Toshiyuki Wakatsuki

Shimane University · Department of Agricultural and Forest Sciences

Rice yield in Indonesia tripled (1.8–4.5 t ha−1) during the first 30 years (1970 to 2003) of Green Revolution (GR). To examine changes in physicochemical properties of paddy (sawah) soils of Java Island, the rice granary of the country, in this period, we performed a statistical reanalysis of soil data collected in 1970 and 2003 from 40 paddy field...

In the present study, we assessed the changes in topsoil fertility status in 30 paddy fields of Bangladesh over the last 50 years (1967–2018) using a time-series archived soil data collected from the surveys in 1967/68 (S1), 1994/95 (S2), and 2016/17/18 (S3). Herein the first (P1: 1967/68–1994/95) and second period (P2: 1994/95–2016/17/18) correspo...

Over 50 years of the Green Revolution since the 1960s, the global population has increased by 2.5 times, cereal production by 3.3 times and the use of N, P and K fertilisers by 9.4, 4.2 and 4.3 times, respectively. Information is still limited, however, on the influence of these impacts on the fertility status of agricultural soils. Here we investi...

Laboratory wastewater must be managed and handled properly so as not to damage the environment. The management was carried out starting from the separation and labeling of the wastewater according to its character, to processing it with a wastewater treatment plants (WWTP). The chemical waste resulting from the analysis which was classified as haza...

Soil and water management research on adapting the promising sawah ecotechnology for lowland rice farming in West Africa has largely focused on the abundant inland valleys; floodplains which too represent a huge agricultural resource in the region have not been so involved. Sawah refers to a bunded, puddled and leveled basin for rice, with water in...

This study examined the effect of information sources on farmers’ adoption of Sawah eco-technology in Nigeria. Purposive sampling technique was used to select 166 sawah farmers from Delta, Ebonyi, Kebbi, Kwara, Niger and Ondo states. Interview guide was used to elicit information on the farmers’ personal and production characteristics, sources of i...

This study investigated the physico-chemical and geochemical properties of soils under sawah in Nigeria. It was found that soils under sawah were majorly sandy loam to sandy clay loam having acidic reactions, low exchangeable Ca, Mg, K and Na. These soils were deficient in available P, SiO2, S, Total Nitrogen and Total Carbon while SiO2, Al2O3 and...

Assessment of land‐use types has conventionally been on spatial rather than temporal scales, thus limiting the inference on relative potential of land‐use types against soil degradation, needed to validate their allotment to ecosystems on agricultural watersheds. The study assessed the changes in key indices of soil degradation among four land‐use...

Purpose Rice-mill wastes are generated in large amounts in Ishiagu, Ebonyi State, Nigeria. These wastes can potentially be utilized for rice production and in improving soil attributes. This study evaluated the effects of rice-mill wastes on soil chemical properties and rice yield in sawah rice management. Methods A sawah rice field in an inland v...

In the present study, the multiple regression analysis of mass balance equations of seven major geochemical elements (Al, Fe, Ca, Mg, K, Na, Si), among rock, soil, stream water, and precipitation in a watershed was used to simultaneously estimate the rates of rock weathering (RWR) and soil formation (SFR) in two template forest watersheds of Centra...

Multi-soil-layering (MSL) wastewater treatment systems consist of soil units (soil mixture blocks, SMB) arranged in a brick-like pattern surrounded by permeable layers of zeolite or alternating particles of homogeneous sizes that allow for a high hydraulic loading rate. This study evaluated the performances of MSL systems that have been operating f...

This study examined factors influencing the adoption of sawah technology in Kebbi State, Nigeria. Sawah refers to levelled rice field surrounded by banks with inlet and outlet for irrigation and drainage. Using pre-tested interview guide, data were collected from 300 sawah farmers in the study area. Data collected were analysed with both descriptiv...

Biochar is as a solid material gotten from the carbonization of biomass that is proficient in improving the soil fertility and agricultural productivities. The basic process of producing a biochar from biomass is by thermos-chemical conversion. The thermos-chemical conversion includes the processes of gasification and pyrolysis. In pyrolytic proces...

