Phosphorus fractions

Awareness of Phosphorus (P) fates when applying biochar to soil is required. Because, P retention and releasing mechanisms provide vital indication for the effective management of P to boost crop production and sustain soil. This study was conducted to evaluate the effects of coffee husk biochar (CHB) produced at two temperatures (350 and 500 0 C) and applied at a rates of (0, 5, 10 and 15t/ha) on phosphorus sorption and desorption in two soils with different P sorption capacities Fe and Al dominated strongly acid (pH=5.08) and Ca dominated alkaline calcareous soil (pH=7.85). Composite air dried, ground and sieved (2mm) soil samples were mixed with biochar and a 2 months incubation experiment was conducted at ambient temperature. In addition, P sorption characteristics of soils amended with biochar and in combination with and without mineral KH 2 PO 4 fertilizer were determined. The results showed significant effects (p<0.05) on selected soil chemical properties by increasing soil pH and reduced exchangeable acidity, exchangeable aluminum, and exchangeable iron in a way that increased the availability of P from 4.52 to 23.21mg/kg (83%) in acidic soil after 2months of incubation and when CHB500 0 C was applied at a rate of 15t/ha and from 8.2 to 27.4mg/kg (70%) in calcareous soil when CHB350 0 C was applied at a rate of 15t/ha. Application of highly alkaline biochars to calcareous soil significantly increased the sorption of P and decreased the availability of P by higher biochar application rates. We concluded that CHB500 0 C and applied at 15t/ha is promising to potentially increase soil P availability in acidic soil and decreased in calcareous soil but, increased in calcareous soil when CHB350 and applied at 15t/ha. Moreover, further researches at field scale are needed to evaluate the effect of biochar on availability and fates of phosphorous in acidic and calcareous soil.

This in-depth study explores the transformative effects of biochar incubation on key soil properties, emphasizing sulphate, phosphate, and chloride retention, soil pH alteration, and dissolved organic matter dynamics. Initial analyses of the soil used revealed a fertile soil environment with a slightly alkaline pH, moderate phosphorus availability, and a loam texture conducive to robust plant growth. A comprehensive materials and methods ensured the reliability of results. Different biochar types (rice husk and corn cob) were accurately applied at four levels (0 tonsha-1, 5 tonsha-1, 10 tonsha-1 and 20 tonsha-1). The investigation into soil pH alterations post-biochar incubation highlighted a dose-dependent relationship, revealing variation on acidity and alkalinity. The study placed a particular emphasis on sulphate, phosphate, and chloride retention, elucidating the intricate interplay between biochar feedstock, application rates, and soil conditions. Sulphate retention exhibited notable variations influenced by biochar type, with corn cob biochar (0.16 mgkg-1) demonstrating distinct advantages over rice husk biochar (0.11 mgkg-1). Phosphate retention showcased a dose-response relationship, correlating with increased biochar application levels. Surprisingly, chloride retention demonstrated a complex trend, with the highest retention observed at control levels (0 tonsha-1 = 1.82 mgkg-1), challenging conventional expectations. The examination of dissolved organic matter dynamics revealed consistent responses to biochar application levels, indicating its potential to influence nutrient cycling and microbial activity. Remarkably, the study contributes valuable insights into biochar's role as a sustainable soil amendment, providing a foundation for tailored soil management practices that enhance nutrient availability and overall soil health. 

Ashes from agricultural biomass in agro-based industries have been found to have most of the plant nutrients except nitrogen and sulphur but are treated as waste material. The present study was conducted to evaluate the potential of biomass ashes as source of P and their effect on bioavailability of micronutrients in wheat crop. We conducted the pot experiment at glass house of the Department of Soil Science, Punjab Agricultural University, Ludhiana, India. The experiment consisted of combinations of four P sources [bagasse ash (BA), rice husk ash (RHA), rice straw ash (RSA), fertilizer P (Fert-P)] supplying P at three levels (10, 20 and 30 µg g -1 ) along with one zero-P control. This experiment was laid out in completely randomized design (CRD) having three replications. Application of P through RSA produced significantly higher grain yield (14.3 g pot -1 ) than BA (12.8 g pot -1 ) and RHA (12.9 g pot -1 ) but statistically at par with Fert-P (13.5 g pot -1 ). Grain Zn content decreased maximum than other micronutrients with application of P from all sources, hence maximum increased P/Zn ratio. Phosphorus applied from all the biomass ashes significantly increased biomass and yield over control. With increase in P application, micronutrients content in grain was significantly decreased, hence decreased bioavailability of micronutrients in wheat grain.

