Analysis of the fertilizer efficacy characteristics and field performance of various fertilizers
In agricultural production, accurately understanding the fertilizer efficacy of various types is the foundation for rational fertilization and achieving efficient utilization of nutrients. The "effective time" of a fertilizer usually refers to the duration required for the crop to show visible growth responses after application, while the "efficacy period" refers to the time during which the fertilizer continuously releases its effective nutrients. Below, by combining common types of fertilizers, we will summarize and analyze their fertilizer efficacy characteristics.
I. Nitrogen-based Fertilizers
Urea (containing approximately 46% nitrogen)
It is amide nitrogen, which needs to be converted into ammonium nitrogen through the action of urease in the soil before it can be absorbed by crops. Generally, the effect can be observed about 7 days after application, and the fertilizer efficacy lasts for about 45 days. Its fertilizer efficacy release is relatively stable, suitable for use as base fertilizer or topdressing. In dry land, it is necessary to apply it deeply and cover the soil to prevent ammonia volatilization loss.
Ammonium carbonate (sodium bicarbonate, containing approximately 17% nitrogen)
It is an ammonium-based nitrogen fertilizer, which is highly soluble in water and has strong quick-acting properties. After being applied to the soil, it takes effect approximately within 1 day, but its efficacy period is relatively short, generally lasting about 15 days. This fertilizer has unstable chemical properties and is prone to decomposition and volatilization. It is suitable for use as a topdressing and should be covered immediately after application. It is not recommended to be spread on the surface of soil in high-temperature or high-pH soil environments.
Ammonium chloride (containing approximately 25% nitrogen)
It is a physiological acidic fertilizer. It takes effect relatively quickly, with visible results within about 3 days, and the fertilizer's effectiveness lasts for about 25 days. It is suitable for crops such as rice and wheat. However, crops that are sensitive to chlorine (such as tobacco, potatoes, etc.) should avoid using it. Long-term application requires attention to the issue of soil acidification.
II. Phosphorus and Potassium Fertilizers
Superphosphate (containing 12% - 18% P₂O₅)
It is a water-soluble phosphorus fertilizer. When applied to the soil, it is easily fixed and has low mobility. Generally, it shows effect within 7 days, and the fertilizer efficacy lasts for about 20 to 30 days. It is recommended to apply it concentratedly near the root system or mix it with organic fertilizer to reduce fixation and improve utilization rate.
Potassium chloride (containing about 60% K₂O)
Quick-acting potassium fertilizer takes effect approximately 3 days after application, with a fertilizer efficacy period of 30 to 40 days. It is also a physiological acidic fertilizer and is suitable for most field crops. Crops that are sensitive to chlorine should use potassium sulfate instead.
Potassium sulfate (containing K₂O 50% - 52%)
The effect takes about 7 days to show, and the fertilizer's effectiveness can last for up to 60 days. It is particularly suitable for crops that are sensitive to chlorine. Long-term use has less impact on soil acidification compared to potassium chloride.
III. Compound and Quick-acting Fertilizers
Compound fertilizer (such as a triple-nitrogen-phosphorus-potassium compound fertilizer)
The nutrient release is relatively balanced. Usually, it takes effect around 10 days after application, and the fertilizer effect lasts for a long time, up to about 90 days. The fertilizer effect is related to the formula ratio, process type (such as blending type or compound type), and soil conditions. It is suitable for use as base fertilizer or mid-term topdressing.
Water-soluble fertilizer (with macronutrients)
It dissolves quickly and has high absorption efficiency. Generally, it takes effect within 5 days after application, but its fertilizer effect period is relatively short, about 20 days. It is mostly used in precise fertilization methods such as drip irrigation and surface application, and is suitable for rapid supplementation when there is a urgent need for nutrients during the growth period or when the root absorption capacity is limited.
IV. Organic Fertilizers
Organic fertilizers (including manure, compost, commercial organic fertilizers, etc.)
Its nutrients exist in an organic form and need to be gradually mineralized by microorganisms before they can be absorbed by the crops. Therefore, the effect is relatively slow and it usually takes 30 days or even longer to observe obvious results. However, the fertilizer effect is long-lasting, and the nutrient release is stable. A sufficient application once can maintain the fertilizer effect for 1 to 2 years, and it also has multiple ecological functions such as improving soil structure and enhancing microbial activity.
Field Application Suggestions
Match fertilizer efficiency according to the reproductive period
During the critical periods of crop nutrition and the periods of maximum efficiency, quick-release fertilizers (such as water-soluble fertilizers and ammonium nitrate) should be selected; while for the base fertilizers, long-lasting fertilizers (such as organic fertilizers, compound fertilizers, and slow-release fertilizers) should be chosen.
2. Pay attention to soil and climate conditions
Soil texture, pH value, temperature and humidity all affect the transformation and release of fertilizers. For instance, in clayey soil, the mobility of fertilizers is poor, so they can be applied earlier; in cold seasons, quick-release nitrogen fertilizers or application in advance are recommended.
3. Pay attention to the compatibility of fertilizers and the application methods
Combining quick-release fertilizers with long-lasting fertilizers, and integrating organic and inorganic fertilizers can coordinate nutrient supply and prevent nutrient depletion or excessive growth. Pay attention to deep application and soil covering, as well as timely irrigation to enhance fertilizer utilization.
4. View "Effectiveness Time" Rationally
The fertilizer efficacy is influenced by various factors such as crop type, growth stage, climate and soil conditions. The data in the table represent the field observation experience under general conditions. In actual application, adjustments need to be made based on specific circumstances.
The selection and application of fertilizers essentially involve matching the nutrient supply and demand in the crop-soil-fertilizer system over time. Understanding the fertilizer efficacy characteristics of different fertilizers helps to develop more precise, efficient and environmentally friendly nutrient management strategies, laying the foundation for achieving high-yield and high-quality crops and sustainable soil health.
