Draft:Tea Production in Shizuoka

Overview

Shizuoka Prefecture is the largest tea-producing region in Japan, accounting for approximately 40% of the nation's total tea output. While the area is traditionally known for its sencha and deep-steamed varieties such as fukamushi-cha, it has also developed a distinct system for matcha production in recent years—especially in the western Kakegawa region and surrounding highlands.

Matcha cultivation in Shizuoka often centers around the traditional Chagusaba agricultural system. This method integrates native grassland preservation with tea field management. Local grasses, including Miscanthus sinensis and bamboo grass, are harvested, dried, and laid between tea rows to improve soil structure, regulate temperature and humidity, and enhance biodiversity.

Although the term “matcha” is more commonly associated with Kyoto’s Uji region, Shizuoka has increasingly established a regional identity in the high-grade matcha market. This development is supported by advancements in shading techniques, cultivar optimization, and the use of low-temperature processing technologies.

Chagusaba Farming and Its Agricultural Principles

The Chagusaba method (茶草場農法) is a traditional grassland–tea intercropping system practiced primarily in Shizuoka Prefecture, most notably in Kakegawa. In this method, farmers maintain native grasslands—often consisting of susuki (Miscanthus sinensis) and sasa (bamboo grass)—around tea fields. These grasses are harvested in autumn, dried, and then spread between tea rows as organic mulch.

This technique is not simply for weed control or moisture retention. It reflects generations of accumulated agronomic knowledge regarding local climate, soil dynamics, and ecosystem balance. Research shows that the grass mulch:

- Suppresses weed growth and reduces pesticide dependency - Elevates soil temperature and organic matter content - Enhances microbial activity, aggregate structure, and moisture retention

A 2013 designation by the Food and Agriculture Organization (FAO) recognized Chagusaba as a *Globally Important Agricultural Heritage System (GIAHS)* due to its blend of ecological function, cultural preservation, and community participation.

Recent analysis also indicates that Chagusaba-grown tea shows higher levels of L-theanine and chlorophyll, which are crucial to matcha's umami and color quality.

A detailed exploration of how Chagusaba farming supports matcha cultivation—particularly in foggy microclimates like Kakegawa's Ohayashi Highlands—can be found in Liu, C. (2025).

Scientific Studies on the Impact of Chagusaba on Matcha Quality

In recent years, research on how the Chagusaba farming method influences the chemical composition and sensory attributes of matcha has expanded. From 2020 to 2022, Japan’s National Agriculture and Food Research Organization (NARO), in collaboration with the Faculty of Agriculture at Shizuoka University, conducted field trials in Kakegawa and Mori towns to analyze the effects of grass mulching under shaded cultivation on first-harvest (Ichibancha) tea leaves used for matcha production.

The trials involved two sets of tea fields: one long-managed with Chagusaba mulch, and a control field managed without mulch. Both groups were shaded identically (85% shading for 20 days) prior to spring harvest. Researchers measured the concentrations of amino acids, caffeine, catechins, and pigments in the harvested tea leaves.

Results showed that the Chagusaba-managed fields produced tea with an average L-theanine content of 26.7 mg/g, significantly higher than the control’s 21.2 mg/g. Catechin and caffeine levels were slightly lower, reducing the bitterness score by approximately 12%. In terms of appearance, matcha processed from the mulched fields had 18.5% higher total chlorophyll (a + b) concentration, giving the powder a more vivid, jade-green hue.

Furthermore, gas chromatography analysis revealed a higher proportion of aromatic compounds like phenylethanol (floral notes) and pyrazines (nutty notes) in the Chagusaba group, suggesting improved aromatic complexity.

Researchers concluded that these enhancements are not attributable to a single factor but arise from a combination of microclimate stabilization, slow-release nitrogen availability, and improved soil structure. The findings support the ongoing relevance and sustainability of the Chagusaba system for producing high-grade matcha material.

Cultivation Techniques of Matcha in Shizuoka

Although the term "matcha" has historically been associated with Kyoto's Uji region, Shizuoka has in recent decades developed a distinct cultivation system for high-quality matcha. Particularly in the western areas of Kakegawa, Mori, and Kanaya, farmers have established a unique terroir-driven model that combines shading techniques, the Chagusaba grass-mulching system, and high-altitude cultivation.