Planning and suitable management is necessary for optimal use of soil and for this; spatial variability of soil characteristics is important which may be edcarried out through geostatistical methods of parametric and non-parametric predictors such as TPSS, WMA, Kriging and Co-kriging. This research work was done in Southern part of Uromieh plain with 36690 ha surface area in order to study the spatial variability of soil lime, sand and saturation moisture percentage. Distance between soil profiles ranged 1300 to 4700 meters. For estimation and prediction of them in non-sampled points, the Kriging, Co-kriging and Weighted Moving Average were used in Geographic Information System environment. For selecting suitable interpolation method, Cross validation and MAE and MBE parameters were used. Selected method was also used for estimating and mapping of the selected soil characteristics. The Sturges rule was used for defining map classification. Results showed that the Kriging method has the highest accuracy with correlation coefficient of 0.83 and error of 3.98 percent for prediction of soil characteristics in non-sampled points.

Surface sediments and three sediment cores from the western basin and one sediment core from the Sandusky basin were analyzed to document spatial and temporal changes in five phosphorus fractions and total phosphorus (TP). The areal distributions of the bioavailable fractions NaCl-Pi, NaBD-Pi, and NaOH-Pi and the refractory organic fraction Res-P were broadly consistent and contrasted with those of the detrital fraction HCl-Pi which showed that high concentrations occurred mostly in high-energy littoral zones and low concentrations largely in profundal depositional areas. The contrasting distributions were induced by interactions among tributary inputs, wave action, circulation, and biogeochemical cycling and transfer in the basin. As revealed by the Sandusky basin sediment record, the detrital fraction HCl-Pi was dominant (70% of TP) during European settlement and decreased rapidly by 28.0% in the early 1910s due largely to impoundments of the Maumee and Sandusky Rivers. While HCl-Pi has ever since remained relatively constant, NaCl-Pi, NaBD-Pi, and NaOH-Pi increased significantly between 1950 and 1970 in the two basins. However, the post-regulation sediment records differed considerably among these coring sites. There was a marked increase of TP in two cores, corresponding to recent return of eutrophication and massive harmful algal blooms but contrasting with a relatively constant, low loading into the lake. This signified the role of internal loading as derived partialy from legacy pollution. Furthermore, NaCl-Pi has increased progressively throughout all the records. We conclude that the increased levels of NaCl-Pi in surface sediments may have altered the internal loading and contributed to the resurgences of harmful algal blooms in Lake Erie.

Purpose To evaluate the effect of palm bunch ash and mycorrhiza on soil properties and the performance of cucumber in Calabar. Method Factorial combination of five levels of palm bunch ash-PBA (0, 3, 6, 9 and 12 t/ha) and two mycorrhiza treatments (inoculated and non-inoculated), laid out in randomized complete block design (RCBD) with three replications. Data were collected on crop growth and yield indices, soil properties (physical, chemical and biological) each year, then combined and analyzed. Duncan's Multiple Range Test (DMRT) at 5% probability was used to compare the means. Results There was increase in soil pH, organic carbon, phosphorus, potassium, calcium and magnesium as a result of PBA and mycorrhiza applications. PBA, mycorrhiza and their interactions significantly (p <.0. 05) influenced the vegetative growth and fruit yield of cucumber. Cucumber treated with 12 t/ha PBA had the highest vegetative growth and fruit yield values, which however were similar with those obtained from cucumber treated with 9 t/ha of PBA. Cucumber inoculated with mycorrhiza had superior growth and fruit yield than non-inoculated cucumber. The interaction of mycorrhiza and 12 t/ha PBA produced the highest values of vegetative growth and fruit yield indices, though similar with the interaction of mycorrhiza and 9 t/ha PBA. Conclusion Palm bunch ash was sufficient at 9 t/ha and is therefore recommended with mycorrhiza for effective soil nutrient enhancement and optimum cucumber production in Calabar.

