The persistence of 2‐chloro‐6‐(trichloromethyl)‐pyridine in soil

Abstract

The half‐life of 2‐chloro‐6‐(trichloromethyl)‐pyridine in three soils varied from 43 to 77 days at 10 C and from 9 to 16 days at 20 C. The Q₁₀ values were highest in coarse textured soils.     

Influence of nitrapyrin on the evolution of N2O from an organic medium with and without plants

Abstract

Nitrapyrin in the presence of a plant decreased N₂O evolution after a five to six day period of incubation. These findings show that the inhibiting effect of nitrapyrin on the denitrification process is indirect. Evidence is also presented that suggest N₂O evolution is greater in the presence of a plant and thus cropped soils, than from bare soils.     

K‐Fertilization under different Agroecological conditions studied with maize

In Hungary the AL‐method using ammonium lactate acetic acid as extradants has been widely used for serial analysis of soil potassium and phosphorous available to plants in the last 30 y. Because of the considerable increase of the price of fertilizers and decline of the economic situation, there is a pressing need for cost‐effective fertilizer use. Recently this highlighted the importance of nutrient recommendations based on soil analyses. Small plot long‐term field fertilization experiments are the best means to quantify the efFect or the efficiency of K‐fertilization. Long‐term data sets can reveal on which soil type which crop responds most favourably to the different fertilizer doses and nutrient ratios under different, long‐term balanced soil nutrient levels. Since the experimental data of the National Long‐Term Field Trials reflect the agro‐ecological conditions of nine experimental sites representing different soil types of Hungary, these experiments provide excellent opportunity to study this topic. The trials were set up in 1967 with 20 fertilization treatments including three increasing N‐and P‐levels each, two K‐levels and their different combinations. From the experimental data of great number only those of four sites will be shown. Winter wheat, maize, and pea have been grown as test plants. In the experiment selected for presentation, maize had statistically proved responses to K‐fertilization. The efficiency of K‐fertilizer on different soil types shows, however, significant differences, which can not be completely explained with the results of K‐analysis gained with the AL‐method.     

Effect of auxins on the native proteolytic activity of forest soils

The soil proteolytic complex plays an important role within mineral nutrient cycling in ecosystems. Both auxins and proteases are produced by soil microbiota, and reciprocally, their activities affect the metabolic role of biota in soil. The objective of this study was to find out whether auxins (indole‐3‐acetic acid, indole‐3‐butyric acid, 1‐naphthaleneacetic acid and 2‐naphthoxyacetic acid) have a stimulatory or inhibitory effect on the activity of native proteases in soil. The results presented here demonstrate the positive effect of auxins on the native proteolytic forest soil activity. For example, in organic Oe horizons synthetically produced auxins stimulated native proteolytic activity in the European beech stands, where NOA led to the highest increase in L‐tyrosine production (from 564.02 µg at 0 µg auxin to 645.19 µg at the auxin dose of 100 µg). Comparing organic and organomineral horizons, auxins promote a higher stimulation of protease activity in the organic horizons. Comparing the different forest stands, auxins promote a high stimulation of protease activity in European beech stands. In the organomineral soil horizons, auxins promote a high stimulation of protease activity in Leptosols in European beech stands and Cambisols in pedunculate oak stands. The results confirmed the interrelationships between auxins and the native proteolytic forest soil activity from the viewpoint of dead organic matter decomposition. Furthermore, the general importance of substances produced in the rhizosphere for nitrogen cycling was verified.     

Heavy‐metal toxicity in plants 1. A crisis in embryo

Abstract

Heavy metals are often added indiscriminantly to soils in pesticides, fertilizers, manures, sewage sludges, and mine wastes, causing an imbalance in nutrient elements in soils. Heavy‐metal toxicity causes plant stress in various degrees dependent on the tolerance of the plant to a specific heavy metal. The objectives of this study were (i) to show that plant species and soils respond differently to heavy metals and (ii) to show the necessity for proper quantity and balance of heavy metals in soils for plant growth.

Three Fe‐inefficient and three Fe‐efficient selections of soybean, corn, and tomato were grown on two alkaline soils with Cu and Zn ranging from 14 to 340 and Mn from 20 to 480 kg/ha. Heavy‐metal toxicity caused Fe deficiency to develop in these plants. The Fe‐inefficient T3238fer tomato and ys₁/ys₁ corn developed Fe deficiency on all treatments and both soils. T3238FER tomato (Fe‐efficient) did not develop heavy metal toxicity symptoms on any treatment or soil. The soybean varieties and WF9 corn were intermediate in their response.

