Non-calcareous Soils Research Articles

Modeling soil acidification in typical Chinese cropping systems

We applied the adapted model VSD+ to assess cropland acidification in four typical Chinese cropping systems (single Maize (M), Wheat-Maize (W-M), Wheat-Rice (W-R) and Rice-Rice (R-R)) on dominant soils in view of its potential threat to grain production. By considering the current situation and possible improvements in field (nutrient) management, five scenarios were designed: i) Business as usual (BAU); ii) No nitrogen (N) fertilizer increase after 2020 (N2020); iii) 100% crop residues return to cropland (100%RR); iv) manure N was applied to replace 30% of chemical N fertilizer (30%MR) and v) Integrated N2020 and 30%MR with 100%RR after 2020 (INMR). Results illustrated that in the investigated calcareous soils, the calcium carbonate buffering system can keep pH at a high level for >150years. In non-calcareous soils, a moderate to strong decline in both base saturation and pH is predicted for the coming decades in the BAU scenario. We predicted that approximately 13% of the considered croplands may suffer from Al toxicity in 2050 following the BAU scenario. The N2020, 100%RR and 30%MR scenarios reduce the acidification rates by 16%, 47% and 99%, respectively, compared to BAU. INMR is the most effective strategy on reducing acidification and leads to no Al toxicity in croplands in 2050. Both improved manure and field management are required to manage acidification in wheat-maize cropping system.

Changes in bacterial community of soil induced by long-term straw returning

Straw returning is an effective way to improve soil quality. Whether the bacterial community development has been changed by long-term straw returning in non-calcareous soil is not clear. In this study, the following five treatments were administered: soil without fertilizer (CK); wheat and corn straw returning (WC); wheat straw returning with 276 kg N ha−1 yr−1 (WN); manure, 60,000 kg ha−1 pig manure compost (M) and wheat and corn straw returning with 276 kg N ha−1 yr−1 (WCN). The high-throughput 16S rRNA sequencing technology was used to evaluate the bacterial communities. The results showed that the community was composed mostly of two dominant groups (Proteobacteria and Acidobacteria). Bacterial diversity increased after the application of straw and manure. Principal component analyses revealed that the soil bacterial community differed significantly between treatments. The WCN treatment showed relatively higher total soil N, available P, available K, and organic carbon and invertase, urease, cellulase activities and yield than the WC treatment. Our results suggested that application of N fertilizer to straw returning soil had significantly higher soil fertility and enzyme activity than straw returning alone, which resulted in a different bacterial community composition, Stenotrophomonas, Pseudoxanthomonas, and Acinetobacter which were the dominant genera in the WC treatment while Candidatus, Koribacter and Granulicella were the dominant genera in the WCN treatment. To summarize, wheat and maize straw returning with N fertilizer would be the optimum proposal for improving soil quality and yield in the future in non-calcareous fluro-acquic-wheat and maize cultivated soils in the North China Plain in China.

Soil-applied phosphorous is an effective tool to mitigate the toxicity of copper excess on grapevine grown in rhizobox

Abstract The aim of the present study was to evaluate the effectiveness of P soil addition to mitigate the toxic effect of excess of Cu on grapevine on sandy non-calcareous soil. Micro-propagated plants of 1103 Paulsen rootstock were grown according to a factorial experimental design with two factors: Cu addition (0, 100, 200 and 300 mg kg −1 dw) and P addition (0, 50 and 100 mg kg −1 soil dw). The experiment was conducted in the greenhouse and plants were grown on a sandy soil in rhizoboxes. At the end of the trial, plants were destructively harvested, the biomass and the nutrient concentration of organs were determined. Root growth was evaluated during the trial and the concentration of organic acid in root tissue and exudates was determined. Shoot length and plant biomass declined as Cu concentration in soil increased; the application of P enhanced plant growth and nutritional status. Root biomass decreased at Cu > 100 mg kg −1 and increased in P at 100 mg kg −1 . Phosphorous stimulated root length, diameter and the number of apexes. Root citric acid increased as a response of Cu at 300 mg kg −1 , root ascorbic acid decreased with the increase of Cu (200 and 300 mg kg −1 ) and P at 100 mg kg −1 . The concentration of citric acid from root exudations was higher in Cu at 300 mg kg −1 and Cu at 200 mg kg −1 (compared to control) and P at 100 mg kg −1 soils. The application of P fertilization seems to be a valuable strategy to overcome the toxicity of high concentration of Cu in soil.