Large quantities of rice husk ash (RHA), bagasse ash (BA) and coal fly ash (FA) are available in many Asian countries as waste materials, which create a serious disposal problem. Recycling of these ashes on agricultural land can help to improve physical and chemical fertility of soil. The present field experiment was conducted for three and half years to explore the possibilities to utilize these waste materials as soil amendments to improve productivity of rice-wheat system (RWS). The treatments consisted of application of RHA and BA at 10 Mg ha −1 to either wheat or to rice or to both wheat and rice and 20 Mg ha −1 to rice alone. The rates used for FA were 15 and 30 Mg ha −1. Addition of RHA and BA significantly increased the grain yield of wheat and rice but FA caused small increases in crop yields. Direct application of RHA and BA to wheat was significantly superior than their application to rice in the RWS. Direct application of RHA and BA to wheat resulted in 25 and 24% increase in mean grain yield of wheat and 10 and 11% increase in subsequent rice crop, respectively. However, direct application to rice resulted in 8 and 11% yield increase in rice and 10 and 14% increase in subsequent wheat for RHA and BA, respectively. Application of RHA and BA at 20 Mg ha −1 to rice resulted in lower RWS productivity than that applied at 10 Mg ha −1 to wheat. There was no significant effect of these ashes on heavy metal contents in grain and straw of the 7th crop of wheat. Application of three types of ashes generally resulted in positive P balance in RWS, however, K balance remained negative. These results suggest that RHA and BA can be recycled successfully in rice-wheat system to improve its productivity with no adverse effect on soil health.

ABSTRACT: Soil phosphorus (P) availabili ty and fractions are influenced to a large extent by land use and cover changes. Inorganic P (IP) and organic P (OP) fractions in surface soils (0–20 cm) under typical vegetation types, including subalpine coniferous forests, alpine ...

Understanding of phosphorus (P) retention and release mechanisms provides crucial information for the effective management of phosphorus to enhance crop production and sustain soil. In acidic soil, available phosphorus is fixed by aluminum and iron. To overcome this problem, soils are limed to fix aluminum and iron. But this practice is not economical for small scale farmers and also it is not environmentally friendly. This study was conducted to improve phosphorus availability using biochar produced from coffee husk and corn cob to fix aluminum and iron instead of phosphorus. Acidic soil samples were mixed with biochar applied at the rates of 0, 5, 10 and 15 t ha-1 and incubated in laboratory for 2 months at ambient temperature. The results showed significant effects (p<0.01) on selected soil chemical properties by increasing soil pH and reduced exchangeable acidity, exchangeable aluminum, and exchangeable iron in a way that enhanced the availability of phosphorus. Due to the incorporation of biochar the available P level increased to a level ranging 3.64±0.34-23.21±0.07 mg/kg after an incubation period of 2 months and it increased by 84.3% available phosphorus when coffee husk biochar produced at 500°C temperature was applied at a rate of 15t/ha. Moreover, further field researches are needed to evaluate the effect of biochar on availability, the fate and uptake of available P in soil.

Although the savanna biome of South Africa is a major resource for rangeland management, little is known about how differences in rangeland management systems affect soil properties in such biomes. Near to Kuruman, commercial farms have practiced rotational grazing for decades. In communal areas of former homeland Bophuthatswana, similar strategies were used prior to 1994. Nowadays, a continuous grazing system is common. We hypothesized that these changes in management affected soil properties. To test this, we sampled soils at communal and commercial land along a gradient with increasing distance to water points. The results revealed that communal systems with continuous grazing showed enlarged spatial gradients. The soils were depleted in most nutrients close to the water relative to those of commercial systems. In contrast, as the distance to the water increased, the nutrient stocks of these communal systems were higher. Changes in soil nutrient stocks were related to a zone of increased bush encroachment (up to 25%). Specific analyses (phosphorus fractions, particulate organic carbon, d 13 C) confirmed that the soils of the communal grazing systems benefited from the shift of grass-dominated to bush-dominated system with woody Acacia vegetation, while the rangeland degraded in the sense that it lost palatable grass species.

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Although the savanna biome of South Africa is a major resource for rangeland management, little is known about how differences in rangeland management systems affect soil properties in such biomes. Near to Kuruman, commercial farms have practiced rotational grazing for decades. In communal areas of former homeland Bophuthatswana, similar strategies were used prior to 1994. Nowadays, a continuous grazing system is common. We hypothesized that these changes in management affected soil properties. To test this, we sampled soils at communal and commercial land along a gradient with increasing distance to water points. The results revealed that communal systems with continuous grazing showed enlarged spatial gradients. The soils were depleted in most nutrients close to the water relative to those of commercial systems. In contrast, as the distance to the water increased, the nutrient stocks of these communal systems were higher. Changes in soil nutrient stocks were related to a zone of increased bush encroachment (up to 25%). Specific analyses (phosphorus fractions, particulate organic carbon, d 13 C) confirmed that the soils of the communal grazing systems benefited from the shift of grass-dominated to bush-dominated system with woody Acacia vegetation, while the rangeland degraded in the sense that it lost palatable grass species.