The unpredictable response of both the soil and the plant to heavy metals make general recommendations difficult. In order to maintain highly productive soils, we need to know what we are adding to soils and the consequences. Without some control, the continued addition of heavy metals to soils is a crisis in embryo.     

Biomass production and N fixation of five Mucuna pruriens varieties and their effect on maize yields in the forest zone of Cameroon

Mucuna has been tested intensively in past years as green manure for intensive maize production in West Africa. However, information is missing about the yield effect of different existing mucuna varieties. Five Mucuna pruriens varieties were grown for 40 weeks followed by sole maize (Zea mays L.) in order to determine differences in biomass production, nitrogen fixation, and effects on maize yield. Mucuna varieties differed in length of growing period, total biomass production (5.9—8.8 Mg ha^—1), seed production (0.65—1.3 Mg ha^—1), nitrogen (N) uptake (147—222 kg ha^—1), N fixation (87—171 kg ha^—1), and the amount of N retained in residues (138—218 kg ha^—1). The grain yield of maize grown immediately after the short mucuna fallow was significantly higher after mucuna vars. jaspaeda (4.60 Mg ha^—1), utilis (3.49 Mg ha^—1), and cochinchinensis (3.44 Mg ha^—1), compared with a non‐fertilized control (1.93 Mg ha^—1) which had a maize crop and vegetation regrowth before. After mucuna vars. ghana and veracruz, 2.90 and 2.65 Mg ha^—1 of maize grain were produced, respectively. No significant correlation between mucuna biomass and its N uptake and maize grain yield was found, whereas maize stover yield showed a significant positive correlation. Application of 30, 60, and 90 kg ha^—1 N as <?tw=98%>urea on sub‐plots of the control yielded 2.20, 3.19, and 3.46 Mg ha^—1 <?tw>of maize grain in the first year. Only the difference between 0 and 90 kg ha^—1 N was significant. Fertilizer N equivalent values for mucuna varieties ranged from 41 to 148 kg ha^—1. The yield advantage of vars. jaspaeda, utilis, and cochinchinensis versus the control without N fertilizer application was confirmed in the following year, with no significant difference in maize grain yield between mucuna and the control with N fertilizer application.<?show $6#>     

The evolution of glucose‐6P‐dehydrogenase and 6P‐gluconate‐dehydrogenase activities and the ortho‐diphenolic content of sunflower leaves cultivated under different boron treatments.

Both enzymatic activities increased under B‐deficient and B‐toxic treatments. The ortho‐diphenolic content did not change with B levels.

Our results suggest that the primary B action on the OPP pathway is at the first enzyme (glucose‐6P‐dehydrogenase) level and that the B effect on 6P‐gluconate‐dehydrogenase is secondary to this. The B action on the enzymatic activities seems not to be caused by any direct interaction with substrates, as B infiltration of B‐deficient culture “in vivo”; seems to result in long term effects on cell structures and/or processes not easily r

In this paper the glucose‐6P‐dehydrogenase and 6P‐gluconate ‐ dehydrogenase activities and ortho‐diphenolic content of hydroponically‐cultivated sunflower‐leaves with moderately deficient, normal and toxic B levels were measured. The change in these parameters during time was considered, together with the restoration of enzymatic activities by means of borate infiltration of deficient and normal leaves. The micronutrient content of the leaves was alsversible by B infiltration of leaves. The positive correlation found between the 6P‐gluconate‐dehydrogenase activity and the Zn content in leaves might be interpretable as and indirect B effect on that activity through modification of Zn content.     

Comparing Different Infiltration Methods of the HEC‐HMS Model: The Case Study of the Mésima Torrent (Southern Italy)

The Hydrologic Engineering Center – Hydrologic Modelling System (HEC‐HMS) model has been widely applied for estimating hydrological variables at event scale. The choice of the most suitable infiltration method simplifies model's applicability under different environmental conditions. A proper case study for evaluating the runoff prediction capability of HEC‐HMS by the available infiltration methods is the semi‐arid torrents typical of Southern Italy as they are small and intermittent water courses, often subject to high‐magnitude flash floods and erosive events. HEC‐HMS performance of the ‘SCS‐CN’, ‘Green‐Ampt’ and ‘Initial and Constant’ infiltration methods in predicting runoff volume and peak flow was evaluated at the outlet of the Mésima torrent, Calabria, Southern Italy. Fourteen rainfall–runoff events were simulated by HEC‐HMS and compared with the corresponding observations by a quantitative approach. A good accuracy in predicting runoff volume was achieved using the ‘SCS‐CN’ method after calibration of the initial curve numbers. Peak flow was better estimated using the ‘Initial and Constant’ method, also thanks to calibration of the ‘constant rate’ parameter. The calibrated hydrographs were very similar to the observations for both ‘SCS‐CN’ and ‘Initial and Constant’ methods. Adopting the ‘Green‐Ampt’ equations, however, showed low reliability. The evaluation of the time to flood peak was in some cases inadequate. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of biochar application on soil potassium dynamics and crop uptake

