Agriculture and Science 2023/1

Aiming to be a company that continues to contribute to Japanese agriculture

Jcam Agri Co.
Susumu Asano, Chairman and Representative Director

Happy New Year
　At the beginning of the year 2023, I would like to take this opportunity to extend a few words to all of you who read this issue of "Agriculture and Science.
　I was appointed Chairman and Representative Director of JCAM Agri Co. Establishment
We are committed to being a company that can continue to contribute to Japanese agriculture, which has been our management policy since the time of our founding.
We will make a sincere effort to live up to your trust and expectations, and we would like to ask for your continued guidance and encouragement.
We appreciate your understanding and cooperation.

　Last year, the agriculture and fertilizer businesses faced unprecedented changes in the environment and business risks. Specifically, in addition to the impact of the Corona disaster, the Ukraine crisis triggered (1) food shortages and a sharp rise in international prices due to export restrictions in grain exporting countries, (2) difficulties in procuring raw materials for fertilizers, which are highly dependent on imports, and a sharp rise in prices, and (3) increasing demands to address global warming and biodiversity conservation.

　In response to (1) and (2), the Ministry of Agriculture, Forestry and Fisheries (MAFF) launched the "Emergency Measures to Support Procurement of Chemical Fertilizer Raw Materials" in April, and in July decided on the "Project to Cope with Soaring Fertilizer Prices," which was followed by prompt support measures. The latter measure is a short-term measure to protect farmers' businesses by compensating for 70% of the fertilizer price hikes through a combination of effective use of fertilizers (20% reduction in fertilizer use), but the long-term vision also includes a deeper discussion on the essentials of improving food self-sufficiency from the perspective of food security, and measures to increase farm incomes through the large-scale conversion of farmlands are being implemented. It is my earnest hope that the implementation of measures that lead to larger farmland and higher farm income will foster young successors and boost agricultural production.

　In January 2022, against the background of the "Law Concerning the Promotion of Resource Recycling of Plastics" enacted in June 2021, the fertilizer industry formulated a policy based on measures to prevent environmental pollution, such as "implementation of measures to control runoff of coated fertilizer shells from farmland" and "development and diffusion of new technologies" with regard to coated fertilizer processed with plastics and the like. In January 2022, the fertilizer industry announced a policy based on measures to prevent environmental pollution, including "implementation of measures to control runoff of coated shells from farmland" and "development and dissemination of new technologies.

　In response to these changes in the environment, JCM Agri is working to contribute to solving the problems of Japanese agriculture by providing a stable supply of chemical fertilizers to ensure the stable production of domestic agricultural products, and by launching a new coated fertilizer that reduces the amount of resin in the coating and inhibits runoff from farmland. In addition, we are also developing technologies to completely decompose fertilizers in the natural environment ahead of our competitors.

　In addition to stabilizing yield and quality and reducing the amount of wasted fertilizer that is not used for crop growth, it also has environmental benefits, such as reducing the runoff of nutrients into groundwater and other bodies of water, and reducing the emission of dinitrogen monoxide, a greenhouse gas. This fertilizer also has environmental benefits, such as reducing nutrient runoff into groundwater and other bodies of water and inhibiting the generation of nitrous oxide, a greenhouse gas. By addressing environmental issues with our superior technological development capabilities, we hope to realize the government's policy of "effective utilization of fertilizers - reduction of fertilizer use" and "increase in farmers' income through stabilization of yield and quality," and thereby contribute to the advancement of agricultural production in Japan.

　We will continue to make company-wide efforts to meet your expectations. We look forward to your continued support and encouragement.
　In closing, I would like to wish you a happy and prosperous New Year and hope that you will continue to read our journal "Agriculture and Science" in the coming year.

