Properties Of Calcareous Soil Research Articles

Physical and mechanical properties of calcareous soils: A review

Calcareous soil is widely distributed throughout tropical areas. Due to its unique sedimentary environment and soil behaviors, severe engineering problems and disasters have occurred in many regions. To understand the differences in the mechanical properties of calcareous soils in different regions, material composition, physical and mechanical properties of calcareous soils, including specific gravity and void ratio, compression properties, shear properties, and strength properties, were analyzed. The relationship between the sedimentary environment, material composition, and mechanical properties of calcareous soil was examined based upon the results. Results show that the calcareous soil in the South China Sea has a high calcium carbonate content, large particle size, high compressibility, and low bearing capacity, while sand from the Kish Island in the Persian Gulf and Agami sand from Egypt have low compressibility and high bearing capacity. In the South China Sea, Calcareous soil is more difficult to crush than those from the Hormuz Island and Bushehr Port in the Persian Gulf, Dog’s Bay in Ireland, and Quiou in France. Overall, calcareous soils from various locations exhibit significant differences in properties based upon their physical traits. It is suggested that the influence of sedimentary environment and geological conditions should be considered in engineering constructions.

Fate of Citric Acid Addition on Mineral Elements Availability in Calcareous Soils of Jordan Valley

The variation in physical and chemical properties of calcareous soils in Jordan valley has been changed dramatically due to use large amount of fertilizers in regular manner. Addition of organic acid such as citric acid (CA), can greatly change the pH which can affects plant growth and production, the weakly ionized organic acid present in the calcareous soil mostly in the form of organic matter, can play major rule in soils to raise the availability of mineral nutrients that are essential for crops, by lowering soil density, reducing soil salinity and the effects of suspended particles in soil which may hinder plant growth.
 The reduction in the pH of the soil enhance the availability of nutrients such as Fe, Cu, Zn, ions, by converting the metallic insoluble state to ionic form, and thus nutrients are easily available for plants intake, the salinity of the soil did not change by increasing the citric acid concentration, while the pH of the soil decreases.
 Data are presented to show the effects of citric acid (CA) concentration, ionic concentration of iron, copper, Zinc and manganese and the decrease in soil PH and soil density.

Effect of Adding Dilute Sulphuric Acid on Calcareous Soil Properties in Jordan Valley

Calcareous soil that contains enough free calcium carbonate to effervesce visibly, releasing carbon-dioxide gas, when treated with diluted sulfuric acid. Analysis of calcareous soil in Jordan valley after treatment with aqueous low concentration sulfuric acid shows some change in the physical prosperities of the soil such as reduction of calcium carbonate from 66% to 30%, soil density from 1.60 g/cm3 to 1.19 g/cm3 . Soil texture is convert from silt clay loam to silt loam this physical changing makes soil permeability is easier so it could be suitable for agricultural without effect in plant growth also we show reduce soil PH and increasing in soil filtration tare. We showed several changes in the plants, which planted in the treated soil by sulfuric acid as increasing in the product from 10 - 25 %, would reduce in using chemical fertilizers from 15-30% and absence of soil diseases.

Biological reclamation of a calcareous sandy soil with improving wheat growth using farmyard manure, acid producing bacteria and yeast

Two pot experiments were performed in the Experimental Farm, Soils and Water Department, South Valley University, Qena, Egypt during two successive winter seasons (2018/2019 and 2019/2020). The main objective is to evaluate the effect of four addition levels of farmyard manure (FYM) (0, 10, 20 and 30 g/Kg of soil) combined with acid producing bacteria (APB) + molasses, yeast + molasses or their mixture on improving the chemical properties of a calcareous sandy soils and enhancing wheat growth. The results showed that, the results showed that with the increasing added level of FYM the soil pH and CaCO3 content were decreased and the soil EC, OM, total N and available P and K were increased. In addition, plant dry matter, N, P and K uptakes and use efficiencies were increased. Also, the application of APB + molasses, yeast+ molasses or their mixture with (FYM) were more effective than adding FYM alone in the improvement of calcareous soil properties and enhancement of wheat growth. It could be concluded that the best treatment in improving the calcareous sandy soil properties and increasing wheat growth, nutrients uptake and use efficiencies was the treatment of FYM with APB + yeast+ molasses especially when FYM was applied ate level 30 g/kg soil.