Biochar has been suggested as a possible means for enhancing soil fertility, including soil potassium (K). However, understanding of the effects of biochar on soil K dynamics remains limited. In this study, a pot trial was conducted to investigate the influence of biochar application (0, 5, 10, and 25 g kg^?1 soil) on soil K dynamics and crop K uptake under a winter wheat–maize rotation in two types of soil (an Alfisol, which contained a high initial available K and an Entisol, which contained a high abundance of 2 : 1 K‐bearing minerals). Changes in soil K in various forms following biochar application and cropping were determined, and their contributions to plant K uptake were evaluated. Soil microbial activity, especially the development of K‐dissolving bacteria (KDB), was evaluated to obtain insights into its effects on the weathering of K‐bearing minerals in the soils. During the wheat growth period, crop K uptake was more enhanced (13.6–40.5% higher) in the Alfisol than in the Entisol due to the higher availability of water‐soluble and exchangeable K, while K fixation occurred in the Entisol because of the higher content of 2 : 1 K‐bearing minerals. During the maize period, crop K uptake was generally higher in the Entisol soil due to the release of non‐exchangeable K. In addition, biochar application enhanced the growth of KDB in both soils, which was associated with changes in soil pH and water‐soluble K. However, improved mineral K release was observed only in the Entisol. It is concluded that biochar application could be a feasible soil amendment to improve soil K availability, but crop K uptake responses may vary depending on soil types. Soils abundant in 2 : 1 K‐bearing minerals tend to prolong biochar effects on crop K uptake. Biochar application enhanced the growth of KDB, which may facilitate mineral K weathering in soils with abundant K‐bearing minerals.     

No‐tillage farming: co‐creation of innovation through network building

This paper studied the development of no‐tillage by combining concepts of co‐creation of knowledge and actor‐network theory. Reconstructing the process of no‐tillage development in Switzerland has made it possible to show that no‐tillage development may be regarded as a dynamic process of co‐creation of innovation, where human and non‐human actors are building networks by reciprocally transforming and translating each other and the relations between them. This conceptualisation reveals that spread of no‐tillage requires fundamental transformations within the network of conventional plough‐tillage agriculture, including institutional arrangements, farm equipment, work organisation, concepts of agriculture and personal and professional identities. Against this background, the limited spread of no‐tillage—despite its economic and ecological advantages—can be explained by the fact that the required transformations are too radical for many agricultural actors. This conceptualisation also implies that policy interventions are not understood as top down measures that intend to induce one‐to‐one direct causal chains between knowledge and action of farmers, but as mediators in a complex process of reciprocal translations between farmers, experts and scientists, as well as many non‐human actors. We conclude that investigating processes of co‐creation of knowledge from the perspective of actor‐network theory is a promising complement to hermeneutic approaches to co‐creation of knowledge such as social learning. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of slow releasing nitrogen fertilizers on nutrient status across wheat rhizosphere grown on volcanic ash

Abstract

The volcanic ash of the Mount Pinatubo in Philippines was used in this study. The major drawbacks of this ash for growing agricultural crops are nitrogen (N) and iron (Fe) deficiencies with low organic matter contents. The main objective of this study is to investigate the wheat grown on the volcanic ash to and determine the nutrient status across its rhizosphere using a rhizobox system. Either oxamide or polyolefinresin‐coated urea (PORCU) along with potash and phosphate fertilizers was applied to each rhizobox containing the volcanic ash. Plants were grown on the central compartment (CC) of the rhizobox. The nutrient status was examined by the assessment of distribution patterns of NH₄ ⁺‐N, NO₃ ^‐‐N, Ca²⁺, Mg²⁺, K⁺, Cl^‐, SO₄ ^2‐, PO₄ ^3‐, and associated pH. Although NH₄ ⁺‐N in both oxamide and PORCU treatments was accumulated to a somewhat considerable extent of the rhizosphere. The rhizosphere effect was more prominent in oxamide treatment. While NO₃ ^‐‐N concentrations in either of the treatment was low with a mere rhizosphere effect in PORCU treatment and a rugged distribution in oxamide treatment. Dominant anions and cations accumulated in the CC and the near by compartments of oxamide treatment were Cl^‐, SO₄ ^2‐ and Ca²⁺, respectively. In contrast, SO₄ ^2‐ and K⁺ were accumulated in the CC and the adjacent PORCU treated compartments. Thus the overall distribution of nutrients and pH across the wheat rhizosphere was rugged. Despite of this, it seems that with a rugged nutrient distribution and pH, the effects of slow releasing N fertilizers may well ensure the N benefit on plants while growing on the volcanic ash under circumstances of low N content.     

