Phosphorus Fertilizer Management Research Articles

Phosphorus transformation and balancing under a long-term rice-rice cropping system in an inceptisol of India

Phosphatic fertilizers applied to soil, with time, alters into different insoluble soil phosphorus fractions. Since P fertilizers are expensive and raw material supplies are limited, it is essential to evaluate changes in phosphorus fractions and balance in soil in order to determine appropriate phosphorus fertilizer management strategies for sustainable yields. A long-term experiment (20 years) was conducted in an inceptisol with rice-rice cropping system. Soil samples were collected from six treated plots and one fallow; analyzed for phosphorus fractions using sequential extraction method. Phosphorus balance was computed. The results reveled that yield was 51.5, 112.0, 147.7 and 116.7% higher under 50% NPK, 100% NPK, 150% NPK and 100% NPK + FYM over control. Irrespective of the treatments, the abundance of the various fractions of phosphorus (P) in soil as follows: Organic P (32.4% of total P) > Calcium-P (27.76% of total P) > Mineral P (24.17% of total P) > Iron-P (6.65% of total P) > Aluminum-P (3.46% of total P) > Reductant soluble P (3.22% total P) > Occluded P (1.44% of total P) > Saloid P (0.89% total P). Phosphorus activation coefficient (%) was recorded higher under 150% NPK followed by 100% NPK + FYM > 100% NPK > 50% NPK > 100% N > control > Fallow. Hence, 100% NPK + FYM treatment has maintained phosphorus fractions in a good proportion and sustainable yields under rice-rice cropping system.

Phosphorus fertilizer management for high yields in intensive winter wheat-summer maize rotation system: Integrating phosphorus budget and soil available phosphorus

Overuse of phosphorus (P) fertilizer in crop cultivation accelerates the consistent increase in soil P accumulation and increases the risk of P leaching from the agricultural system. The long-term implications of balanced P management on soil P availability and crop P uptake are still unknown. A three-year field experiment with six different P rates was conducted to determine the effect of a balanced P application strategy on crop yield, P uptake, soil P accumulation, and P transformation in a winter wheat-summer maize rotation system. The results found that the yield and P uptake of summer maize and wheat increased linearly with P fertilization up to 12.5 kg P ha–1, after which they stabilized, and the critical threshold is 50 kg P ha–1 for winter wheat. The soil P budget under agronomic thresholds from 2017 to 2020 was observed as –2.99 to –11.04 kg P ha−1 for maize but 15.1–24.5 kg P ha–1 for wheat. Excessive P fertilization accelerated the downward movement of soil P and stocked it in the deep soil in the form of soil labile P and moderately labile P, increasing the risk of soil P leaching. The annual application of 600 kg ha–1 P fertilizer substantially increased the total P concentration by 30%–99% from deep soil to topsoil compared to the no P treatment, while the 75 kg ha–1 and 150 kg ha–1 P fertilizer treatments did not affect soil P accumulation along the soil profile. Soil Olsen-P concentration to meet crop yield requirements is still far from meeting the critical environmental threshold of 47.6 mg kg–1 and increased slightly by an annual 2.39 mg kg–1 under the balanced P fertilization strategy. An annual negative soil P budget of 3–11 kg ha–1 for summer maize could sustain optimal yields and P use efficiency. Winter wheat cultivation required additional P application to reach the agronomic threshold, set at 15–25 kg ha–1 annually. In conclusion, balanced P fertilization can reduce soil P surplus and subsoil P stock while maintaining crop yields.