Phosphorus use efficiency and critical P content of stevia grown in acid and non-calcareous soils of Bangladesh

Knowledge of phosphorus (P) uptake and its use efficiency by crop plants is essential for adequate management of the plant nutrients to sustain food production with a minimal environmental impact. To study the effects of P on the growth, leaf biomass production, P content and uptake and to estimate P use efficiency (PUE), minimum P requirement and critical leaf P content of stevia, a pot experiment was conducted in the net house of the Department of Agricultural Chemistry, Bangladesh Agricultural University following completely randomized design (CRD) with three replications in acid and non-calcareous soils of Bangladesh. The applied treatments was six viz. 0 (P0), 25 (P25), 50 (P50), 75 (P75), 100 (P100) and 150 (P150) kg P ha-1. Plant samples were collected at 15 days interval to obtain different parameters. Collective results indicated that significantly highest values of different parameters were obtained with P @ 100 kg ha-1 and the lowest from P control. Phosphorus application increased leaf dry yield at harvest by 55 to 510% in acid soil and 70 to 488% in non-calcareous soil over control. The rapid growth of the plant was recorded at the later stages (30 to 60 days after planting). Phosphorus content and uptake was directly proportional with the increased levels of P except the treatment P150 in both soils. Maximum PUE and fertilizer P use efficiency (FPUE) was observed at P100 treatment. Critical P content was estimated to be ca 0.19 and 0.30% in the leaves of stevia plants grown in acid and non-calcareous soils, respectively. For maximum leaf biomass production of stevia grown in acid and non-calcareous soils, the minimum requirement of P was also estimated to be ca 109 and 104 kg ha-1, respectively. The information of this finding would contribute to optimize the soil P use and improve fertilizer management for stevia cultivation.Res. Agric., Livest. Fish.4(2): 55-68, August 2017

Characterization of Some Calcareous Soils from Henan and Their Proposed Classification in Chinese Soil Taxonomy

Calcareous soils are those soils containing layers of carbonate accumulation formed by either secondary accumulation or inheritance of CaCO3 from calcareous parent materials. These soils are widely distributed in arid, semi-arid and even some humid climate environments. However, in the Chinese Soil Taxonomy (CST, 3rd version), the soils that contain large amounts of CaCO3 but do not meet requirements of Aridosols are classified as Hapli-Ustic Cambosols. This group also includes many non-calcareous soils and those soils strongly affected by secondary carbonate accumulation together with quite dissimilar soils in terms of their morphology and properties. This study was conducted to determine calcification patterns and calcic processes occurring in representative pedons of calcareous soils in northwestern Henan Province, China and to classify these soils in CST. A Calcic subgroup was proposed to add within the Hapli-Ustic Cambosols. A diagnostic key was also provided to separate this subgroup from the Typic subgroup. In this way the different calcification degrees of soils were better reflected in the classification, which should lead to more uniform interpretive groups for better soil management.

Influence of calcareous soil on Cry3Bb1 expression and efficacy in the field.