Distribution of DTPA‐extractable Fe,Zn, and cu in soil particle‐size fractions

Abstract

To examine the distribution of DTPA‐extractable Fe, Zn, and Cu in clay, silt, and sand fractions; surface soils were collected from cultivated fields of North Dakota, South Dakota, West Virginia, Iowa, Ohio, and Illinois. Clay, silt, and sand fractions were separated after sonic dispersion of soil water suspension and analyzed for DTPA‐extractable Fe, Zn, and Cu. In general, clay had the highest and sand the lowest amount of DTPA‐extractable metals. Consequently, clay had the highest and sand the lowest intensity and capacity factors for these metals since DTPA micronutrient test measures both these factors.     

Effects of temperature on phosphate sorption isotherms and phosphate desorption

Abstract

Phosphorus sorption isotherms were constructed for two Idaho soils with widely different chemical properties. The soils were equilibrated with various amounts of Ca(H₂PO₄)₂ in 0.01 M CaCl₂ for 1, 3, 7, and 11 days at temperatures of 5°C and 20°C. The two soils which had been equilibrated previously for 11 days at 20°C with various amounts of Ca(H₂PO₄)₂ in 0.01 M CaCl₂ were desorbed at 5°C and 20°C.

The rates of sorption and desorption were decreased as the equilibration temperatures were lowered. The effect of temperature on these processes was detected during the first day of equilibration. Less P was found in the equilibrating solution at the lower temperature. The two soils varied widely in sorption and desorption properties.     

Incidence of chocolate spot (Pseudomonas syringae), northern corn leaf blight (Helminthosporium turcicum), and lodging of corn as influenced by soil fertility

Abstract

Applied N and soil test K were negatively correlated with the incidence of Chocolate Spot (CS). Applied N was also negatively correlated with Northern Corn Leaf Blight (NCLB), but no relationship existed between soil test K and this disease. Levels of exchangeable K above 170 lbs/acre essentially eliminated the CS infection. Lodging of corn was positively correlated with applied N and negatively correlated with soil test K. Levels of soil test K above 170 lbs/acre markedly reduced the amount of lodging. Six different hybrids were included in this study. The hybrids showed significant differences in the incidence of the CS disease. Multiple regression equations indicated that corn yield:, were maximized at a level of 160 lbs/acre of applied N and a soil test of approximately 280 lbs/acre of K.     

Dynamics of soil chemical properties in shifting cultivation systems in the tropics: a meta‐analysis

The forest cultivation system (slash‐and‐burn or shifting cultivation) has contributed to the transformation of social systems since the early Neolithic period. Despite being considered by conservationists and public policymakers as a system of low productivity that generates environmental degradation and contributes to the maintenance of rural poverty, the shifting cultivation system (SCS) is being declared a practice that is highly ecologically and economically efficient. Such dichotomy of opinions is the consequence of the disparate results of studies assessing the effects of SCS on soil properties of rainforests throughout the last three decades. To circumvent this apparent inconsistency, we used a systematic quantitative review method (meta‐analysis), with the objective of integrating and synthesizing the data published in the literature to assess the overall effects of SCS on soil chemical properties. Four variables traditionally assessed in primary studies were chosen for the meta‐analyses: pH, cation exchange capacity (CEC), total carbon (Total C) and total nitrogen (Total N). Our results show that pH values increase under SCS conditions, while Total N and C content are significantly reduced under SCS. No significant impacts are observed on CEC. Our results on pH and CEC support the position from researchers who argue for the sustainability of SCS and highlight the importance of evaluating the soil system as a soil/vegetation complex. Also, our results indicate that soil chemical properties under SCS scenarios are better conserved and more readily recoverable, provided there is a rather longer fallow period than has been traditionally employed.     