Exploring phosphorus fertiliser management in wheat production

Efficient utilisation of phosphorus (P) is paramount for crop production, resource sustainability, and food security. For responsible management of P fertilisers across varying fertilisers supply scenarios in wheat cultivation, it is imperative to systematically assess the impact of soil characteristics, crop varieties, and crop rotation practices on P efficiency. The yield response to applied P (YRP) and the agronomic efficiency of applied P (AEP) were investigated in 2872 field experiments across the major wheat production areas of China. The influence and relative importance of these factors under the different P treatments were quantified and identified. Across all farms, the average wheat yields in the CK (no P application), 100%P (locally recommended dosage), 50%P, and 150%P treatments were 5574, 6472, 6098, and 6384 kg ha−1, respectively. The highest YRP was obtained in the 100%P treatment (18.2%), while the AEP decreased from 20.7 kg kg−1 to 10.8 kg kg−1 as the P supply increased from 50%P to 150%P treatment. Both YRP and AEP were significantly influenced by soil organic matter (SOM) and available P (Olsen-P). In addition, varieties with better advantages in terms of YRP and AEP were identified in Regions I, II, and III. Random forest analysis showed that the importance of the variables for YRP and AEP differed substantially with different P treatments, suggesting that different strategies are required for different farmland management units. However, regardless of whether P fertilisers was insufficient or excessive, variety was the most important variable for enhancing P-use efficiency. In conclusion, this analysis is useful for the better management of P fertilisers in wheat production.

Polyphosphate fertilizer impacts the enzymatic and non-enzymatic antioxidant capacity of wheat plants grown under salinity

By 2050, the predicted global population is set to reach 9.6 billion highlighting the urgent need to increase crop productivity to meet the growing demand for food. This is becoming increasingly challenging when soils are saline and/or deficient in phosphorus (P). The synergic effect of P deficiency and salinity causes a series of secondary stresses including oxidative stress. Reactive Oxygen Species (ROS) production and oxidative damage in plants caused either by P limitation or by salt stress may restrict the overall plant performances leading to a decline in crop yield. However, the P application in adequate forms and doses could positively impact the growth of plants and enhances their tolerance to salinity. In our investigation, we evaluated the effect of different P fertilizers forms (Ortho-A, Ortho-B and Poly-B) and increasing P rates (0, 30 and 45 ppm) on the plant's antioxidant system and P uptake of durum wheat (Karim cultivar) grown under salinity (EC = 3.003 dS/m). Our results demonstrated that salinity caused a series of variations in the antioxidant capacity of wheat plants, at both, enzymatic and non-enzymatic levels. Remarkably, a strong correlation was observed between P uptake, biomass, various antioxidant system parameters and P rates and sources. Soluble P fertilizers considerably enhanced the total plant performances under salt stress compared with control plants grown under salinity and P deficiency (C+). Indeed, salt-stressed and fertilized plants exhibited a robust antioxidant system revealed by the increase in enzymatic activities of Catalase (CAT) and Ascorbate peroxidase (APX) and a significant accumulation of Proline, total polyphenols content (TPC) and soluble sugars (SS) as well as increased biomass, Chlorophyll content (CCI), leaf protein content and P uptake compared to unfertilized plants. Compared to OrthoP fertilizers at 45 ppm P, Poly-B fertilizer showed significant positive responses at 30 ppm P where the increase reached + 18.2% in protein content, + 156.8% in shoot biomass, + 93% in CCI, + 84% in shoot P content, + 51% in CAT activity, + 79% in APX activity, + 93% in TPC and + 40% in SS compared to C+. This implies that PolyP fertilizers might be an alternative for the suitable management of phosphorus fertilization under salinity.

Corn and Soybean Yield as Affected by Cover Crop and Phosphorus Fertilizer Management

Corn and Soybean Yield as Affected by Cover Crop and Phosphorus Fertilizer Management

Agronomic and economic implications of cover crop and phosphorus fertilizer management practices for water quality improvement.

