Phosphorus Fertilizer Efficiency Research Articles

Effect of Phosphorus and Magnesium Fertilizers on Mineral Nutrition and Yield of Winter Wheat depending on Liming of Sod-Podzolic Soil

In long-term field experience on strongly acidic, poorly cultivated sod-podzolic soil, high efficiency of phosphorus fertilizers combined with magnesium and liming in the cultivation of winter wheat of the Moskovskaya 56 variety was revealed. Under these conditions, the content of nitrogen, phosphorus and magnesium in plants in the flowering phase increased. Improving the mineral nutrition of plants in this case provided the highest yield (75.3 c/ha), exceeding the background level of nitrogen-potassium fertilizers by 2.7 times, the payback of mineral fertilizers (NPK) increased by 2.5 times, reaching 16.7 kg/kg. The use of phosphorus fertilizers on highly acidic soil increased yields by 65% at 27.5 c/ha against the background of nitrogen-potassium fertilizers. On calcified soil with a slightly acidic reaction of the medium, the yield from the use of phosphorus fertilizers increased by 19% compared to the background of 58.1 kg/ha. Yield increases when using magnesium fertilizers against the background of full fertilizer (NPK) decreased as soil acidity decreased and were significant: on medium acidic soil – 4.9 and slightly acidic – 6.1 c/ha. At the maximum yield of winter wheat, due to the use of phosphorus and magnesium fertilizers and a decrease in the acidity of sod-podzolic soil, the removal of nutrients by the winter wheat harvest increased: nitrogen – by 3.5, phosphorus – 3.7, potassium and magnesium – 3 times.

Energy and Environmental Assessment of Bacteria-Inoculated Mineral Fertilizer Used in Spring Barley Cultivation Technologies

In the scientific literature there is a lack of information on the integrated effect of bioenriched complex mineral fertilizers in the energy and environmental aspects of spring barley production technology. The aim of this study was to validate the type of phosphorus-releasing bacteria and to carry out an energy and environmental assessment of the use of mineral fertilizers enriched with them for barley fertilization. The experimental field studies (2020–2022) were carried out in open ground on sandy loam soil in southern Lithuania. Four barley cultivation technologies (SC) were applied. Control (SC–1) did not use complex mineral fertilizers; in SC–2, 300 kg ha−1 of N5P20.5K36 fertilizer was applied. In SC–3, the same fertilizer was enriched with a bacterial inoculant (Paenibacillus azotofixans, Bacillus megaterium, Bacillus mucilaginosus, and Bacillus mycoides) at a rate of 150 kg ha−1, and in SC–4, 300 kg ha−1 of N5P20.5K36 fertilizer were applied and the same enrichment with the bacterial inoculant was carried out. The results confirmed the hypothesis that spring barley cultivation technologies using bacterial inoculants (SC–3 and SC–4) have higher mineral fertilizer efficiency than SC–2. In all three years, the bacterial inoculant had a positive effect on phosphorus fertilizer efficiency. In SC–4 (2020) it was 8%, in 2021—7%, and in 2022—even 17% higher compared to SC–2. In terms of energy balance, a significant influence of the bacterial inoculant was found. In 2020 and 2021, the energy balance of SC–4 was 10%, and in 2022, 22.8% higher compared to SC–2. The increase in fertilizer use efficiency resulted in a positive environmental impact, with greenhouse gas (GHG) emissions decreasing by 10% in 2020, 15% in 2021, and 19% in 2022 when comparing SC–4 and SC–2. The use of the tested bacterial formulations, without changing the mineral fertilizer rate, can lead to an average reduction in GHG emissions of about 15%. This study demonstrates that enriching mineral fertilizers with specific bacterial inoculants for spring barley cultivation significantly enhances phosphorus efficiency, improves energy balance, and reduces greenhouse gas emissions, underscoring the potential for bioaugmented fertilizers to optimize agricultural sustainability.