Behavior of iron‐supplying materials in incubated calcareous soils 1

Two Fe chlorosis‐inducing calcareous soils were incubated for up to 5 months, at room temperature and field capacity, with Fe‐EDDHA, Fe‐DTPA, FeSO₄, an amino acid chelate “Fe‐Metalosate”;, an oxide “Micronized‐Iron”;, and a precipitated Fe‐S compound “Iron‐Sul”;. Other treatments included DTPA chelate alone, elemental S and H₂SO₄ at comparable rates. Both water‐soluble, and DTPA‐extractable Fe fractions were measured periodically from each sample. All water‐soluble sources decreased with time. Soluble Fe was highest after Fe‐EDDHA addition but was not detectable after “Fe‐Metalosate”; and FeSO₄. Acidification to neutralize CaCO₃ significantly increased DTPA‐extractable Fe, which remained high with increasing incubation time. “Micronized‐Iron”; and S had only a slight effect on DTPA‐ extractable Fe. Though Fe‐EDDHA is the most efficient Fe material, pelleted acidified Fe sources, i.e., “Iron‐Sul”;, may be more economical for some crops in the long term.     

Cadmium‐induced oxidative stress and protection by L‐Galactono‐1, 4‐lactone in winter wheat (Triticum aestivum L.)

Two hydroponic culture experiments were conducted to investigate cadmium (Cd)‐induced oxidative stress in winter wheat (Triticum aestivum L.) seedlings and the effects of L‐Galactono‐1, 4‐lactone (GalL), the biosynthetic precursor of the antioxidant ascorbate (AsA), on the oxidative stress induced by Cd. In experiment 1, with application of Cd (0, 10, 25, 50 µM) in nutrient solution, hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) levels as well as membrane permeability in both shoots and roots were significantly increased, indicating Cd‐induced oxidative stress and lipid peroxidation as well as plasma‐membrane damage in the plants. In experiment 2, H₂O₂ levels in plants exposed to Cd were significantly reduced by the addition of GalL (25 mM), associated with increased activities of peroxidase (POD), indicating that GalL alleviated the oxidative stress induced by Cd. Unexpectedly, however, the MDA levels were not reduced by the addition of GalL. Does Cd also induce lipid peroxidation directly besides via formation of reactive oxygen species (ROS)? This needs further study.     

Iron‐Binding Properties of TTf,a Salt‐Induced Transferrin from the Alga Dunaliella salina

Abstract

Iron deficiency induces accumulation of a transferrin‐like protein, TTf, in plasma membranes of the halotolerant alga Dunaliella salina. In vivo iron binding and uptake studies provided evidence for the role of TTf in iron acquisition in Dunaliella. In this report, we characterized the iron binding activity of solubilized TTf, purified from plasma membrane vesicles of iron‐starved cells. The characteristics of iron binding to TTf generally resembled those of animal transferrins (Tfs) in an obligatory requirement for bicarbonate as a co‐ligand, specificity for ferric ions and pH dependence of both binding and release. Unlike animal Tfs, Fe binding activity of TTf was stimulated by high NaCl concentrations. The stimulation was not associated with changes in Fe binding affinity. The results unequivocally confirm the role of TTf in Fe binding and uptake in Dunaliella and demonstrate its uniqueness as a membrane‐associated, salt‐stimulated transferrin.     

Plant‐available nitrogen in the soil: Relationships between pre‐plant and pre‐sidedress nitrate tests for corn production

Corn (Zea mays L.) producers in the rainfed regions sometimes sidedress fertilizer N according to pre‐plant–nitrate test (PPNT) results based on the assumption that there is a linear relationship between pre‐sidedress nitrate test (PSNT) and the PPNT. There has been no report on such relationship in Ontario (Canada) and elsewhere in the nonirrigated corn‐growing regions. A field study was conducted near Ottawa, Canada for 7 y to (1) determine changes in soil available N from pre‐planting to shortly after the sidedress stage (late June) for corn and (2) establish a quantitative relationship between PPNT and PSNT. In each year, soil samples from fields of three to four plot experiments with different cropping histories, soil textures, and management levels, taken at 7 to 10 d intervals, and from on‐farm trials taken at pre‐planting and pre‐sidedress, were extracted with 2 M KCl. The concentrations of NO ‐N were determined colorimetrically. It was found that soil NO ‐N concentration of PSNT was a linear function of PPNT with an average slope of 1.7. However, the slope of the regression equations differed dramatically among cropping sequences, and to a lesser extent, soil textures. The NO ‐N concentration after planting to pre‐sidedress was influenced by air temperature and precipitation during this period of time. Both PPNT and PSNT positively correlated with corn‐grain yield. Our data suggest that cautions must be taken when deciding the rate of fertilizer N for sidedress application to corn based on PPNT test, especially under more humid northern climate conditions.