On July 9, 2026, the General Administration of Customs of China issued Announcement No. 97 of 2026, effective July 16, adding export regulatory condition "B" (export commodity inspection) for ammonium sulfate (HS Code 3102210000) and ammonium sulfate–Ammonium Nitrate double salts and mixtures (HS Code 3102290000, i.e., ASN). This marks the end of ASN's long-standing "export exemption" era, replacing it with a "inspect-before-release" procedure for customs clearance.

Behind this policy shift lies ASN's rapidly growing export scale. In 2025, China's ammonium sulfate exports reached 21.36 million metric tons, with an export dependency of 89.82%. As the last major bulk nitrogen fertilizer category in China to be brought under mandatory inspection, ASN had long suffered from the "large volume, low price" dilemma – the extremely low export threshold attracted a flood of small and medium sized traders, and some intermediaries dumped low quality products, preventing domestic ammonium sulfate from gaining international pricing power. The new regulation signals a transition from "volume first" to "quality first" for the industry.

Shift Two: Geopolitics Disrupt the Global Urea Market

Unlike ASN's policy driven adjustment, the urea market is bearing the brunt of geopolitical shocks. Since late February 2026, escalating Middle East conflicts have disrupted shipping through the Strait of Hormuz, affecting about one third of global fertilizer trade transport. The Persian Gulf region, accounting for about 30% of global urea exports and the world's largest urea exporting area, may see production reduced by approximately 7 million tons.

International urea prices have consequently swung violently. In April this year, prices surged from roughly $400/ton to over $850/ton; Middle East prices briefly approached $900/ton, a near 80% spike within weeks. Meanwhile, China, through stringent urea export quota management, has kept domestic urea prices stable at around RMB 1,800/ton. The price gap between domestic and international markets once exceeded RMB 3,000/ton, making China a global "price floor" for urea.

Two Nitrogen Fertilizers, Two Distinct Logics

On one side, ASN is leaving behind its "exemption" era and stepping into a new chapter of regulated exports; on the other, urea is rocked by geopolitical volatility. Against this backdrop, revisiting the value comparison between ASN and urea is especially timely. Their differences in nitrogen form, nutrient composition, and fertilizer efficiency are evolving from a mere "content contest" into a broader contest of "efficiency" and "security."

Below, we systematically compare ASN and urea across multiple dimensions: nitrogen form, sulfur content, nitrogen losses, field performance, and soil acidity/alkalinity.

1. Nitrogen Form: The Fundamental Divide Between Quick Acting and Slow Release

The most fundamental difference between urea and ASN lies in the chemical form of their nitrogen.

Urea contains amide nitrogen, which cannot be directly taken up by crops. It must be hydrolyzed by soil urease over several days (typically about 7 days) into ammonium nitrogen before it becomes available. This "conversion waiting period" not only delays fertilizer response but also exposes nitrogen to greater volatilization and leaching risks during the transformation.

ASN, in contrast, contains both ammonium nitrogen (NH₄⁺) and nitrate nitrogen (NO₃⁻). Ammonium nitrogen can be adsorbed by soil colloids, ensuring good retention; nitrate nitrogen can be directly absorbed by crop roots, offering fast action. This "quick acting + slow release" dual nitrogen combination allows ASN to rapidly meet crop nitrogen demand during critical growth windows while providing sustained nitrogen supply.

2. Sulfur: ASN's "Hidden Ace"

ASN's label typically reads "26 0 0 24" or "26 0 0+13S," and the ~13% sulfur (as SO₃) it contains is a key differentiator that urea lacks.

Sulfur is an essential secondary nutrient for synthesizing cystine, methionine, proteins, and enzymes, and plays an irreplaceable role in chlorophyll formation and nitrogen metabolism. Sulfur deficient soils are expanding globally – in India, for example, about 40% of arable land suffers from sulfur deficiency. In such regions, applying ASN is akin to "buying nitrogen and getting sulfur for free," saving the cost of separate sulfur fertilization.