Shading Techniques (Kabuse)

The raw material for matcha is typically "shaded first-flush tea" (Ichibancha). In Shizuoka, two primary shading methods are used: upright-frame structures (立体型) and suspended net canopies. These systems reduce sunlight by approximately 85% for 20–25 days prior to harvest. The aim is to suppress photosynthesis, thereby increasing L-theanine and chlorophyll while decreasing catechin levels and bitterness.

In higher elevation gardens—such as the north slope of Mt. Awagatake and the Ohayashi Highlands—multi-layer shading structures are employed to regulate diffuse light and minimize leaf hardening. To mitigate the risk of late spring frost, some farms use thermal systems such as underground heating pipes or small-scale hot air blowers to protect new shoots during nighttime.

Cultivar Selection and Field Management

Popular cultivars in Shizuoka’s matcha fields include *Yabukita*, *Gokou*, and *Samidori*. *Yabukita* is widely used for its adaptability and clear aroma, making it suitable for standard-grade matcha. *Gokou* and *Samidori* are favored for their high amino acid content and refined fragrance, often selected for premium grades.

To enhance L-theanine concentration and leaf thickness, some tea producers apply controlled-release organic nitrogen fertilizers in late February to early March, triggering early bud sprouting. This strategy proves especially effective in Chagusaba-managed plots, where nitrogen is also slowly released through decomposing grass mulch—creating a dual nitrogen source from both organic fertilization and biological fixation.

Climate and Terrain Advantages

Shizuoka’s western regions are dominated by hilly and mountainous terrain. Core production areas such as Kakegawa, Mori, and the upper Oi River valley are situated between 150–400 meters elevation. These locations frequently experience spring fog (yamagiri), contributing to high humidity and diffused light—ideal for stable chlorophyll synthesis. The volcanic ash-based soil (Andosol) is well-drained and rich in trace minerals such as zinc and magnesium, which are associated with enhanced aromatic complexity in tea.

Shading Management Practices in the Highlands of Kakegawa

In the highland zones of western Shizuoka—such as the north-facing slopes of Mt. Awagatake and the Ohayashi Highlands—shading methods have been further refined to adapt to the region’s foggy and thermally volatile conditions.

Farmers commonly use multi-layered shading (double or triple overlapping black nets) to reduce scattered light penetration and stabilize L-theanine synthesis. To prevent temperature stress during the shading period, some tea gardens install nighttime warming systems—such as soil-heating pipes or small-scale warm air devices—to protect delicate buds from frost.

These high-input techniques are primarily reserved for premium-grade matcha. According to field trials conducted jointly by farmers in the Ohayashi Highlands and the Mori Tea Research Station, first-flush buds grown under multi-layer shading and night heating exhibited a 12% increase in average length and an 18–22% rise in L-theanine concentration. The enhanced moisture retention in leaves also slows oxidation post-harvest, preserving flavor precursors during subsequent processing。

Climatic Features of Shizuoka and Recent Changes

Shizuoka Prefecture, located on the Pacific coast of central Honshu, is one of Japan's most important tea-growing regions. Tea plantations are concentrated in the central and western mountainous areas at altitudes between 100 and 400 meters. The region’s long-recognized advantages for producing high-quality tea—particularly for matcha base material—include:

• **Humid oceanic climate**: Mild winters and rainy summers, with average annual temperatures between 15–16°C.
• **Large diurnal temperature variation**: Cool nights and sunny spring days facilitate amino acid accumulation.
• **Frequent fog**: Particularly common in the Ōi River basin, Kakegawa hills, and northern slopes of Mt. Awagatake, where morning fog softens sunlight exposure.
• **Volcanic Andosol soils**: Well-drained, rich in organic matter, and conducive to stable micronutrient uptake by deep-rooted tea bushes.

