Acid Sandy Soils Research Articles

Changes in physical properties of sandy soil after long-term compost treatment

Abstract Studying the long-term effect of composted sewage sludge application on chemical, physical and biological properties of soil, an experiment was established in 2003 at the Research Institute of Nyíregyháza in Hungary. The applied compost was prepared from sewage sludge (40%), straw (25%), bentonite (5%) and rhyolite (30%). The compost was ploughed into the 0-25 cm soil layer every 3rd year in the following amounts: 0, 9, 18 and 27 Mg ha−1 of dry matter. As expected, the compost application improved the structure of sandy soil, which is related with an increase in the organic matter content of soil. The infiltration into soil was improved significantly, reducing the water erosion under simulated high intensity rainfall. The soil compaction level was reduced in the first year after compost re-treatment. In accordance with the decrease in bulk density, the air permeability of soil increased tendentially. However, in the second year the positive effects of compost application were observed only in the plots treated with the highest compost dose because of quick degradation of the organic matter. According to the results, the sewage sludge compost seems to be an effective soil improving material for acidic sandy soils, but the beneficial effect of application lasts only for two years.

Acid and calcareous soils affect nitrogen nutrition and organic nitrogen uptake by beech seedlings (Fagus sylvatica L.) under drought, and their ectomycorrhizal community structure

The role of different soil types for beech productivity and drought sensitivity is unknown. The aim of this experimental study was to compare mycorrhizal diversity between acid sandy and calcareous soils and to investigate how this diversity affects tree performance, nitrogen uptake and use efficiency (NUE). Beech trees were germinated and grown in five different soil types (pH 3.8 to 6.7). One-and-a-half-year-old plants were exposed for 6 weeks to sufficient or low soil humidity. Tree biomass, root tip mycorrhizal colonization and community structure, root tip mortality, leaf area, photosynthesis, nitrogen concentrations, NUE and short-term 15N uptake from glutamine were determined. Soil type did not affect photosynthesis or biomass formation, with one exception in calcareous soil, where root mortality was higher than in the other soil types. Beech in acid soils showed lower mycorrhizal colonization, higher nitrogen tissue concentrations, and lower NUE than those in calcareous soils. Drought had no effect on nitrogen concentrations or NUE but caused reductions in mycorrhizal colonization. Mycorrhizal species richness correlated with nitrogen uptake and NUE. Nitrogen uptake was more sensitive to drought in calcareous soils than in acid soils. Beech may be more drought-susceptible on calcareous sites because of stronger decrease of organic nitrogen uptake than on acid soils.

Restoration of former agricultural fields on acid sandy soils: Conversion to heathland, rangeland or forest?

Three restoration strategies on agricultural fields with acid sandy soil were evaluated after 18 and 25 years: conversion to heathland, rangeland and forest. Changes in soil microstructure, chemical characteristics, availability of N and P, and vegetation composition were analyzed in agricultural soils, three undisturbed reference sites and five types of restored former agricultural fields.Agricultural soils were characterized by organic slurry without much soil life. Soil nutrients were especially high for P, mostly in mineral form, and P-desorption rates were high. Partial and complete topsoil removal, aiming at heathland restoration, led to (much) lower soil organic matter and nutrients, but not to recovery of soil life, nor to P-limited soils. Heather was accompanied by many grassland species, even with complete topsoil removal. Conversion to rangeland did not decrease nutrient stocks, but led to improved soil life, although different from reference grasslands due to the higher pH. P-availability remained high, but net N-mineralization and plant N-content were clearly lower after 25 than after 18 years. Plant diversity was relatively high, and cover of eutrophic grasses decreased to 8–39% in intermediate and productive rangelands. Nutrient-poor species remained absent, but the slightly higher pH improved conditions for many grassland herbs. Afforestation did also not lead to nutrient-poor conditions, but soil life clearly increased and nutrients were used for rapid tree growth. Undergrowth species however remained eutrophic.It was impossible to retrieve the P-limited reference ecosystems within 25 years of restoration, not even with complete topsoil removal. Differences in plant diversity between expensive topsoil removal and much cheaper conversion to rangeland were also relatively small. For restoration on a landscape scale, it may thus be better to focus on conversion to semi-natural grasslands and afforestation. The half-open, nutrient-, mineral-, and species-rich landscape offers opportunities for large grazers, but also for many insects and birds.