In the face of rapid growth of the population and the need for food production sectors, one of the ways to achieve this is to increase the production per unit area. In modern agriculture, the preparation of soil fertility map seems to be necessary to plan for appropriate use of fertilizers for crops. This study was conducted to prepare a distinct map for evaluating the soil fertility according to soil chemical properties in 191 soil samples of Ardabil Plain in Ardabil Province. To achieve this goal, the available N and P, K, EC, Fe, Zn, Mn and the organic matter of soil were mapped using geostatistical Kriging estimator into the Geographic Information System (GIS) by the ArcGIS software. The Analytical Hierarchy Process (AHP) was used for weighting the soil fertility factors as the input data. Then, a membership functions was defined for each factor by factorial scoring and the map of soil fertility was prepared and classified by using the AHP technique into the GIS program. The results showed that most of nitrogen and phosphorus with the weight of 0.293, 0.202 had the mostly infraction on the soil fertility and production. Survey map of the distribution showed that most of the factors were studied in the northern region with the low nutrients. The results also showed that 23.7 percent of cultivated land fertility maps had a poor fertility status, 28.3 percent of the land had a moderate fertility status, 25.4 percent of the land was good and the fertile land with 22.6 percent had a very good fertility status.

Organic manures are safer sources of plant nutrients and a good source of micronutrients therefore; pot experiments were carried out to estimate some extractable iron contents as influenced by organic manure application in the soils of Lake Geriyo, Adamawa state, Nigeria. Two types of organic manures; poultry droppings, cow dung and control were used for the experiment. Three levels of organic manures; 5, 10 and 15 tons per hectare (ton ha-1) and three sampling time (30, 60 and 90 DAS were laid down in a completely randomized (CRD) design replicated three times. Results obtained revealed that rate, type of organic manures and time of submergence significantly (P ≤ 0.05) changed Fe content in the soil. Mean extractable iron concentrations of 42.01, 56.13 and 24.63 mgkg-1 were recorded for ammonium oxalate extractable iron, Citrate Bicarbonate Dithionite extractable iron and sodium pyrophosphate extractable iron in the first experiment while 45.81, 59.29 and 28.89 mgkg-1 were recorded...

The formation of phosphorus (P) compounds including iron-P, aluminum-P and calcium-P in highly weathered tropical soils can be altered upon biochar addition. We investigated the effect of corn cob biochar (CC) and rice husk biochar (RH) pyrolyzed at three temperatures (300°C, 450°C and 650°C) on phosphorus (P) fractions of three contrasting soils. A 90d incubation study was conducted by mixing biochar with soil at a rate of 1% w/w and at 70% field capacity. Sequential P fraction was performed on biochar, soil and soilbiochar mixtures. Increase in most labile P (resin-P i , NaHCO 3-P i) and organic P fraction (NaHCO 3-P o + NaOH-P o) in CC and RH biochars were inversely related to increasing temperature. HCl-P i and residual P increased with increasing temperature. Interaction of CC and RH with soils resulted in an increase in most labile P as well as moderately labile P (NaOH-P i) fractions in the soils. CC increased most labile P in the soils more than RH. The increase in most labile P fraction in soils was more significant at relatively lower temperatures (300°C and 450°C) than 650°C. However, the increase in HCl-P i and residual P of the soils was more predominant at high temperature (650°C). The study suggested that biochar pyrolyzed at 300-450°C could be used to increase P bioavailability in tropical soils.

• Effects of four biomass ashes vs. a P fertiliser (TSP) on two crops were studied. • Ashes increased crop yields with P availability similar to TSP on P-depleted soil. • Barley biomass and Cd uptake did not respond to high ash rates on a normal P soil. • Cd concentration of crops on ash-amended soil was in the range of TSP treatments. • High levels of soil available P remained after harvest at high ash applications.