Greater than expected injury by western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) to Cry3Bb1 expressing maize hybrids (Zea mays L.) has been reported in southwestern Nebraska. Affected areas of some fields are often associated with high pH calcareous soils where maize growth is poor and iron chlorosis is common. As part of a comprehensive study to understand potential causes of unexpected injury, experiments were conducted during 2013 and 2014 to ascertain whether the calcareous soil conditions and associated poor maize growth negatively affect the expression of Cry3Bb1. Quantitative determination of Cry3Bb1 protein expression levels in root tissues was carried out on plants at V5-V6 growth stage using the enzyme-linked immunosorbent assay. Cry3Bb1 and non-Bt near isoline maize hybrids were artificially infested with Cry3Bb1-susceptible WCR eggs to measure survival and efficacy of Cry3Bb1 maize in calcareous and non-calcareous soils. Results showed that there was not a significant difference in expression of Cry3Bb1 protein between plants from calcareous and non-calcareous soils (18.9-21.2µg/g fresh weight). Western corn rootworm survival was about sevenfold greater from the non-Bt isoline than Cry3Bb1 maize indicating that Cry3Bb1 performed as expected when infested with a Cry3Bb1 susceptible rootworm population. When survival from calcareous and non-calcareous soils was compared, no significant differences were observed in each soil. A significant positive correlation between soil pH and expression of Cry3Bb1 protein in roots was detected from samples collected in 2014 but not in 2013. No such correlation was found between soil pH and survival of WCR. Results suggest that Cry3Bb1 expression levels were sufficient to provide adequate root protection against WCR regardless of soil environment, indicating that lowered Cry3Bb1 expression is not a contributing factor to the greater than expected WCR injury observed in some southwestern Nebraska maize fields.

Sorption and mobility of Co(II) in relation to soil properties

The kinetic and equilibrium sorption data of Co(II) ions were obtained from batch sorption experiments, using soils samples with a wide range of texture, carbonate and organic content. Sequential extraction protocol was applied to evaluate Co(II) interactions with soil fractions. The parameters, obtained from kinetic and isotherm data modeling, as well as the results of Co(II) distribution and desorption studies, were correlated with soil properties. Kinetics of Co(II) sorption was fast and obeyed the pseudo-second order kinetic model at the contact time ranged from 30min to 30days, using Co(II) concentration of 1.5×10−3molL−1. Maximum sorption capacities were highly correlated with soil pH. The sorbed Co(II) was associated with Fe,Mn-oxide and carbonate phase of calcareous soil, whereas in other soil types ion-exchangeable fraction was dominant. The effect of aging on Co(II) stabilization in soil was more pronounced for lower contamination levels and soils with higher pH. For non-calcareous soils, the desorption of Co(II) could be achieved by EDTA and HCl solutions.

Application of GIS in General Soil Mapping of Bangladesh

Bangladesh is a densely populated country where food crisis is one of the major issues where proper soil mapping is lacking till now. The purpose of this study is to prepare soil mapping of Bangladesh including different soil factors like pH, salinity, nutrients, texture, porosity, toxicity etc., along with general soil types and land availability through application of Geographical Information System (GIS). Q-GIS software and secondary data are used in this study. In present study, it was found that 12 types of soil texture were present in all around of Bangladesh and the maximum percentage of soil porosity values varied from 20% to 70%. A medium range of soil organic matter and strongly acidic soil was found all around the Bangladesh. It was found that the southern part of Bangladesh had slightly saline to highly saline soil. The major part of Bangladesh had medium high land which is very much preferable to agriculture. In Bangladesh, three categories of land such as highland, medium highland and low land cover 29%, 35% and 21% of total land, respectively. Agriculture land covers 9.5 million hectares in Bangladesh. The shifting rate based on agricultural use had been reported to be about 1% per year. At present, the amount of forest land covers 9.84% of total land of our country but 1976 it was 12.11%. Mangrove is now at 4.07% of total land mass of our country. In generally, 20 types of soils were found all around the country. Mapping of soil types described these 20 general soil types under 5 main categories and these are calcareous soil, non-calcareous soil, terrace soil, gray soil, peat and hill soils. This study will be helpful for the cultivator to cultivate appropriate crops in appropriate places after exploration at a glance.