Improving Chemical and Microbial Properties of Calcareous Soil and its Productivity of Faba Bean (Vicia faba L.) Plants by using Compost Tea Enriched with Humic Acid and Azolla

This study evaluated the effect of compost teas enriched with humic acid and/or azolla on soil chemical and microbial properties as well as on yield and plant measurements of faba bean (Vicia faba L. c.v. 843) plants. A field experiment was carried out on calcareous soil of El Nobaria area, El-Beheira Governorate, Egypt during grown winter season of 2018/2019. The four compost teas treatments were: without any supplemental (NECT), enriched with humic acid (ECTH), enriched with azolla extract (ECTAz) and enriched with humic acid and azolla extract (ECTHAz). All treatments were applied to calcareous soils at two different rates (120 and 240 L.ha-1), through drip irrigation system. At 50 day of planting, nodules number, dehydrogenase activity (DHA) as well as fresh and dry weights of shoots were determined. Also, at harvest stage, straw and seeds yields of faba bean and soil chemical properties (pH, EC, CEC, CaCO3 and OM) and its content of macro-micronutrients (N, P, K, Fe, Mn, Zn and Cu) were determined. Generally, in most of the studied attributes in soil or plants, the greater effect was found with the treatment of ECTH, ECTAz and/or ECTHAz treatments. There is a superior increase effect of enriched compost teas (ECTH, ECTAz, ECTHAz) on nodules numbers, DHA, straw and seeds yield of faba bean plants compared to these of NECT and control treatments. The treatments of enriched compost teas significantly increased the seeds macro-micronutrients content compared to control. Also, enriched compost teas applications improved soil chemical and microbial properties and its content of available macro and micronutrients than those found with NECT treatments. Compost tea especially that enriched with humic acid and azolla extract can be used to improve calcareous soil and its productivity of faba bean plant.

Integrated use of bio-organic fertilizers for enhancing soil fertility–plant nutrition, germination status and initial growth of corn (Zea Mays L.)

Abstract The need for cheap and affordable alternate sources of plant nutrient inputs to boost the nutrient level of degraded arable farmlands has been a major concern for soil scientists, agronomists, and local farmers. In 2018, a greenhouse and laboratory pot experiment was carried out under control conditions for 21 weeks to evaluate the effect of plant growth-promoting rhizobacteria (Azospirillium brasilense), spent grain (SG) organic wastes from the beer industry, and chemical fertilizer (CF) on the soil fertility–plant nutrition, corn (Zea Mays L.) germination rate in calcareous soil. The treatments consisted of CK (control), SG (spent grain, 20 g kg−1 soil), Az (Azospirillium seed inoculation), CF (100% of NPK recommended fertilizers), bio-organic (Az with SG), bio-mineral (Az with CF), and organo-mineral (50% of SG +50% of CF). These treatments were arranged in a randomized complete block design and replicated three times. Results showed that after 10 and 21 weeks, SG application significantly increased soil organic carbon by 69% and 67.8%, total nitrogen (TN) by 87.66% and 85.44%, and raised available P (P) by 75.7% and 87.23%, respectively. The final germination percentage (FGP), germination index (GI), coefficient of velocity of germination (CVG) and plant height were significantly higher in the amended pots than that of the control pots after 21 days of planting. The SG with Az treatments had the highest GI, CVG, and FGP of 9.23, 0.19 day−1, and 100 %, respectively, while the least values were obtained in the CF 2.37, 0.12 day−1, and 61.6%, respectively. The highest values of N/P ratio, available Fe2＋, Zn 2 + , and Mn 2 + were 401, 20.35 mg kg−1, 7.27 mg kg−1, and 16.58 mg kg−1 respectively, as well as bio-fertilizers enhanced the dehydrogenase and urease enzymes by 1117.3 μ g TPF ml−1, and 275.4 mg NH 3 − Hg−1h−1 respectively, after 21 weeks of seed sowing. The final results among all treatments were in the order of SG > Bio-organic > Az > Organo-mineral > Bio-mineral > CF > CK. In conclusion, the application of SG and Az is recommended to improve TN and P use efficiencies, micro-nutrients uptake, plant seed germination performance of maize, and enhancement of calcareous soil properties.