Phosphorus (P) fertilization practices and winter cover crops are promoted to protect water quality yet can potentially influence crop yield and profitability. This study examined the impacts of three P fertilizer management practices (no P, fall broadcast P, and spring injected P) and winter annual cover crop use on yields, net returns, and water quality in a no-till corn-soybean rotation. Treatments were replicated in a 4-yr field study where sediment, total P, and dissolved reactive P (DRP) losses in edge-of-field surface runoff were continuously monitored. Production budgets were developed for each treatment and coupled with water quality data to identify optimal practices and opportunity costs for improving water quality. Applying P fertilizers increased crop yield regardless of application method or cover crop, but the response was more pronounced in corn than soybean. The cover crop reduced corn grain yield in 1 yr with high temperature and low precipitation but did not impact grain yield in the other corn year or either year of soybean. The most profitable treatment was fall broadcast P fertilizer with no cover crop, which also had the greatest total P and DRP losses and near greatest sediment loss. The lowest-cost methods of reducing total P, DRP, and sediment losses were, respectively, no P fertilizer without a cover crop ($47.56kg-1 total P), spring injected P fertilizer without a cover crop ($56.47kg-1 DRP), and spring injected P fertilizer with a cover crop ($0.16kg-1 sediment). Widespread adoption of these practices will likely require monetary incentives.

Closing county-level yield gaps through better phosphorus fertilizer management in Northeast China

The limited available information on variations in yield gaps (differences between actual yields and the theoretically attainable yields) restricts the development of rational strategies to optimize yields and reduce environmental costs. Quantifying the yield potential and the variations in yield gaps will help identify factors that limit yields and will enable a narrowing of the current yield gap. Here, we applied an analytical framework to yield data to identify options for closing the yield gap at the county level. We used a database containing yields for 40 counties and data from 87 representative on-farm experiments in Jilin Province, China, from 2006 to 2008. The yield potential was simulated for each region-year using a Hybrid-Maize model (http://www.hybridmaize.unl.edu/) and weather data. We then conducted a systematic and spatial analysis of actual yields to identify yield gaps at the county level. The simulated average potential yield at 27 representative sites was 15.2 Mg ha−1 (range 8.1–17.6 Mg ha−1) in Jilin Province. The on-farm experiments suggested an attainable potential yield ranging from 8.7 to 16.7 Mg ha−1 across Jilin Province. During this period, the actual maize yield varied between 4.1 and 11.9 Mg ha−1, according to the county-level data. Farmers’ fields, therefore, achieved 52% of the model yield potential and 77% of the attainable potential yield. Widely different amounts of P fertilizer input among farmers contributed significantly to regional variations in YGE. Soil Olsen-P and rainfall were also major factors. The results indicate that there is great potential to substantially increase the maize yield in non-optimal P management regions, such as in the western Jilin Province. Hence, improvements in regional P management strategies, such as at the county level, need to be assessed separately to provide a basis for increasing the actual maize yield.

Enrichment and Ecological Risk Assessment of Available Phosphorus in Paddy Soil of Fujian Province Over Past 40 years

The ecological risks such as water eutrophication caused by soil phosphorus loss have attracted extensive attention, and its dynamic changes and enrichment effects are the basis for formulating reasonable control measures. In this study, based on the paddy soils of 1.8×106 hm2 in Fujian province, the dynamic changes and ecological risks of available phosphorus in paddy soils over the past 40 years were analyzedusing a soil database of 1:50000. The soil database contained 1471, 215534, and 2895 paddy soil samples in different periods, respectively. The paddy soil samples were derived from the 1982 Second National Soil Census, the 2008 Ministry of Agriculture and Rural Areas Soil Testing and Formulated Fertilization Project and the 2018 Ministry of Agriculture, and the Rural Areas Arable Land Quality Monitoring Project, respectively. The results showed that from 1982 to 2018, the content of available phosphorus in paddy soils increased by 47 mg·kg-1, and the enriched area reached 1.65×106 hm2, accounting for 91% of the total paddy soils in Fujian province. From 1982 to 2008, the available phosphorus content of paddy soils in Fujian province increased by 28 mg·kg-1, with the enriched area reaching 1.47×106 hm2, accounting for 82% of the total paddy soils in Fujian province. From 2008 to 2018, the available phosphorus content of paddy soils in Fujian province increased by 19 mg·kg-1, with the enriched area reaching 1.22×106 hm2, accounting for 69% of the total paddy soils in Fujian province. Further ecological risk assessment showed that from 2008 to 2018, the area of paddy soil with ecological phosphorus enrichment risk in the province gradually increased, mainly distributed in percogenic paddy soils and hydromorphic paddy soils with a slope of less than 2°. In the future, effective phosphorus fertilizer management measures should be formulated for different types of paddy soil to prevent the occurrence of environmental problems such as water eutrophication.