Effect of Phytase and FYM on Soil Enzyme Activities, Microbial Population and Nutrient Availability of Non-Calcareous Soil

A pot culture experiment was conducted to assess the effect of phytase and FYM levels on soil enzyme activities and nutrient availability of non-calcareous soil under soybean cultivation. The treatment consisted of four levels of phytase (0, 1200, 2400 and 3600 IU) and FYM (0, 2.5, 5.0 and 7.5 t ha−1). Enzyme activities and nutrient availability in soil was assessed at 50% flowering and harvest of soybean. It was observed that application of phytase @ 3600 IU recorded significantly higher acid and alkaline phosphatase and dehydrogenase activity at both the growth stages of soybean. Results revealed that significant interaction effect with combine application of phytase @ 3600IU and FYM @ 7.5 t ha−1 recorded higher bacterial, fungal and actinomycetes population. Combined application of phytase @ 3600 IU and FYM @ 7.5 t ha−1 recorded significantly higher available nitrogen (289.3 and 213.6 kg ha−1) and potassium (295.0 and 270.6 kg ha−1) at 50% flowering and at harvest of soybean, respectively. However, in case of phosphorus (P), at 50% flowering significantly higher available P was recorded with phytase @ 3600 IU + 7.5 t ha−1 (23.9 kg ha−1). Reduction trend obtained for calcium carbonate content from 4.24 to 3.68% at 50% flowering and from 4.20 to 3.60% at harvest stage was obtained with the application of phytase @ 3600 IU. This study suggest that application of phytase in combination with manure substantially improves soil biological activities as well as better nutrient supply to crop.

Derivation of ecological criteria for copper in land-applied biosolids and biosolid-amended agricultural soils

The difference in availability between soil metals added via biosolids and soluble salts was not taken into account in deriving the current land-applied biosolids standards. In the present study, a biosolids availability factor (BAF) approach was adopted to investigate the ecological thresholds for copper (Cu) in land-applied biosolids and biosolid-amended agricultural soils. First, the soil property-specific values of HC5add (the added hazardous concentration for 5% of species) for Cu2+ salt amended were collected with due attention to data for organisms and soils relevant to China. Second, a BAF representing the difference in availability between soil Cu added via biosolids and soluble salts was estimated based on long-term biosolid-amended soils, including soils from China. Third, biosolids Cu HC5input values (the input hazardous concentration for 5% of species of Cu from biosolids to soil) as a function of soil properties were derived using the BAF approach. The average potential availability of Cu in agricultural soils amended with biosolids accounted for 53% of that for the same soils spiked with same amount of soluble Cu salts and with a similar aging time. The cation exchange capacity was the main factor affecting the biosolids Cu HC5input values, while soil pH and organic carbon only explained 24.2 and 1.5% of the variation, respectively. The biosolids Cu HC5input values can be accurately predicted by regression models developed based on 2–3 soil properties with coefficients of determination (R2) of 0.889 and 0.945. Compared with model predicted biosolids Cu HC5input values, current standards (GB4284-84) are most likely to be less protective in acidic and neutral soil, but conservative in alkaline non-calcareous soil. Recommendations on ecological criteria for Cu in land-applied biosolids and biosolid-amended agriculture soils may be helpful to fill the gaps existing between science and regulations, and can be useful for Cu risk assessments in soils amended with biosolids.

Changes in Olsen P in Relation to P Balance in Contrasting Agricultural Soils

Maintaining soil phosphorus (P) at adequate levels for plant growth requires assessing how the long-term P balance (viz., the difference between P inputs and outputs) results in changes in soil test P. The hypothesis that routinely measured soil properties can help predict the conversion factor of P balance into Olsen P was tested at 39 sites in agricultural areas of the Mediterranean region in Spain. A set of soil samples from each site was analyzed for Olsen P, inorganic P (P extracted using 0.5 mol L−1 H2SO4), pseudototal P (P extracted using 0.5 mol L−1 H2SO4 following ignition at 550 °C), and organic P (the difference between pseudototal P and inorganic P). Organic and Olsen P were uncorrelated in most of the 39 soil sets, which suggests that organic P content changed little with P inputs and outputs. The slopes of the regression lines of Olsen P against pseudototal and inorganic P, which were used as two different measures of the conversion factor, ranged widely (from 0.03 to 0.25 approximately), with their average values (about 0.10) being similar to those found in long-term experiments conducted in temperate areas. Neither conversion factor was significantly correlated with any routinely measured soil property; however, the conversion factor for inorganic P was significantly lower for calcareous soils than for noncalcareous soils. Our negative results suggest the need to isolate the influence of soil properties from that of management systems and environmental factors relating to P dynamics in future studies.

