—Bryan G. Hopkins 是美国Idaho州立大学推广学教授，他写了很多玉米生产和科研的科普性论文。本文很简洁的讲述了磷肥高效利用的原理与方法。原文见，翻译略有删减。
Phosphorus Use in High Yield Cropping Systems
The P concentration in harvested produce is somewhat consistent regardless of yield. Thus, higher yields result in greater crop P uptake and removal. In many cases, increased yields have depleted soil P in regions where it has not been replenished (IPNI, 2015).
无论产量高低，收获农产品中的磷浓度都基本相似。因此，产量越高，作物对磷的吸收和去除就越大。在许多情况下，增加的产量耗尽了尚未补充磷的地区的土壤磷（IPNI，2015）。
The remarkable characteristic of phosphorus is that it undergoes all kinds of adsorption and sedimentation in all kinds of soil, so that it has almost no mobility in the soil. These processes do not cause phosphorus to move out of the soil, but to transform into forms that crops cannot absorb quickly. The static property of phosphorus makes it ineffective if the root system can not contact the applied phosphorus fertilizer closely. This makes phosphate fertilizer the lowest utilization rate of all kinds of fertilizers in the current season.The above characteristics make the application method of phosphate fertilizer more important than the properties of its fertilizer
磷的显著特点是其在各种土壤中经历各种吸附、沉淀，从而使其在土壤中几乎没有移动性。这些过程不会导致磷移出土壤，但是转化成为作物不能快速吸收的形态。磷的静止性使得如果根系不能密切接触施用的磷肥则这些磷肥就是无效的。这使得磷肥是各种化肥中当季利用率最低的一种。上述特点使得磷肥的施肥方法可能比其肥料的性质更重要。
Fertile Soil – Fertilizer is not a stand-alone nutrient supplier, but rather a partner with soil minerals and organic matter in providing for plant requirements. For P-depleted soils, there is proven benefit in adding P in modest excess of crop removal to maximize production and to improve soil health. Once a moderately high soil reserve is built, P fertilizer application rates can be reduced to maintain this level. Of course, excessive P concentrations can be an environmental risk and should be avoided (Hopkins, 2015). Tracking soil P concentrations over time will assist in making nutrient use decisions, while using consistent sampling methods, depths, and analytical processes.
培肥土壤-肥料不是一个独立的养分供应者，而是一个与土壤矿物和有机物质合作提供植物需求的“伙伴”。对于缺磷的土壤，磷肥的施肥量超过作物移除的磷，以最大限度地提高产量和改善土壤健康已证明是有益的。一旦建立了中高水平的土壤磷储备，就应该降低磷肥的施用量以维持这一水平。磷浓度过高可能是一种环境风险，应该避免（Hopkins，2015）。跟踪土壤磷浓度随时间的变化有助于作出施磷决策的决定，这需要使用一致的采样方法、采样深度和分析方法。
Species Management – Each species differs in its P requirement. For example, potato tends to have shallow, ineffective roots with few root hairs. As such, it typically requires at least twice as much P in the soil to achieve high yields than does corn and most other crops.
There are also intra-species differences in P requirement. For example, the most commonly grown potato variety is ‘Russet Burbank’. This variety requires much more P than some newer developed cultivars, such as ‘Alturas’. In general, older corn hybrids had P uptake rates that plateaued
with the onset of reproduction, but newer hybrids continue to take up P throughout the reproductive stage .
品种管理-不同作物的磷需求量不同。例如，马铃薯的有效根较浅，很少有根毛。因此，要获得高产，土壤中的磷含量通常至少是玉米和大多数其他作物的两倍。磷需要量也存在种内差异。例如，最常见的马铃薯品种是“Russet Burbank”。这种品种比一些新开发的品种需要更多的磷，如'Alturas'。一般来说，较老的玉米杂交种在生殖生长始期磷吸收率趋于峰值，而新的杂交种在整个繁殖阶段都继续吸收磷。
Manage pH – Phosphorus solubility and plant availability is optimum at a soil pH between 6 and 7. If the soil is acidic (7), lowering the pH is possible, but generally not practical or economical. Rather, add relatively more P according to calibrated soil tests.