Physiological and nutritional status of black oat (Avena strigosa Schreb.) grown in soil with interaction of high doses of copper and zinc

Vineyard sandy acid soils from South Brazil have experienced heavy metal contamination due to replacement of copper (Cu)-based by zinc (Zn)-based products to control foliar diseases. Thus, we evaluate physiological and nutritional status of black oat (Avena strigosa Schreb.), a common interrow crop in vineyards from this region. Soil was collected in a natural field from Santana do Livramento, in Rio Grande do Sul, the southernmost state of Brazil. Black oat was cultivated for 30 days in a greenhouse with application of 0, 30, and 60 mg Cu kg−1 combined with 0, 15, 30, 60, 120, and 180 mg Zn kg−1. After the trial period, dry matter accumulation of roots and shoots, Cu and Zn contents in roots and shoots, chlorophyll a fluorescence, photosynthetic pigments and catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) activity were determined. Cu and Zn toxicity was evidenced by the decrease in plant growth of black oat as well as by the decrease of photochemical efficiency associated with the decrease in photosynthetic pigment content, especially with the highest doses of Cu and Zn. Furthermore, the activity of antioxidant enzymes (CAT and POD) was increased in intermediate doses of Zn, indicating the activation of the antioxidant system, but the stress condition in treatments with high levels of Cu and Zn was not reversed.

Concentration of soil CO2 as an indicator of the decalcification rate after liming treatment

Abstract This paper presents the results of investigation of decalcification of acid sandy and loamy sand soils by infiltration waters, and potential Ca-leaching after liming treatment. For this purpose, monthly measurements were made of the concentration of CO2 in the soil air, dissolved inorganic carbon in the soil waters, and their ionic composition. The determined dissolved inorganic carbon ranged from 5.9 to 10.6 mg dm−3 and from 9.9 to 16.5 mg dm−3 for the sandy and loamy sand soil, respectively. The Ca concentration in soil waters was determined as 5.9-12.4 mg dm−3 in sandy soil and 14.2-19.8 mg dm−3 in soil loamy sand. The calculated rate of decalcification amounted to 23.0 kg ha−1 year−1 in soil sandy and 19.4 kg ha−1 year−1 in loamy sand soil. The potential Ca-leaching is predicted as 124 kg ha−1 year−1 for S and 87 kg ha−1 year−1 for loamy sand soil. At the treatment level of 3 000 kg ha−1 4 year−1 of CaO, ~20% of the Ca-fertilizer can be leached after the liming treatment. The results of the CO2 concentration in the soil air may be useful in estimation of Ca-leaching from soils developed by slightly clayey sands and clayey sands in zones with a moderate climate.

Red mud as acidic sandy soil ameliorant: a microcosm incubation study

AbstractBACKGROUNDRed mud is increasingly considered a valuable by‐product requiring development of new re‐use technologies instead of deposition as waste. This paper reports the results of a microcosm study aiming to reveal the beneficial effects of the Ajka red mud, as soil ameliorant, on a specific acidic sandy soil in eastern Hungary.RESULTSThe red mud amount mixed into the sandy soil ranged between 0 and 50%. The experiment was monitored by an integrated methodology combining physical and chemical methods with biological and ecotoxicological measurements. The adverse effects of red mud were examined by ecotoxicity tests using test organisms from three trophic levels: Aliivibrio fischeri (luminescent bacterium), Sinapis alba (plant), Triticum aestivum (plant) and Tetrahymena pyriformis (unicellular animal). The results showed that red mud applied at 5% had positive effects on the degraded acidic sandy soil, significantly increasing soil pH, improving soil texture and water holding capacity. In addition, according to the ecotoxicological test results 5% w/w red mud had no significant adverse effects on the tested organisms as members of the soil ecosystem.CONCLUSIONThe results demonstrated the beneficial effects of red mud as an ameliorant of acidic sandy soils under continental climatic conditions. © 2016 Society of Chemical Industry

Overgrazing decreases soil organic carbon stocks the most under dry climates and low soil pH: A meta-analysis shows

