The properties and genesis of “Tora-Han” (tiger-like) soil on the high terrace,North of Akashi City

On the high terrace to the north of Akashi City, Sanyo District. th ere is a heavy text ured soil which is charac te rized by the presence of altern ate red and gray bands in lower hor izons (photo.) . This soil is called "Tora-han" Soil as a local name by reason of its morph ological resemblance to “tora” (tiger^*). Heavy textured soils which have tiger-like (or zebra-like) mot tlings in lower hor izons are also found in other parts of Japan alm ost excl usively on high ter races , and hav e long attracted th e attent ion of Japanese pedologists.     

Physico – biochemical properties of tomato (Solanum lycopersicum) grown in heavy – metal contaminated soil

The present study was undertaken to investigate the effect of soil contamination with heavy metals on physico-biochemical properties of tomato fruit. The deleterious effect of soil contamination on the quality and quantity of tomato plant yield was determined. Harvested tomato fruit characteristics including fruit length, diameter, volume and fresh and dry weights, total soluble solids, titratable acidity, lycopene and carbohydrates contents were measured in tomato fruits cultivated in soil contaminated with industrial effluents. In addition, some secondary metabolites (total phenols and flavonoids), micro- and macronutrients were also detected. Residual heavy metals (Cd, Co, Ni and Pb) were examined in the harvested fruits. The obtained results were compared with those of tomato fruits cultivated in non-contaminated soil. Results demonstrate that soil contamination with heavy metals have a negative effect on tomato fruits characteristics, titratable acidity, total soluble solids, lycopene, ascorbic acid, micro-elements and carbohydrates content. Moreover, fruits originated from plants grown in contaminated soil possess high phenols and flavonoids contents and higher heavy metals content compared to control fruits. It is recommended that fruits cultivated in that area not to be eaten by large quantities, to avoid excessive accumulation of heavy metals in the human body.

Abbreviations: (AsA): Ascorbic acid; (DTPA): diethylenetriamine penta acetic acid; (TA): Titratable acidity; (TSS): Total soluble solids     

The effect of biochar addition on N2O and CO2 emissions from a sandy loam soil – The role of soil aeration

Biochar application to soil has significant potential as a climate change mitigation strategy, due to its recalcitrant C content and observed effect to suppress soil greenhouse gas emissions such as nitrous oxide (N₂O). Increased soil aeration following biochar amendment may contribute to this suppression.Soil cores from a Miscanthus X. giganteus plantation were amended with hardwood biochar at a rate of 2% dry soil weight (22 t ha⁻¹). The cores were incubated at three different temperatures (4, 10 and 16 °C) for 126 days, maintained field moist and half subjected to periodic wetting events. Cumulative N₂O production was consistently suppressed by at least 49% with biochar amendment within 48 h of wetting at 10 and 16 °C. We concluded that hardwood biochar suppressed soil N₂O emissions following wetting at a range of field-relevant temperatures over four months. We hypothesised that this was due to biochar increasing soil aeration at relatively high moisture contents by increasing the water holding capacity (WHC) of the soil; however, this hypothesis was rejected.We found that 5% and 10% biochar amendment increased soil WHC. Also, 10% biochar amendment decreased bulk density of the soil. Sealed incubations were performed with biochar added at 0–10 % of dry soil weight and wetted to a uniform 87% WHC (78% WFPS). Cumulative N₂O production within 60 h of wetting was 19, 19, 73 and 98% lower than the biochar-free control in the 1, 2, 5 and 10% biochar treatments respectively. We conclude that high levels of biochar amendment may change soil physical properties, but that the enhancement of soil aeration by biochar incorporation makes only a minimal contribution to the suppression of N₂O emissions from a sandy loam soil. We suggest that microbial or physical immobilisation of NO₃⁻ in soil following biochar addition may significantly contribute to the suppression of soil N₂O emissions.     