Super-efficient fertilization of sudachi

Tokushima Prefectural Technical Support Center for Agriculture, Forestry and Fisheries
Natural Resources and Environment Research Division
Mika NII

Introduction

　In the mountainous areas of Tokushima Prefecture, many aromatic citrus fruits such as sudachi (Citrus sudachi), yuzu (Citrus yuzu), and yuko (Citrus yuko) are cultivated.
In particular, sudachi is a major crop in Tokushima Prefecture, which accounts for 951 TP3T of the nation's production. However, due to the aging of producers, labor shortages, and rising production costs, there is concern about the frequency of fertilizer application and the content of fertilizers, especially the amount of nitrogen applied. The results of soil monitoring surveys conducted by the Center indicate that phosphoric acid and potassium have accumulated in orchard soils due to consecutive years of application, but growers concerned about the runoff of fertilizer components due to the frequent torrential rains that have been occurring recently have been applying fertilizer in what could be considered excessive amounts to maintain the green color of the peel, an important appearance quality of sudachi. However, there have been cases where growers concerned about runoff of fertilizer components due to frequent torrential rains have applied what could be considered excessive amounts of fertilizer in order to maintain the green color of the peel, an important appearance quality of sudachi. Therefore, we developed a one-shot fertilizer for sudachi, which can be applied once a year with the same efficacy as conventional fertilizer, and conducted a cultivation test using this fertilizer. This test was conducted under contract with ZEN-NOH.

2. Method

　The test plot consisted of a one-shot fertilizer zone where fertilizer mixed with coated fertilizer was applied ("one-shot zone") and a control zone where a sudachi-specific fertilizer containing organic fertilizer was applied according to the prefectural standard (Table 1).

　In the control plot, a special sudachi fertilizer (N: P2O5: K2O = 12:6:9; ingredients: ammonium sulfate, urea, potassium chloride, by-product phosphate fertilizer, rapeseed oil cake, and FTE), which is commonly used in sudachi fields in the prefecture, was applied in the surface layer. The amount of fertilizer applied was 35 kg/10a of nitrogen, 17.5 kg/10a of phosphate, and 26.3 kg/10a of potassium based on the prefectural fertilizer standard.

　One-shot plots were produced by blending Emcoat L70, Emcoat L100, and Ecolong 413 (L-type 70 type) based on the leaching simulation shown in Figure 1. The amount of fertilizer applied for nitrogen component was 24.5 kg/10a, which is 301 TP3T less than the control, phosphoric acid component was 4.4 kg/10a, about 751 TP3T less, and potassium component was 5.1 kg/10a, about 80% less, referring to the amount carried out of the field through harvest (5.2 kg/10a).
　The test site was a field (brown forest soil) in Kamiyama-cho, Nasai-gun, Tokushima Prefecture, and five sudachi trees were tested in 45 m2 per treatment, with a planting interval of 3 m × 3 m. The trees were planted in the same area as the other five treatments.

Results

(1) Nitrogen leaching of prototype one-shot fertilizer

　Figure 2 shows the results of nitrogen leaching measured according to the composition of the prototype one-shot fertilizer. The one-shot fertilizer gradually leached from one month after burial, and in June, the leaching rate exceeded 201 TP3T of the fertilizer amount and the cumulative leaching rate exceeded 371 TP3T. 781 TP3T was leached at the end of the harvest in late September. In the simulation of the trial, it was assumed that nitrogen components would be leached stably from immediately after fertilizer application to the harvesting period, but actual measurements showed that nitrogen leaching was delayed more than originally assumed, with a maximum in June.

(2) Changes in soil chemistry

(1) Nitrate nitrogen (Figures 3-1 and 3-2)
　On the surface, the one-shot plot remained high in 2014, 2016, and 2017, but in 2013 and 2015, the control plot and the
No differences were observed. In the second layer (10-20 cm), no treatment-area differences were observed.

(2) Available phosphoric acid (data omitted)
　The amount of phosphate fertilized in the one-shot plot was about one-fifth of that in the one-shot plot, but the amount of soluble phosphate in the soil was about one-fifth of that in the one-shot plot in 2015 and 2016.
　remained high in the wards.
(iii) Exchangeable potassium (Figures 4-1 and 4-2)
There was a trend of lower exchangeable potassium in the next layer of one-shot plots starting around 2015, the third year of the project.

(3) Changes in inorganic constituents in leaves

　Leaf constituent content did not differ among treatments for nitrogen and phosphorus, but potassium tended to be higher in the one-shot treatments than in the control treatments (Fig. 5).

(4) Yield and fruit quality

　During the harvest period (late August to mid-September), fruits that reached 2L size (3.6 to 4.0 cm in lateral diameter), which has a high unit sales price, were harvested one after another, and the number of fruits and their weight at harvest were measured. According to the results of the five-year cumulative yield survey shown in Figure 6, the yield per unit tree volume in the one-shot area was 25.5 kg/m3 and 23 kg/m3 in the control area, indicating that the yield of the one-shot area was about 101 TP3T higher than that of the control area. For the fruit quality survey at harvest, 10 2L-class fruits were collected per tree, and peel color was measured with a colorimeter and greenness was calculated. As shown in Table 2, there were no differences among treatments, but at the end of the harvest, the one-shot treatments showed
A trend toward darker peel green was observed.

