The following day, August 23rd.
Jin, operating through his Double, was selecting land for new fields under Rolona’s guidance. Naturally, Reiko and Anne accompanied them.
"Ah, how about this area?" Jin asked.
The land sloped gently toward the south. A small stream meandered nearby, suggesting that water access would be convenient. To the north stood a coniferous forest, which would likely serve as a windbreak against the cold northern air.
"Yes, but the soil here is poor," Rolona replied, her expression troubled. "Far too poor."
Indeed, hardly any grass grew on the plot. Reiko crouched down and dug into the earth with her hands, uncovering a mixture of sand, gravel, and volcanic clay. She placed a sample on her palm and showed it to Jin.
"I see. It lacks organic matter," Jin noted.
"Organic matter?" Rolona tilted her head curiously. Though she was Istalis’s mother, she appeared to be in her late twenties.
Demon race lifespans were roughly five times those of humans. Rolona had claimed to be two hundred years old, which made her the equivalent of a forty-year-old human. However, since the aging process for demons reportedly only began after they reached four hundred, she still possessed a youthful appearance.
"Yes, organic matter," Jin explained. "Like humus and compost. Also, the soil has become far too compacted; we’ll need to plow it deeply."
Jin had already forged iron plows and hoes the previous day. By reinforcing the blades with adamantite, he ensured the tools wouldn't easily wear out, even when subjected to a golem’s immense strength.
"Now, for the soil improvement..."
Even for Jin, agricultural science was a subject where he had only basic knowledge. He vaguely recalled a news story about using superabsorbent polymers to green the desert, but beyond that, his expertise was limited to concepts like slash-and-burn farming and the role of root nodule bacteria in legumes.
"Well, nitrogen, phosphorus, and potassium are the essentials."
He remembered at least those three primary elements of plant cultivation, so he decided to start there.
"Um, what are those?" Rolona asked.
Even when he explained, Rolona could only tilt her head in confusion. It was a charming gesture, though she was a married woman and a mother of three.
"Nitrogen helps leaves and stems grow, phosphorus is for flowers and fruit, and potassium is vital for root development."
"I see... is that also part of your knowledge as a Magi Craft Meister?"
"Perhaps. Who can say?"
For the time being, they set about preparing humus, plant ash, bone meal, and oil cake. Jin made sure the humus contained as few coniferous needles as possible, as the turpentine-like oils in them could hinder root growth. The plant ash was produced by burning the trees and weeds cleared from the site, while the bone meal was recycled from local waste.
As for oil cake—the residue left after pressing oil from seeds like sesame or rapeseed—they had none. Since the clan didn't produce vegetable oils, they had no such byproduct to use.
"Well, if we start with kuromugi and beans, the land should eventually become fertile," Jin said.
The roots left in the soil and the husks after harvest could also be repurposed as organic fertilizer. As Jin imparted this basic wisdom to Rolona, Istalis arrived and began listening with rapt attention.
"Istalis, do you plan to follow in Rolona-san’s footsteps?" Jin asked.
"Yes. I hope to succeed my mother and take responsibility for our food supply."
Hearing her resolve, Jin felt encouraged to go into even greater detail. Grati-fied by her interest, he found himself rambling about various tidbits of agricultural lore.
"There’s something called commercial fertilizer that people buy, and in the past, even things like dried sardines were used as fertilizer."
"In addition to the three core elements, trace amounts of calcium, magnesium, and sulfur are supposedly beneficial."
"The nodules on bean roots house root nodule bacteria, which live in symbiosis with the plant to fix nitrogen from the air."
"Soil should ideally have a crumb structure—when it forms into clusters of granules, the roots can breathe more easily and grow better."
"You can bury vegetable scraps in shallow pits, and after a few months, they turn into excellent fertilizer."
"If there’s peat available, that should work as fertilizer, too."
Even when she didn't fully grasp the science, Istalis listened with all her might, determined to memorize every word. Since Jin’s knowledge was only that of a home gardener, he soon ran out of topics.
"...That’s about all I can tell you for now."
"Thank you very much, Jin-sama."
Jin reflected privately that the demon race had likely neglected technology because they could rely on powerful magic. As their bloodlines thinned and their mana weakened over generations, they had been left without the tools to sustain themselves.
While Jin talked with Rolona and Istalis, the twenty Agrii units finished clearing about two hectares of land. At this pace, they would likely clear ten hectares by the end of the day.