DIFFERENT PHOSPHORUS DOSES IN GRAIN SORGHUM UNDER CERRADO CONDITIONS, GOIÁS, BRAZIL

Sorghum bicolor is an important grain species used for food and feed production, where P is a key element/nutrient in grain production. The effect of increasing phosphorus doses to grain sorghum in Cerrado soil with sandy texture and low fertility in Cerrado conditions was evaluated. The study was conducted at the Pântano Farm, Jataí, Goiás, Brazil. The sorghum cultivar used was AG 1085. The doses of 0 (control), 40, 80, 120, and 160 kg ha-1 of P2O5 were used, whose source was triple superphosphate 46% of P2O5, with five replications each, designed in random blocks. The evaluated variables were stem length, stem diameter, leaf area, shoot dry mass, leaf phosphorus content, nutrient accumulation, fertilization efficiency, chlorophyll a, and chlorophyll b. For the variables shoot dry mass in (g plant-1), leaf phosphorus content, dry mass expressed in (kg ha-1), and chlorophyll b (CFI), the effect for the application of P doses in cultivar had a linear effect. The analysis of variance of the regression showed a quadratic effect for the variables stem length, stem diameter, leaf area, and phosphorus use efficiency, and for chlorophyll a (CFI), showing a maximum point at the best dose and best values ​​of the variables. The application of Phosphorus influenced the development of the grain sorghum cultivar. The 129 kg ha-1 of P2O5 had the highest efficiency of phosphorus fertilization corresponding to 82.02%.

Screening of calcium- and iron-targeted phosphorus solubilizing fungi for agriculture production

The average efficiency of phosphorus fertilizer is relatively low around the world because the plant-available phosphorus can be readily immobilized by the soil minerals, such as iron, aluminum, and calcium, when phosphorus fertilizer is applied to the field. Phosphorus solubilizing microorganisms can release phosphorus from insoluble phosphorus and help plant grow. This study screened phosphorus solubilizing fungi (PSF) from 153 fungi species by Pikovskayas Agar media and National Botanical Research Institute's phosphate growth medium broth. There were 47 Ca-targeted PSF, and among them, 34 PSF could dissolve FePO4. Epicoccum dendrobii (B-27) was the best Ca-targeted PSF with the released free phosphorus of 35.49 ± 2.11s% in 4-day incubation, while Aspergillus sp. (A-5) was the best Fe-targeted PSF with 28.75 ± 6.43% of Fe–P dissolved. Besides, Penicillium sp. (Sarita-12) was superior in dissolving both Ca3(PO4)2 and FePO4 with 34.43 ± 2.22% and 24.27 ± 4.09% released in the supernatant, respectively. The growth kinetic experiments showed that except B-27, all the pH of the selected PSF inoculated media decreased during the incubation, indicating that inorganic/organic acids might be metabolized to dissolve the insoluble phosphorus. The results suggested that the phosphorus solubilizing capability of the selected PSF was different with Ca–P and Fe–P substrates. The screened Sarita-12 strain has great potential to be used as phosphorus-solubilizing bio-fertilizer in calcareous alkaline soils and acidic soils to enhance phosphorus assimilation by plants and improve the phosphorus fertilizer efficiency.

Co-occurrence network in core microorganisms driving the transformation of phosphorous fractionations during phosphorus recovery product used as soil fertilizer

Phosphorus recovery from water and the subsequent reuse of its products can solve both water eutrophication and phosphorus resource waste issues. However, the potential use of the final recovered products as crop phosphorus fertilizers and the transformation of phosphorus fractions in soils have rarely been analyzed. In this study, the effects of a phosphorus recovery product (w-HC/CSH/P) obtained from our previous phosphorus recovery study on pepper growth were investigated. The association between soil phosphorus fraction transformation and the microbial co-occurrence network was investigated using high-throughput sequencing. The results showed that amendment with w-HC/CSH/P could promote the growth and chlorophyll content of pepper, which exhibited high phosphorus fertilizer efficiency. In addition, applying w-HC/CSH/P in soils could increase the microbial alpha-diversity during pepper cultivation and induce changes in the microbial community, leading to an increase in the relative abundance of Povalibacter, Lysobacter, and GP10 and a decrease in GP17. The proportion of Resin-P and NaHCO3-Po decreased, whereas that of NaOH-Po increased during pepper cultivation. psOTU331 (g_Latescibacteria), psOTU377 (g_Lysobacter), and psOTU461 (g_Pseudoxanthomonas) were the key microorganisms driving the transformation of phosphorus fractionation in the microbial co-occurrence network. Latescibacteria and Lysobacter were closely correlated with the transformation of NaHCO3-Po to NaOH-Po, and Pseudoxanthomonas was significantly correlated with a decrease in Resin-P. These observations highlight the potential of phosphorus recovery products as fertilizer for pepper and provide new insights into the transformation of phosphorus fractions corresponding to the microbiome in soils.

