Academic Research on NOChI-CP

Kuwada, M. and Horie, T. (2002) Effects on silkworm larvae attractiveness of mulberry learves grown at different fertilizer application rates. J. Seric. Sci. Jpn., 71: 75-81. DOI: 10.11416/ kontyushigen1930.71.75

Study on Fertilization Levels and Silkworm Feeding Behavior (Kuwada & Horie, 2002) A comparison of mulberry leaves grown under different fertilization levels showed that leaves grown without fertilization exhibited the strongest attractiveness to silkworms.The research findings were published in 2002 in the Journal of the Sericultural Science of Japan, Vol. 71, pp. 75–81.

Background

It is known that fertilization conditions of mulberry trees can alter the quality and aromatic components of the leaves, which in turn affect the feeding behavior of silkworm larvae. However, there have been no reports comparing the degree of attraction of silkworms to mulberry leaves grown under different fertilization levels.

Objective

To clarify how different fertilization levels affect the chemical composition of mulberry leaves and the attraction behavior of silkworm larvae.

Methods

Three approaches were used for the investigation:

1.The number of silkworm larvae (3rd to 5th instar) attracted to mulberry leaves grown without fertilization and those grown with standard chemical fertilization was compared.
2.Four fertilization levels were set: no fertilizer, no nitrogen, half nitrogen, and standard nitrogen. Attraction tests were conducted with 5th-instar larvae.
3.The content of phenethyl alcohol—an attractant compound—was quantified in leaves from the no-fertilizer and standard-fertilizer plots, and differences between fertilization levels were analyzed.

Results

The results were as follows:

1.Leaves grown without fertilization attracted significantly more larvae than standard-fertilized leaves—6.6 times more during the spring rearing season and 52 times more during the late autumn season.
2.The lower the nitrogen application level, the higher the attraction; 63% of the larvae were attracted to leaves from the no-fertilizer plot.
3.The phenethyl alcohol content in the no-fertilizer plot was nine times higher than that in the standard-fertilizer plot.

Conclusion

Mulberry leaves grown without fertilization develop a natural aromatic balance favored by silkworms, resulting in a higher degree of larval attraction.

Kuwada, M. and Horie, T. (2004) Susceptibilities to a toxic substance, phloxine, of silkworm larvae reared by mulberry leaves grown at different fertilizer application rates. J. Seric.l Sci. Japan, 73: 71-76 (Japanese).

Study on Fertilization Levels and Phloxine Sensitivity (Kuwada & Horie, 2004) It was shown that silkworms reared on mulberry leaves grown without fertilization exhibited greater resistance to the foreign substance phloxine (a dye). The research findings were published in 2004 in the Journal of the Sericultural Science of Japan, Vol. 73, pp. 71–76.

Background

Fertilization conditions of mulberry trees can alter the chemical composition of the leaves, which may in turn affect the physiological responses and xenobiotic sensitivity of silkworm larvae. In particular, nitrogen fertilization may modify leaf constituents and thereby influence the larvae’s response to foreign substances.

Objective

To clarify how different fertilization levels affect the sensitivity of silkworm larvae to phloxine.

Methods

Mulberry trees were cultivated under multiple fertilization levels, ranging from no fertilizer to standard fertilization. Silkworm larvae were exposed to phloxine while being fed leaves from each treatment group, and their mortality rates and sensitivity indices (LC₅₀ and LT₅₀) were compared and evaluated.

Results

Differences in phloxine sensitivity were observed among fertilization treatments. Based on LC₅₀ values, larvae reared on fertilized mulberry leaves were approximately ten times more sensitive to phloxine than those reared on unfertilized leaves. Differences in amino acid composition of the leaves were suggested as a possible contributing factor.

Conclusion

Silkworm larvae reared on unfertilized mulberry leaves exhibited greater resistance to foreign substances such as phloxine.

Kuwada, M., Shiraiwa, T. and Horie, T. (2006) Changes in Total Nitrogen Carbon Contents in Soil and the Leaf Yield of a Long-Term Unfertilized Mulberry under Field Condirtion. Jpn. J. Crop Sci., 75: 28-37. DOI: 10.1626/jcs.75.28

Study on Mulberry Growth under No Organic or Chemical Input Crop Production (NOChI-CP) (Kuwada, Shiraiwa & Horie, 2006) Long-term cultivation of mulberry trees without fertilizers or pesticides was shown to maintain a near-equilibrium balance between soil nitrogen and carbon contents, while also sustaining relatively high and stable mulberry yields. The research findings were published in 2006 in the Memoirs of the Crop Science Society of Japan, Vol. 75, pp. 28–37.

Background

It is necessary to comprehensively clarify the long-term effects of continued fertilizer management—including non-fertilization—on soil nutrient dynamics and the long-term trends of mulberry growth and yield in mulberry fields.

Objective

To report the long-term trends (over 19 years) in mulberry leaf yield and soil total nitrogen and carbon contents in mulberry fields cultivated without fertilization and those continuously cultivated with chemical fertilizers.

Methods

Mulberry fields under non-fertilized and standard chemical fertilization conditions were analyzed for mulberry leaf yield, leaf nitrogen content, and soil total carbon and total nitrogen contents.