Sole dependence on rainfall, poor water management and low soil fertility largely explain the fluctuations in agricultural productivity in West Africa. Lowlands for sawah-based rice farming often offer opportunities for small-scale supplemental irrigation but these are rarely explored and their interaction with other critical factors on sawah-rice...

This study examined the effect of land tenure on the adoption of sawah rice production system in Nigeria. Using pre-tested interview guides, data were collected from 124 randomly selected sawah farmers. The results showed that rice farmers were predominantly male, married and had Quranic education, with the mean age of 42.30 years, farm sizes range...

p>Rice cultivation in our study site at Central Java, Indonesia, is constrained by water scarcity and blast disease problems. A field experiment was thus conducted to evaluate the effect of water management and silicon (Si) application (with 500 kg ha^-1 of silica gel) on improving rice growth and productivity and blast disease infection...

Silicon (Si) is known as a beneficial nutrient in the cultivation of rice, playing a key role in photosynthesis enhancement, lodging resistance and tolerance to various environmental stress. The present study aimed to examine available Si content in both lowland soils (n = 29) and neighboring upland soils (n = 21) collected from Benin and Nigeria a...

Si fertilizer was never used in rice cultivation by farmers in Indonesia. To evaluate the effect of Si application on blast disease, plant morphologies, and stomata formation on rice plant, a field experiment was conducted in West Java, Indonesia. Two treatments, Si+ (with 1000 kg ha-1 of silica gel) and Si- (without Si application) were set in a r...

Sawah, an Indo-Malaysian word for rice paddy, is used in West Africa to refer to a lowland rice field that is bunded, puddled and levelled for ease of water control and management. There are insufficient data on lowland soil and rice responses to sawah preparation intensity, defined by relative completeness of these three land preparation activitie...

Soil physicochemical properties were determined for soils under cropland and forest at the headquarters of the International Institute of Tropical Agriculture in Ibadan, Southwestern Nigeria to examine the 30-year effects of different land use on the fertility of five soil series toposequences underlain by a Basement Complex. The cropland had been...

The purpose of this study is to evaluate the relationship between the improvement of soil permeability upon mixing with gravel-size materials and the water purification performance of a multi-soil-layering system. Focusing on the practical use of regional resources, zeolite, Sekisyu roofing tiles, Kimachi stone, Corbicula shell and bamboo charcoal,...

Cerasus jamasakura and Padus grayana are wild cherry species indigenous to Japan. These wild cherries have high values in secondary forests. However, their population declines due to forest degradation are concerned recently in sub-urban areas. To collect fundamental information on forest ecology, we conducted an assessment on all woody stems in a...

The present study aimed to examine the influence of termites (Isoptera) on soil clay mineralogy. To this end, we analyzed the clay mineralogy in the mound structures of Macrotermes bellicosus (Macrotermitinae) and in the adjacent natural (termite-free) soil horizons along an inland valley toposequence in central Nigeria, and compared them using dif...

Lowland sawah farmers often puddle to improve soil hydrophysical conditions for rice, but the puddling intensity beyond which no extra yield increases occur is unknown. Agronomic effects of six mechanical puddling intensities were assessed in three Nigerian inland-valley bottoms. All puddled plots, irrespective of intensity, produced similar effect...

The roles of fine-earth materials in the cation exchange capacity (CEC) of especially homogenous units of the kaolinitic and oxyhydroxidic tropical soils are still unclear. The CEC (pH 7) of some coarse-textured soils from southeastern Nigeria were related to their total sand, coarse sand (CS), fine sand (FS), silt, clay, and organic-matter (OM) co...

Quantitative data on carbon stock (C stock) in and beyond the topsoil (0-30 cm) under natural terrestrial ecosystems in West African savanna could provide information about their relative potential, and management options, for C sequestration, but these data are still scanty in the region. In selected locations (Nsukka, Obimo, and Ibagwa-aka) in th...

