The Amount of Rainfall and Humidity for Cultivating Oud

When it is said that oud trees are the daughters of the rainforests, the water is at the heart of this sentence: abundant rains, humid air, and a soil that rarely dries completely. In this article we pause at the amount of rainfall and humidity and their role in the environment of oud trees — how much rain it is said they are accustomed to, how its distribution matters, not its amount alone, and what the place of atmospheric humidity is in the scene — in descriptive, reserved language, without numbers we assert.

1. Rain and humidity in brief

The general conclusion upon which most of what is circulated about the environment of oud trees agrees is that they are accustomed to abundant rains, distributed across the year to a great extent, with high atmospheric humidity of the kind that prevails in the tropical rainforests. The species of Aquilaria and Gyrinops in their habitat arose in an environment that the water scarcely leaves for long, neither rain descending nor humidity suspended in the air. This is the frame upon which every talk of water in the cultivation of oud trees is built.

And we place this article in its position from the larger picture: it details a single element of the elements of the climate that we summarized in the climate suitable for cultivating oud. That article presents the climatic scene in full — heat, humidity, and light — while here we pause at the water specifically: the descending rain and the surrounding humidity. And it is other than the managed irrigation that the farmer provides in the dry seasons, which is a door we devote separately later in this guide.

And we affirm from the outset that all that will come are qualitative descriptions, not quantitative. When we say "abundant" or "distributed" or "high" we describe the character of the environment, we do not draw its bounds with numbers. And any number we assert — of annual millimeters of rain, or a percentage of humidity, or a number of dry months — may mislead a reader who supposes it a guaranteed recipe, while these values vary widely from one island to another and from one location to a location.

2. The amount of rainfall

The first thing mentioned about water in the environment of oud trees is the abundance of rain. The regions to which these trees are ascribed in their habitat are known for their heavy rains, since the tropical rainforests were only named rainy because the rain in them is much, not scant. And this abundance means that the soil usually remains humid most of the time, and that the tree arose upon a generous water supply, not upon a scarcity it manages.

And we deliberately avoid here mentioning any amount for the rain with numbers. How many millimeters in the year does the tree need? This is a question we do not answer with a number, because the sources vary in their estimation, and because the amount that suits one location may not mean the same thing in another location differing from it in soil, heat, and drainage. The conceptual description suffices us: an abundant rain of the kind that the humid tropical regions know, far from the scarcity of the arid or semi-arid regions.

And abundance alone does not suffice to understand the scene. The heavy rain that descends in a single season then cuts off for long is not like the heavy rain distributed across the year. Therefore the talk of the "amount" of rain leads directly to the talk of its "distribution," which is what we devote the following section to, because they, in the environment of oud trees, are two faces of a single matter that do not separate.

3. The distribution of rainfall across the year

There is a principle mentioned often when the water of the tropical trees is spoken of: the distribution of the rain may matter as much as its amount matters, or more. A tree that arose upon a near-constant humidity may not be accustomed to a long cutting-off of water even if the total of the annual rain is large. And the model rainforest is described as having its rain distributed across the year to a great extent, not confined to a short season followed by an extended aridity.

From here it is mentioned that prolonged periods of aridity may be a source of stress for trees accustomed to a continuous humidity. When the rains cut off for a long period, and neither irrigation nor a retained soil humidity compensates them, the tree may enter into a water stress. And we put this forward as a general consideration that is spoken of, not a technical judgment we issue, because the extent of tolerance of aridity differs with the difference of the species, the age, the soil, and the location, and it is the affair of the specialist, not the supplier.

And we do not mean by that that every season of less rain is an inevitable catastrophe; many tropical locations know a moderate seasonal variation between more abundant months and others less so, and the trees live alongside it. What is meant is rather the distinction between a tolerable seasonal variation and a severe, prolonged aridity that departs from the familiar of the environment. And because this thread is fine, its estimation remains local — by measuring the pattern of the rains in the location itself — more precise than any general rule we drive from afar.

4. Atmospheric humidity

Alongside the descending rain, there is a water of another kind that distinguishes the environment of oud trees: the high atmospheric humidity. The air of the rainforest is saturated with humidity, and the tree does not live on what wets its roots only, but there also surrounds it humid airs that wrap its leaves and its stem. This surrounding humidity is an authentic part of the local climate in which these trees arose and adapted to over the course of generations.