Cover crop and phosphorus fertilizer management impacts on surface water quality from a no-till corn-soybean rotation

Best management practices that reduce potential phosphorus (P) loss and provide flexibility in P fertilizer management are needed to help producers protect water quality while maintaining crop yield. This study examined the impacts of P fertilizer management (no P, fall broadcast P, and spring injected P) and cover crop use on annual concentrations and loads of sediment, total P, and dissolved reactive P (DRP) in edge-of-field runoff from a no-till corn (Zea mays)-soybean (Glycine max) rotation in the Central Great Plains, USA, from September 2015 through September 2019. The spring injected P fertilizer treatment generally had 19% less total P and 33% less DRP loss compared to the fall broadcast treatment, confirming the importance of P fertilizer management as a practice for reducing P loss. The addition of a cover crop had an inconsistent effect on total P loss, with no effect in 2016 and 2017, increasing loss in 2018 by 56%, and decreasing it in 2019 by 40%. The inconsistent impact of cover crops on total P loss was related to cover crop effects on sediment loss. Although cover crop impacts on total P losses were inconsistent, the addition of a cover crop increased DRP loss in three of four years. Cover crop use consistently reduced sediment loss, with greater sediment reduction when P fertilizer was applied. Results from this study highlight the benefit of cover crops for reducing sediment loss and the continued need for proper fertilizer management to reduce P loss from agricultural fields.

Intensive management of phosphorus fertilization in Camellia oleifera Abel. to minimize phosphorus losses to the environment

Camellia (Camellia oleifera Abel.) plantation often needs fertilizer application to ensure fruit yield, and camellia fruit yield might be affected by soil phosphorus supply and microbial community and function. However, a large fraction of applied phosphorus is lost through leaching and runoff, which may cause eutrophication risks in waterbodies. Intensive management of phosphorus fertilization based on the comprehensive balance among fruit yield, soil nutrient and microbial property is required to quantify appropriate phosphorus fertilization rate. In this study, a camellia plantation located in southern China was selected, and four different fertilization treatments were established: control without P fertilizer (P0); 114.5 kg phosphorus pentoxide ha−1 applied as sodium dihydrogen phosphate (P1); 229.0 kg phosphorus pentoxide ha−1 (P2) and 343.5 kg phosphorus pentoxide ha−1 (P3). The fruit yields of P1, P2 and P3 treatments were approximately 1.5, 2.0 and 2.0 times of that measured from the P0 treatment, respectively. Bacterial community richness estimators and diversity indices in the P2 treatment were significantly higher than those in the P3 treatment. Relative abundances of Bacteroidetes, Planctomycetes, Verrucomicrobia and Eremiobacterota were significantly affected by the phosphorus fertilization. The gram-negative bacterial relative abundance was significantly lower in the P3 treatment than in the other treatments. Relative to the P2 treatment, the P3 treatment had significant decreases in soil pH, bacterial community diversity and gram-negative bacterial relative abundance, which might offset the stimulation of higher phosphorus supply for fruit yield. Based on the comprehensive balance among fruit yield, fertilization input cost, soil environment impact and microbial property, 229.0 kg phosphorus pentoxide ha-1 fertilization is appropriate for this camellia plantation. Future phosphorus fertilization in the camellia plantation should consider the comprehensive balance among yields, soils and microbial properties.