The trial was conducted at the Federal University of Agriculture; Abeokuta, Nigeria in 2010/2011 and 2011/2012 cropping season to evaluate the performance of lowland rice-ratooned rice-okra as influenced by fertilizer rates in sawah rice based system. Field was manually cleared and bunded but power tilled, puddled and leveled with inlet and outlet...

Lowland sawah is viewed as a sustainable alternative to traditional rice culture in West Africa. Sawah (a bund-de-marcated, puddled, leveled, and water-regulated rice field) has received growing research attention lately, but no data exist yet on the system's long-term agronomic impact. In a clayey inland-valley soil in southern Ghana, 10-year-old...

This paper describes a model of manpower development in the sawah technology development and dissemination. The process includes formal and non-formal manpower development process. The areas of manpower development with greater focus on graduate development include soil science, eco-technology, wetland agronomy, agroforestry, agricultural economics...

The paper provides an insight into the problem of land degradation in Sub-Saharan Africa, with emphasis on soil erosion and its effect on soil quality and productivity, and proposes a lowland-based rice-production technology for coping with the situation. Crop yields are, in addition to the degree of past and current erosion, determined by a number...

The adoption of new agricultural techniques of which sawah rice production technology is an example, is a key route out of poverty for many in the developing world. This paper analyzed whether and how a farmer's decision to adopt a new technology depends upon the adoption decision of other farmers in their social group, which, unlike most of the ex...

Puddling during sawah rice cultivation destabilizes the soil structure. The re-formation of soil water-stable aggregates (WSA) following puddling and amendments, and their associated organic carbon (SOC) and total N were studied at Akaeze and Ikwo in south-eastern Nigeria. The amendments, which were randomized in triplicate, include control, NPK fe...

This paper examined farmers' perception of Sawah rice production technology in Nigeria. Using a large sample size technique of n > 30, forty farmers were selected and interviewed. A structured questionnaire with a reliability coefficient of 0 .85 wa s u sed to elicit information on socio-economic cha racteristics a nd fa rm characteristics. Farmers...

The role of mounds of the fungus-growing termite Macrotermes bellicosus (Smeathman) in nutrient recycling in a highly weathered and nutrient-depleted tropical red earth (Ultisol) of the Nigerian savanna was examined by measuring stored amounts of selected nutrients and estimating their rates of turnover via the mounds. A study plot (4 ha) with a re...

This study investigated the influence of mound-building termites on soil particle dynamics on the land surface and in soil-forming processes by examining the amount of soil particles in mound structures of Macrotermes bellicosus in a highly weathered Ultisol of tropical savanna. Soil particle turnover via the mounds was estimated using particle sto...

This study identified the constraints to adoption of sawah system of rice production in Nigeria. Data were collected from 124 randomly selected sawah-rice farmers. Data were analysed using correlation and regression analyses to determine the relationships between the study variables. The results showed that respondents were predominantly male (98.8...

Despite the agronomic, economic and food values of soybean (Glycine max L. Merrill), there is still dearth of information on the tillage need and the implications of surface mulch for the crop in the eastern part of the forest-savanna transition zone of Nigeria. This study was therefore carried out on a sandy loam Ultisol at Nsukka with a sub-humid...

This study examined the gender role in Sawah system of rice production in Nigeria. This study was carried out in five states where Sawah is being practiced. The states are Niger, Kaduna, Ondo, Kwara and Ekiti. Data used in this study were collected in all the Sawah sites in Nigeria namely: Ejetti, Etzuzhegi and Nasarafu in Niger state, Nakala Pampa...

Although the West African inland valleys are characteristically wet all-year-round, their hydrological conditions are known to be site-specific and may differ markedly between the rainy and the dry seasons. Information on their physical properties would be useful for proper water management under the sawah rice culture and for planning dry season c...