Grasslands occupy about 40% of the world’s land surface and store approximately 10% of the global soil organic carbon (SOC) stock. This SOC pool, in which a larger proportion is held in the topsoil (0–0.3m), is strongly influenced by grassland management. Despite this, it is not yet fully understood how grassland SOC stocks respond to degradation, particularly for the different environmental conditions found globally. The objective of this review was to elucidate the impact of grassland degradation on changes in SOC stocks and the main environmental controls, worldwide, as a prerequisite for rehabilitation. A comprehensive meta-analysis was conducted using 55 studies with 628 soil profiles under temperate, humid, sub-humid, tropical and semi-arid conditions, to compare SOC stocks in the topsoil of non-degraded and degraded grassland soils. Grassland degradation significantly reduced SOC stocks by 16% in dry climates (<600mm) compared to 8% in wet climates (>1000mm) and Asia was the most affected continent (−23.7%). Moreover, the depletion of SOC stock induced by degradation was more pronounced in sandy (<20% clay) soils with a high SOC depletion of 10% compared to 1% in clayey (≥32% clay) soils. Furthermore, grassland degradation significantly reduced SOC by 14% in acidic soils (pH≤5), while SOC changes were negligible for higher pH. Assuming that 30% of grasslands worldwide are degraded, the amount of SOC likely to be lost would be 4.05Gt C, with a 95% confidence between 1.8 and 6.3Gt C (i.e. from 1.2 to 4.2% of the whole grassland soil stock). These results by pointing to greater SOC losses from grasslands under dry climates and sandy acidic soils allow identification of grassland soils for which SOC stocks are the most vulnerable, while also informing on rehabilitation measures.

Acidic sandy soil improvement with biochar — A microcosm study

Biochar produced from a wide range of organic materials by pyrolysis has been reported as a means to improve soil physical properties, fertility and crop productivity. However, there is a lack of studies on the complex effects of biochar both on the degraded sandy soil physico-chemical properties and the soil biota as well as on toxicity, particularly in combined application with fertilizer and compost.A 7-week microcosm experiment was conducted to improve the quality of an acidic sandy soil combining variations in biochar types and amounts, compost and fertilizer application rates. The applied biochars were produced from different feedstocks such as grain husks, paper fibre sludge and wood screenings. The main purpose of the microcosm experiment was to assess the efficiency and applicability of different biochars as soil amendment prior to field trials and to choose the most efficient biochar to improve the fertility, biological activity and physical properties of acidic sandy soils. We complemented the methodology with ecotoxicity assessment to evaluate the possible risks to the soil as habitat for microbes, plants and animals.There was clear evidence of biochar-soil interactions positively affecting both the physico-chemical properties of the tested acidic sandy soil and the soil biota.Our results suggest that the grain husk and the paper fibre sludge biochars applied to the tested soil at 1% and 0.5 w/w% rate mixed with compost, respectively can supply a more liveable habitat for plants and soil living animals than the acidic sandy soil without treatment.

Effect of rice-husk biochar on selected soil properties in tropical Alfisols

Despite the large number of studies on biochar and soil properties, few studies have investigated the effects of biochar in contrasting soils. A study was conducted including four rice-husk biochar rates (0%, 0.1%, 0.5% and 1%) to understand the effects on selected soil properties of two Alfisols (sand and sandy loam) in Sri Lanka. Significant changes in soil properties including increases in pH, cation exchange capacity (CEC), organic carbon, water retention at field capacity and saturated hydraulic conductivity, and reduction in bulk density, were observed at higher rates of biochar (0.5% and 1%). Mean-weight-diameter increased only at 1% biochar application rate in sandy soil, whereas it significantly increased across all the rates in sandy loam soil over the control. Electrical conductivity showed no significant increase in either soil, indicating no threat of salinity. Biochar showed a potential for ameliorating acidity, especially in slightly acidic sandy soil. Soil aggregation and water flow improved markedly in sandy loam soil over sandy soil. Further, CEC and water retention of sandy soil had pronounced effects compared with sandy loam soil. Our study highlights the importance of soil type in determining the value of rice-husk biochar as a soil amendment to improve soil aggregation, water retention and flow and CEC.