Long Term Effect of Organic, Inorganic and Integrated Nutrient Management on Phosphorous Dynamics under Different Cropping Systems of Typic Ustochrept Soil of India

ABSTRACT Information on phosphorus (P) dynamics in soil is crucial for careful management of phosphorus fertilization in respect to the sustainable development of agriculture in IGP regions. The sorption and desorption of phosphate, different fractions of phosphate, dehydrogenase activity, acid and alkaline phosphatase activity were studied in soils under organic inorganic and integrated nutrient management practices in four different cropping systems. The P adsorption maxima of long-term organic soil was highest (77.52 µg P g−1) under coarse rice-barley-green gram cropping system. The bonding energy of phosphorus in the soil solution varies from 0.38 to 0.20 ml µ−1. Average across the cropping systems, the bonding energy of adsorb P were 68.54% and 39.05% higher under organic and integrated nutrient-managed plots respectively as compared to the inorganic nutrient management. Maximum buffering capacity of phosphate was observed (29.59 ml g−1 soil) under Coarse rice-barley-green gram cropping systems in organic nutrient management practice. Application of organic nutrient management practice increases 26.04% higher water-soluble phosphorus (WSP) as compared to the inorganic nutrient management practice, average across the cropping systems. All other fractions of phosphorus in the soil were higher under inorganic nutrient management that leads to higher amount of total of phosphorus, average across the cropping systems. Long-term application of organic for 14 years increases the bonding energy and adsorption capacity for P in soil but decreased its desorption potential, increasing P availability to the plant and leading to higher P uptake irrespective of cropping systems.

Physiological and developmental traits associated with the grain yield of winter wheat as affected by phosphorus fertilizer management

Although researchers have determined that attaining high grain yields of winter wheat depends on the spike number and the shoot biomass, a quantitative understanding of how phosphorus (P) nutrition affects spike formation, leaf expansion and photosynthesis is still lacking. A 3-year field experiment with wheat with six P application rates (0, 25, 50, 100, 200, and 400 kg P ha−1) was conducted to investigate this issue. Stem development and mortality, photosynthetic parameters, dry matter accumulation, and P concentration in whole shoots and in single tillers were studied at key growth stages for this purpose. The results indicated that spike number contributed the most to grain yield of all the yield components in a high-yielding (>8 t/ha) winter wheat system. The main stem (MS) contributed 79% to the spike number and tiller 1 (T1) contributed 21%. The 2.7 g kg−1 tiller P concentration associated with 15 mg kg−1 soil Olsen-P at anthesis stage led to the maximal rate of productive T1s (64%). The critical shoot P concentration that resulted in an adequate product of Pn and LAI was identified as 2.1 g kg−1. The thresholds of shoot P concentration that led to the maximum productive ability of T1 and optimal canopy photosynthetic capacity at anthesis were very similar. In conclusion, the thresholds of soil available P and shoot P concentration in whole plants and in single organs (individual tillers) were established for optimal spike formation, canopy photosynthetic capacity, and dry matter accumulation. These thresholds could be useful in achieving high grain yields while avoiding excessive P fertilization.

Effects of Cover Crops and Phosphorus Fertilizer Management on Soil Health Parameters in a No-Till Corn-Soybean Cropping System in Riley County, Kansas

Effects of Cover Crops and Phosphorus Fertilizer Management on Soil Health Parameters in a No-Till Corn-Soybean Cropping System in Riley County, Kansas

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.

Phosphate sorption and desorption by two contrasting volcanic soils of equatorial Africa.