The green revolution has yet to be realized in Sub-Saharan Africa (SSA) even 40 years after its success in tropical Asia, suggesting that there was a missing element in the basic principles underlying the Asian green revolution when they were transferred to SSA. The authors argue that this missing element is 'ecotechnology'. Ecotechnology improves...

In multi-soil-layering (MSL) systems, the effect of the materials and structural differences on the wastewater treatment performance and clogging mechanisms are not fully understood because of insufficient quantitative evaluations of water movement properties inside the system. In the present study, water movement properties were examined using lab...

A key indicator of soil quality as organic carbon needs to be enhanced in the highly weathered soils predominant in southeastern Nigeria through appropriate tillage-mulch practices and cropping systems. We subjected a degraded Typic Paleustult (sandy loam) at Nsukka to no-till (NT) and conventional tillage (CT) and bare fallow (B) and mulch cover (...

A key indicator of soil quality as organic carbon needs to be enhanced in the highly weathered soils predominant in southeastern Nigeria through appropriate tillage-mulch practices and cropping systems. We subjected a degraded Typic Paleustult (sandy loam) at Nsukka to no-till (NT) and conventional tillage (CT) and bare fallow (B) and mulch cover (...

This study examined factors affecting the adoption of sawah technology in Nigeria. A structured interview guide was used to collect data from 124 farmers purposefully selected based on their participation in sawah. The results showed that respondents were predominantly male, married and had Quranic education, with mean age of 42.30 years. The mean...

Data were collected from 124 sawah farmers purposefully selected using a well-structured interview guide to identify the knowledge and training needs in Nigeria. The study was carried out in Ogun, Ondo, Niger, Ebonyi, Kaduna and Abuja, the Federal Capital Territory. The results showed that respondents were predominantly male, married and had Qurani...

One peculiar feature of the inland valleys abundant in West Africa is their site-specific hydrology, underlain mainly by the prevailing landforms and topography. Development and management of these land resources under the increasingly popular sawah (a system of bunded, puddled and levelled rice field with facilities for irrigation and drainage) te...

Wastewater treatment has not been much concerned in many developing countries ， especialy in humid tropic regions ， as the availability of water is very high ． However ， recently ， as economica status is improving ， environmenta pollution has become severe， In Indonesia， people started to concern about protection of environment ， especially water e...

The water treatment performance of multi-soil-layering (MSL) systems has been mainly evaluated by measuring differences in the quality of wastewater and treated water. Changes in water quality inside the system have not been assessed together with the water movement. In this study, therefore, quantitative evaluation of the treatment processes insid...

Two species of Xystodesmid millipedes, Parafontaria laminata and Parafontaria tonominea are known to periodically swarm and influence on nutrient cycling in ecosystems through their feeding activities. We investigated difference of chemical properties of the feces of these two millipede species being influenced by changes of soil and leaf litter ty...

This paper explores the linkages among land tenure, investment and adoption of Sawah rice production technology in Nigeria and Ghana. Focus group discussion was held with farmers adopting Sawah technology; in all the villages where Sawah rice technology had been introduced. The study found that in Nigeria, land tenure system was predominantly throu...

In the present study, we provide a land use planning recommendation for land conservation and agro- economical production for the Sumani watershed in West Sumatra, Indonesia, where intensive agriculture has long been practiced. We based our land conservation management recommendations on soil erosion rates using the Universal Soil Loss Equation (US...

A key indicator of soil quality as organic carbon needs to be enhanced in the highly weathered soils predominant in southeastern Nigeria through appropriate tillage-mulch practices and cropping systems. We subjected a degraded Typic Paleustult (sandy loam) at Nsukka to no-till (NT) and conventional tillage (CT) and bare fallow (B) and mulch cover (...

c1 Corresponding author. ijewelle@yahoo.com

There is the need to take seriously the task of conserving soil moisture in agricultural fields and free-water surfaces in reservoirs, especially in recent years of climate change. Many strategies exist for achieving this task and improving the productivity of arable soils. These strategies traditionally come under biological and physical or mechan...