Efficiency of Phosphorus Fertilizers Derived from Recycled Biogas Digestate as Applied to Maize and Ryegrass in Soils with Different pH

Three phosphorus (P) fertilizer fractions recycled from biogas digestates were tested alone and in combination for their efficiency in two agricultural surface soils with different pH: a silty sandy loam and a clay loam. The experiments were carried out in pots under greenhouse conditions, using mineral triple superphosphate (TSP) as a reference. Maize was cultivated for 50 days, followed by ryegrass cultivation for an additional 84 days in the same soil, without additional fertilization. The variables investigated were above-ground plant biomass production, plant phosphorus concentration and content, and plant available phosphorus concentration in soil. The dry matter (DM) yield of maize was increased by the organic P fertilizers equal to or more than TSP in both soils. In the neutral soil, biomass was almost doubled compared to TSP when using one of the fractions (Struvite containing P-Salt) alone or in combination with dried solid fractions. P concentration in maize cultivated in the neutral soil was not significantly different between the P fertilization treatments. However, associated with biomass increase, the total P content in maize plants was equal to or higher than that with TSP. In the acidic soil, P concentration and total P content in maize plants, as well as the calcium-acetate-lactate extractable P (CAL-P) concentration in soil, were equal to or even higher than TSP. Ryegrass DM yield was unaffected by all P fertilizers, independent of the soil, although P concentration and total P content increased in the acidic soil with all fertilizers. Our results show that recycled P fertilizers from biogas digestates are effective P fertilizer alternatives to mineral TSP for maize cultivation under acidic and neutral soil conditions. The lack of growth effects in ryegrass indicates that recycled P fertilizers do not require changes in weed control. On the other hand, P extraction by ryegrass in overfertilized acidic soils as an option for soil remediation also works in soils fertilized with biogas digestate fractions.

Agronomic Efficiency of Phosphorus Fertilizers With Associate Technology in Soy Crop in Cerrado Soil

For commercial soybean production, the presence of phosphorus in the soil is essential, not only to increase productivity but also because it affects basic functions in plant metabolism. Phosphate fertilizers have low efficiency in Cerrado soils. For this reason, the use of technologies associated with phosphate fertilizers is important to increase their efficiency in the soil. The experiment was conducted at Fazenda Rio Brilhante in Coromandel, MG. The experiment was laid out in a randomized block design in a 4 × 4 + 1 factorial arrangement. Treatments consisted of four phosphate fertilizer sources (MAPCONVENCIONAL, MAPpol 1, MAPpol 2, and FOM), four P2O5 doses (40, 80, 120, and 160 kg ha-1), and the control treatment (no phosphorus application). The soybean cultivar RK8115 IPRO with a plant population of 340 thousand plants per hectare was used. The experimental plots consisted of five planting lines with a spacing of 0.5 meters and a length of 7 meters. In the experiment, phosphorus leaf, morphological evaluation of plant height, stem diameter, number of stems, and pods were measured. For plant biomass, the dry matter of leaves, stems, and pods were determined. For yield evaluation, the calculation of productivity and RAE was compared with MAPCONVENCIONAL. For sources, data were subjected to analysis of variance, and means were separated by Tukey’s rate test (p < 0.05). For P2O5 doses, regression model fitting was performed using the ExpDes.pt package of R Studio software. Morphological assessments responded linearly to P doses, except for DPM. Leaves and pods P content and yield were affected by P dosage and P sources, with a quadratic response to P dosage. Maximum yield efficiency was achieved at P2O5 doses of 122.73; 145.07; 112.03; and 94.71 kg ha-1, with yields of 3818.30; 4064.67; 4089.03; and 3952.63 kg ha-1 for MAPCONVENCIONAL, MAPpol 2, MAPpol 1, and FOM, respectively. However, MAPpol 1 and FOM provided a dose reduction of 26 and 15 compared to the maximum yield of MAPCONVENCIONAL, respectively.