To support a clan of one hundred people, they would need roughly fifteen tons of grain annually, requiring at least thirty hectares of cultivated land. Since the All-Creation clan currently only numbered about fifty members, it seemed sufficient, but Jin was calculating for a surplus and fallow periods to prevent soil exhaustion. Given the cold climate and the risk of poor harvests, he wanted at least forty hectares.
From what Jin could see, the current fields covered almost exactly thirty hectares. They were living on the edge, with no room for stockpiling.
"The question is whether we can sow the kuromugi in time," Jin mused.
According to Istalis, the first frost usually arrived between the end of October and the beginning of November, followed by the first snow in late November.
"Kuromugi is very vulnerable to frost," Istalis noted. It was a fact they knew well from years of struggling with the climate.
"It can be harvested in two months at the earliest, though," Jin said.
Having cleared the fields on a south-facing slope would provide some natural protection, but it wouldn't be enough.
"Wait... that's it! A barrier!"
Jin, who had been watching the Agrii units work, suddenly had an inspiration and dashed toward the workshop. In his excitement, the behavior of the man and his Double was identical.
"Let’s see... the strength doesn't need to be high. But I need to maximize the effective range..."
"Jin, what are you making?" Sion asked, peeking into the workshop.
Istalis arrived a moment later, slightly out of breath. Despite being a demon, she had been outrun by the physical capabilities of the Double.
"A barrier to prevent frost damage," Jin replied.
"Wait, is that possible?"
A standard physical defense barrier could block frost, but covering dozens of hectares with one was usually far too taxing. However, Jin knew several ways to combat frost from his knowledge of Earth. In inland Japan, farmers burned oil to create smoke screens or used large fans to circulate the air and prevent radiant cooling.
"It’s a solid barrier with its strength reduced to the absolute limit," Jin explained. "I should be able to cover a full hectare with a single unit."
What Jin created was a solid barrier so weak it was useless for defense—a mere ten-thousandth of its usual strength. However, it was more than enough to prevent the warmth absorbed by the earth during the day from radiating away and to block the intrusion of freezing air. Best of all, because it was so weak, people could pass through it without any resistance.
"...Wow. That’s incredible," Sion said, quickly grasping the utility of the device.
"It should even be enough to keep out light snow flurries," Jin added.
With this, a two-crop system for kuromugi might actually be viable. Jin advised them that it would be best to grow beans from spring to summer and kuromugi from summer to autumn.
"Even without a greenhouse, this should significantly improve the yield..."
The weak heat-retention effect would likely raise the temperature by two or three degrees, potentially extending the growing season by one or two months.
"To think you could solve the root of our conflicts with a method like this... You truly are the Magi Craft Meister, Jin-sama!" Istalis praised him warmly. Jin merely scratched his cheek in embarrassment.
At the end of the day, Jin asked to see the zirconia mining site.
The mine was located deep within a horizontal tunnel dug into a seaside cliff. When Jin saw the interior, he was stunned. Clear, colorless zirconia crystals were being unearthed in massive quantities.
"...How?"
Thinking it over, the sheer abundance of colorless zirconia felt completely unnatural.
"Sonar."
He secretly probed the area and found that the deposit continued deep into the cliff. However, the distribution was geometric—far too orderly to be a natural formation. He suspected it was semi-artificial. Strictly speaking, the zirconia being mined appeared to contain specific additives.
Unfortunately, Jin wasn't an expert on gemstones, so he couldn't determine exactly what those additives were or what their purpose might have been. However, it was easy to imagine that something significant had occurred at this site in the distant past.
Still, since uncovering ancient mysteries wasn't his immediate goal, he decided that as long as it provided usable materials, he would leave it at that for now.
"My Lord, that is a magnificent invention," Laojun said.
Back on Hourai Island, Laojun was full of praise for Jin’s latest breakthrough.
"Yeah, I think it was a good idea. It might be niche in this region, but in areas with high free ether concentrations, it'll be incredibly practical."
"It will also serve as an excellent diplomatic gift for the other moderate factions," Laojun noted.
If they could demonstrate a clear path to food self-sufficiency, the primary cause of demon instability would be solved. The moderate factions would be far more inclined to cooperate.
"Right. We should plan to visit the other moderate factions soon."
"Understood. On my end, we are beginning to grasp the movements of the radical faction."
"Good. Let me know once you’ve synthesized the data."
"As you wish, My Lord."