This paper examines the profitability of different sawah rice production models within lowlands in Nigeria. This is predicated on the fact that since the introduction of sawah production technologies by Japanese institutions in Nigeria, different typologies as found applicable within the farmers' environment had been adopted. The study was carried...

Millions of dollars are spent each year on research and development initiative on rice in order to improve the livelihood of farmers and other stakeholders in the rice value chain, however little has been the impact. Major reasons for this failure include the limited collective learning that occurs between various stakeholders and the neglect of bu...

This paper examined the incidence of replacement adoption through varietal substitution among farmers adopting Sawah-ecotechnology rice production technology in Nigeria and Ghana. A simple random sampling was used to select 80 farmers in Nigeria and 70 farmers in Ghana. Data were collected in June 2010 with a structured questionnaire in villages wh...

Quantitative evaluation of soil erosion rates provides important baseline data to investigate, manage and improve land use systems. However, soil erosion analyses have not been sufficiently conducted in Indonesia. In the present study, we investigated the spatial distribution of soil erosion rates in relationship to land use patterns in the Sumani...

In this paper, we review the soil fertility characteristics and the nature of material in the West African lowlands in comparison with paddy soils in tropical Asia to examine their potential for rice cultivation. Soil samples collected from major lowland ecosystems, i.e., inland valleys (185 locations) and flood plains (62 locations), in 13 countri...

The development and dissemination of sawah rice eco-technology in Nigeria and Ghana as prerequisites for the actualization of green revolution in West Africa were described. It showed that the neglect of the eco-technology and the overemphasis of the biotechnology have rendered the ineffective transferability of the green revolution process from As...

There has been less concern about soil mineralogical alteration than about soil physical, chemical and biological changes induced by termite nest-building activity. Furthermore, much less attention has been paid to free sesquioxides than to phyllosilicate minerals. In the present study, we conducted field morphological observations and selective di...

This paper examined the effect of field days on scaling up of the adoption of sawah rice technologies among farmers in Nigeria. Data were collected with semi-structured surveys during field days organized in each of the sites on awareness and willingness to adopt sawah technology. Follow up visits were made to randomly selected 40 farmers using a l...

The importance of rice in Nigeria is no longer the question but rather how to meet the growing demand, reduce import and be self-sufficient. Consumption per capita jumped from 2.9 kg in 1970-1974 to 25 kg in 2004. Production figure increased 6 times within the period to 3.27 million tons for importation figure reaching a climax in 1998 at 1 million...

Teak, Tectona grandis (Verbenaceae), plantations are increasingly established in Ghana because of quick economic returns from its multi-purpose uses. Tectona grandis growth is, however, dependent on site conditions, and relationships have been established between various mineral nutrients, other fertility parameters and moisture of soils and teak g...

This paper reviews past efforts to kick start Green Revolution in sub-Saharan Africa (SSA) with the emphasis that there are missing prerequisites for the actualization and realization of Green Revolution due to the absence of suitable growing environment for rice production on farmers fields in SSA. Sawah eco-technology was described in the paper a...

This study assessed the balance of N, P, K, Si, Ca, Mg, and Na in a lowland sawah (rice fields) in the Citarum Watershed, Java, Indonesia. The soil properties at sites studied were not significantly different (P>0.05) in terms of pH, available P, available Si, and exchangeable Ca, K and Na, while TC, TN, and exchangeable Mg showed different levels....

Primary and some secondary nutrient labile fractions concentrations of dissolved soil nutrients (Ca, Mg, K, N. Av. P and NO) were determined in cocoa plantation (DC), secondary forest (DS) and primary forest (FB) land uses in Dwinyan watershed in Ghana. Zero-tensioned lysimeters were buried at 0-15, 15-30 cm, 30-45 cm and 45-60 cm soil depths in th...

Shortage of organic matter hinders agricultural production in the Sahel, and this lack of enough organic matter is more severe for peri-urban horticulture, which depends heavily on it. Alternative sources of organic matter that offer new options for peri-urban horticulture can help reduce the potential for conflict over finite resources between tra...