Alkaline soils typically occur in arid regions. These soils have carbonate minerals (lime) present. In addition, they are often irrigated with “hard water” high in dissolved lime. Carbonates further reduce P solubility and buffer the soil pH against change. When present, carbonates require the addition of more P fertilizer compared to where carbonate minerals are not present. For example, an additional 10 lb P2O5 /A is recommended to be added to potatoes for each 1% soil lime, up to 80 lb. Other crops also likely benefit from additional P in calcareous soils, but this is not as well documented with research.
土壤pH管理：土壤pH6-7之间，磷的溶解度和植物利用率是最佳的。如果土壤呈酸性（7），则可以降低pH值，但通常不实用或不经济。相反，根据校准的土壤试验，添加相对更多的磷。
碱性土壤通常发生在干旱地区。这些土壤中含有碳酸盐矿物（石灰）。此外，他们经常用高溶解石灰的“硬水”灌溉。碳酸盐进一步降低了磷的溶解度，缓冲了土壤pH值的变化。与不存在碳酸盐矿物的情况相比，石灰性土壤需要施用更多的磷肥。例如，对于每1%的土壤石灰且种植土豆，建议额外施磷肥10 lb P2O5/A，最大可达80 lb/a。其他作物也可能从石灰性土壤中的额外磷中获益，但这一点在研究中没有得到充分的记录。
Placement – Phosphorus is used most efficiently when it is placed in close proximity to the root system. Subsurface application of P fertilizer is generally most effective, but may not be compatible with cropping systems using reduced tillage techniques.
施肥位置-当磷靠近根系时它的效率最高。深施磷肥通常是最有效的，但可能与使用少耕技术的耕作制度不兼容。
Starter Fertilizer – Although there is benefit from the bulk soil having an ample P concentration, the most efficient use comes from fertilizer placed in a concentrated band in the path of growing roots. A relatively small amount of low-salt index, starter P fertilizer helps satisfy the nutritional demands for vigorous seedling growth. In general, the smaller the seed size, the greater the need for early-season P, but also the greater the susceptibility to potentially harmful effects of soluble fertilizer salts.
启动肥-尽管整个土层都含有充足磷浓度对作物最适合，但最有效的磷肥施肥方法是将磷施用在根系密集的条带。较少量的低盐指数的磷肥有助于满足作物健壮生长的营养需求。一般来说，种子越小，对早季磷的需求就越大，但也越容易受到可溶性肥料盐潜在危害的影响。
Concentrated Bands – Relatively high P application rates are possible when the fertilizer band is placed a few inches from the seed, often 2 in. (5 cm) to the side and down for crops with typical diagonal root patterns. But, understanding root morphology, architecture, and growth patterns are important. For example, sugarbeet has a largely downward-growing taproot with little lateral growth during the first 8 to 10 weeks after planting. Its roots explore the subsoil, which typically has little P, during the critical time when it is setting the final yield potential. A band of P fertilizer directly below the seed is often a key to obtaining high yields, even in soils with a relatively high P concentration.
集中条施-集中带-当施肥带距离种子几英寸（通常位于侧方和下方2英寸或5cm）时，磷效率可能较高。但是，了解根的形态、结构和生长模式是很重要的。例如，甜菜的主根主要向下生长，在种植后的8到10周内几乎没有侧根生长，但是这一阶段决定了其产量潜力。这个时期它的根系主要从底土吸收磷，而通常这个深度磷浓度很低（因此，甜菜施用启动肥的深度需要>5cm-译著）。即使在磷浓度相对较高的土壤中，种子正下方的磷肥带也是获得高产的关键。
Enhanced Efficiency – There are various P fertilizer sources and/or additives that may provide enhanced efficiency. For example, certain organic acids blended or chemically bonded with P can sometimes improve nutrient uptake and yields, especially in calcareous, low organic matter soils. Other additives and controlled-release P sources have also been shown to be effective in some circumstances. In these cases, it is noteworthy that use of these products on soils with high P concentrations, or at high rates of application often results in no yield benefit, or perhaps a negative yield response.