Twelve‐year tillage and crop rotation effects on yields and soil chemical properties in northeast Iowa

Abstract

Long‐term tillage and crop management studies may be useful for determining crop production practices that are conducive to securing a sustainable agriculture. Objectives of this field study were to evaluate the combined effects of crop rotation and tillage practices on yield and changes in soil chemical properties after 12 years of research on the Clyde‐Kenyon‐Floyd soil association in northeastern Iowa. Continuous corn (Zea mays L.) and a corn‐soybean [Glycine max L. (Herr.)] rotation were grown using moldboard plowing, chisel plowing, ridge‐tillage, or no‐tillage methods. Tillage and crop rotation effects on soil pH, Bray P1, 1M NH₄OAc exchangeable K, Ca, and Mg, total C, and total N in the top 200 mm were evaluated. Profile NO₃‐N concentrations were also measured in spring and autumn of 1988. Crop yields and N use efficiencies were used to assess sustainability. Bray P1 levels increased, but exchangeable K decreased for all cropping and tillage methods. Nutrient stratification was evident for no‐tillage and ridge‐tillage methods, while the moldboard plowing treatment had the most uniform soil test levels within the 200 mm management zone. Chisel plowing incorporated fertilizer to a depth of 100 mm. Soil pH was lower with continuous corn than with crop rotation because of greater and more frequent N applications. Profile NO₃‐N concentrations were significantly different for sampling depth and among tillage methods in spring 1988. In autumn the concentrations were significantly different for sampling depth and for a rotation by tillage interaction. Estimated N use efficiencies were 40 and 50 kg grain per kg N for continuous corn, and 48 and 69 kg grain per kg N for rotated corn in 1988 and 1989, respectively. The results suggest that P fertilizer rates can be reduced, but K rates should probably be increased to maintain soil‐test levels for this soil association. Crop rotation and reduced tillage methods such as ridge‐tillage or chisel plowing appear to meet the criteria for sustainable agriculture on these soils.     

Changes in nitrogen and phosphorus concentrations of silicon‐fertilized rice grown on organic soil 1

Rice grown on the organic soils of the Everglades is routinely fertilized with silicon (Si). The objective of this research was to investigate changes in nitrogen (N) and phosphorus (P) concentration in various plant parts in response to Si fertilization. Two cultivars were grown in lysimeters filled with low‐Si soil. Half the lysimeters were fertilized with calcium silicate to provide 2Mg Si ha^‐1 and the other lysimeters remained unfertilized as a control. Nitrogen concentration decreased in all plant parts with Si fertilization. Phosphorus concentration increased with Si. Maturity was earlier in the Si fertilized rice.     

Effect of extractable zinc,phosphorus, and soil ph on zinc concentrations in leaves of field‐grown corn

Abstract

The variability in corn yield responses to applications of Zn fertilizer appears to be associated with several complex soil and climatic factors that affect the availability of endogenous soil Zn to the crop under specific conditions. Among the soil chemical properties that influence availability of endogenous Zn are soil pH, organic matter content, and extractable P. Over a period of several years, soil and plant analysis data were collected from 54 field experiments, field trials, and diagnostic visits to producer's fields. These data were subjected to multiple regression analysis, resulting in an equation: Zn_leaf = 37.14 + 1.513 Zn_st ‐4.04 pH_st ‐ 1.791 ln(P_st/100) where Zn_st, pH_st, and P_st were 0.1N HC1 extractable soil Zn (kg/ha), 1:1 soil‐water pH, and Bray's 1 extractable soil P (kg/ha), respectively. These factors accounted for 67% of variation in leaf Zn, which was a large portion of the variability in Zn_leaf considering that climatic conditions, management levels, and varietal differences were uncontrolled in most instances. Using the previously published critical level in the leaf opposite and below the ear as 17 μg Zn/g, these data can be used to set required soil test levels of Zn at different levels of extractable P and soil pH. Inadequate levels of extractable Zn would range from 2.5 (at pH 6.0, P = 70 kg/ha) to, 9.5 kg/ha (at pH 7.5, P = 420 kg/ha).     