Temporal changes of calcareous soil properties and their effects on cadmium uptake by wheat under wastewater irrigation for over 50 years

Calcareous soil has a strong buffering capacity for neutralizing acid and stabilizing cadmium (Cd) because of the high calcium carbonate (CaCO3) content. However, it is not clear whether the buffering capacity of calcareous soil can be maintained after long-term wastewater irrigation. We selected a typical area in western China that has been irrigated with wastewater for over 50 years to study the temporal changes of soil properties and their effects on Cd uptake by wheat. The results showed that compared with the background level before the 1960s, the soil pH and CaCO3 content in 2018 were lower by 0.80 units and 35%, respectively, while the soil organic matter (SOM) content, Olsen phosphorus (P) content, and soil total Cd content in 2018 increased by 1.54, 13.05, and 164 times, respectively. Due to the significant decrease in the soil pH and CaCO3, the high load of soil total Cd and electrical conductivity, the low soil clay content, and the coupling of SOM with soil nitrogen and P, the input Cd was activated. Furthermore, the activated Cd was effectively taken up by wheat roots and transported to grains with the assistance of dissolved organic carbon. Our results highlight that long-term wastewater irrigation caused irreversible damage to soil buffering capacity, resulting in the Cd activation and the enhancement of Cd uptake by wheat.

Water and soil management for Drought Rice

Rice is an economically important and widely consumed cereal that achieves high yields under submerged condition. Moreover, due to degradation in physical properties of calcareous soils it is difficult to apply flood irrigation for sowing rice crop. So, the soil and water management is favorites. Whether, Draught rice with different levels of organic manure and water depletion used to achieve this target. The obtained results revealed that increasing organic addition (sheep dung) increased soil heat capacity and air permeability by 23.7% and 65% respectively, and decreased soil impedance by 21%. Whilst, increasing moisture depletion raised soil impedance and air permeability by 2.5 and 6.8% respectively while the feeble effect was for heat capacity (0.05%). When the two factors coupled together gave the major effects on previous properties. Also, roots weight increased by increasing soil heat capacity and air permeability and by decreasing soil impedance. Moreover, improving root growth and soil organic matter resulted in increasing rice cereal and straw yield while moisture depletion show a negative significant relation with cereal and negative non significant relation with straw, but when coupled with other factors it show a highly significant relation. Water consumption increase by increasing plant livetime and moisture depletion by144% (181.27m3) and 1.5 % ( 53.38m3) respectively. While, increasing roots weight and organic addition resulted in decreased water consumption by 5.3% (189.8m3) and 3.95% (140.4m3). Finally, by increasing organic additions and roots weight increased both cereal and straw water use efficiency by (21, 23%) and (35, 36%) respectively, While it decreased to (9.4%) and 5.6% as increasing of moisture depletion.