Effects of vermicompost on growth and leaf biomass yield of stevia and post harvest fertility status of soil

In view of the growing awareness about eco-friendly organic farming, vermicompost (VC) could be a very good option for increasing crops yield. The organic carbon in VC releases nutrients slowly and steadily into the system and enables the plant to absorb these nutrients. To assess the effect of VC on soil fertility, growth and yield of stevia in acid and non-calcareous soils, an experiment was undertaken in the net house of the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh, during February to May, 2012. Four levels of VC viz. 0, 5, 7.5 and 10 t ha-1 in two contrasting soils (Acid and Non-calcareous) were examined following CRD with three replications. Growth and yield attributes such as plant height, branch and leaf number, leaf area, fresh and dry weight of leaves were significantly influenced by different levels of VC. All the plant parameters increased with the advancement of growth period as well with increased rate of VC up to 7.5t ha-1 and then declined with further additions. The leaf biomass yield was 335% and 338% higher in acid soil and in non-calcareous soil, respectively over control. The overall performance of non-calcareous soil was superior to acid soil in terms of both plant and soil parameters studied. The acidity of both soils significantly decreased with the increased application of VC ranging from 4.9 to 5.7 in acid soil and 6.5 to 7.2 in non-calcareous soil. Total N, available P, exchangeable K, Ca, Mg, available S, Zn, B were also significantly increased with the increased levels of VC up to its highest level (VC @ 10t ha-1) in both soils. Thus the results suggest that VC @ 7.5t ha-1 should be applied for getting maximum leaf biomass yield of stevia and 10t ha-1 for increasing the fertility of both soils under the agro-climatic conditions of the studied area.J. Bangladesh Agril. Univ. 13(2): 169-174, December 2015

Integrated effects of poultry manure and chemical fertilizer on the growth, leaf yield and stevioside content of stevia

Stevia is important for its leaves which are used as non calorie sweetener and also in many therapeutic applications including diabetes. The present investigation was carried out in the net house of the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh to investigate the integrated effects of poultry manure (PM) and chemical fertilizer (CF) on the growth, leaf biomass yield and stevioside content of stevia grown in two contrasting soils (acid and non-calcareous) of Bangladesh. Six combinations of PM and CF viz. PM0+CF0, PM0+CF100, PM3+CF50, PM3+CF75, PM5+CF50, PM5+CF75 were used. The study revealed that PM along with different percentages of chemical fertilizers exerted significant influence on the growth, leaf yield and stevioside content of stevia. The highest values of all the parameters except stevioside were found from the plant receiving PM @ 3 t ha-1 along with 75% CF. The leaf biomass yield was 1088% and 867% higher in acid soil and non-calcareous soil, respectively, over control. Stevioside content was increased with increasing the levels of PM up to 5 t ha-1 and also with the advancement of growth period from 30 to 60 days after planting. The highest amount of stevioside (10.45%) was detected in the leaves of the plant that received PM @ 5 t ha-1 along with 75% CF at 60 DAP in acid soil and it was 9.11% in non-calcareous soil at the same period. The lowest values of all the parameters including stevioside content were obtained from the plant which received neither PM nor CF. Considering the overall performance, farmers may be advised to cultivate stevia in acid soil applying PM @ 3 t ha-1 along with 75% chemical fertilizer to boost up the production of stevia under the agro-climatic condition of the study area in the context of Bangladesh.J. Bangladesh Agril. Univ. 13(2): 175-182, December 2015