Phosphorus availability and grass growth in biochar‐modified acid soil: A study excluding the effects of soil pH

AbstractThe low efficiency of phosphorus fertilization in weathered soils can limit plant development. The application of biochars in these areas has been seen as an important way to increase the efficiency of phosphorus fertilization and to promote better plant growth. However, biochars are alkaline materials that can increase soil pH and thus change the nutrient dynamics, which has been often ignored in studies of this nature. Here, all treatments had their pH standardized at 6.1 to eliminate the influence of pH on biochar application responses. The main goal of this study was to evaluate the real potential of coffee straw and eucalyptus bark biochars, produced under different pyrolysis temperatures, in the optimization of phosphorus fertilization and the development of Brachiaria brizantha. A greenhouse experiment was set up in a 2 × 2 × 5 factorial scheme, conducted for 120 days. The biochars, prepared from coffee straw and eucalyptus bark at 350 and 600°C, were applied at five rates in a Red‐Yellow Oxisol. The application of biochars may reduce the demand for nutrients and correctives, optimize phosphorus fertilization and improve the development of Brachiaria brizantha, but this ability depends on the raw material and the pyrolysis temperature used in its production. All analysed biochars can contribute to higher tillering and dry matter production, but only coffee straw biochars and eucalyptus bark biochar produced at 350°C were efficient in the optimization of phosphorus fertilization until 120 days of cultivation of Brachiaria brizantha.

INVESTIGATION OF PHOSPHATE-ION RETENTION STRENGHT IN SOME TYPES OF KAKHETI SOILS

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

Application of fishpond sediment and water to increase the efficiency of phosphorus fertilization in land integrating agriculture and fishery

The utilization of water from Mount Salak by farmers in addition to agriculture activities is also for fishponds that are widely spread among agricultural lands. The phosphate from fishpond sediment and water flowing to the river was supposed contributing to the enriched phosphate in the Jakarta Bay. The use of fishpond sediment and water in agricultural land was expected to decrease the load of phosphate to the river and increase the efficiency of phosphorus (P) fertilization by decreasing P sorption and increasing the release of P. The fishpond sediment with the rates of 0, 2.5%, 5.0%, 7.5% and 10% were combined with fishpond water or distilled water for watering. They were incubated for one month. The experiment was set up in Completely Randomized Design with three replicates. The results showed that fishpond sediment treatments decreased P bonding energies of P sorption and after P desorption and also the rate constant of P sorption. The best treatment in this experiment was the application of 10% of fishpond sediment watered by fishpond water for those determined parameters. The results suggested that application of fishpond sediment and water increased the efficiency of P fertilization in land integrating agriculture and fishery.

Investigation of phosphate-ion retention strenght in some types of Kakheti soils

The presented article describes the soil types existing in east Georgia, particularly in several villages of Gurjaani Municipality-Vazisubani, Kalauri, Mukuzani, Shashiani. Meadow-brown and brown soils represent good soil types for viticulture development in Kakheti. The vineyards cultivated on these soils produce such wellknown wines as Tsinandali, Vazisubani, Mukuzani, Akhasheni, Gurjaani, Manavi. The study explores brown carbonate and meadow-brown soil lab tests to examine the absorption of phosphate ions by them. The study showed that the amount of phosphorus deposited through soils is sufficiently absorbed under various conditions, having a positive effect on the amount of crop. Was compared the rates of phosphate absorption in these soils with the efficiency of phosphorus fertilizers, which showed that the higher the absorption of phosphorus, the lower the amount of phosphorus available to the plant and the lower the yield, and the lower the strength of phosphorus retention, the higher the amount of phosphorus to be consumed by the plant and the higher the yield. But under the conditions of high cultivation degree, the strength of phosphorus absorption became weak, resulted in a large amount of exchangeable and movable phosphates already existing in the soil, which is available to the plant. So, the efficacy of phosphorus fertilizers on such soil is weak. The speed of phosphorus absorption in the soil of Gurjaani municipality villages is satisfactory. However, in case of a high degree of cultivation (or in case of excess fertilization), the degree of phosphorus retention decreases. Accordingly, phosphorus-containing fertilizers should be used within strictly controlled limits.