However, in the last decade, the effects of global climate change have become increasingly visible in Shizuoka. According to a joint report by the Shizuoka Meteorological Office and the Agricultural Technology Center (2023), the average temperature has risen by approximately 0.7°C since 2010. Spring warming now occurs 8–10 days earlier than in previous decades, and extreme summer heat events have become more frequent. These shifts have introduced several agronomic challenges:

1. **Earlier bud emergence**, disrupting shading schedules and prompting farmers to begin kabuse shading as early as early April, often combined with nighttime temperature regulation. 2. **Alternating drought and extreme rainfall**: Affects nutrient absorption and soil stability, prompting increased use of mulching techniques like Chagusaba to retain moisture. 3. **Changes in pest populations**: Warming conditions have enabled the northward spread of certain pests such as *Empoasca onukii* (tea green leafhopper), creating new challenges for shaded tea cultivation. 4. **Compressed aroma development**: Elevated temperatures accelerate the transformation of aroma precursors, reducing floral and beany aromatic complexity in matcha.

To address these challenges, farmers have begun implementing precision weather monitoring systems, adopting heat-resistant cultivars such as Fujieda No. 20, and reviving traditional adaptive practices like Chagusaba for improved climate resilience.

Terroir Characteristics and Site Variability of Shizuoka Matcha

Topography and Orientation

Matcha tea gardens in Shizuoka are typically located on rolling hillsides and mountainous slopes, with southeast- and south-facing plots favored for morning light and protection from harsh afternoon sun. Prominent examples include:

• **Northern slope of Mt. Awagatake (Kakegawa)**: High fog density, steep gradient, well-drained soil.
• **Ohayashi Highlands**: Elevation 280–350 meters, ancient volcanic terrain with stable soil temperatures.
• **Mukai-Amagata area in Morimachi**: A core Chagusaba region with high ecological integrity.

These sites are often among the first to begin shading operations and serve as key sources for first-flush kabusecha used in matcha production.

Soil Composition and Microbial Ecology

Shizuoka’s matcha-producing gardens are predominantly situated on volcanic Andosols, which offer several benefits:

• High porosity for root respiration
• Excellent moisture retention during shading periods
• Rich in potassium, zinc, and magnesium—essential for amino acid synthesis and aroma development

Studies have shown that Chagusaba-managed soils exhibit significantly higher activity of actinomycetes and rhizobia compared to bare-soil fields, contributing to greater resistance and elevated amino acid content.

Irrigation Systems and Water Management in Shizuoka Matcha Fields

Traditionally, Japanese tea gardens have relied on natural rainfall and fog moisture. However, with increased climate instability and the frequency of spring droughts, artificial irrigation has become more important, particularly in shaded matcha cultivation.

In hillside areas such as Kanaya, Kakegawa, and Morimachi, some high-end tea producers have introduced intelligent drip and mist irrigation systems. These tools allow:

• **Precise soil moisture control** before and during the shading period.
• **Reduction in flavor inconsistency** year over year.
• **Optimized absorption of nitrogen and other nutrients**, crucial for developing umami and chlorophyll.

This modern infrastructure is often integrated with traditional Chagusaba methods, providing a balance between ecological sustainability and consistent sensory quality.

The Role of Mountain Fog in Flavor Formation of Shizuoka Matcha

One of the most defining climatic features of Shizuoka’s tea-growing regions is persistent mountain fog, especially concentrated in the Ōi River basin, the northern slopes of Mt. Awagatake, and the Ohayashi Highlands. According to the Shizuoka Agricultural Technology Center, these regions experience over 180 foggy days annually, with peak fog coverage occurring between April and June—corresponding to the first flush harvest period.

Light Modulation: Reducing Direct Sunlight and Enhancing Diffuse Light

High-quality matcha depends on elevated levels of amino acids—particularly L-theanine—and suppressed levels of catechins, which are associated with bitterness. Direct sunlight promotes catechin synthesis and inhibits L-theanine accumulation. Mountain fog acts as a natural shading agent by:

• Reducing direct light intensity and increasing the proportion of diffuse light, which supports balanced amino acid synthesis
• Flattening peak fluctuations in photosynthetic rates and slowing chlorophyll degradation
• Reinforcing the effects of artificial kabuse shading and stabilizing shading conditions