The present study was conducted to perform quantitative analysis and comparison of Nitrogen, Potassium and Phosphorus contents in rice husk and wheat bran samples. Rice and wheat are leading staple food and are cultivated in Pakistan at large scale. During refining process the rick husk and wheat bran are removed from rice and wheat grains. Both rice husk and wheat bran contain nutrients in specific proportion, that's why these can be used effectively for different purposes such as soil amendment and organic fertilizer to retain yield and increase soil fertility. In this study the detection of Nitrogen in rice husk and wheat bran samples was done by using elemental analyzer, Potassium detection was done by using Atomic Absorption Spectrophotometer and Phosphorus was detected by using X-Ray Fluorescence Spectrometry. The result of this study shows that rice husk contains more Nitrogen (0.476±0.0687) and Phosphorus (0.0504±0.007211) contents as compared to wheat bran (0.410±0.0679) and (0.0101±0.00387) respectively. However in wheat bran, Potassium content (26.706±2.47) was slightly higher than rice husk (25.986±1.573). It can be concluded that rice husk contains comparatively more nutrient value as eco-friendly organic fertilizer than wheat bran.

Large quantities of rice husk ash (RHA), bagasse ash (BA) and coal fly ash (FA) are available in many Asian countries as waste materials, which create a serious disposal problem. Recycling of these ashes on agricultural land can help to improve physical and chemical fertility of soil. The present field experiment was conducted for three and half years to explore the possibilities to utilize these waste materials as soil amendments to improve productivity of rice-wheat system (RWS). The treatments consisted of application of RHA and BA at 10 Mg ha −1 to either wheat or to rice or to both wheat and rice and 20 Mg ha −1 to rice alone. The rates used for FA were 15 and 30 Mg ha −1. Addition of RHA and BA significantly increased the grain yield of wheat and rice but FA caused small increases in crop yields. Direct application of RHA and BA to wheat was significantly superior than their application to rice in the RWS. Direct application of RHA and BA to wheat resulted in 25 and 24% increase in mean grain yield of wheat and 10 and 11% increase in subsequent rice crop, respectively. However, direct application to rice resulted in 8 and 11% yield increase in rice and 10 and 14% increase in subsequent wheat for RHA and BA, respectively. Application of RHA and BA at 20 Mg ha −1 to rice resulted in lower RWS productivity than that applied at 10 Mg ha −1 to wheat. There was no significant effect of these ashes on heavy metal contents in grain and straw of the 7th crop of wheat. Application of three types of ashes generally resulted in positive P balance in RWS, however, K balance remained negative. These results suggest that RHA and BA can be recycled successfully in rice-wheat system to improve its productivity with no adverse effect on soil health.

Organic manures are safer sources of plant nutrients and a good source of micronutrients therefore; pot experiments were carried out to estimate some extractable iron contents as influenced by organic manure application in the soils of Lake Geriyo, Adamawa state, Nigeria. Two types of organic manures; poultry droppings, cow dung and control were used for the experiment. Three levels of organic manures; 5, 10 and 15 tons per hectare (ton ha-1) and three sampling time (30, 60 and 90 DAS were laid down in a completely randomized (CRD) design replicated three times. Results obtained revealed that rate, type of organic manures and time of submergence significantly (P ≤ 0.05) changed Fe content in the soil. Mean extractable iron concentrations of 42.01, 56.13 and 24.63 mgkg-1 were recorded for ammonium oxalate extractable iron, Citrate Bicarbonate Dithionite extractable iron and sodium pyrophosphate extractable iron in the first experiment while 45.81, 59.29 and 28.89 mgkg-1 were recorded...

Pot experiments were carried out from January to July, 2013 to study the effects of some organic manure on uptake of N, P, K, Zn and Fe in straw and grains of rice in the soils of Lake Geriyo Irrigation Scheme, Adamawa State, Nigeria. Two types of organic manures; cow dung, poultry droppings and control were used for the experiment. Three levels of organic manures 5, 10 and 15 tons per hectare (tonha ) and two sampling 1 time; maximum tillering and harvest were chosen. Results obtained revealed that nitrogen uptake in straw ranged from 15.07 to 18.11 and 15.62 to 18.32gkg for the first and second experiments, respectively. Mean nitrogen 1 uptake in grains of 8.80 and 9.44gkg were also recorded for the first and second experiments, respectively. 1 Mean of 2.04 and 32.84mgkg and 2.31 and 33.28mgkg were recorded for zinc and iron for the first and second 1 1 experiments respectively. Level, type of organic manures as well as time of sampling significantly (P&lt;0.05) influenced N, P an...