Effect of Millet Growth, N Sources and Previous Phosphorus Availability on the Efficiency of P Sources

The efficiency of phosphate fertilization has been a major challenge for tropical agriculture. Lately, cover plants better adapted to tropical conditions have allowed non-tillage in these areas. Our aim was to investigate the effects of soil and plant (millet) on the efficiency of different P sources combined with N sources in an oxisol with medium and low initial P availability. For this, rhizotubes filled with oxisol under different combinations of P and N source were exposed to the absence and presence of millet plant (Pennisetum glaucum L., Leeke). We characterized the soil before and after, as well the fertilizer sources and plants. There was no effect of medium or low initial P availability in the soil on the P recovery rate (PRR). NH4+ was advantageous mainly combined with a soluble P source, increasing up to 40% the P recovery rate in relation to NO3−. Bayóvar phosphate rock (PR) had higher solubilization than Araxá PR, as well as a significant soil pH increase. Without plants, there was no significant correlation among the variables evaluated, evidencing the plant’s role in dissolving less soluble P sources in an oxisol. Our findings suggest no effect of previous medium P availability on the P recovery rate regardless of phosphorus sources. In addition, an improvement in the P recovery rate when an ammoniacal source is used is observed when soluble phosphate fertilizers are used. Cover plants on oxisols are crucial for increasing the efficiency of phosphorus fertilizers and their plant availability over time.

Teor de macronutrientes e produtividade da soja influenciados pela compactação do solo e adubação fosfatada

The objective of this study was to evaluate the influence of compaction and phosphorus fertilization on the macronutrient tenor and productivity of soybeans in Chapada dos Parecis-MT. The study was conducted on Latossolo Vermellho, in a randomized block design, factorial 2x4x4 and three repetitions, two forms of phosphorus fertilization (broadcasted and groove), four doses of P2O5 (0, 50, 100 and 150 kg ha-1) and four compaction levels (PT0, PT2, PT4 and PT8 - tillage with compression-induced tractor traffic at zero, two, four and eight strides, respectively). Compaction, the form of fertilizer and P2O5 levels influenced the availability of phosphorus in the soil and the absorption of the element by the plant, and in the more compressed systems fertilized by throwing the P levels in soybeans were below the limits considered appropriate. The compaction reduced N, P, Ca and Mg and increased or K and S and P2O5 doses increased the Mg content of the soybean shoot. Fertilization by throwing in compacted areas reduced the efficiency of phosphorus fertilization with consequent reduction in soybean yield.

Evaluation of effects of water-saving superabsorbent polymer on corn (Zea mays L.)yield and phosphorus fertilizer efficiency

There is growing interest in using a reduced rate of mineral fertilizer along with water-saving superabsorbent polymer (WSAP) for field crop production in arid and semiarid regions of the world. The overall objective of this study was to evaluate the effects of hydrogel applications on the phosphorus fertilizer efficiency parameter, yield, and selected physiological properties of corn (Zea mays L.) grown at different levels of water deficiency in greenhouse conditions. The experimental design consisted of 3 completely randomized blocks in a factorial arrangement, with 9 hydrogel doses (0%, 0.01%, 0.02%, 0.04%, 0.08%, 0.12%, 0.2%, 0.4%, and 0.6%), 4 phosphorus fertilizer doses (0, 80, 160, and 240 kg ha-1), and 4 water deficiency levels (50%, 65%, 80%, and 100%). Overall, 432 pots were used in this study. We found that the irrigation interval of 0.0% WSAP (control) application treatment at water deficient conditions (WDC 50%) was 6 days, although this value could be increased to 11 days with 0.4% WSAP application treatment. The highest yield was obtained from 0.40% WSAP with 240 kg ha-1 P application dose at 35% deficient irrigation conditions according to leaf relative water content, the chlorophyll reading value of corn plants, and P fertilizer efficiency parameters such as agronomic efficiency, physiological efficiency, use efficiency, and apparent recovery efficiency values. These findings suggest that the application of 0.40% WSAP with 240 kg ha-1 P and economic soil management practice could provide an efficient corn production operation in drought-affected regions such as eastern Turkey and other areas with similar ecologies.