Influence of Sulphur Compost Application on Some Chemical Properties of Calcareous Soil and Consequent Responses of Hordeum Vulgare L. Plants

Influence of Sulphur Compost Application on Some Chemical Properties of Calcareous Soil and Consequent Responses of Hordeum Vulgare L. Plants

Integrative Soil Application of Humic Acid and Sulfur Improves Saline Calcareous Soil Properties and Barley Plant Performance

ABSTRACTDuring the 2017 and 2018 seasons, two field experiments were conducted on newly reclaimed saline calcareous soil (7.13 dS m‒1, 16.9% CaCO3) in the experimental farm of the Faculty of Agriculture, Demo, Fayoum Governorate, Egypt. The current work aimed at identifying the potential positive effects of applied humic acid (HA) and elemental sulfur (S) on some soil properties and barley plant performance. The results showed that the application of HA and/or S at different rates ameliorated the adverse effects of saline calcareous soil conditions and significantly reduced some chemical properties of the soil (e.g., pH, ECe, and CaCO3%), while soil organic matter (OM%) and some nutrients (e.g., P, Fe, Mn, Cu, and Zn) contents were significantly increased. In addition, the contents of nutrients (e.g., P, Fe, Mn, Cu, and Zn) in barley plant and yielded grain, grain content of N and protein (%), and the performance (e.g., plant height, spike length, grain and straw yields, and weight of 1000-grain) of barley plant were significantly increased with the application of HA and/or S. The best results were obtained through the integrative application of 100 kg HA + 400 kg S ha‒1 to the tested saline calcareous soil. Therefore, the integrative soil application of 100 kg HA + 400 kg S ha‒1 can be recommended for the cultivation and sustainability of crop production in saline calcareous soil, in addition to rationalize the use of mineral fertilizers, which represent a surplus point for the sustainable agriculture system.

Chemical Properties of Compost in Relation to Calcareous Soil ‎Properties and Its Productivity of Wheat ‎

Two field experiments were conducted during the two successive growing winter ‎seasons in a private farm at Abu El-Matamir, El-Beheira Governorate Egypt, on ‎wheat plant, to study the effect of three types of composts prepared from three ‎plant residues, i.e., maize (CMR), tomato (CTR) and vine (CVR) on chemical ‎properties of sandy calcareous soil (i.e., pH, EC, OM, CEC, CaCO3 and available ‎of some macro- and micronutrients) and its productivity of wheat yield and its ‎components. These composts were analyzed for their chemical composition and ‎content of available macro- and micronutrient. Each compost was added at rates ‎of 0, 5, 10 and 20 ton fed-1. ‎The prepared composts had wide variations in their chemical composition. For ‎example, CTR had a highest content of organic matter, total nitrogen and ‎available macro- and micronutrients, while the lowest values were found in ‎CMR. Soil pH, EC and CaCO3 were decreased as a result of compost ‎applications, while soil CEC, OM and available macro- (N, P, K, S, Ca and Mg) ‎and micronutrients (Fe, Mn, Zn and Cu) were increased. The high relative ‎changes of the determined soil chemical properties and its content of available ‎nutrients were found in the soil treated with CTR followed by those resulted from ‎CVR treatments. Increasing application rates of the used composts were ‎associated with an increase of both straw and grain yields of wheat and their ‎relative changes (%), where the highest yield was found with the treatment of ‎CTR followed by that of CVR. Also, CTR gave the highest value of agronomical ‎efficiency of wheat plants compared with the other two composts. Finally, the ‎application of CTR (20 ton fed.-1) was superior in greatly improving soil chemical ‎properties of the studied soil and reflected on wheat productivity and nutrients ‎uptake. ‎

Evaluation of Some Synthetic Soil Conditioners and Nitrogen Rates on Nitrogen Use Efficiency by Maize - Wheat Crops System in Calcareous Soil