Volcanic soils cover 1% of the Earth’s surface but support 10% of the world’s population. They are among the most fertile soils in the world, due to their excellent physical properties and richness in available nutrients. The major limiting factor for plant growth in volcanic soils is phosphate fixation, which is mainly attributable to active species of aluminium and iron. The sorption and desorption of phosphate is studied on the surface horizons of two African agricultural soils, a silandic Andosol (Rwanda) and a vitric Andosol (São Tomé and Principe). Both soils are slightly acid. The silandic Andosol is rich in active aluminium forms, while the vitric Andosol has high amounts of crystalline iron and aluminium oxides. Sorption isotherms were determined by equilibrating at 293K soil samples with phosphate solutions of concentrations between 0 and 100 mg P L−1 in NaNO3; phosphate was determined by visible spectrophotometry in the equilibrium solution. To study desorption, the soil samples from the sorption experiment were equilibrated with 0.02 M NaNO3. The isotherms were adjusted to mathematical models. In almost all the concentration range, the adsorption of phosphate by the silandic Andosol was greater than 90% of the amount added, being lower in the vitric Andosol but always higher than 65%. The high sorption by the silandic Andosol is attributed to its richness in non-crystalline Fe and Al, while in the vitric Andosol crystalline iron species seem to play a relevant role in the adsorption. The sorption isotherms of both soils fitted to the Temkin model, the adjustment to the Langmuir or Freundlich models being unsatisfactory; throughout the range studied, the sorption increases with increasing phosphorus concentration, a maximum sorption is not predictable (as occurs when the sorption is adjusted to the Langmuir model). For an added P concentration of 100 mg L−1 (3.2 mmol L−1), the sorption is 47.7 µmol P g−1 in the silandic Andosol and 41.6 µmol P g−1 in the vitric Andosol. The desorption is low and the comparison of the sorption and desorption isotherms reveals a pronounced hysteresis, that is, the irreversibility of the sorption. The high phosphate sorption and its irreversibility are comparable to those published for other volcanic soils with high contents of allophane, active aluminium and free iron. The strong phosphate adsorption is a serious limiting factor for plant growth, which requires a careful management of phosphorus fertilization.

Transforming soil phosphorus fertility management strategies to support the delivery of multiple ecosystem services from agricultural systems

Despite greater emphasis on holistic phosphorus (P) management, current nutrient advice delivered at farm-scale still focuses almost exclusively on agricultural production. This limits our ability to address national and international strategies for the delivery of multiple ecosystem services (ES). Currently there is no operational framework in place to manage P fertility for multiple ES delivery and to identify the costs of potentially sacrificing crop yield and/or quality. As soil P fertility plays a central role in ES delivery, we argue that soil test phosphorus (STP) concentration provides a suitable common unit of measure by which delivering multiple ES can be economically valued relative to maximum potential yield, in $ ha−1 yr−1 units. This value can then be traded, or payments made against one another, at spatio-temporal scales relevant for farmer and national policy objectives. Implementation of this framework into current P fertility management strategies would allow for the integration and interaction of different stakeholder interests in ES delivery on-farm and in the wider landscape. Further progress in biophysical modeling of soil P dynamics is needed to inform its adoption across diverse landscapes.

Impact of Cover Crops and Phosphorus Fertilizer Management on Nutrient Cycling in No-Tillage Corn-Soybean Rotation

Impact of Cover Crops and Phosphorus Fertilizer Management on Nutrient Cycling in No-Tillage Corn-Soybean Rotation

Phosphorus fractions and correlation with soil attributes in a chronosequence of agricultural under no-tillage

In no-tillage (NT) soils, changes in the quantity and quality of soil organic matter (SOM) have been observed over time. These changes can interfere with the dynamics of P in surface soil layers. Thus, the objectives of this study were: to evaluate the organic and inorganic fractions of P and their degree of lability (labile, moderately labile, and moderately recalcitrant) in an Oxisol under NT for 6 years (NT6), 14 years (NT14), and 22 years (NT22) and cultivated with a succession of soybean and corn/wheat. The fractions were evaluated for 16 years of NT, with the last four years under integrated corn second crop and Brachiaria (NT16+B). We also analyzed an area of native forest, as well as analyzing the correlations between the results of the P fractions of these areas with other attributes such as total carbon content, vegetable waste deposited on the ground, phosphorus and humic fractions remaining in SOM. From each of the areas, samples were collected at 0.00-0.05 m and 0.05-0.10 m. A completely randomized design with 5 replicates was used. Management of phosphorus fertilization and SOM following adoption of the SPD of time (6 to 22 years) increased the levels of all fractions of inorganic P (0.0 to 0.10 m), as well as the fractions of labile (0.05-0.10 m), moderately labile (0.0-0.10 m), and moderately recalcitrant (0.05-0.10 m) organic phosphorus. The correlation matrix shows interactions between the evaluated soil attributes, especially between inorganic phosphorus fractions and fulvic and humic acids and between the moderately recalcitrant organic phosphorus and humin fraction.