Effect of Gérce alginit on the fertility of an acid sandy soil

The effect of alginit on the soil and on triticale was studied over three years, from 2012 to 2014, in a long-term field experiment set up on acidic sandy soil in Nyirlugos 53 years ago. A 100 t•ha-1 rate of alginit was applied in autumn 2011 on plots given 0, 50, 100 and 150 kg•ha-1•year-1 N. The originally 5 x 10 = 50 m2 plots were halved, and the halves without alginit treatment served as controls. The 4N + 4N (with alginit) = 8 treatments × 4 replications = 32 plots. The main results are as follows: 1. Physical soil measurements showed that alginit treatment had no effect on the total porosity or water capacity of the soil. The field capacity increased by 4.4% on average, but this was not significant. The saturation percentage (KA according to Arany) rose significantly from 30.2 to 31.6. 2. On alginit-treated plots the pH(KCl) increased from 3.9 to 6.2, CEC from 1.3 to 3.6, EC from 21 to 67 ms/cm and base saturation from 53% to 74%, while the hydrolytic acidity decreased from 10 to 6 after the first year. 3. NH4-acetate + EDTA-soluble Ca increased from 154 to 730, K2O from 50 to 62, Mg from 18 to 104, Sr from 0.9 to 4.4 mg•kg-1 and Ni from 125 to 330 μ g•kg-1 on the alginit-treated plots. 4. The straw and grain yield of triticale increased in all three years. Alginit treatment generally doubled the yields, especially on plots treated with 150 kg•ha-1•year-1 N, which became acidified and impoverished in Ca, Mg, K and P. 5. Alginit treatment increased the Mg, Mo and Cd uptake and reduced that of Mn, Zn and Ba by triticale seeds. The Ca, Mg, S and Mo concentrations increased in the straw, while the incorporation of Mn, Zn, Ba, Cu, Ni and Co was inhibited by alginit. 6. Alginit is a suitable mineral for the amelioration of similar acid sands, which may eliminate the acidity caused by excessive N supplies and improve the water holding capacity, colloidal and nutrient status and drought-tolerance, and thus their fertility.

Maceration affects mineral composition and pH of wines

Mineral composition of wines is affected by many ecological and technological factors. These variables are mostly discussed focusing on certification of origin and human health. This paper gives data on possible changes in mineral composition and pH of wines due to 4 hours skin maceration (1st trial) and fermentation sur marc (2nd trial). Experimental site is situated on acidic sandy soil in middle east Hungary. The variety collection was established in 2003 with own rooted planting material in 3x1 m spacing, trained for single curtain trainingsystem. Mineral composition of wines was determined with ThermoFischer Scientific iCAP 6300 ICP-OES, pH was measured with pH10pen (VWR International) in field, and with SevenEasyTM pH meter (Mettler Toledo) in laboratory. 1st trial with 9 PIWI white wine grape varieties pointed to demonstrate effects of skin maceration, which is abundantly used to elevate aroma content. 2nd trial with the use of ‘Medina’ red PIWI grape variety aimed to demonstrate effects of double pasta skin maceration in rose and red wine technology. Data of 1st trial show, that K, Cu, Mn and P respective increase with skin maceration, despite Fe show considerable decrease. Data of 2nd trial show, that K, Mg, Mn, P, Sr and B increase with longer skin contact and higher fermentation temperature, despite Fe and Ba decrease with this technology. In regard to pH, data show, that skin maceration and fermentation sur marc increase K content with about 30-70% respectively, withstanding that pH also increase with a considerable 0,4-0,5 value. K content can be higher in the end product, despite to earlier higher level of tartrate formation. An attention should be driven to lower level of tartaric acid and consequently higher pH characteristic for wines produced with the application of skin maceration or fermentation sur marc.

Long-term influences on nitrogen dynamics and pH in an acidic sandy soil after single and multi-year applications of alkaline treated biosolids

We present results of a four year field study examining the changes in seasonal soil mineral nitrogen (SMN) and soil pH from the application of an alkaline treated biosolid (ATB) in an acidic sandy loam soil. Results of two management practices, annual ATB applications and a single application, and different rates of ATB (0, 7, 14, 28 and 42Mgha−1) were also compared over the four year study period. Corn (Zea mays L.) was used as the test crop throughout the study. Soil pH was effectively modified in all treatments receiving ATB rates, compared to the control, under both management practices but best results were achieved under annual ATB application. Soil cation exchange capacity was increased under annual ATB applications, by 3× at the highest ATB. Compared to the control, soil nitrogen and pH displayed significant changes under frequent additions with increasing rates of ATB. Our results indicate that a single application at the highest ATB rate had a residual effect on soil pH but little impact on subsequent SMN dynamics. Average soil mineral nitrogen (SMN) concentrations in the single application management ranged from 8.3 to 9.3mgkg−1 in the final three years of the study but ranged from 8.5 to 12.1mgkg−1 under the annual application management. In contrast, annual applications of ATB at rates ≥14Mgha−1 increased seasonal SMN by 15–42% and soil pH by 1–1.5 pH units. Seasonal SMN dynamics under different ATB rates and management practices were also examined using a soil nitrogen ratio (SNR) and as an area under the seasonal SMN curve.

