temperature, and yields for each location.

Effects of Cd and Pb on the survival and juvenile production of Sinella coeca and Folsomia candida

Degradation factors can cause both quantitative and qualitative changes in fauna and thus affect soil functioning. The use of bio-indicators may help to detect environmental changes. The aim of this study was to evaluate the effects of lead and cadmium on the biology (mortality, reproduction, egg hatching) of two euedaphic collembolans, Sinella coeca and Folsomia candida and to evaluate sensitivity differences between the two species. The results showed that low concentrations of lead did not cause dramatic effects on the survival and reproduction of both species. Reproduction of both species was reduced when the soil contained a nominal concentration of Pb at 1000 μg g –1. S. coeca and F. candida showed a high sensitivity to cadmium and both their reproduction and survival were significantly reduced on exposure to 50 μg g –1. Moreover, egg hatching of F. candida was affected by the cadmium concentrations in the soil, and by the amount of time that the eggs stayed in contact with cadmium. This study showed that the inhibition determined by Cd on F. candida juvenile production was caused in part by inhibition of deposition and, in part, by reduction of egg viability.

The effect of transgenic nematode resistance on non‐target organisms in the potato rhizosphere

Summary Plant‐parasitic nematodes are important pests of agriculture and transgenic plants with potential for nematode control are currently being developed. The expression of cysteine proteinase inhibitors (cystatins) in potato confers partial resistance to potato‐cyst nematode (PCN). Here, we used field studies to test for effects of cystatin‐expressing potato on non‐target soil organisms. Microbial community structure, soil microarthropods and litter decomposition were studied during two growing seasons. In the second year, nematode control options of cystatin‐expressing plants and an oxime carbamate nematicide application were compared for their non‐target effects. In the first year, the transgenic lines had no effect on the abundance, evenness or metabolic activity of the soil microbial community as determined by ester‐linked phospholipid fatty acid analysis (PLFA). However, one transgenic line (D6/7) influenced the structure of the soil microbial community. PLFA suggested it favoured fungal growth relative to bacterial growth during the latter parts of the growing season. A second transgenic line (D5/13) was more effective against PCN. It reduced the abundance of the fungal fatty acid 18 : 2ω6 in late season, suggesting a suppression of fungal growth. In the second year PLFA analysis suggested microbial abundance was reduced by 15% and 23% in the nematicide and transgenic treatments, respectively, relative to the control. Nematicidal treatment reduced the bacterial fraction of the microbial community, whereas the transgenic plants suppressed both the bacterial and fungal community components. The observed changes in soil microbial community structure did not result in changes in the rate of leaf litter decomposition. The transgenic lines had no significant effect on the abundance of soil microarthropods or free‐living nematodes. The study is the first stage of a risk assessment of the impact of transgenic nematode resistance on non‐target soil organisms. It has highlighted the importance of including currently used management options when studying the effect of transgenic plants on non‐target organisms. Both nematicide use and the transgenic plants affected components of the soil microbial community. However, the changes brought about by the two treatments were not sufficient to affect soil functioning, as measured by rates of litter decomposition.