提高磷肥效率：不同磷肥品种或者添加剂可以提高效率。例如，某些有机酸与磷混合或化学结合有时可以提高养分吸收和产量，特别是在石灰性、低有机质含量的土壤中。其他添加剂和控释磷源在某些情况下也被证明是有效的。在这些情况下，值得注意的是，在高磷浓度或高施用量的土壤上使用这些产品通常不会产生产量效益，或可能产生负的产量反应。
Tissue Analysis – Chemical analysis of the plant tissue is used to inform in-season P fertilization decisions. In some circumstances, crops have shown a response to in-season P fertilization via fertigation or foliar application, even though it is relatively less effective than preseason soil application (or not effective at all) in some cropping systems. Phosphorus is not very mobile in soil and thus it is important that there are abundant fine roots in moist soil near the surface for in-season P applications to be effective. Adjustments need to be made in future years to deliver all of the crops P needs into the soil prior to planting—using tissue analysis to verify if this objective is met.
组织分析-植物组织的化学分析用于在P季节施肥决策。在某些情况下，作物通过施肥或叶面施肥表现出对季内P肥的响应，尽管在某些种植制度中，其效果相对不如季前土壤施肥（或根本无效）。磷在土壤中的流动性弱，因此在湿润土壤中有丰富的细根是当季施磷有效的重要条件。植物组织磷分析的另外一个作用是校验施用的磷肥是否有效改善的作物磷营养。
Vascular Health – Root hairs are the site of most P uptake for plants and it is subsequently transported throughout the plant via the vascular system. Roots need to continuously explore new soil for continued P supply due to low soil mobility. Good overall plant health, including avoiding pest and mechanical damage to roots, is key in achieving maximum nutrient efficiency and plant growth. Vascular health can be evaluated by visually inspecting both the exterior and interior of root and shoot tissues, and where appropriate, tested for pathogens. Albeit not desirable or efficient, foliar applications can sometimes be a rescue treatment to deliver nutrients to the foliage when root growth is impaired.
维管健康-根毛是植物吸收磷的主要部位，随后通过维管系统运输到植物外。由于P土壤流动性低，根系需要不断探索新的土壤（区域）以持续供磷。良好的整体植物健康，包括避免害虫和机械损伤的根，是实现最大的营养效率和植物生长的关键。可以通过目视检查根和芽组织的外部和内部来评估维管健康，并在可能的情况下测试病原体。尽管不可取或效率不高，但在根系生长受到损害时，叶面施用有时可以作为一种补救措施，为叶片输送养分
Microbial Health – Although some soil microbes are damaging to plant growth, most are beneficial. The prospect of obtaining high yields is enhanced with a large and diverse microbial population that has sufficient soil organic matter as an energy source. This biodiversity increases competition against many important crop pathogens. Additionally, some rhizosphere microbes are specifically beneficial for P recovery (although beware that there are many claims in this area that do not prove to be effective). For example, mycorrhizal fungi have a symbiotic relationship with roots as they take energy from the plant in exchange for water and nutrients they bring in from their extended hyphal network. This relationship is well known in low fertility/water systems, but its importance in high-yield environments is beginning to be understood and managed. As with all practices, it is vital to follow scientifically proven practices specific to each cropping system.
微生物健康-尽管一些土壤微生物对植物生长有害，但大多数都是有益的。微生物种群数量的增加和多样性的提高，是获得高产的重要途径。此外，一些根际微生物特别有利于磷的回收（尽管要注意，在这方面有许多说法并没有被证明是有效的）。例如，菌根真菌与根部建立共生关系，它们从植物获取能量，以交换从其扩展的菌丝网络中带来的水分和养分。这种关系在低肥力/水系统中是众所周知的，但它在高产环境中的重要性正开始被理解和管理。与所有的实践一样，遵循每种耕作制度所特有的经科学证明的实践是至关重要的。
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