The use of synthetic soil conditioners such as polyvinyl alcohol (PVA), bitumen (Bit.) and polyacrylamide (PAC) can be considered as a specific management to improve the efficiency of the use of nitrogen fertilizers and some chemical properties of calcareous soils that are reflected in crop productivity. Two rates of synthetic soil conditioners (PAV, Bit. and PAC) and three rates of nitrogen fertilizer (50, 75 and 100% N of recommended dose) were included in this study to evaluate their effects on some chemical properties, nutritional status and yield components of both maize and wheat crops along with nitrogen use efficiency. Field experiments were conducted in calcareous soil at Nubaria Agriculture Research Station farm during two successive seasons, summer season cultivated with maize (Zea mays L., cv Giza 10) and winter season cultivated with wheat ( Triticum aestivum L., cv Giza 168). Results showed that the highest significant yield components of maize and wheat crops along with their total content of the indicated macronutrients were observed when applied high rate of polyvinyl alcohol (0.2 %) accompanied with high rate of nitrogen fertilizer (100% N of recommended dose) as compared to other tested treatments. On the contrary, application of high rate polyacrylamide combined with low rate of nitrogen fertilizer generally was inferior for yield components of both maize and wheat plants. Also, data revealed that the nitrogen use efficiency was the highest (65.0 and 42.4) for maize and wheat plant, respectively, receiving 50 % nitrogen fertilizer rate in presence of 0.2 % polyvinyl alcohol. However, applied high rate of polyvinyl alcohol accompanied with low rate of nitrogen fertilizer was superior decreased pH values of soil as compared to either control or other tested treatments. An opposite trend for EC values which were superior increased in presences of all nitrogen fertilizer rates. Also, CaCO3 values were lower when applied high rate of polyacrylamide in two seasons. The highest values of available nitrate and ammonium in soil were due to applied 0.2 % of polyvinyl alcohol combined with 75 % of nitrogen fertilizer rate compared to the other tested treatments.

Effect of Thiobacillus, sulfur, and phosphorus on the yield and nutrient uptake of canola and the chemical properties of calcareous soils in Iran

ABSTRACTThis factorial experiment consists of four levels of sulfur+Thiobacillus and three levels of triple superphosphate arranged in a completely randomized block design in three regions. With an increased sulfur+Thiobacillus and phosphorus (P), grain yield, phosphorus, iron (Fe), and zinc (Zn) uptake of canola increased in Qom and Mazandaran. Combined treatments of S2000T40 and P100% showed these properties most. In Safiabad, S1000T20 resulted in a significant increase of P, Fe, and Zn uptake of canola, and no significant effect was found on the grain yield. The highest Fe and Zn concentrations in Qom soil was measured in S2000T40. In Safiabad, maximum Fe concentration in soil was registered by S1000T20 and P65%. The minimum soil pH of Qom and Mazandaran was recorded by S1000T20 and S2000T40, respectively. The effect of sulfur and Thiobacillus on nutrients uptake and canola yield was good and indicates its potential for alleviating the impacts of calcareous soils.

How amending calcareous soils with municipal solid waste compost affects Fe fractionation and availability to plant

The solubility of iron (Fe), as an important micronutrient for plant growth, is not high in the calcareous soils, and hence efficient methods must be used to increase its availability for plant use. Accordingly, a two-year research work was conducted to investigate the effects of composted municipal solid wastes (MSW) on Fe accumulation and fractionation in a calcareous soil. Treatments including MSW levels at (0 (control), 15 (MSW1), 30 (MSW2) and 60 (MSW3) t ha−1 dry weight) and usage time (yearly (T1) or biyearly usage (T2)) were tested in a factorial experiment on the basis of a completely randomized block design with three replications. The compost was salty and contained the total Fe of 16200 mg kg−1. The concentrations of plant available Fe fractions including the exchangeable (EX), carbonates-bound (CA), organically-bound (OM), and Fe-Mn-oxide-bound (FM) as well as the residual (RE), DTPA- and Total-Fe fraction were determined. MSW increased levels significantly enhanced Fe concentration in different soil fractions as the least and the highest Fe concentrations were resulted by the control and the MSW3 treatments, respectively. The effects of T treatment were also significant on different Fe fractions excluding CA fraction. The Fe fractionation using the Tessier consecutive extraction method indicated the following order of Fe distribution and concentration in different soil fractions: RE > FM > OM > CA > EX. Iron was mostly found in the following fractions RE (>90%), FM (>6%) and OM (>2%). Different soil properties including EC (positively), pH (negatively), CEC (positively) and organic matter (positively) were highly and significantly correlated with different Fe fractions indicating how the use of MSW can affect the properties of calcareous soils. It is possible to increase Fe availability in different soil fractions using composted municipal solid wastes, which is of agronomical, health and environmental significance.

