Farmers’ interest in the rehabilitation of hardé soils strongly depends on the mode of tenure. When they are owners, they agree to invest in implementing the various actions of rehabilitation. On the contrary, the farmer cannot improve the land for fear of losing the operating license for attempt to appropriation or see the rental price increase in relation to the improvement of soil fertility in the exploitation.Analysis of the survey results relating to organizational capacity of rural communities and the existence of organizations that can assist them in the implementation of different actions show a lack of organization within the community. Similarly, the study reveals that 93% of the study population are totally unaware of the existence of organizations or endogenous and exogenous associations working in the field of hardé soils rehabilitation. Each farmer conducts its activities independently and isolated from others. Though Seignobos pointed out that the turning to profit of hardé soils must necessarily be collective in one or more land since it imposes changes pasture’s habits. The absence of organisms that can supervise or coordinate the villagers’ rehabilitation actions has a significant impact on the adoption of certain rehabilitation methods which efficacy has been proven in other lands. This means that there is no integration of local knowledge in the implementation of the project and the direct consequences are localized and ephemeral efficiency, but also not conclusive results. A study made by Kinane et al. showed that belonging to a farmer organization is fundamental for the adoption of a technique. Construction of earth dikes for example requires a significant investment in time and materials, which can be a real handicap for some farmers. This handicap could be quickly filled by the support system commonly used in the region.Local techniques discussed here ultimately contribute to the rehabilitation of soil fertility through improving of their physical, flower pot chemical and biological properties.

Integration of new approaches in order to effectively rehabilitate the soil proves to be necessary. But the implementation of an innovation in rural areas must take into account the factors of ownership and inscribe in a well defined trajectory. This trajectory must be dynamic and reflexive where local knowledge will be associated with expert knowledge to ensure impact and sustainability of innovation. The contribution of organic matter seems to be a unifying element, which has an influence on different soil properties. How can one bring organic matter in the Sahel area so as to circumvent the difficulties posed by these local techniques? The contribution of DMC developed by CIRAD researchers seems to be a best solution. Vegetation cover protects the soil against erosion, increases infiltration through the absence of tillage, reduces evaporation, reduces variations in soil temperature, creates a favourable environment for the development of biological activities, control weeds and increase soil organic matter content . Besides these benefits, it plays an important role in the biogeochemical cycling of elements, and could be a useful forage value for livestock in inter-culture. However, the sustainability and adaptability of technical changes go through awareness-raising and thus empowerment of stakeholders.Forests constitute 30% of the total land area on earth. Forests occupy 68% or 2/3 of the total land area in Japan, making it the country with the second highest percentage of forests in the world, after Finland. The healing effect of forests has attracted wide attention in recent years and can be considered one of the benefits of forest resources. There have been studies that reported a reduction in stress and a decline in the mortality rate from cardiac disease by “forest bathing” . In the forest, fallen leaves and withered branches cover the forest floor. The layer of such deposited fallen leaves is called the humus layer. In soil science, it is called the O layer . Organic matter in the O layer decomposes within several years. Some of this matter is emitted into the atmosphere as carbon dioxide or becomes dissolved organic matter and remains in the soil as microbial metabolites. Thus, in the forest, fallen leaves go into the soil, which results in material circulation. Soil is not only the largest feature of the forest, but also is a source of its scent. However, there has been very little attention paid to the effects of the scent that is emitted from the soil. Interest is increasing in clarifying the effect of the scent of a forest on humans in the field of aromatherapy. In it, the report of an antitumor action etc. is made about the effect to the humans of monoterpenes, such as an herb and a needle-leaf tree. Nakamura, et al. examined and identified the components of the forest atmosphere such as terpenes, and reported that human beings can easily absorb such components. However, there are no reports on the scent that occurs from soil, which is one of the biggest features of the forest environment. Hanyu et al. examined soil and reported that the scent and texture of soil in a forest have a relaxing effect; however, there are very few reports on the effect of the scent of soil on human beings.