Manejo de la fertilización fosforada en el cultivo de maíz, El Ejido, Panamá 2004-2013.

<p class="p1">El objetivo del presente trabajo fue determinar, en el cultivo de maíz, el efecto del manejo de la fertilización fosforada a mediano y largo plazo con dos métodos de aplicación. Se estableció un experimento en El Ejido, Panamá, del 2004 al 2013 en un suelo Udic Haplustalf. Se evaluaron dos componentes en un factorial 5 x 4 con arreglo de fajas bajo un diseño de bloques al azar con tres repeticiones. En la parcela principal se aplicó P al voleo en dosis de 0, 25, 50, 75 y 100 kgP/ha (aplicado sólo el primer año), en las sub-parcelas se aplicó durante diez años, P en banda junto al N y K en dosis de 0, 10, 20 y 30 kgP/ha. El máximo rendimiento de grano se logró con la aplicación acumulada de 304 kg (en promedio 30,4 kgP/año). El efecto residual de las aplicaciones de 0 y 25 kgP/ha al voleo presentaron un rendimiento relativo por debajo del 80%. El tratamiento de 50 kgP/ha se mantuvo en 82%, mientras que el de 75 disminuyó a partir del año 2007 a un valor cercano al 80%. El tratamiento de 100 kgP/ha al voleo presentó un rendimiento relativo cercano al 100%. La aplicación al voleo de más de 50 kgP/ha no difirió de la respuesta obtenida con aplicaciones anuales de 30 P/ha en los primeros cinco años. Estos resultados sugieren que el efecto residual de la aplicación del fósforo al voleo e incorporado previo a la siembra, bajo el tipo de suelo empleado varió según la dosis aplicada inicialmente, en donde las dosis superiores a 50 kg/ha deben repetirse después de seis años para mantener una buena productividad, ya que, a partir de este tiempo el efecto residual se redujo en forma drástica.</p>

Effect of Cow Dung, Biogas Slurry and Vermicompost on Phosphorus Adsorption Behavior of Soil

One of the approaches for phosphorus fertilizer management is controlling the soil phosphorus adsorption behavior. To examine the effect on phosphorus adsorption behavior, three amended soil samples were prepared by mixing 10% (w/w in dry basis) cow dung, biogas slurry and vermicompost with soil. Phosphorus adsorption behavior was examined by using Langmuir, and Temkin adsorption isotherms. Initially, biogas slurry and vermicompost increased the maximum phosphorus adsorption capacity (MPAC) of soil from 461 µg g-1 (control) to 558.0357 and 586.17 µg g-1 respectively, and then decreased steadily and reached 429.92 and 398.41 µg g-1 respectively in five weeks. Whereas in case of cow dung, MPAC was initially decreased, then reached maximum in 17 days and ultimately decreased. Thus application of cow dung along with phosphate fertilizer seems to increase the loss of the fertilizer through runoff and leaching. Conversely, biogas slurry and vermicompost prevent phosphorus loss by regulating phosphorus release through initial enhancement followed by gradual decrease in phosphorus adsorption capacity of soil. Both biogas slurry and vermicompost can be considered as good soil amendments as they have the ability to control the release of phosphorus fertilizer as per the need of the plants.