Eiji Yamaji

Rice crop growth and yield as influenced by changes in ponding water depth, water regime and fertigation level

Irregularities in land leveling, such as low lying areas or reverse grades, can cause too little or too much ponding water depth resulting in a variation in the crop yield within a plot, especially if paddy field is a large sized one. Experiments were conducted in Wagner pots to evaluate the effect of different ponding depths (created by surface irrigation practice) on paddy rice growth and yield. Wide ranges of ponding water depths were created under continuous, intermittent and variable ponding water regimes and under no, low, medium and high fertigation conditions. Plant height and grain yield were measured under 0, 3, 6, 9, 12, 15 and 18 cm ponding depth treatments. Results indicated that an optimum ponding depth of 9 cm can improve paddy growth and production conditions compared to too shallow or too deep ponding water depths. High values of water productivity were found at 9 cm ponding water depth under different water regimes and fertigation levels. Less yield reduction occurred at shallower depths than that of deeper ponding depths. Hence, high leveling accuracy is needed in paddy fields to have maximum production.

Assessment of System of Rice Intensification (SRI) and Conventional Practices under Organic and Inorganic Management in Japan

Abstract The system of rice intensification (SRI) is a production system that involves the adoption of certain changes in management practices for rice cultivation that create a better growing environment for the crop. This system was compared with conventional practices and assessed under organic and inorganic management. SRI practices showed significant response in root number, number of effective tillers per hill, days to flowering and harvest index. In addition, SRI was found effective in minimizing pest and disease incidence, shortening the crop cycle, and improving plant stand. Grain yield was not different from conventional method. Except for harvest index and plant lodging percentage, there were no significant effects from management treatments. Synergistic responses were noted when SRI practices were combined with organic management for plant height, number of effective tillers per hill, days to flowering and to maturity. The improved panicle characteristics, lower plant lodging percentage and higher harvest index that ultimately led to comparable grain yields. Net returns increased approximately 1.5 times for SRI-organic management regardless of the added labor requirements for weed control. However, comparatively higher grain yield from conventional-inorganic methods underscore the need for further investigations in defining what constitutes an optimum set of practices for an SRI-organic system specifically addressing grain yield and weed management.

Urban people as paddy farmers: The Japanese Tanada Ownership System discussed from a European perspective

The degradation of the traditional cultural landscape due to abandonment of agricultural management is perceived as a serious problem in different parts of the world. Rising consciousness concerning this issue in Japan led to the formation of numerous voluntary civil farming programs. This paper presents a multi-method case study conducted in Japan (Ōyamasenmaida, Chiba prefecture) about a highly relevant rural–urban cooperation, where landholders lease out their rice terraces to city dwellers to grow their own rice under the intensive instruction and well-organized support by local farmers and other local experts. The activity is known as ‘Tanada Ownership’ (tanada means rice terrace). It is spread over the country and promises, in contrast to the short-term individualistic European models, long-term rural–urban relations, the valorization of local knowledge and natural resources as well as the maintenance of the rice-terrace landscapes in several regions of Japan. The particular goal of this research is the investigation of the ‘how’ and ‘why’ of the system and the motivation of its participants. The Japanese approach is compared with similar European initiatives and conclusions focus on the particularities of the Japanese Ownership System and its transferability to the European context. Despite the innovativeness and popularity of the Ownership System, scientific studies are relatively scarce and none of them published are in English. This article therefore presents an original and important contribution to the scientific community, as it provides insights into the Tanada Ownership System and puts it into an international context by comparing it with European initiatives of voluntary farm work.

Labor requirements of system of rice intensification (SRI) in Cambodia

Abstract Local governments, NGOs, system of rice intensification (SRI) adopters, and researchers in Cambodia have extensively discussed the SRI. Agreement on the benefits, however, remains elusive. Some claim SRI increases rice yields at lower costs; others state that the evidence is still inconclusive. The adoption and impact of innovations influenced by the most practical SRI principles, which adopters can and do implement, as well as other SRI labor requirement have yet to be comprehensively investigated. This study aimed at elucidating and comparing distinct aspects of SRI labor requirements and conventional practices that can lead to more intensive SRI adoption. A household survey and field observations were conducted in three rain-fed villages in the southern part of Cambodia: two in Kampot Province and one in Kampong Speu Province. Findings showed little or no difference between SRI labor requirements and conventional practices. Laborers are in high demand when preparing land and nurseries, transplanting seedlings, and harvesting. Rice farmers alone or hired laborers have generally proved sufficient to date. Hired labor costs depend on the supply of farmer-family labor and the efficacy of the “Sharing-hand” system, not on farming techniques per se. This system helps alleviate hired labor costs, one of the highest cost factors. The findings also indicated that the degree of SRI adoption shows no correlation between the home-to-plot distance and availability of farmer-family labor or hired labor. The key factors for improving the degree of SRI adoption are farmer zeal and careful attention rather than the home-to-plot distance and availability of labor.