Wood ash and N fertilization in the Canadian boreal forest: Soil properties and response of jack pine and black spruce

Wood ash fertilization has yet to be investigated in Canadian boreal forests. Ash often improves soil acid–base status, but without N addition it seldom increases tree growth on poor mineral soils. We report results of a large scale experiment conducted in a boreal jack pine (Pinus banksiana Lamb) stand growing on sandy acidic soil in Northeastern Canada. The experiment was completely random with four replications (1ha each) of five treatments (0, 1, 2, 4 and 8 dry Mgha−1) of loose fly ash with and without urea (280kgNha−1). Soils were sampled in the 0, 2, and 8Mgha−1 treatment up to eight years after application. Foliar nutrition and stand growth were assessed in all treatments one and two years and five years after treatment, respectively.Even under low ash loading, forest floor exchangeable base cations, pH, and base saturation increased within a year of application. Ash application also resulted in a swift decrease in forest floor organic C and an increase in N potential net mineralization rate. The initial dominant pattern of upper mineral soil properties in relation to ash loading was a curvilinear relationship with the highest values observed in the 2Mgha−1 treatment. Eight years after ash application, significant linear relationships were found between ash loading and base cations and base saturation in the forest floor and mineral soil (0–10cm, 10–20cm). Contrary to N fertilization, ash had no effect on jack pine foliar nutrition and on its five-year growth. However, a decrease of 30% in relative growth rate was observed between the control and the 8Mgha−1 ash treatment for large (⩾10cm DBH) black spruces (Picea mariana (Mill.) BSP). Black spruce is the dominant commercial species of Canadian eastern boreal forests and thus, additional studies are needed to validate the deleterious effect of ash on spruce growth and to elucidate the mechanisms involved.

A BLEND OF BIOASH AND GYPSUM UTILIZED FOR AGRO-ENVIRONMENTAL PURPOSES IN A SOIL INCUBATION EXPERIMENT

Soil impover, nutrient supplier and heavy metal stabilizer effects of ash residue remaining after the process for K recovery was examined in a soil incubation model experiment using two soil types (acid sandy soil and neutral loam soil) at 4 ash residue dose levels (0,1,3,5%). Possible environmental risks posed ba its application were also studied by ecotoxicological assays.

What Constitutes Plant-Available Molybdenum in Sandy Acidic Soils?

Molybdenum (Mo) is critical for the function of enzymes related to nitrogen cycling. Concentrations of Mo are very low in sandy, acidic soils, and biologically available Mo is only a small fraction of the total pool. While several methods have been proposed to measure plant-available Mo, there has not been a recent comprehensive analytical study that compares soil extraction methods as predictors of plant Mo uptake. A suite of five assays [total acid microwave digestion, ethylenediamenetetraaacetic acid (EDTA) extraction, Environmental Protection Agency (EPA) protocol 3050B, ammonium oxalate extraction, and pressurized hot water] was employed, followed by the determination of soil Mo concentrations via inductively coupled mass spectroscopy. The concentrations of soil Mo determined from these assays and their relationships as predictors of plant Mo concentration were compared. The assays yielded different concentrations of Mo: total digest > EPA > ammonium oxalate ≥ EDTA > pressurized hot water. Legume foliar Mo concentrations were most strongly correlated with ammonium oxalate–extractable Mo from soils, but an oak species showed no relationship with any soil Mo fraction and foliar Mo. Bulk fine roots in the 10- to 30-cm soil horizon were significantly correlated with the ammonium oxalate Mo fraction. There were significant correlations between ammonium oxalate Mo and the oxides of iron (Fe), manganese (Mn), and aluminum (Al). Results suggest that the ammonium oxalate extraction for soil Mo is the best predictor of plant-available Mo for species with high Mo requirements such as legumes and that plant-available Mo tracks strongly with other metal oxides in sandy, acidic soils.