And we are reserved here — as is our habit — about mentioning any percentage of humidity. How much is the suitable humidity? This is a question we set no number for, because the atmospheric humidity swings during the day and the season, and differs between the heart of the dense forest and an adjacent open space. The general principle suffices us: humid airs of the manner of the rainforest, not a dry air like that which prevails in the desert or the dry continental regions.

And why does the atmospheric humidity matter to this extent? Because it is part of the integrated climate that the tree is accustomed to, and because its sharp decline may make the environment more like other than its original habitat even if the water is available to the roots. From here comes the challenge when oud trees are cultivated in open spaces less humid than the dense forest: imitating the humidity of the forest is not an easy matter, and it is among the considerations that the specialized farmer balances when choosing the location and designing the planting.

5. Rain and drainage — when the water increases

It may be understood from what precedes that "the more the water the better," and this is an incomplete understanding that needs correcting. The abundant water is a blessing as long as it finds its way to the drainage; but when it stagnates and is retained around the roots it may turn into a harm. The constant saturation with stagnant water — what is known as the drowning of the roots — is mentioned generally as harmful to many trees, and among them what is said about oud trees that are accustomed to a humidity, not a drowning.

Therefore the talk of the abundance of the rain does not separate from the talk of the soil that receives it. The well-drained soil allows the excess water to penetrate instead of being retained, which is what balances between the tree's need for humidity and the danger of drowning its roots. And we have devoted to this aspect an independent article on the soil suitable for cultivating oud that explains why the mention of "good drainage" recurs as among the most important of what is looked into.

And the conceptual conclusion here is an equation of two sides: an abundant humidity on one hand, and a good drainage that prevents stagnation on the other. The ideal environment spoken of is not a permanently flooded land, but a humid, living land in which the water moves and does not stand. And this alone explains why one is not content with the question "how much rain falls?" but adds to it always the question "and how is it drained?".

6. Natural rain versus irrigation

There is a difference that ought to be clarified: this article speaks of the natural rain and the surrounding humidity that the environment itself provides, not of the irrigation that the farmer manages with his hand. In the humid tropical habitat the natural rain alone may suffice most of the time, because it is abundant and distributed. But when the trees are cultivated in locations of less rain, or when periods drier than usual pass, the role of supplementary irrigation comes to compensate the deficiency and preserve the humidity of the soil.

And we distinguish between the two matters deliberately so they do not mix. The natural rain is an environmental factor that describes the habitat of the tree, and the irrigation is an agricultural practice by which the human intervenes. The farmer may rely on the first entirely where the sky suffices him, and may resort to the second where it is scarce. And the details of irrigation — when, how much, and how — are an independent technical door that is the affair of the specialist, which we devote later in this guide within the talk of the irrigation of oud trees and link here when it is completed.

And what matters in this place is that the reader realize that "the tree's need for water" is one thing, and "the source of this water" is another thing. The need is relatively constant — an abundant humidity with a good drainage — while the source may be a rain descending from the sky, or a managed irrigation from the farmer, or a mixture of the two. And the closer the location is to the natural abundance, the less the need for the intervention of the human; and the farther it is from it, the more the reliance on irrigation.

7. The conclusion for the farmer and the buyer

We can gather what precedes in a single principle: the system of water — rain, humidity, and drainage — is among the foundations upon which the environment of oud trees is built, not a marginal detail. The abundance, the distribution, the atmospheric humidity, and the good drainage all gather to draw the environment that the tree is accustomed to in its habitat. And we repeat that the detailing of all this numerically — of millimeters of rain, percentages of humidity, and irrigation schedules — its reference is the agricultural specialists and the extension services in each country, and that the most precise thing relied upon is the local measurement in the location itself, not a general rule transmitted from afar.

As for the buyer, the conclusion is closer and simpler: when you choose an Indonesian oud, you are choosing the fruit of a humid tropical environment generous with water, in which the tree arose at its leisure between an abundant rain and a humid air. And this origin is part of the story of the oud and its character, even though it is not tested by the rain directly but by the scent, the grade, and the origin. And for whoever wants to distinguish the authentic from other than it, we have set a practical guide in how to choose authentic Indonesian oud that helps him to choose with confidence.

And the best thing that brings this theoretical talk closer to your sense is that you try for yourself. Instead of committing to a quantity before you know, begin with a sample of oud by which you test the scent, the origin, and the grade, and sense in it the effect of that generous tropical environment in the piece in your hands.