Response of stevia to foliar application of prilled urea

Urea can be supplied to plants through the foliage, facilitating optimal N management, which minimizes N losses to the environment. The efficiency of N assimilation through foliage depends upon several factors including N levels and varieties or genotypes. No information is available on the effect of the foliar application of urea on stevia (Stevia rebaudiana, Bertoni). The objective of the study was to evaluate the effect of foliar application of prilled urea applied in different concentrations on the growth, yield components, leaf biomass yield, N content and its uptake by stevia. Seven levels of urea viz. 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3g 2L-1 were sprayed 10 days after planting (DAP) in acid and non-calcareous soils at an interval of one week up to 60 DAP. Foliar urea application significantly increased plant height, branch and leaf number, leaf area, fresh and dry leaf weight, leaf N content and uptake by stevia. Most of the parameters were increased with the advancement of growth period from 30 to 60 DAP. The foliar spray of 2.0g urea solution was found to be most effective for enhancing the growth, leaf yield and yield attributes of stevia. The yield increase was 478% in acid soil and 485% in non-calcareous soil over control. Further increase in the concentrations of urea spray (2.5 and 3.0g) was not found to be useful as it declined the leaf yield by 135% in acid and 175% in non-calcareous soil probably due to its toxicity. N content in stevia leaves was significantly increased with the increased levels of urea up to 3.0g in both soils. Conversely, the trend of N uptake did not follow the trend of N contents of stevia leaves. N uptake as expected increased as foliar application of urea increased up to 2.0g and then decreased with further addition. The results suggest that farmers can be advised to apply prilled urea as foliar spray @ 1g L-1 for higher leaf biomass yield and N uptake by stevia either in acid or non-calcareous soils under the agro-climatic conditions of Bangladesh Agricultural University, Mymensingh.J. Bangladesh Agril. Univ. 13(1): 39-46, June 2015

Growth parameters and leaf biomass yield of stevia (Stevia rebaudiana, Bertoni) as influenced by different soil types of Bangladesh

Soils of different types affect crop production according to their capability as a nutrient supplier based on plant requirement. Soil provides physical support to plant as well as supplies necessary water and nutrient elements for plant growth and development. Suitable soil for stevia cultivation in Bangladesh is yet to be identified. A high concentrate sweetness producer plant, stevia (Stevia rebaudiana Bertoni) was grown in earthen pots in some soils of Bangladesh to choose the most suitable soil/s for the growth and leaf yield of stevia. Seven soil types namely acid, calcareous, non-calcareous, charland, saline, peat and acid sulphate were used as treatments. The soils were mostly light grey in colour and clay to clay loam in texture. Bulk density, particle density and field capacity ranged from 1.24-1.45, 2.20-2.58 and 27.03-30.19%, respectively. pH, EC and organic matter content ranged from 3.90-8.00, 0.25-14.00 dS m-1 and 0.88-16.40%, respectively. Total N, exchangeable K, available P and S contents ranged from 0.05-0.96%, 0.17-0.70 cmol kg-1 soil, 3-12 and 11-735 ?g g-1 soil, respectively. Different soil types significantly influenced the growth and leaf yield of stevia. The highest values of plant height, branch and leaf number, leaf area, fresh and dry weight of leaves were obtained from the plant grown in non-calcareous soil which was identical with the plant those grown on acid soil while the lowest values of all the parameters were found from the plant grown in acid sulphate soil. Leaf biomass yield increase ranged from 16.18% in peat soil and 90.11% in non-calcareous soil over acid sulphate soil. The performance of the soils in terms of stevia leaf production was of the order non-calcareous> acid> calcareous> charland> saline(4.43 dS m-1)> saline(6.08 dS m-1)> saline(8.68 dS m-1)> peat >acid sulphate soils. The overall results suggest that farmers could be advised to grow stevia either in non-calcareous soil or acid soils of Bangladesh.J. Bangladesh Agril. Univ. 13(1): 31-37, June 2015