Application of soil amendments to contaminated soils for heavy metal immobilization and improved soil quality—a critical review

ABSTRACT

Today, soil metal pollution has become a significant environmental issue of great public concern. This is because soil is both a major sink for heavy metal(loid)s (HMs) released into the environment, by both pedogenic and anthropogenic activities; and also a major source of food chain contamination mainly through plant uptake and animal transfer. In addition, HM contamination of soil leads to negative impacts on soil characteristics and function by disturbing both soil biological and physiochemical properties (e.g. extreme soil pH, poor soil structure and soil fertility and lack of soil microbial activity). This eventually leads to decreased crop production. Various soil remediation techniques have been successfully employed to reduce the risks associated with HMs efflux into soil. Among these, the use of low-cost and environmentally safe inorganic and organic amendments for the in-situ immobilization of HMs has become increasingly popular. Immobilization agents have successfully reduced the availability of metal ions through a variety of adsorption, complexation, precipitation, and redox reactions. Soil amendments can also be a source of nutrients and thus can also act as a soil conditioner, improving the soil’s physiochemical properties and fertility, resulting in enhanced plant establishment in metal contaminated soils. This article critically reviews the use of immobilizing agents in HM contaminated agricultural and mining soils paying particular attention to metal immobilization chemistry and the effects of soil amendments on common soil quality parameters.     

Integrated effect of potassium humate and α-tocopherol applications on soil characteristics and performance of Phaseolus vulgaris plants grown on a saline soil

Soil salinity is one of the major problems of agriculture that limits plant performance, particularly in arid and semiarid regions. Therefore, the effect of potassium humate (KH) and α-tocopherol (TOC), used singly or in integration, on soil characteristics, and on plant performance, physio-biochemical attributes and antioxidative defense system of Phaseolus vulgaris L. plants grown under salt stress (EC = 6.35–6.42 dS m^?1) was investigated. Half g KH kg^?1 soil was used as soil amendment before sowing and 1.0 mM TOC was used as foliar spray twice; at 25 and 40 days after sowing. Results showed that, KH significantly improved soil physical and chemical properties, which positively reflected on plant growth and productivity, physio-biochemical attributes, mineral nutrients (N, P, K and Ca), osmoprotectants (soluble sugars and proline), non-enzymatic (ascorbic acid, glutathione and TOC) and enzymatic (superoxide dismutase, catalase and guaiacol peroxidase (GPOX)) antioxidants compared to untreated controls. The single TOC foliar application recorded the same positive results of KH. Integrated KH + TOC treatment was most effective compared to the single treatments. The above results recommended benefits of this integrated KH + TOC for the possibility of sustainable agronomic performance of common beans grown on saline soils.     

The effect of soil ph on the activity of oryzalin and metribuzin on five common weeds in no‐till crop production

Abstract

Metribuzin [4‐amino‐6‐tert‐buty1–3‐(methylthio)‐as‐triazine‐5(4H)‐one] and oryzalin (3,5‐dinitro‐N ⁴ N ⁴‐dipropylsufanilamide) at two rates each were applied to pots of Cecil sandy loam soil adjusted to pH levels of 5.8, 6.2, 6.8, and 7.2 containing five weed species. Redroot pigweed (Amaranthus retroflexus L.) and large crabgrass [Digitaria sanguinalis (L.) Scop.] were completely controlled by both herbicides at all rates and all pH levels. Sicklepod (Cassia obtusifolia L.) was controlled by metribuzin, but not completely, by oryzalin. Jimsonweed (Datura stramonium L.) and tall morningglory [Ipomoea purpurea (L.) Roth] were not controlled by either herbicide. Soil pH had no effect on jimsonweed control with either herbicide. Morningglory was best controlled by both herbicides at higher soil pH.     

Effects of compost amended lead–arsenate contaminated soils on total and inorganic arsenic concentrations in rice

Rice (Oryza sativa L.), a staple crop for over 50% of the world's population, is also a source of dietary arsenic (As) because of it's efficiencyat accumulating As. Lead–arsenate pesticide was used in agriculture, these soils potentially may be used for rice production. The objective of this study was to determine the effects of compost on total and inorganic As concentrations in rice grown on lead–arsenate contaminated soils. Three lead–arsenatesoils were amended with 10% by weight of compost and planted with rice under flooded and non-flooded conditions. Rice grain yieldwas higher with compost but not flooding. Flooding significantly increased total and inorganic As concentrations. In most cases, rice inorganic Asconcentrations were higher than the limit set by Chinaat 0.2 mg kg^?1. Compost at therate used did not reduce rice grain As to safe levels.Lead–arsenate contaminated soils are not recommended for rice production.     