(5) Cost estimation

　The trial one-shot fertilizer was launched by JA Zen-Noh Tokushima in March 2021 under the trade name "Sudachi Haru Ippatsu." The fertilizer cost per 10 a was calculated based on the fertilizer amount and price of this one-shot fertilizer and a conventional compound fertilizer (Sudachi King) exclusively for Sudachi. The annual nitrogen fertilizer application rate was reduced by 301 TP3T, assuming 24.5 kg N/10a, because fertilizer with a regulated fertilizer effect generally has high fertilizer application efficiency, and because it has been reported that fruit quality and yield are excellent even with a 301 TP3T reduction in the application of coated fertilizers to Onshu mandarins.

　According to the estimation results shown in Table 3, the annual cost of fertilizer was 40,326 yen for the one-shot fertilizer, while the cost was 53,229 yen for the control area, where the annual nitrogen fertilizer application was 35 kg N/10a (based on interviews with JA Meisei-gun).

　This means that the Sudachi one-shot fertilizer developed here can be applied to reduce the cost of fertilizer to about 761 TP3T of conventional Sudachi-specific fertilizer, and the number of annual fertilizer applications can be reduced from four to one, which is considered a significant labor saving in terms of both cost and work.

At the end.

　A wide variety of fertilizers with different leaching periods and leaching patterns are now on the market. In rice and vegetable cultivation, fertilizer application techniques such as total basal application, total seedling application, and local application are widely used to save labor and improve fertilizer application efficiency. On the other hand, fruit tree cultivation has also been introduced to fruit production such as Onshu mandarin oranges and ponkan orange, as well as to the cultivation of young trees, etc. However, these techniques have not yet been widely used in fruit tree production sites in Tokushima Prefecture.

　Citrus fruits such as sudachi, yuzu, and Onshu mandarin oranges are grown continuously for 30 years or more.
In addition, because nutrients are accumulated in the tree, the effect of fertilizer application is not readily apparent in a short period of time. Therefore, there is concern about the effects of long-term application of only one-shot fertilizer on soil and plants. However, the exchangeable potassium in the soil tended to decrease after the third year in the one-shot treatments.

　The yield of the one-shot area during this test period was about 2 t/10a, and the potassium component in this crop was about 5.2 kg/10a. The amount of potash applied by one-shot fertilizer is 5.1 kg/year, and considering the loss of potash due to runoff, etc., the potash balance may be deteriorated. Therefore, it is necessary to analyze the soil regularly and pay attention to the deficiency of potassium components.

　However, the fertilizer is also applicable to fertilizer application using drones, which are expected to be introduced in the future. We would like to introduce and promote the use of this super-laborsaving fertilization technology in production sites as an effort to solve labor shortages and improve efficiency in field management operations.

No Soil - Part 18
　　How plants absorb insoluble substances
　　-Secretes substances from the roots that aid in dissolution.

Hokkaido Branch Office, JCM Agri Co.
　Teruo Matsunaka Technical Advisor

　Plants select and absorb the nutrients they need from the water (soil solution) in the soil. In the last issue, I explained how this works. If nutrients are easily soluble in soil solution, it was explained. But what do plants do when nutrients exist in the soil as insoluble substances that are difficult to dissolve in water?
　In this article, I would like to look at the amazing mechanism by which plants absorb nutrients from substances that are difficult to dissolve in soil solution.

1. phosphorus and iron are insoluble substances in the field

　Among plant nutrients, phosphorus and iron exist in the soil in the form of substances that are insoluble in water (insoluble substances, such as aluminum phosphate, iron phosphate, and iron hydroxide). However, when the soil surface is covered with water and the soil is in a reduced state due to lack of oxygen, as in paddy fields, the insoluble iron phosphate and iron hydroxide are transformed into water-soluble substances. Therefore, rice plants are seldom significantly deficient in these nutrients.

　On the other hand, in field soil, oxygen is connected to the atmosphere and remains in an oxidized state. For this reason, phosphorus and iron exist as insoluble substances, which are difficult to dissolve in soil solution, making them difficult for plants to absorb. However, plants absorb such nutrients by taking measures as described below.