Accordingly, this report aims to examine the effect of the scent of forest soil on human beings.Physiological evaluation was performed by measuring heart rate and heart rate fluctuation for which 2-lead electrocardiogram recorders were used. The R-R interval was computed with a memory heart rate meter , and heart rate , low frequency component , High frequency component , and ratio  of LF component and HF component were analyzed by the heart rate fluctuation real-time analysis program. Psychological evaluation was made using the Visual Analogue Scale , Profile of Mood States , and open-ended questions. Measurement of VAS was conducted using a measure where the left end  of the scale  indicated a state of “no feeling” and the right end  indicated a state where the subject had “maximum feeling”. The subjects were directed to indicate their current state by checking the scale and evaluating the VAS results by the distance  from the left end of the scale to the checked point . Using the VAS scale, there were 12 questions for the control group and 13 for the stimulation group with the addition of a question for evaluating the scent of soil . The short form of the Profile of Mood States  was used to evaluate 30 items on mood states with afive-grade evaluation and to determine T-Scores for the six mood scales of “Tension-Anxiety”, “Depression”, “Anger-Hostility”, “Vigor”, “Fatigue” and “Confusion”.The experiment was conducted in a room with a room temperature of 24˚C ± 0.5˚C, and relative humidity of 31% ± 1%. The subjects sat quietly for about 10 min. after entering the room. Physiological evaluation was measured as follows: 5 min. rest , 1 min. no stimulation or stimulation , and 15 min. rest. The subjects sat with their eyes closed during measurement .At Post, the evaluation included the time when the scent was detected.Before starting the experiment, the bottle with a screw-on cap for scent stimulation into which soil was put, was positioned so that the opening of the bottle was 10 cm from the nose of the subject. The scent stimulation was made by opening/closing the cap. After 5 min. rest with the cap closed  the control group sat with the cap closed  and the stimulation group  sat with the cap open so they were able to smell the scent. After that, both groups rested for 15 min.  with the cap closed.For physiological evaluation, the mean for each value of Pre., No Stim., Stim., Post 5, Post 10, and Post 15 was determined. For heart rate  and heart rate fluctuation  the Fisher  multiple comparison was conducted on each group in the generalized linear model for five points . Temporal changes between both groups were examined by two-way analysis of variance  in the generalized linear model. Wilcoxon signed-rank test was used for VAS and POMS. The data for the physiological/psychological evaluation was indicated by mean ± standard deviation.In this study, we compared subjects which were presented with the scent of soil  and those which were not . Consequently,hydroponic grow system although the control group showed no physiological changes, the stimulation group showed a significant decrease in heart rate .

The heart rate is determined by the firing frequency of the sinus node . This frequency is influenced by the dominant sympathetic nerve and vagus nerve, thus leading to either excitability or inhibitory. For this reason, periodic activity of the brain stem and higher order cerebral cortex that synchronize with signals from arteries and veins and changes in blood pressure influence behavior, emotions, circadian rhythm, which increase through hyperactivity of sympathetic nerve functions, and decrease through hyperactivity of parasympathetic nerve functions. In this study, the heart rate of the stimulation group decreased, but there was no significant difference between HF that is a parasympathetic nerve index of heart rate fluctuation and LF/HF that is a sympathetic nerve index. Thus, we conclude that neither the parasympathetic nerves nor the sympathetic nerves function independently. In the open-ended questions about what kind of image subjects associated with the soil scent, some of the answers included “insect collecting” in the mountains, a forest, and horticultural therapy. A study on POMS reported that “forest bathing” improved mental health and horticultural therapy reduced negative emotions. For psychological evaluation, POMS scores of “Tension-Anxiety” and “Vigor” decreased in the control group. Moreover, VAS scores of “Feel excited” and “Feel thrilled” decreased. In the stimulation group, POMS scores of “Tension-Anxiety”, “Anger-Hostility”and “Confusion” decreased. In addition, VAS scores of “Feel nervous” decreased and “Feel comfortable”, “Feel relaxed” and “Feel soothed” increased. From the above results, we conclude that subjects expressed improvement in their mood and were more relaxed when they were presented with the scent of soil. Some of the answers indicated that the scent of soil recalled childhood memories with subjects using such phrases as “in my early childhood”, “in my childhood” or “when I was a child”. In many cases, the scent made subjects recall memories of early childhood that were older than those created by visual or verbal cues and raised a more emotional response. The sense of smell enters the limbic system which is responsible for processing memory and creating emotion and reaches the hypothalamus that is also an autonomic nerve center. Accordingly, the emotional response from an individual who is stimulated by a scent can cause physiological changes in brain waves and various autonomic nerve functions.

The heart rate is adjusted by the autonomic nervous system or endocrine system, and can change according to the subject’s posture, and physical and mental activities. Therefore, for the heart rate that showed significant difference, we performed a Pearson’s correlation analysis among the degrees of changes at the points of Stim and Post 15 against Pre, and the degree of changes at the point of Post against Pre in VAS and POMS, and examined the psychological factors related to heart rate . As a result, the degree to which the heart rate decreased after smelling soil scent had a significant negative correlation with the factors “feel relaxed” and “feel soothed” as indicated by the increase in the VAS scores. Therefore, in this study, we found that the healing effects and autobiographical memories induced from smelling the soil may lead to hyperactivity of parasympathetic nerve functions or suppression of sympathetic nerve functions which may influence the heart rate.According to a recent report by the United Nations, the world’s population continues to increase, reaching nearly 7.6 billion in mid-2017, adding one billion people since 2005 and two billion since 1993. The global population is growing by around 83 million per year and is expected to reach 8.6 billion in 2030, 9.8 billion in 2050 and 11.2 billion in 2100. Ensuring that agricultural production can satisfy the needs of a growing population, not only globally but also locally, presents a tremendous challenge for farmers, scientists, and governments in the 21st century.It is estimated that agricultural production will have to increase by 60% by 2050 to satisfy the expected demands for food and feed. During the Green Revolution of the 1960’s, the world was able to meet the demand of the growing population for food and fiber by predominantly developing new high-yielding crop hybrids, increasing the application of farm inputs , and improving mechanization of farming operations. At that time, however, the potential environmental impacts of considerably increasing application of farm inputs was not a major concern as it is today.