Nitrogen requirement and critical N content of stevia grown in two contrasting soils of Bangladesh

Nitrogen is recognized as one of the most limiting nutrient for crop growth in Bangladesh and can be supplemented with inorganic fertilizers like urea. The experiment was conducted in the net house of the Department of Agricultural Chemistry, Bangladesh Agricultural University during March to July 2012. The objective was to examine the effects of different levels of N on the growth, leaf biomass yield, N content and to estimate minimum N requirement and critical N content of stevia. The treatments included six N rates (0, 100, 150, 200, 250 and 300 kg ha-1). Plant sampling was done at 15, 30, 45 and 60 days after planting (DAP) to measure plant height, number of branches and leaves, fresh and dry weight of leaves, leaf area and N concentration. The results revealed that all the characters were significantly affected by different N rates. The highest values of all parameters except plant height and N concentration were obtained from 250 kg N ha-1 and the lowest values from N control. Nitrogen application at all levels increased leaf dry yield at harvest by 99 to 505% in acid soil and 69 to 438% in non-calcareous soil, respectively over control. The growth of most parameters was rapid at the later stages (30 to 60 DAP). Leaf N content proportionately increased with the increasing rates of N. The highest N concentration was obtained from its highest application (300 kg N ha-1). The minimum amount of N for maximum leaf biomass production in the plants grown in acid and non-calcareous soils was estimated to be ca 273 and 257 kg ha-1, respectively. The critical N concentration to achieve 80% of the maximum production of stevia leaf was also estimated to be ca 1.43 and 1.50% in the leaves of stevia plants grown in acid and non-calcareous soils, respectivelyRes. Agric., Livest. Fish.3(1): 87-97, April 2016

Agricultural soil acidity and phosphorus leaching risk at farm level in two focus areas

ABSTRACTPoland has the largest agricultural area within the Baltic Sea drainage basin and reducing the risk of phosphorus (P) and nitrogen (N) leaching from Polish soils to water is therefore essential. Increased acidity is known to reduce soil fertility and may trigger P leaching from non-calcareous soils. As part of advisor training, 25 farms each in Pomerania and north-western Mazovia were visited and 1500 ha arable soil, including 180 ha grassland soil, were monitored in 2013–2014. The soil was mainly coarse textured, but 25% of the Pomeranian farms were dominated by silty or clayey soils. More or less regular drainage systems were found on 20% of the farms, while 50% had simpler, older (>30 years) systems with a few single pipes. The farmers often used only ammonium sulphate or other acidifying N mineral fertiliser. Median pH on the Pomeranian farms, analysed in potassium chloride solution [pH(KCl)], was 5.2 and liming was advised for fields on most (72%) of these farms. Soil P content, measured by double-lactate extraction (PDL), was positively and significantly correlated (Pearson coefficient 0.57; p < .001) with soil pH and was generally higher for pig farms. Mean PDL (P given in elemental form) tended to be lower on dairy farms and arable farms and was significantly lower (mean 51 mg PDL kg−1 soil) on mixed farms (with just a few cows and poultry) than on pig farms (mean 122 mg PDL kg−1 soil). Farm-gate balances indicated deficits of P and potassium (K) on many of the small mixed farms in Pomerania and the soil can be expected to be nutrient depleted. In contrast, the pig farms demonstrated surplus farm-gate P balances (mean 27 kg ha−1). The P leaching risk is discussed relative to soil threshold values and to results from Swedish long-term field experiments.