INFLUENCE OF ORGANIC AND BIO CONDITIONERS ON CALCAREOUS SOIL PROPERTIES AND YIELD OF BROAD BEAN PLANT

A field experiment was conducted on calcareous soil at El- Nubaria (private farm at the 10,000 Fed Village), El- Behera Governorate for two successive winter seasons (2015- 2016) and (2016- 2017) . Broad bean plant ( Vicia faba . Nubaria 1) was used as a tested plant to study the efficiency of some conditioners, compost (town refuse), potassium humate as organic and Rhizobium leguminosarum bv. Viceae strain ICARDA 441 as bio fertilizers on some calcareous soil properties and yield of broad bean. The treatments were: A-The cultivation methods (row and strew). B-The conditioners: organic (compost 10 ton fed-1 and potassium humate 15 L fed-1) and bio (Rhizobium leguminosarum bv. viceae strain ICARDA 441). Results indicated that, EC, pH and CaCO3 % of the studied soil were decreased, where OM was increased as a result of using both organic and bio conditioners compared to the control treatment. An improvement in soil physical properties as affected by soil conditioners was observed. Wherever a slight decreased soil bulk density (BD), an increase in total porosity (TP) and soil aggregation as dry and wet stable aggregates at using organic conditioners than biofertilizer were occurred. As well as soil hydraulic conductivity (HC) and moisture content at both field capacity (FC) and available water (AW) were increased compared to the control. Town refuse compost application achieved the highest biological, grain yield and 100 grains weight of broad bean plant followed by potassium humate treatment. Generally, the different soil properties and crop yield of broad bean plant grown on calcareous soil was more affected by the row cultivation method, town refuse compost and potassium humate, than bio fertilizer addition compared to the control.

EFFECT OF ORGANIC ADDITVES ON EFFEICENCY OF SULPHUR FERTILIZATION

This study carried to evaluate the effect of elemental sulphur additives on some agriculture wastes (maize stalks and farmyard manure) during composting process at different composting periods on many compost properties and its content of some macro- and micronutrients. Effect of compost and sulphur individually or in together at different application rates on some chemical properties of calcareous soil and its content some available macro- and micronutrients were studied. Also, the effect of the studied treatments of compost and sulphur on barley plant growth and its content of some macro- and micronutrients were studied. Compost pH and its content organic matter were decreased, but compost EC and its content N, P, K Ca, Mg, S, Fe, Zn, Mn and Cu were increased with the increase of both added S and composting period. Increasing rate of added S and compost resulted in a decrease of Soil pH and its content of CaCO3 where the same treatments were associated by an increase of soil CEC (except with the individual S applications) and its content of available macro- and micronutrients. In additions, the same studied treatments of both S and compost were associated by an increase of fresh and dry weights of barley plants (roots and shoots) and its content of macro- and micronutrients.

Reclamation of calcareous soil and improvement of squash growth using brewers’ spent grain and compost

Abstract Brewer’s spent grain represents approximately 85% of the by-products generated by the beer industry. It is acidic and rich in organic matter and nutrients. In Egypt, spent grain has no value and is available at no cost all year. Incubation and germination experiments were conducted to assess the potential of using spent grain and compost to increase soil fertility and squash ( Cucurbita pepo L.) growth in a calcareous soil. Amendments were two rates of spent grain (13.5, 26.7 g kg −1 ), two rates of compost (24.7, 49.4 g kg −1 ), a blend of lowest rates of compost and spent grain and a control. Treatments were mixed with calcareous soil, placed in pots and incubated anaerobically under field conditions for one month. After incubation 15 squash seeds were planted in the soil pots. Highest rate of spent grain most effectively increased soil water holding capacity, organic matter, macronutrients, micronutrients, germination parameters, and reduced soil pH. Mixing compost with spent grain was more effective than high rate of compost in increasing water holding capacity, soil nutrients, and decreasing soil pH. While both treatments were equally effective in enhancing squash germination and increasing soil organic matter. Spent grain is more effective than compost in improving properties of calcareous soils, and is much less expensive.