To study the behaviour of phosphorus (P) sorption in the agricultural soils of Khoy region and the effect of long-term cultural management with the application of poultry manure on the P sorption parameters, bath experiments were carried out with 16 soil samples (8 cultivated and 8 virgin soils) and 9 initial P concentrations from 0 to 30 mg L-1 in 0.01M CaCl2 as a background solution. After equilibrium, the remaining amount of P in solution was measured and the experimental sorption data were fitted to the Langmuir (R 2 =0.93-0.99) and Freundlich (R 2 =0.87-0.99) models. The results showed that P sorption was increased with enhancing the initial P concentration, eventually reaching the steadystate plateau. Based on the coefficient of determination (R 2) and the standard error of estimate (SE), both isotherms models, Langmuir and Freundlich, showed a relatively good fit to the experimental data. The maximum mono layer sorption of Langmuir (qmax) varied from 233 to 486 and from 340 to540 mg kg-1 , and the energy parameter of Langmuir (KL) ranged from 0.12 to 0.50 and from 0.22 to 0.71 for the cultivated and virgin soils, respectively. Freundlich sorption capacity (KF) and intensity (n) parameters showed the same trends and KF varied from 36.4 to 123 and 59.3 to 145.2; also n varied from 1.18 to 1.50 and 1.47 to 1.71 in the cultivated and virgin soils, respectively. Consequently, all sorption parameters and the buffering indices showed a decreasing trend in the cultivated soils, as compared to the corresponding virgin soils and the cultural and fertilization management; especially, the application of the poultry manure in this region reduced phosphorus sorption by soil and then increased phosphorus availability to plants. Hence, less fertilizer would be needed to maintain a favourable P concentration in the soil solution for the optimum plant growth.

Background and Objectives: Phosphorus (P) has been one of the major nutrients limiting agricultural production in many rice growing regions of the world, and certainly this is the case in north of Iran, where soils deficient in proper and balanced P management in the cultivated paddy fields. Phosphorus (P) chemistry in paddy soils is complicated due to various chemical and biological processes involve in its availability through various P fraction pools. Therefore, P fractions play a crucial role on soil available P supplying capacity especially in paddy fields. Proper and effective managerial practices of P and assessment of their effects on rice production requires an understanding of their variability in concentration across the fields. The spatial variability of soil properties and P content is the outcome of the interaction of several soil characters and processes and in agricultural fields involves also effects of management practices. Thus, the objective of this study was to conduct a large-scale analysis of the spatial variability of available and organic P, and also inorganic P fractions, and the important physical and chemical soil characters on P factions’ distribution for better fertilizers managerial practices.

Materials and Methods: This experiment was conducted at Some-e-Sara city in Guilan province. Soil samples were collected from 103 paddy fields with uniform geographical distribution in grids of 2x2 km. Soil samples were analyzed to determine available P, organic P, their effective physical and chemical properties (Texture, pH, CEC, T.N.V, Clay and O.C), and also sequentially extracted to determine inorganic P fractions(soluble P, Al-P, Fe-P and Ca-P). Descriptive and spatial variability analysis, and mapping was done by using SPSS (ver. 16), GS+ (ver. 5.1) and Arc GIS (Ver. 9.1), respectively.

Results: The highest coefficients of variation belonged to available P and its controlling P fractions, Al and Fe bounded P, about 132 and 194, respectively, whereas, pH showed the lowest CV, 10.6. The nugget to sill ratio ranged from 12 to 60% for almost all the studied data sets, showing moderate to strong pattern of spatial dependence. The small to moderate nugget effects also indicate that the sampling grid used was proper to reflect the spatial dependence of the studied soil properties and P fractions. Analysis of semivariogram corresponding to experimental data sets showed that the values for the range of spatial dependence of the semivariogram models varied from 2700 to 6000 m. Based on the results obtained from linear correlation analyses and spatial distribution maps, available P strongly correlated with both Al and Fe-P fractions and OC, about 0.84, 0.94 and 0.40, respectively.