Difference in the pH values of hydromorphic soils in field and laboratory analyses

There are marked differences in the pH values determined in water suspension under laboratory conditions and in soil solution under field conditions in hydromorphic soils (gleysols and stagnosols). The value δpH = pHsusp–pHsol can be either positive or negative. Among the main factors that affect the value of δpH are the laboratory preparation of soil samples and the suspension effect. The sign of the pH effect (value of δpH) depends on the participation of humus, carbonate, and exchange bases in the formation of aggregates destructed in the laboratory. The value of δpH is negative in noncalcareous soils with low content of exchangeable bases and fulvate composition of humus and positive in calcareous soils or soils enriched with exchangeable bases and humate composition of humus. In cases of a significant δpH effect, the value of pHsusp cannot be regarded as an adequate measure of soil acidity.

Dietary mineral supplies in Malawi: spatial and socioeconomic assessment

Dietary mineral deficiencies are widespread globally causing a large disease burden. However, estimates of deficiency prevalence are often only available at national scales or for small population sub-groups with limited relevance for policy makers. This study combines food supply data from the Third Integrated Household Survey of Malawi with locally-generated food crop composition data to derive estimates of dietary mineral supplies and prevalence of inadequate intakes in Malawi. We estimate that >50 % of households in Malawi are at risk of energy, calcium (Ca), selenium (Se) and/or zinc (Zn) deficiencies due to inadequate dietary supplies, but supplies of iron (Fe), copper (Cu) and magnesium (Mg) are adequate for >80 % of households. Adequacy of iodine (I) is contingent on the use of iodised salt with 80 % of rural households living on low-pH soils had inadequate dietary Se supplies compared to 55 % on calcareous soils; concurrent inadequate supplies of Ca, Se and Zn were observed in >80 % of the poorest rural households living in areas with non-calcareous soils. Prevalence of inadequate dietary supplies was greater in rural than urban households for all nutrients except Fe. Interventions to address dietary mineral deficiencies were assessed. For example, an agronomic biofortification strategy could reduce the prevalence of inadequate dietary Se supplies from 82 to 14 % of households living in areas with low-pH soils, including from 95 to 21 % for the poorest subset of those households. If currently-used fertiliser alone were enriched with Se then the prevalence of inadequate supplies would fall from 82 to 57 % with a cost per alleviated case of dietary Se deficiency of ~ US$ 0.36 year−1. Household surveys can provide useful insights into the prevalence and underlying causes of dietary mineral deficiencies, allowing disaggregation by spatial and socioeconomic criteria. Furthermore, impacts of potential interventions can be modelled.

Can earthworms alleviate nutrient disorders of plants subjected to calcium carbonate excess?

Earthworms are recognized to affect soil nutrient cycling with important consequences for plant growth. Nutrient bioavailability is often limited in calcareous soils. Exactly how earthworms can impact availability of nutrients in higher plants grown on calcareous soils still remains an open question. The objectives of this study were to investigate in pot experiments complex nutrient dynamics of interactions between non-calcareous soil and earthworms with special emphasis on the availability of iron (Fe), zinc (Zn), manganese (Mn) and nitrogen (N) to plants (Cucumis sativus L. and Zea mays L.) subjected to calcium carbonate (CaCO3) excess. A combination approach was performed including analysis of nutrient mobility in casts/soil, micronutrient movement via xylem of plants and plant elemental analysis. Addition of CaCO3 (5% DW) significantly lowered the concentrations of Zn and Mn in xylem sap and/or shoot (by 1.8–5.7 times) of both cucumber and maize in comparison with plants that had not received CaCO3. Bioavailability of Fe, however, was not affected by CaCO3 treatment. Beneficial effects of earthworms— endogeic Aporrectodea caliginosa (Savigny) and anecic Lumbricus terrrestris L., for plant nutrient acquisition include an increased mobility of all micronutrients (by 1.3–4.0 times) and N (by 1.5–27 times) in casts or soil either with or without CaCO3 treatment. However, these earthworm species were generally not of major importance in improving Zn and Mn translocation from roots to shoot in cucumber and maize, which was strongly impaired in CaCO3 applied soil. The results clearly demonstrated that earthworm capabilities to alleviate plant Zn and Mn deficiencies induced by CaCO3 applications are limited.