Results

In the long-term non-fertilized mulberry field, soil total nitrogen and carbon contents reached equilibrium after approximately 15 years. Annual yields were found to be stable and comparable to those under fertilized conditions (1,800–2,000 g m⁻² per year). Although the total nitrogen content of the whole plant was lower in the non-fertilized field than in the fertilized one, the nitrogen allocation ratio to the leaf blades was higher in the non-fertilized field.

Conclusion

Soil nutrient levels in the non-fertilized field became stabilized, while mulberry production was maintained. This stability is presumed to result from natural nitrogen supply mechanisms, such as nutrient uptake from deep soil layers or biological nitrogen fixation from the atmosphere. Further investigation is required to elucidate the detailed sources and mechanisms of this natural nitrogen supply.

T. Tada et al. (2024) "No Organic or Chemical Input Crop Production (NOChI-CP) and Activities of the NPO No Organic or Chemical Input Crop Production Research Group." Journal of Integrated Field Science 21: 13-17.

A Review on the Comprehensive Effects of No Organic or Chemical Input Crop Production (NOChI-CP) (Tada et al., 2024) This mini-review summarizes the findings to date on No Organic or Chemical Input Crop Production (NOChI-CP) and introduces the NPO Association for Research on No Organic or Chemical Input Crop Production (NPO Muhiken). It was published in 2024 in the Journal of Integrated Field Science, Vol. 21, pp. 13–17.

Background

In recent years, growing public concern for human health and environmental conservation has led to extensive research on environmentally friendly agricultural practices such as organic farming. Under these circumstances, some farmers have been adopting alternative approaches, practicing crop production without resorting to chemical fertilizers or organic materials, a method referred to as no-organic or chemical input crop production (NOChI-CP).

Definition of NOChI-CP

No Organic or Chemical Input Crop Production (NOChI-CP) is a cultivation method that avoids the use of fertilizers, pesticides, and even organic materials. Mokichi Okada, the pioneer of NOChI-CP, asserted that soil inherently possesses the capability to yield edible plants sufficient for sustaining human life, a quality he termed “natural power”. NOChI-CP is a cultivation method designed to allow the soil to fully harness this natural power. We had previously referred to it as “Nature Farming,” but we opted to name it “NOChI-CP” (NOChI sounds the same as the Japanese word for “agricultural field”) to avoid confusion arising from diverse interpretations.

Objective

To introduce the current state of research on NOChI-CP and to present the activities of the NPO Association for Research on No Organic or Chemical Input Crop Production (NPO Muhiken), which promotes the dissemination of this agricultural method.

Research on NOChI-CP

Experiments and field surveys were conducted to elucidate the nature of NOChI-CP, primarily in rice paddy fields.

1. Rice Cultivation: Productivity and Nutrient Supply
　・Yield and Stability: Case studies at nine field sites have confirmed that rice grown under NOChI-CP maintains relatively high and stable yields.
　・Suitable Varieties: Varieties characterized by “panicle weight-type” and “late-maturing cultivars” showed better adaptation to NOChI-CP conditions.
　・Nutrient Supply Mechanism: Stable production is supported by a complex mechanism in which natural soil fertility supplies about 62% of nitrogen, irrigation water contributes 26%, and biological nitrogen fixation accounts for 12%.
　・Root Growth: In a study comparing the growth of rice plants under NOChI and conventional fertilization, it was observed that the crop relative growth rate, especially in roots, decreased more slowly in the late grain filling stage in the NOChI field than that in the conventional field.
　・Resistance to Diseases and Pests: Rice grown under NOChI-CP exhibited higher resistance to plant diseases and pests than conventionally fertilized rice.
2. Mulberry Cultivation and Effects on Silkworms
　・Productivity: In a 19-year comparative study, annual fresh-leaf yields in NOChI fields remained stable between 1,800 and 2,000 g m⁻², comparable to fertilized fields.
　・Attractiveness to Silkworms: The attractiveness of NOChI mulberry leaves to silkworm larvae was significantly higher than that of fertilized leaves.
　・Health Effects: Silkworm larvae raised on NOChI mulberry leaves exhibited approximately 10-fold stronger resistance to phloxine, a known carcinogenic substance, than those raised on fertilized leaves.

NPO “Muhiken”: Dissemination and Current Status

The NPO Association for Research on No Organic or Chemical Input Crop Production (NPO Muhiken) is primarily dedicated to research and dissemination of NOChI-CP. As of December 31, 2023, the organization comprised 119 regular members and 35 supporting members. Its activities are centered on four main areas: research, public relations, technical support, and certification. By the same date, the area of fields registered as NOChI fields totaled 62.5 hectares.

Summary and Outlook

Scientific studies have demonstrated that, despite the absence of fertilizer and chemical inputs, NOChI-CP can maintain stable and acceptable yields in rice and achieve yields comparable to conventional methods in mulberry cultivation. Further studies are required to comprehensively elucidate the mechanisms underlying the stable yields. Through its ongoing initiatives, NPO Muhiken continues to promote this unique cultivation system, which holds significant potential for contributing to environmental conservation and food safety.