The first record of Rubus apricus in Hungary – on the southernmost point of the distribution area

Rubus apricus Wimmer, a species of Rubus ser. Hystrix, is reported from Hungary for the fi rst time. Th is Central European nemophilous bramble species was found at one locality in the Belső-Somogy region, SW Hungary; this record represents by far the southernmost point of the distribution area. The paper presents the morphological features and the distribution of the species, the characterisation of the newly discovered locality and the assessment of the possible ways of the introduction. Th e Hungarian locality is situated in an approximately 80 years old, mixed Scots pine plantation on mesic-slightly wet acidic sandy soil. Th e origin of the stand is dubious, both the introduction by saplings or seeds used during forest regeneration and a natural colonisation as a consequence of a long distance endozoochorous dispersal event are possible. The latter variation is strengthened by the presence of several other Central European bramble species in the pine plantations of the region.

Millet response to microdose fertilization in south–western Niger: Effect of antecedent fertility management and environmental factors

Soil fertility is a major constraint to agricultural development in most of the Sahel, with P being the most limiting nutrient for millet production on acid sandy soils. To address this issue, microdose applications of P fertilizer have been widely advocated in recent years. However, little is known regarding the effect of farmer management practices and environmental factors on millet's yield response to this technique. For this purpose, 276 farmer demonstrations were setup across a 3-year period in the Fakara region, western Niger. Five strata were considered based on antecedent organic manure management (corralling or transported manure). At each demo site, conventional management was compared to basal microdose fertilizer application of DAP (2ghill−1), NPK (6ghill−1), or DAP (2ghill−1) with urea (1ghill−1) applied at tillering. Millet grain yields on control plots were low (84%<400kgha−1), reflecting the unfavorable environmental conditions of the area. On average, the application of DAP, NPK and DAP+urea increased grain yields by 43, 46 and 69kgha−1 (2001–2002). A positive response to microdose fertilization was observed for 92% of the sites where yields on control plots were <100kgha−1 but only for 32% of the sites where yields on control plots were >500kgha−1. In particular, the positive response to microdosing increased with later sowing given that late sowing tended to reduce yields on control plots. Higher rainfall during the early growing season favored a positive response to microdosing. On average over DAP and DAP+urea, 36% of the demonstrations had value-cost ratios (VCR)<1. However, for low yielding control plots (<200kggrainha−1), 26% of the demonstrations had VCR<1, whereas for high yielding plots (>400kggrainha−1), 55% had a VCR<1. Not accounting for labor, DAP and DAP+urea had similar economic returns. The use of NPK could not be recommended as the cost per unit P is 3 times higher than DAP. It appears that, for the Fakara study area, microdosing may best be targeted to areas with low expected yields. In particular, it may serve as a famine mitigation strategy in case of late sowing. Nevertheless, for poorly endowed areas such as the Fakara, the economic risk associated with microdosing (2gDAPhill−1) appears higher than has hitherto been reported and widespread adoption may not be warranted without institutional support.