A conceptual framework for eco-friendly paddy farming in Taiwan, based on experimentation with System of Rice Intensification (SRI) methodology

Abstract This paper reviews the constraints and challenges of paddy farming in Taiwan. Based on those evidences, a set of eco-friendly rice farming practices raised by SRI principles are proposed from exploratory SRI trials conducted in Taiwan. The trials show that even with less exact leveling in the SRI field than is ideally provided, the average yield for SRI was higher than for CP; with an aerobic soil situation, the combination of biocontrol agent application and SRI management was seen to give better rice blast control; and the highest paddy yield was obtained from single-seedling transplants from potted nursery trays which protect the young seedlings’ roots from shock or twisting, compared with the planting of more numerous seedlings grown on flat nursery trays by a mechanical rice transplanter. In conclusion, a conceptual framework for eco-friendly paddy farming is formulated to encourage farmers to practice SRI principles. Among the participants in this collaboration, a co-operating group of SRI farmers is organized under investor sponsorship to guarantee the quality and safety of food, integrating an inspection service and food-source traceability from field to market with the production process. It is seen that in Taiwan, SRI principles can be adopted by local farmers without need for additional premiums through eco-friendly collaboration that can raise simultaneously the productivity of land, capital, and irrigation water. In addition, this collaboration can take advantage of increasing consumer demand for safe food with fewer chemicals and for supporting a greater level of biodiversity.

Esthetic and spiritual values motivating collective action for the conservation of cultural landscape—A case study of rice terraces in Japan

Japans rice terrace landscapes are not only used for food production but also appreciated as a place of high biocultural value. This paper pursues the question as to how far esthetic and spiritual values influence the motivation to participate in collective agricultural actions aiming at the conservation of traditional land use systems, the respective cultural (= traditional rural) landscapes and their biocultural diversity. Our results show that in the Ownership System of Ōyamasenmaida (Chiba Prefecture, Japan) landscape beauty is the main motivator for the mainly urban volunteers (the ‘tenants’) to participate in activities of the local Preservation Association, as well as for visitors who merely come to enjoy the scenery of the rice terraces. The active tenants, however, differ from the ‘passive’ visitors in their ecological interest and emotional attachment to the area. Interestingly, there is also a difference regarding the belief in nature spirits. A higher percentage of people who can imagine that such spirits are always present have been found among the tenants than among the visitors. Even more significant in this respect was the difference between female tenants and female visitors. To what extent spirituality is the cause for or an effect of involvement in nature conservation activities cannot be concluded from this survey. Future studies should therefore take a closer look at the connection between spirituality/religiosity and engagement in nature conservation activities. In Western countries (mainly in Central Europe or North America), nature conservation works on a more ‘scientific’ level, mobilizing engagement through scientific evidence on, for example, losses of species or biodiversity. Addressing the motivations of the volunteers on an emotional, esthetic or social level could be a promising way forward.

Promoting plant residue utilization for food security and climate change mitigation in Thailand

Burning is the most simple and cheap method for small-scale farmers to manage plant residue. This practice does provide immediate benefits to farmers, but the wider immediate and long-term negative impacts are much larger. The objective cally sound plant residue management that benefits all stakeholders particularly in terms of food security, income generation and climate change mitigation. The study found that there are several factors disrupting the adoption of non-burning practices in the study district such as land and labour scarcity, costs and the risk of wildfire. The study revealed that elementary schools and students have the capacity to manage certain amounts of plant residues and to produce vegetables and compost for the communities. Considering the weaknesses, threats and opportunities of existing policies, the study proposed a new model to manage plant residues involving local partnership and participation. This model would benefit relevant stakeholders: government, farmers, private sector actors, schools, students and the communities. Food security and income generation in the district would be the visible benefits attracting the interest of all stakeholders. Reduced greenhouse gas emissions and improved air quality would be benefits for the region and the globe.

Modeling of 3-D structure for analysis of canopy reflectance from rice crop

In order to diagnose a rice crop and predict yield from remotely sensed data, the relation between rice canopy reflectance and the canopy characteristics is analyzed. It is shown that modeling of 3-D structure is effective for this. Thus, rice 3-D structure is modeled with a proposed stereo matching method.<<ETX>>

Estimation of landcover proportion in an IFOV of a mixel using a precise edge locator

Assuming that IFOVs of most mixels in a remote sensing image lie on landcover boundaries, in order to estimate landcover proportion high contrasted edges in a mixel IFOV can be approximately considered to locate an edge in a mixel very precisely. A precise edge locator which is based on the moment preserving principle is tested in computer experiments in order to estimate landcover proportion in a mixel in this research. The experiments show that: 1) the estimated landcover proportions were affected by the length of the edges, the noise, the window sizes of the locator and the PSF, 2) the magnitude of errors on long and high contrasted straight edges is almost smaller than 20%, 3) some improvements of the algorithm to estimate landcover proportion in mixels are necessary.<<ETX>>