The influence of brine contamination and phospho‐gypsum amendments on soil chemical properties and plant response

Abstract

Phosphogypsum (PG), the by‐product of wet acid production of phosphoric acid from rock phosphate, was found to be effective as a soil conditioner for sodic, solonets, and solonetzic soils. Unlike mine gypsum, PG contains impurities whose release into soil and ground water need to be monitored. PG was incorporated with soils contaminated with oilfield brine to determinate the influence of PG amendments and brine contamination on soil chemical properties and plant response in a growth chamber. Application rates of PG were 0, 25, 50, 100, 200, and 400 Mg ha^‐1 and the testing crop was Barley (Hardeum vulgare L.). Phosphogypsum provides a means of remediating brine spills and can result in benefits expressed as increased plant growth. Soil salinity of brine contaminated soils was ameliorated as evidenced by reduced the electrical conductivity, SAR and exchangeable Na levels in 0–15 cm depth of the columns. There is no evidence that application of PG increased the level of trace elements in plants. Contamination of soil with brine spill is the major factor dominating plant growth and soil‐plant element content. From plant growth point of view, two elements could be excessive, namely Boron (B), and Cadmium (Cd). The high level of B in the plant arose from brine spill and the cause for the excessive Cd level in barley grain is unknown and currently under investigation. The distribution of trace elements in soil profiles demonstrated that there was little, if any, potential for movement of trace elements into greater depths.     

Interactions of gamma‐irradiated sewage,nitrogen and phosphorus for Sorghum on a calcareous soil

Abstract

The interaction of gamma‐irradiated sewage sludge, nitrogen and phosphorus fertilizers on dry matter production, phosphorus concentration and phosphorus uptake of sorghum was examined. Three crops of sorghum were grown in the greenhouse in 19 1 plastic buckets. The phosphorus and sludge treatments were applied at the initiation of the experiment only. Nitrogen was applied to the corresponding nitrogen treatment pots before each of the three croppings.

There was a significant nitrogen x sewage interaction for dry matter production, phosphorus concentration and phosphorus uptake in each harvest. There was a significant phosphorus sewage sludge interaction in the first harvest for phosphorus uptake. All other possible interactions were not statistically significant. The 67 metric ton/ha sludge rate produced nearly the same yield as the nitrogen treatment. In the first harvest, sludge significantly increased plant phosphorus uptake from the fertilizer phosphorus. The phosphorus uptake in sorghum from 472 and 944 kg P/ha from the sludge treatments was comparable to that from 1299 and 2598 kg P/ha from triple superphosphate.     

Negligible effect of X-ray μ-CT scanning on archaea and bacteria in an agricultural soil

X-ray Microfocused Computed Tomography (X-ray μ-CT) allows a non-destructive and three-dimensional observation of microbial habitats (i.e. pore space) in soil. A major premise for microbiological studies integrating X-ray μ-CT is that soil microorganisms are not affected by irradiation dose in terms of physiology and composition. However, the compatibility of X-ray μ-CT and soil biological experiments has been evaluated controversially.We performed an incubation experiment with packed microcosms to assess the effect of X-ray μ-CT on native microbial populations with emphasis on soil archaea and bacteria. Before (14 days) and after (1 and 14 days) scanning we analyzed (i) respiration, (ii) enzyme activity, (iii) microbial biomass, (iv) abundance and (v) community structure in scanned and control treatments.None of the microbial parameters exhibited significant differences among scanned and unscanned soil samples at all sampling times with the exception of lower archaeal cell numbers subsequent to X-ray μ-CT. Incubation time was the main factor that induced a significant alteration of microbial soil populations while irradiation had no or only very little effect thereupon. Taken together, three-dimensional in situ data obtained via X-ray μ-CT may well be combined with microbiological analyses in soil.     

Effects of pasture‐applied biosolids on forage and soil concentrations over a grazing season in north Florida. I. macrominerals,crude protein,and in vitro digestibility