In contrast, urea supplies nitrogen only, with no other nutrients. For sulfur loving crops (e.g., rapeseed, soybean, peanut, onion, garlic), this "added value" of ASN often becomes a decisive factor in yield.

3. Nitrogen Losses: Whose Nitrogen Stays Put?

Nitrogen loss is a silent drain on fertilizer efficiency. Common loss pathways include ammonia volatilization, nitrate leaching, and denitrification.

For urea, when amide nitrogen is converted to ammonium nitrogen and applied to the soil surface, ammonia volatilization can exceed 20%. A study on potatoes showed that ammonium sulfate and Compound Fertilizers were most effective in reducing ammonia emissions.

ASN, with its stable combination of nitrate and ammonium nitrogen, reduces loss risks during conversion. Its nitrogen release is better synchronized with crop uptake, thereby effectively improving nitrogen use efficiency (NUE).

4. Field Performance: Comparable Yields, Different Efficiencies

When it comes to yield, multiple field trials yield interesting conclusions.

A two year field study by the University of Alberta on spring wheat found no significant yield difference between ASN and urea – urea averaged 77.6 bushels/acre, ASN was intermediate, and CAN (Calcium Ammonium Nitrate) averaged 77.0 bushels/acre. For grain protein content, urea was 12.3% and ASN 12.0%, also statistically indistinguishable.

This means that at equal nitrogen application rates, ASN can fully achieve yield levels comparable to urea – despite having only slightly more than half the nitrogen content.

In forage studies, ASN and ammonium sulfate outperformed urea significantly under high nitrogen rates. Other research found that ASN produced significantly higher fresh and dry matter yields in silage maize compared to urea. These differences are often attributed to ASN's additional sulfur contribution.

5. Soil Acidity/Alkalinity: A Tunable Property

Urea is a physiologically neutral fertilizer with broad adaptability. Conventional ASN formulations, however, contain ammonium sulfate, making them typically physiologically acidic – after crops absorb ammonium ions, the residual sulfate radicals increase soil acidity.

But this property is not fixed. By adjusting the ratio of ammonium sulfate to ammonium nitrate in ASN, the formulation can be optimized to become physiologically neutral. This tunability gives ASN a unique advantage in alkaline soils and saline alkali lands – physiologically acidic fertilizers can neutralize soil alkalinity and improve nutrient availability.

6. Selection Guide: From "Looking at Content" to "Calculating the Total Picture"

Based on the above analysis, the choice between the two fertilizers should follow these principles:

Choose Urea when:

You aim for the lowest cost per unit of nitrogen
You are growing sulfur insensitive field crops (e.g., certain rice, maize, wheat varieties)
Soil is not sulfur deficient and is neutral or acidic

Choose ASN when:

Growing sulfur loving crops(rapeseed, soybean, peanut, onion, garlic, potato, etc.)
Soil is sulfur deficientor alkaline
You need quick acting nitrogenfor top dressing
You prioritize higher nitrogen use efficiencyand are willing to pay a reasonable premium for reduced environmental losses and integrated nutrition

Conclusion

Urea stands as the benchmark for a "high concentration, low cost" nitrogen source, while ASN exemplifies "high efficiency, multi functional" nitrogen fertilization. As fertilizer selection becomes ever more sophisticated, truly intelligent fertilization decisions are not about comparing who has the higher nitrogen content, but about whose nitrogen can be more fully absorbed and more comprehensively utilized by the crop. ASN is redefining the cost effectiveness formula of nitrogen fertilizers through the synergy of nitrogen and sulfur. Especially at a time when global urea markets are volatile due to geopolitical tensions and supply chain risks are mounting, ASN – as a nitrogen fertilizer with diverse raw material sources and freedom from single source geopolitical dependence – is gaining increasing attention for its strategic value and stability.