Moist Microenvironment: Protecting Buds and Enhancing Aroma Development

Fog contains high levels of atmospheric moisture, often forming a natural dew layer on tea leaves during early morning hours. This microclimate contributes to:

• Reduced stomatal opening, minimizing water loss and supporting metabolic equilibrium
• Protection of leaf edges from springtime dry winds that may cause tip-burn or curling
• Enhanced accumulation of aroma compounds such as terpenoids and alcohols (e.g., floral and marine aromas)

Topographic Distribution and Terroir Differentiation

Fog distribution is highly localized due to terrain. Notable microclimatic variations include:

• **Northern Mt. Awagatake**: Night fog typically starts after 1 AM and dissipates by 9 AM, creating a "night fog zone" ideal for shaded matcha.
• **Kamimukai block in Morimachi**: Shorter total sunlight and consistent fog throughout the year, often linked to high L-theanine concentrations.
• **Kikugawa river-adjacent blocks**: Strong air currents dissipate fog quickly, making the area more suitable for sencha rather than matcha production.

Subsurface Drip Irrigation (SDI) and Water Management

Since 2018, some tea producers in Shizuoka have implemented **subsurface drip irrigation (SDI)** in shaded tea gardens. In these systems, irrigation pipes are buried 10–15 cm below the surface to deliver water directly to root zones, avoiding surface moisture accumulation that could increase the risk of disease in shaded environments.

• • Advantages include:**

• Water savings of 30–40%
• Avoidance of surface mud, which can hinder manual harvesting
• Precise hydration even under shading nets without disrupting operations

Sensor-Linked Soil Moisture Control

Advanced gardens now use sensor-based automated irrigation. Soil moisture probes are installed at multiple locations and synced with weather forecast data. The system activates irrigation only when thresholds are met, optimizing water volume and duration.

According to the Shizuoka Prefectural Agricultural Testing Station (2022), maintaining a volumetric soil moisture content of 16–18% during the shading period significantly boosts L-theanine concentration while preventing edge-burn caused by high temperatures and dry conditions.

Springwater Reservoirs and Ecological Recycling

In mountainous regions such as Morimachi and Kawane, where municipal water access is limited, some tea farms construct gravity-fed **reservoirs** using nearby mountain springs. Water is delivered through low-energy drip systems, offering high control with minimal ecological disturbance.

Additionally, some farmers collect **organic leachate** generated from decomposing Chagusaba mulch and reuse it for pre-harvest irrigation in the following spring, creating a **low-intensity water recycling loop** that supports flavor consistency while preserving environmental integrity.

Pest Management: Integrated Strategies in Shizuoka’s Premium Matcha Gardens

In high-grade matcha farms of Shizuoka, pest and disease management is largely based on suppressive ecological strategies rather than conventional pesticide use. This integrated system emphasizes biodiversity, shade management, and traditional methods such as Chagusaba to maintain balance in the ecosystem.

Major Pests and Recent Trends

Key threats include:

• *Empoasca vitis* (green leafhopper), which affects amino acid synthesis in young leaves and is particularly harmful in shaded gardens;
• *Ectropis obliqua* (tea looper), a voracious foliar pest most active in May;
• *Sclerotium rolfsii* (southern blight), a soilborne pathogen that thrives under high humidity;
• *Pestalotiopsis spp.*, which affects the appearance of tea leaves and is problematic for high-grade matcha aesthetics.

Recent climate warming has led to the northward expansion of *Empoasca vitis*, increasing its prevalence in previously unaffected regions.

Chagusaba and Shade Farming’s Indirect Suppression Effects

Fields utilizing **Chagusaba mulch and artificial shading** display lower pest pressure due to several ecological mechanisms:

• Volatile compounds such as sesquiterpenes from dried native grasses show repellent properties;
• Organic matter from the mulch enhances root vigor and disease resistance;
• Lower light intensity under shade nets suppresses photophilic pest activity;
• Increased soil microbial diversity helps inhibit pathogenic fungi.

Some matcha gardens have reportedly remained pesticide-free for over five consecutive years while maintaining stable yields through ecological methods.