Abstract

The rationale for this experiment was to determine forage nutrient concentrations as affected by biosolids fertilization. We studied the effects of single applications of two exceptional quality biosolids to bahiagrass (Paspalum notatum) pasture with regard to satisfying beef cattle nutrient requirements. Twenty‐five 0.8‐ha pastures were divided into five blocks. Two biosolids were applied as normal and double agronomic rates. The control plot received NH₄NO₃. Forages were analyzed for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), sodium (Na), crude protein (CP), and in vitro organic matter digestibility (IVOMD), and soils were analyzed for Mehlich I extractable Ca, P, Mg, and K. Single (agronomic or twice this) applications of biosolids to pastures had little effect on Ca, P, Na, and K forage concentrations, but forage Mg was elevated in several treatments late in the season. Crude protein concentrations were elevated above the control for all biosolids treatments late in the season, whereas only small differences were observed at early sampling times. Trends were similar for IVOMD. In general, all treatments were associated with soils with adequate Ca, P, and Mg concentrations, while soil K was uniformly low. In relation to grazing beef cattle requirements, all treatments resulted in generally adequate forage levels of Ca, P, Mg, K, CP, and IVOMD, however, Na (<0.06%) was deficient.     

The effect of water and acid‐washing soil treatment on the measurement of pH,delta pH and zero point of charge in some variable charge soils

Abstract

This study was undertaken to determine the effect of previous water and acid‐washing soil treatment on soil pH, Delta pH and Zero Point of Charge of soil surface samples of three Hawaii soils, Molokai (Typic Torrox), Wahiawa (Tropeptic Eutrustox), and Hilo (Typic Hydrandept).

The acid‐washing treatment lowered the soil pH and shifted the Zero Point of Charge to lower pH values. The effect was greater in the Wahiawa and Molokai soils that are dominated by oxidic materials. Whereas the acid‐washing treatment did not change the magnitude of the negative charge in the Wahiawa and Molokai soils, it overestimated the magnitude of the positive charge in the Hilo soil. This phenomena probably was enhanced by the dominance of variable charge clay minerals in the Hilo soil. The results indicated that the acid‐washing treatment changed the nature of the charge characteristics of the soils, hence it should not be recommended in the characterization of the net charge in variable charge soils.     

Influence of poultry manure–derived biochars on nutrients bioavailability and chemical properties of a calcareous soil

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- and B200-treated soils compared to other treatments. It was concluded that biochar prepared at 300°C had the highest positive effect on nutrients availability and lasts longer in calcareous soil compared to the other produced biochars and PM.     

The effects of biocidal treatments on metabolism in soil—V: A method for measuring soil biomass

A new method for the determination of biomass in soil is described. Soil is fumigated with CHCl₃ vapour, the CHCl₃ removed and the soil then incubated. The biomass is calculated from the difference between the amounts of CO₂ evolved during incubation by fumigated and unfumigated soil. The method was tested on a set of nine soils from long-term field experiments. The amounts of biomass C ha^?1 in the top 23 cm of soil from plots on the Broadbalk continuous wheat experiment were 530 kg (unmanured plot), 590 (plot receiving inorganic fertilizers) and 1160 (plot receiving farmyard manure). Soils that had been fallowed for 1 year contained less biomass than soils carrying a crop. A calcareous woodland soil contained 1960 kg biomass C ha^?1, and an unmanured soil under permanent grass 2020. The arable soils contained about 2% of their organic C in the biomass; uncultivated soils a little more—about 3%.     

Effect of mulch rates and tillage systems on infiltrability and other soil physical properties of an Oxisol in Paraná, Brazil

A 7-year-old tillage trial, comprising conventional tillage (CT), minimum tillage (MT) and no-tillage (NT), was chosen to study the relative importance of controlled mulch rates and soil physical properties such as bulk density, pore volume and hydraulic conductivity upon infiltrability. Infiltration measurements were carried out with a portable rainfall simulator. Mulch consisted of soya bean residues.Soil physical analysis showed higher bulk densities in the top 20 cm under NT, whereas CT, and to a lesser extent MT, led to the development of a plough pan in 20–30 cm depth. At the same time, compaction brought about a decrease in macropores and an increase in micropores. Total porosity ranged between 56.6% and 66.4%. Hydraulic conductivity did not differ significantly between tillage systems, and overall conductivity values were very high.The main factor influencing infiltrability was the formation of a surface seal depending on the degree of soil cover by mulch, irrespective of tillage system. For all 3 tillage systems, a 100% soil cover led to the complete infiltration of a 60-mm rainfall, whereas only 20% of the applied rain infiltrated when the soil was bare and the surface completely sealed. Plant residues of 4–6 t ha⁻¹ are proposed, as the minimum amount of mulch needed to reduce runoff and erosion effectively.