Conclusions: Based on the results obtained from linear correlation analyses and spatial distribution maps, available P strongly correlated with both Al and Fe-P fractions and OC. Therefore, we concluded that determination of spatial correlation’s area of these soil chemical properties can effectively improve P fertilizers management in paddy fields. In this case, incorporation of remained rice straw with soil through shallow ploughing two weeks after grain harvesting enhance the oxidative condition of soil and consequent better straw decomposition increase the soil available P balance. These two mechanisms considerably decrease application of P fertilizers. Moreover, due to lack of, and/ or, insufficient P application in studied area, continuous flooding influence on available P condition by altering soil oxidative status to reduced, naturalizing the pH, and increasing P minerals stability.

Ashes from agricultural biomass in agro-based industries have been found to have most of the plant nutrientsexcept  nitrogen  and  sulphur  but  are  treated  as  waste  material.  The  present  study  was  conducted  to  evaluate  the potential  of  biomass  ashes  as  source  of  P  and  their  effect  on  bioavailability  of  micronutrients  in  wheat  crop.  We conducted the pot experiment at glass house of the Department of Soil Science, Punjab Agricultural University, Lu-dhiana, India. The experiment consisted of combinations of four P sources [bagasse ash (BA), rice husk ash (RHA), rice straw ash (RSA), fertilizer P (Fert-P)] supplying P at three levels (10, 20 and 30 μg g-1) along with one zero-P control.  This  experiment  was  laid  out  in  completely  randomized  design  (CRD)  having  three  replications. Application of P through RSA produced significantly higher grain yield (14.3 g pot-1) than BA (12.8 g pot-1) and RHA (12.9 g pot-1) but statistically at par with Fert-P (13.5 g pot-1). Grain Zn content decreased maximum than other mi-cronutrients with application of P from all sources, hence maximum increased P/Zn ratio. Phosphorus applied from all the biomass ashes significantly increased biomass and yield over control. With increase in P application, micro-nutrients  content  in  grain  was  significantly  decreased,  hence  decreased  bioavailability  of  micronutrients  in  wheat grain.

Pot experiments were carried out from January to July, 2013 to study the effects of some organic manure on uptake of N, P, K, Zn and Fe in straw and grains of rice in the soils of Lake Geriyo Irrigation Scheme, Adamawa State, Nigeria. Two types of organic manures; cow dung, poultry droppings and control were used for the experiment. Three levels of organic manures 5, 10 and 15 tons per hectare (tonha) and two sampling 1 time; maximum tillering and harvest were chosen. Results obtained revealed that nitrogen uptake in straw ranged from 15.07 to 18.11 and 15.62 to 18.32gkg for the first and second experiments, respectively. Mean nitrogen 1 uptake in grains of 8.80 and 9.44gkg were also recorded for the first and second experiments, respectively. 1 Mean of 2.04 and 32.84mgkg and 2.31 and 33.28mgkg were recorded for zinc and iron for the first and second 1 1 experiments respectively. Level, type of organic manures as well as time of sampling significantly (P<0.05) influenced N, P and K uptake in both straw and grains of rice grown on the soil of Geriyo Irrigation Scheme. Zinc and Iron uptake in both straw and grains was however decreased with increasing organic manures application. While, reduced Iron uptake may not constitute a problem in the nutrition of rice, the antagonistic effect of the primary nutrients particularly P on zinc should be monitored to sustain yield.

There are large areas of Oxisols in South America, including Brazil, with low fertility and acidity. To improve crop yields on these Oxisols, liming and fertilization is an essential practice. However, besides the high cost of fertilizers, chemical fertilizers cannot be used in organic production systems, except insoluble sources. Ash is one of the alternative source of supplying macro and micronutrients. A field experiment was conducted, in a completely randomized block design in a factorial arrangement (three sources of ash x four rates) resulting on 12 treatments, to evaluate the effect of source and rate of ash application on soil chemical properties. The treatments consisted of three sources (bagasse, bagasse+PJ07-A and bagasse+PJ07-RA) of sugarcane ash applied in four rates as 0; 5; 15 and 30 Mg ha -1 . Results showed that the use of ash significantly improved soil chemical properties such as pH, P, K, Mg, base saturation, K and Mg saturation and significantly reduced soil acidity (H+Al). Depending on the ash source or rate, some of the soil chemical properties were affected, however, the effect of ash source was not so pronounced as compared with ash rate. Ashes application resulted on a soil nutritional condiction enough to guarantee the growth and yield of most annual crops. Ash sources were equally effective in reducing acidity and improving soil fertility under this study condition, while increasing ash rate provides decrease in H+Al content and increase in pH, Mg, P and K.