1、Release of Phosphorus from Laboratory Made Coated Phosphatic Fertilizers in Soil Under Different Temperature and Moisture Regimes

Results indicated that release of P showed a decline trend from first to fourth hour of incubation, then increased and finally reached to a steady state in all the products, except Product-C.

2、Role of Slow

One approach to improving the efficiency of phosphate and urea fertilization is to improve their interaction through nanocomposites that are able to control the release of urea and P in the...

3、Phosphorus activators contribute to legacy phosphorus availability in agricultural soils: A review

It has been suggested that the accumulated (surplus) P in agricultural soils is sufficient to sustain crop yields worldwide for about 100 years. In this paper, we try to clear up the potential for making use of legacy P in soils for crop growth potentially alleviating the global P resource shortage.

4、Controlled Release of Phosphate from Layered Double Hydroxide Structures: Dynamics in Soil and Application as Smart Fertilizer

The preparation strategy resulted in a phosphorus content of around 40 mg·g –1 LDH, which was higher than previously reported for related fertilizers. The release of phosphate into water from [Mg-Al-PO 4]-LDH continued over a 10-fold longer period, compared to release from KH 2 PO 4.

Evaluation of fertilizers solubility and phosphate release in slightly acidic arable soil: Archives of Agronomy and Soil Science: Vol 64 , No 8

Solubility equilibrium of phosphates was calculated by phosphate (P Pot = logH 2 PO 4 – pH) and calcium (Ca Pot = logCa + 2pH) potentials. Next, activity ratio (AR°) and Woodruff potential (ΔF) were considered for estimating phosphate dynamics in the soil.

Development and characterization of phosphate tailings

In this study, activated phosphate tailings-based humic acid slow-release fertilizer (APHF) was successfully prepared by ball milling technology combined with sludge acid to activate phosphate tailings and humic acid. The experimental results showed that the slow-release fertilizer had excellent nutrient-controlled release performance.

Preparation, forms and properties of controlled

Controlled-release phosphate fertilizers include phosphate rocks (PRs) for direct application, partially acidulated phosphate rocks (PAPRs) and thermal phosphates. Phosphate rocks contain apatite as the main P containing mineral, the composition and the chemical nature of which vary between PRs.

Comparative Solubility Study of Four Phosphatic Fertilizers in Different Solvents and the Effect of Soil

The results revealed that release of P were increased on addition of soil irrespective of fertilizers or extractants used. TSP released maximum P (3.05% - 3.27% with soil, 2.11% - 2.22% without soil) by the 7th day of incubation.

Longevities and nitrogen, phosphorus, and potassium release patterns of polymer‐coated controlled‐release fertilizers at 30°C and 40°C: Communications in

All CRFs released nutrients unevenly with the highest rate occurring during the early part of the release period. This pattern was accentuated at 40°C and by the shorter term release formulations. The nutrient release rates of all CRFs declined steadily after their maxima.

Phosphate

Layered double hydroxides as a slow release phosphate fertilizer to boost P recycling and overcome low fertilization efficiency in strong fixing soils are discussed.

The release period of phosphate fertilizers refers to the time required for phosphate fertilizers to gradually release into the soil and be absorbed and utilized by crops after application. This duration varies depending on factors such as the type of phosphate fertilizer, soil conditions, and climatic conditions.

Stages of Phosphate Fertilizer Release

Generally, the release period of phosphate fertilizers can be divided into the following stages:

1. Initial Release Stage: During this stage, the active ingredients in the phosphate fertilizer begin to decompose and transform through microbial activity in the soil, forming inorganic phosphorus that can be absorbed by plants. This stage is relatively short, typically lasting several weeks to a few months.

2. Mid-Term Release Stage: In this stage, the active ingredients continue to undergo microbial decomposition and transformation, while some organic phosphorus is converted into inorganic phosphorus. This stage lasts longer, usually ranging from several months to a year.

3. Long-Term Release Stage: During this stage, the active ingredients accumulate gradually in the soil, forming a stable supply of phosphorus. This stage can extend over years to decades.

Release Periods of Different Phosphate Fertilizers

The release periods vary among different types of phosphate fertilizers:

1. Superphosphate (Ca(H₂PO₄)₂): This type has a relatively short release period, typically requiring several months to one year.

2. Monoammonium Phosphate (NH₄H₂PO₄): This type has a longer release period, generally lasting six months to one year.

3. Diammonium Phosphate (NH₄H₂PO₄·H₂O): The release period of this type falls between superphosphate and monoammonium phosphate, usually taking 1–2 years.

4. Triammonium Phosphate (NH₄H₃PO₄): This type has the longest release period, typically spanning 3–5 years.

Factors Affecting the Release Period

Key factors influencing the release period include:

1. Soil Type: Different soil types have varying abilities to adsorb phosphorus. For example, clay soils strongly adsorb phosphorus, resulting in a shorter release period, while sandy soils weakly adsorb phosphorus, leading to a longer release period.

2. Soil Moisture: Soil humidity affects microbial activity. Wet soils promote microbial activity, accelerating phosphorus release, whereas dry soils inhibit it, slowing release.

3. Soil Temperature: Warmer soils enhance microbial activity, speeding up phosphorus release, while colder soils suppress microbial activity, slowing the process.

4. Fertilization Rate: Higher application rates increase the distribution and utilization of phosphorus in the soil, shortening the release period. Conversely, lower rates reduce distribution and utilization, extending the release period.

5. Application Method: Deep application increases contact between fertilizer and soil, accelerating release, while slow-release fertilizers prolong the release period compared to fast-release formulations.

Understanding the release period of phosphate fertilizers is critical for agricultural production. Farmers can optimize fertilization timing and rates based on soil conditions, climate, and crop requirements to achieve high yields and efficiency.