Agronomic efficiency of polymer-coated triple superphosphate in onion cultivated in contrasting texture soils

Information related to phosphate fertilization and coated phosphate fertilizer in onion is scarce. Thus, this study was carried out to evaluate agronomic efficiency, production and nutritional characteristics of triple superphosphate coated with polymers in onion cultivated in contrasting texture soils. Two experiments were carried out under protected conditions in pots containing 5 kg soil. The experimental design was completely randomized with treatments arranged in a 2 x 5 factorial: triple superphosphate (TSP) and polymer-coated triple superphosphate (TSP+P) applied in five phosphorus rates: Dystroferric Red Latosol (LVdf) (clayey) = 0; 100; 200; 400; 800 mg P2O5 kg-1, and Quartzarenic Neosol (sandy) = 0; 75; 150; 300; 600 mg P2O5 kg-1, with three replications. Results indicated that polymer-coated TSP showed no difference for bulb mass and agronomic efficiency for phosphorus fertilization. Agronomic efficiency of phosphorus fertilization decreased with the increase in the amount of phosphorus applied. Phosphorus accumulation for onion bulb cultivated in Dystroferric Red Latosol (LVdf) was higher with the use of polymer-coated triple superphosphate. Growth, production and nutritional characteristics in onion were affected by phosphorus. The highest bulbs mass production and phosphorus accumulation occurred at the doses of 783; 629 mg kg-1 P2O5 (Dystroferric Red Latosol - LVdf), and of 406; 600 mg kg-1 P2O5 (Quartzarenic Neosol -RQ).

Rendimento de cebola em função da dose e do modo de aplicação de fósforo

A cebola apresenta elevada resposta à aplicação de adubos fosfatados, sendo praticadas aplicações a lanço de doses de fósforo (P) maiores que as preconizadas pelas recomendações oficiais. Devido a seu sistema radicular restrito, é possível que a localização da adubação fosfatada permita o uso mais eficiente do nutriente, reduzindo a dose de P necessária para a cultura. O objetivo deste trabalho foi avaliar a resposta da cebola a doses de P aplicadas a lanço ou na linha de cultivo em um Cambissolo Húmico. Foram testadas cinco doses de P (0, 120, 240, 360 e 480 kg P2O5 ha-1) e dois modos de aplicação (a lanço e na linha de plantio), em delineamento inteiramente casualizado, com quatro repetições, em esquema fatorial 5x2. Foi usada a cultivar EPAGRI 352 Bola Precoce, plantada no dia 22/07/2014 e colhida em 15/11/2014. Houve resposta linear da cebola à aplicação de P, com incremento na produtividade de 16,7 kg e 0,08 mm de diâmetro do bulbo para cada quilograma de P2O5 aplicado. Não foi observada resposta da cultura ao modo de aplicação do P na linha de plantio ou a lanço, indicando que para essa cultura a localização do fertilizante não aumenta a eficiência da fertilização fosfatada.

Resposta de vetiver à aplicação de calcário e fósforo em três classes de solo

O vetiver tem sido bastante utilizado para controle de erosão, principalmente em áreas degradadas em que o horizonte superficial do solo foi removido. O manejo do solo pode influenciar a eficiência de absorção de nutrientes e o crescimento das plantas. Este trabalho objetivou avaliar a produção de matéria seca de vetiver em resposta à aplicação de calcário e fósforo. O experimento foi conduzido em casa de vegetação utilizando-se amostras de horizontes subsuperficiais de um Cambissolo Háplico, um Latossolo Amarelo e um Argissolo Amarelo. O experimento foi instalado no delineamento em blocos ao acaso, com três repetições, em esquema fatorial 2 x 5 sendo duas doses de calcário (0 t ha-1 e dose para elevar a saturação por bases a 60%) e cinco doses de fósforo (0, 50, 100, 200, 400 mg dm-3 de P), totalizando 30 unidades experimentais por solo. Após a incubação foram aplicadas as doses de fósforo e, a seguir, feito o plantio de vetiver. Aos 168 dias após o plantio as plantas foram colhidas separando-se a parte aérea e as raízes. A calagem e a adubação fosfatada promoveram aumento da produção de perfilhos e de matéria seca em vetiver. A calagem aumentou a eficiência da adubação fosfatada e, em consequência, favoreceu o estabelecimento do vetiver.