Manganese Deficiency in Canola Induced by Liming to Ameliorate Soil Acidity

Applying lime to ameliorate soil acidity has been observed to induce manganese (Mn) deficiency in canola (Brassica napus L.) crops grown on acid sandy soils near Albany and gravelly acid sands of the Great Southern Districts of southwestern Australia. These soils were often Mn-deficient in patches for wheat (Triticum aestivum L.) production when they were newly cleared for agriculture requiring application of Mn fertilizer to ensure grain yields were not reduced by the deficiency. Since then, these soils have acidified and in the 1990s, canola started to be grown on these soils in rotation with wheat and lupins (Lupinus angustifolius L.). These limed soils may now have become marginal to deficient in Mn for canola production. The effect of liming may change the effectiveness of fertilizer Mn. In addition, the effect of liming on the residual value of Mn fertilizer applied to these soils for canola production is unknown. Therefore, a glasshouse experiment was conducted using Mn deficient sand. Three levels of finely-powdered calcium carbonate were added and incubated in moist soil for 42 days at 22±2°C to produce 3 soils with different pH values [1:5 soil:0.01 M calcium chloride (CaCl2)]: 4.9 (original soil), 6.3, and 7.5. Five Mn levels, as solutions of Mn sulfate, were then added and incubated in moist soil for 0, 50, and 100 days before sowing canola. To estimate the residual value (RV) of incubated Mn for canola production, the effectiveness of the incubated Mn was calculated relative to the effectiveness of Mn applied just before sowing canola (freshly-applied Mn). The RV of the incubated Mn was determined using yield of dried canola shoots, the Mn application level required to produce 90% of the maximum shoot yield, and Mn content in dried shoots (Mn concentration in shoots multiplied by yield of dried shoots). As measured using both yield of dried shoots and Mn content of dried shoots, the residual value of Mn decreased with increasing soil pH and with increasing period of incubation of Mn with moist soil. The critical Mn concentration, for 90% of the total yield of dried canola shoots, was (mg Mn kg−1) ∼17 in youngest mature growth (apex and youngest emerged leaf, YMG), and ∼22 for the rest of dried shoots. These values were similar to current critical values for un-limed soils suggesting critical Mn concentrations remain the same for limed soils. Plant testing of canola is recommended if soils are to be limed to ameliorate soil acidity. When plant tests indicate a high likelihood of Mn deficiency, foliar Mn sprays need to be applied to that crop to ensure Mn deficiency does not reduce grain production that year, and fertilizer Mn needs to be re-applied to the soil when sowing the next crop to reduce the likelihood of Mn deficiency for subsequent crops.

Pearl Millet Inbred and Testcross Performance under Low Phosphorus in West Africa

ABSTRACTPearl millet [Pennisetum glaucum (L.) R. Br] is a food security crop for millions living in drylands of Africa and Asia. Its production on acid sandy soils of the Sahel is limited by erratic rainfall and poor soil fertility, especially low P soils. We sought to elucidate the genetic variation in West and Central African landrace‐derived inbred lines for grain yield under low P conditions, to determine their performance as inbred lines per se and in hybrid combinations, and to determine quantitative‐genetic parameters to derive an appropriate breeding strategy to enhance grain yield under low P conditions. We evaluated a total of 155 landrace‐derived inbred lines as well as their testcrosses in four locations during two years under two treatments, high P (HP; with P fertilization) and low P (LP; without P fertilization). Results revealed significant effects for genotypes, P‐level, genotype × P‐level, as well as genotype × environment interactions. Grain yield reductions under LP treatment ranged from 7.9 to 35.5%, and 11.2 to 60.9% for inbred lines and testcrosses respectively, with positive midparent heterosis averaging 43.5% under LP. We conclude that direct selection of testcrosses under LP is more effective and that indirect selection for testross performance from inbred line performance is not desirable.

Further east: eutrophication as a major threat to the flora of Vladimir Oblast, Russia

Eutrophication remains a major threat to the flora of Western Europe despite measures to reduce nitrogen emissions. Although nutrient enrichment has been recorded for both inland waters and adjacent seas, there is almost no evidence from Russia for large-scale anthropogenic eutrophication of soils and its impact on terrestrial biota. I used the distribution grid data (337 grid squares, ca. 96 km(2)) on 1,384 vascular plants of Vladimir Oblast for two periods (1869-1999 vs. 2000-2012) to estimate the shifts in mean Ellenberg's indicator values for nitrogen and soil reaction. Decadal changes in the flora of acid sandy Meshchera Lowlands were observed directly during two grid surveys of 2002 and 2012 based on a coarser grid (50 squares, ca. 24 km(2)). Despite the spatial correlation of Ellenberg's indicator values for soil reaction and nitrogen, mean grid values for nitrogen are growing in areas with both acid and neutral soils. The changes in mean grid indicator values for nitrogen are caused by either local extinctions of species from nutrient-poor habitats or spread of nitrophilous plants. I found that oligotrophic habitats are declining rapidly within the eutrophic loamy landscapes. In contrast, changes in landscapes with acid sandy soils are caused by increasing number of records of nitrophilous species, both invasive and native. These two processes have different spatial patterns caused by varying levels of geochemical buffer capacity and should be considered separately. Fragmentary historical data on Vladimir Oblast flora agrees with the overall European picture of eutrophication in the twentieth century.