Biological and Physical Pest Control Measures

To comply with organic and low-residue standards, Shizuoka tea producers use: 1. Yellow sticky traps to attract leafhoppers and loopers; 2. Biological control via predatory mites (*Amblyseius spp.*); 3. UV-frequency insect light traps for nighttime pest reduction; 4. Soil enrichment using beneficial microbes such as *Bacillus subtilis*.

Though these practices require higher labor and costs, they are considered essential in achieving "non-chemical matcha" quality suitable for export to strict markets such as the EU.

Biodynamic Farming: Principles and Emerging Application

Biodynamic agriculture, developed by Rudolf Steiner in 1924, integrates lunar cycles, compost preparations, and spiritual ecology. Although rare in Japanese tea farming, it is gaining traction in select Shizuoka gardens targeting the European market.

Initial adopters in Kawanehon and Morimachi implement:

• Moon-phase planting and shading calendars;
• Cow horn compost (Preparation 500);
• Silica sprays (Preparation 501) to stimulate photosynthesis;
• Leguminous cover crops to cycle nitrogen and improve weed suppression.

These approaches focus more on **soil health and resilience** than on short-term yield increases.

Sensory and Market Outcomes

• **Flavor**: Biodynamic matcha is often described as “transparent in aroma, low in bitterness, and long-lasting in taste”.
• **Market Reception**: Biodynamic-labeled matcha is well received in niche tea salons in Tokyo, Paris, and Los Angeles.
• **Certification**: No Shizuoka farm has yet received Demeter certification; most follow biodynamic practices without formal verification.

Farmers such as **Keigo Murai of Morimachi** state that biodynamics is a way of coexisting with the tea plant, enabling the tea’s “energy” to be more deeply perceived during tasting sessions.

What Distinguishes Shizuoka Matcha?

While Kyoto remains the historical epicenter of Japanese matcha, Shizuoka's growing reputation in premium-grade production can be attributed to three distinct factors: the use of the traditional Chagusaba method, a unique fog-laden climate, and emerging biodynamic farming experiments.

1. Chagusaba Farming and Its Impact on Matcha Quality

In regions such as Kakegawa, tea farmers continue the tradition of *Chagusaba*—cultivating and cutting native grasses like Miscanthus and bamboo grass, then spreading them between tea rows as mulch. This technique:

• Increases soil organic matter and water retention;
• Enhances the L-theanine content in young tea leaves;
• Suppresses catechin formation, reducing bitterness;
• Improves clarity and consistency of the matcha infusion.

The Food and Agriculture Organization (FAO) of the United Nations recognized the Chagusaba system as a *Globally Important Agricultural Heritage System (GIAHS)* in 2013, highlighting its cultural, environmental, and agronomic value.

2. Fog Climate and Its Effect on Aroma and Color

Compared to regions like Kyoto or Kagoshima, mid-to-high elevation zones in Shizuoka—such as the northern slopes of Mt. Awagatake and Kawane—experience frequent fog during the first harvest season (April–May). This fog layer:

• Scatters direct sunlight, mimicking the effect of artificial shading;
• Helps stabilize leaf temperature, supporting extended L-theanine synthesis;
• Protects chlorophyll from photo-degradation.

As a result, matcha from these zones tends to exhibit:

• A more vibrant green hue;
• Fuller, more layered aromas—including *marine*, *bean-like*, and *grassy* notes.

Some researchers have begun classifying this sensory profile as the *Shizuoka-type aroma* (静岡型芳香), distinct from the floral Uji-type or the roasted Kagoshima-type.

3. Biodynamic Agriculture Trials in Matcha Cultivation

In recent years, several younger tea producers in Shizuoka have experimented with **biodynamic farming** principles—aligning planting and harvesting with lunar phases, using horn manure preparations (500/501), and emphasizing soil and cosmic rhythms.

While still experimental in Japan, preliminary field data suggests that biodynamic practices:

• Increase microbial activity in volcanic Andosol soils;
• Improve depth of flavor and length of aftertaste;
• Are appealing to European organic buyers seeking spiritually aligned agricultural products.

Although no Shizuoka farms currently hold formal *Demeter* certification, many are adopting biodynamic-style methods in pursuit of holistic farming and sensory expressiveness.