Conservation of natural capital

Calbee prioritizes quality when purchasing potatoes, and addressing bruising-induced blackening and internal defects has been a key issue. Research indicates that when the calcium concentration in tubers exceeds 250 mg/kg, bruising and blackening are reduced. Surveys conducted at 170 locations in the Kamikawa and Tokachi regions between 2013 and 2024 revealed an average calcium concentration of 135 mg/kg, with no locations exceeding 250 mg/kg. This indicates that calcium is deficient at the above locations, creating conditions where bruising occurs easily and internal damage is more likely to occur. Initially, we used calcium nitrate as a fertilizer, but it proved unsuitable for the soil quality, so we subsequently switched to calcium sulfate. However, some fields showed visible effects while others did not. While investigating the cause, we found that the unique volcanic ash soil was having an impact.

When considering why calcium was not working, we hypothesized that it was due to excessive phosphate in the soil. This is because when there is a lot of phosphorus, it binds with calcium to form calcium phosphate. In volcanic ash soils, phosphate ions are specifically adsorbed onto the surfaces of certain minerals, making it difficult for crops to absorb them. As a result, excessive amounts of phosphate fertilizer have been used. We concluded that the excessive phosphate applied to the soil accumulated and combined with calcium, forming insoluble calcium phosphate. This prevented the calcium from exerting its intended effect.

Therefore, during the trials starting in 2014, we applied calcium fertilizer after reducing phosphorus application.
Since 1960, heavy application of phosphate fertilizer has led to significant phosphorus accumulation in Hokkaido's field soils. It has now been confirmed that potatoes can grow sufficiently even with a substantial reduction in phosphate fertilizer use. At any rate, it was shown that there would be no problem at all even if we reduced the amount of fertilizer by half. In fact, we found that we could get a larger potato harvest by reducing the amount of fertilizer.

Much of Japan’s farmland consists of volcanic ash soil. Agriculture is carried out on soil classified as Andosol, a rare type found worldwide. A key characteristic of this Andosol is its high organic matter content. The surface of the organic matter carries negative ions, which attract and bind a large amount of calcium, a positively charged ion. Soil naturally leaches calcium if it is calcium-deficient, but does not leach if there is enough calcium. This ability to retain calcium is called cation exchange capacity (CEC). Further, although raising the soil's water retention and drainage capability may seem like opposites at first glance, it is necessary to both retain water and drain it. For example, when there is a prolonged drought, crops cannot absorb water if the soil lacks water retention capabilities. And, during sudden heavy rainfalls, the soil’s drainage capability prevents the roots from rotting. Buffering capacity (CEC, water retention, and drainage) refers to the ability to minimize changes in response to various external impacts and factors. I believe that the agricultural industry needs to pay more attention to this aspect.

Ecosystems, such as forests, have a strong buffering power against various external impacts, are rich in biodiversity, and feature a web-like food chain. There is also the diversity of various genetic resources. So, while they may not become extinct easily, they could also be very vulnerable. Farmland is special in that sense. Agriculture eliminates all other plants, as well as beneficial and detrimental microorganisms, diseases, and insects, in order to maximize the productivity of a single crop, which is extreme from the perspective of the ecosystem.

Continuing with that form of agriculture would, in general, reduce the buffering capacity of the soil. In particular, by being aware of this and increasing the buffering capacity of farmland, it is possible to maintain and improve the soil’s own supply capacity. This will ultimately lead to sustainable agricultural production, even in the face of environmental changes or fertilizer shortages.

Once we understand the type of soil we have, we should consider whether to introduce fertilizer or use nutrients supplied by the soil. Both Calbee and we are keen to increase agricultural productivity and improve quality. For that, you need related knowledge such as plant physiology, soil science, and geology. Based on a comprehensive understanding of these fields, fertilizers and other similar measures are a short-term solution, while regenerative agriculture, utilizing organic materials such as green manure and compost, would be a medium- to long-term solution.