Leaching of veterinary antibiotics in calcareous Chinese croplands

Veterinary antibiotics reach the soil environment by manure application, where they accumulate or are prone to vertical translocation. We assumed that a high pH value at slightly calcareous soil properties should retain tetracyclines and fluoroquinolones even at high manure loads, whereas it should facilitate leaching of sulfonamides. Hence, we investigated the transport of manure-added antibiotics in a soil developed from calcareous parent material on a farm in peri-urban Beijing, China. Leachate was collected from zero-tension samplers, installed at 40cm depth under undisturbed soil, which was treated according to (i) routine farm practice and (ii) worst-case conditions (high antibiotic concentrations, irrigation imitating heavy rainfall). Additionally, the soil depth distribution of pharmaceuticals at the end of the leaching experiment was analysed. Under routine farm practice, sulfamethazine was repeatedly detected in the leachate with a maximum concentration of 0.12μgL−1. All applied substances were still detected in soil after 53days, suggesting that there was no overall rapid and complete dissipation. Worst-case conditions enhanced vertical translocation; all leachate samples contained sulfonamides (up to 653μgL−1 sulfamethazine), and even tetracyclines were found in the leachate once, with doxycycline reaching the highest concentration (0.19μgL−1). The concentrated simultaneous occurrence of sulfonamides with the bromide tracer in leachate samples pointed to preferential flow as underlying transport process. The high pH values did not prevent the single leaching event for tetracyclines and hardly affected overall leaching behaviour. The applied fluoroquinolones were not significantly translocated below 4cm depth, irrespective of irrigation and high manure addition.

Transformation kinetics of inorganic P forms in relation to calcareous soil properties of western Iran

This study was conducted to investigate the effect of time on chemical forms of P in 10 calcareous soils of western Iran. Phosphorus was added to soils at the rate of 200 mg kg−1 as KH2PO4. The samples were incubated for 1, 7, 15, 30, 60, 90 and 120 days at 25°C and constant moisture. After incubation, P was fractionated by the sequential extraction procedure: soluble and exchangeable P (NaHCO3-P) Al + Fe-P (NaOH-P), Ca-P (HCl-P) and residual P (Res-P). The distribution of added P into different fractions consisted of two phases involving initial rapid retention followed by a slow continuous retention. In general, the majority of the P applied entered mostly in the HCl-P and Res-P fractions. After 120 days incubation, the HCl-P fraction remained the most dominant in all soils. A combination of silt and sand content of the soils together explained between 88.5 and 83.3% of the variance inNaHCO3-P and HCl-P transformation rates, respectively, 76.6 and 72.8% of which is explained by silt alone. CaCl2-P and electrical conductivity (EC) together accounted for 66.3% of the variation in the rate constant of NaOH-P. The release rate of Res-P was not significantly related to soil properties.

Composted municipal waste effect on chosen properties of calcareous soil

Abstract A 3-year field study was conducted to assess effects of composted municipal waste on some properties, distribution of Zn, Cu in a calcareous soil and uptake of these metals by wheat. The treatments were 0, 25, 50 and 100 Mg ha-1 of municipal solidwastewhichwas applied in three consecutive years. The application of composted municipal waste increased the saturated hydraulic conductivity, the aggregate stability,the organic carbon content and electrical conductivity, whereas it slightly decreased the soil pH and bulk density. A significant increase in the concentration of Zn and Cu were observed with increasing number and rate of compost application. The distribution of Zn and Cu between the different fractions in untreated and treated soils showed that the majority of Zn and Cu were in the residual form. Finally, the levels of Zn and Cu were higher in grains of wheat grown in composttreated plots compared to that grown in the control plots.