2. mechanism of phosphorus absorption from insoluble phosphorus

　In field conditions, phosphorus is often present as the insoluble substances aluminum phosphate and iron phosphate. In addition, phosphorus may also be present in the form of organic phosphorus, which cannot be absorbed without modification. To facilitate the absorption of such water-insoluble phosphorus, plants produce organic acids (citric acid, oxalic acid, piscic acid, etc.) and an enzyme called acid phosphatase in the root cells and discharge them into the soil around the roots (this phenomenon is called secretion) (Figure 1). Of course, these secreted substances must also pass through the cell membrane to exit the root. The transport of these substances is handled by the respective transport proteins (transporters).

　Organic acids secreted by the roots have the ability to dissolve iron phosphate and aluminum phosphate in the soil by stripping their bonds. The dissolved phosphorus in ionic form is transported into the cell membrane through transport proteins and absorbed by the plant. The iron and aluminum that are stripped from their bonds do not remain in the soil solution as ions. They are transformed by organic acids into an encapsulated form (this kind of reaction is called chelation, and the resulting substance is called a chelating substance), which prevents them from rejoining phosphorus.

　Acid phosphatases act on the organic phosphorus present around the roots and deliver water-soluble phosphate ions to the soil solution by enzymatic degradation (Figure 1). The delivered phosphate ions are absorbed into the cell membrane through transport proteins as plant nutrients.

3. expand rooting to absorb phosphorus

　Since phosphorus exists as an insoluble substance, the concentration of phosphorus in the soil solution is low. Therefore, plants sometimes try to absorb phosphorus in low concentrations by increasing root growth and expanding the root surface area. A similar mechanism is used by filamentous fungi (a member of the fungus family, mycorrhizal fungi) that live symbiotically in the roots. Mycorrhizal fungi spread their mycelium widely in the soil, take up phosphorus from the soil solution, and provide it to the host plant, which in turn supplies phosphorus to the plant.

4. two mechanisms of iron absorption from insoluble iron

　Iron in the field state is a poorly soluble iron oxide (this is the same substance as iron rust, which is a form of iron that is not soluble in soil solutions. This form of iron is present in the soil in the form of trivalent iron, Fe(III), Fe3+) and is insoluble in soil solution. If this form of iron is not soluble in soil solution, plants are unable to absorb it and become deficient in it. However, plants growing in field conditions absorb iron by secreting a substance from their roots that dissolves insoluble iron (trivalent iron), as in the case of phosphorus. However, the mechanism of iron absorption is very different between plants other than grasses and grass (Figure 2).

(1) Mechanism of iron absorption in plants other than grasses

　This is known as Strategy-I (left side of Figure 2). First, a loose chelating substance (phenolic acid) that dissolves insoluble iron (trivalent iron) is secreted from the roots. This substance encases (chelates) the trivalent iron and brings it into the cell wall. Then, an enzyme (trivalent iron reductase, FRO) present on the cell membrane surface acts to convert the trivalent iron to divalent iron (Fe(II), Fe2+). This trivalent iron is then absorbed into the cell membrane by the iron transport protein (IRT).

　Other mechanisms utilize trivalent iron, which is more soluble in acidic conditions. There is a transport protein (proton pump, HA) that releases hydrogen ions from root cells to the outside of the root. This proton pump lowers the pH around the roots, making it easier for trivalent iron to dissolve in water and be absorbed.

(2) Mechanism of iron absorption by rice plants

　This is known as Strategy-II (right side of Figure 2). Organic acids such as mugineic acids and their analogues (MAs in the figure, see note in Figure 2 for explanation of the English letters), which are produced by the plant inside the root cells, are secreted outside the cell wall around the root through a transport protein (TOM1). This acts on trivalent iron, which is transformed into a substance (chelate called Fe(III)-MAs) encapsulated in mugineic acids. The chelates made from the iron and mugineic acids are absorbed into the plasma membrane by transport proteins (YS1 and YSL) responsible for their transport (Nozoe et al., 2014).

　This mugineic acid was discovered by Professor Seiichi Takagi of Iwate University in Japan in 1976. Until then, the mechanism of iron absorption by plants other than grasses could not fully explain the iron absorption of grasses. However, this discovery clarified the mechanism. This was truly a major historical discovery.