The effect of phosphate solubilizing microbe producing growth regulators on soil phosphate, growth and yield of maize and fertilizer efficiency on Ultisol

Ultisol is soil that have problem of soil acidity, low organic matter and low available macro nutrient in particularly low P availability. This is only small part of phosphorus is available for plant because most of the phosphate was still present in the soil were fixed by soil colloids. Some soil microbes are known phosphate solubilizing microbes have capability to dissolve phosphate that transform of P fixed into the soluble P. The field experiment conducted at Jatinangor, West Java Indonesia to determine the effect of PSM on phosphate solubility, growth and yield of maize and phosphorus fertilizer efficiency. Design experiment of Randomized Block Design (RBD) was used in field experiment, consisted of two factors and three replications. Phosphate solubilizing microbe as the first factor consisted four levels i.e without, phosphate solubilizing bacteria (PSB), phosphate solubilizing fungi (PSF), mixture of PSB and PSF. While the second factor was P fertilizer consists five levels (0%, 25%, 50%, 75% and 100% doses of recomendation). The results of the field experiment showed that application of phosphate solubilizing microbes significantly improve the yield of maize in Ultisol Jatinangor, but did not significantly affect on soil P, available soil P, phosphatase and P uptake of plants. Application of a mixture of PSB and PSF better effect on soil available P and yield of maize. Phospate fertilizer dosing at a dose of 25 % , 50 % , 75 % and 100 % recommendations increased available soil P. Fertilizer of P could inhibit the activity of phosphatases. Phosphate fertilizer with dose 50 % recommendation gave better effect on soil P and yield of maize.

Effect of phosphorus application on soil available phosphorus and maize phosphorus uptake and yield

为了给玉米磷高效利用提供理论依据, 在低磷土壤(Olsen-P 4.9 mg·kg^-1)上, 通过田间试验, 研究了施磷0(T₀)、50 kg(P₂O₅)·hm^-2(T₁)、100 kg(P₂O₅)·hm^-2(T₂)、200 kg(P₂O₅)·hm^-2(T₃)、1 000 kg(P₂O₅)·hm^-2(T₄)对两个玉米品种"鲁单9002" (LD9002)、"先玉335"(XY335)的产量、磷素吸收利用及根际磷动态变化的影响。结果表明: 两玉米品种根际土、非根际土速效磷含量在不同生育时期都表现为T1<T2<T3<T4; 播种后61 d时施磷200 kg(P₂O₅)·hm^-2的T₃处理非根际土转化为根际土土壤磷的量最大, 同时玉米生物量、产量、磷转移量也达到最高, 而施磷1 000 kg(P₂O₅)·hm^-2处理玉米生物量、产量与中磷水平相比没有显著增加, 但植株吸磷量较高。XY335的花后磷转移量小于LD9002。相关分析表明, LD9002根际土、非根际土速效磷含量与茎、叶吸磷量之间显著相关, 以播种后79 d与茎、叶磷浓度、吸磷量、生物量、产量之间的相关系数最高; 而XY335根际土、非根际土速效磷含量与茎、叶磷浓度之间显著相关, 在播种后47 d期间与茎、叶磷浓度、吸磷量、生物量、产量之间的相关性最好。因此, 在低磷土壤上, LD9002和XY335分别在播种后79 d和47 d时是植株对磷的敏感期, 可以通过测试根际土、非根际土速效磷含量来反映土壤的供磷状况; LD9002在79 d时最大吸磷量需要的根际土、非根际土速效磷含量分别为54.95 mg·kg^-1、32.99 mg·kg^-1, XY335品种在47 d时最大吸磷量需要的根际土、非根际土速效磷含量分别为51.24 mg·kg^-1、35.35 mg·kg^-1; 施磷量1 000 kg(P₂O₅)·hm^-2处理两品种玉米产量、生物量、磷积累量与施磷量100~200 kg(P₂O₅)·hm^-2处理没有显著差异。

THE ROLE OF MAGNESIUM IN INCREASING OF PHOSPHORUS FERTILIZER EFFICIENCY AND WHEAT YIELD

The study was conducted during the growing season 2003 to study the influence of four levels of P (0, 60, 100 and 140 kg ha -1 ) and four levels of Mg (0, 40, 80 and 120 kg ha -1 ) at two locations (Bakrajow and Kalar) on growth and yield of wheat and phosphorus fertilizer efficiency. The results indicated to the response of wheat to phosphorous fertilizer at Bakrajow location only. While the application of 40 kg Mg ha -1 caused significant increase in wheat yield at Bakrajow location only. The highest phosphorus fertilizer efficiency was 34.44% and 55.24% at Bakrajow and Kalar respectively while the Mg fertilizer efficiency was 7.6% and 22.8% at Kalar and Bakrajow respectively.