Showing papers by "Atsushi Tsunekawa published in 2017"

Farmers' perception about soil erosion in Ethiopia.

Abstract: Soil erosion is a significant problem in the Ethiopian highlands. The objective of this study was to investigate how farmers perceive the severity of soil erosion in the Upper Blue Nile Basin. The study is based on a detailed survey of 300 households and 1,010 plots owned by these households in three watersheds. Descriptive statistics and a partial proportional odds model were applied to analyze factors that affected farmers' perceived soil erosion severity at the plot-level. Results showed that variables such as plot distance from the residence, plot shape and position on hill slopes affected farmers' perceptions of soil erosion severity, as well as the amount of rainfall during the growing season. Farmer interaction with extension service agents also affected farmers' perception of soil erosion severity. Despite their expected importance, education and number of livestock owned had no effect on the farmers' perception of soil erosion. The results indicate that farmers' perceptions generally match empirical and theoretical findings on soil erosion determinants; thus, farmers should be considered as important partners not only to counter soil erosion, but also to obtain local expertise on soil erosion severity and restoration of degraded land. © 2016 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd.

Factors Affecting Small-Scale Farmers’ Land Allocation and Tree Density Decisions in an Acacia decurrens -Based taungya System in Fagita Lekoma District, North-Western Ethiopia

Abstract: The development of woodlots as an additional source of livelihood and as a land management option for small-scale farmers is a challenging issue in the cereal-based subsistence farming systems of north-western Ethiopia. There is a need to understand why and which factors determine the decisions of small-scale farmers to grow short-rotation woodlots on their land. Data used in this study were collected from a survey of 200 randomly selected households in the region. A Tobit regression model was used to determine predictor variables for farmers’ decisions to allocate land to planting Acacia decurrens (J.C. Wendl.) Willd. and at what density trees are planted on the respective plots. The most important motivations for planting A. decurrens were income, soil fertility management, and soil and water conservation. Having a male head of household, long distance to markets and plots being on marginal land, among other factors, increased the allocation of land to A. decurrens woodlots. Having a male head of household, access to credit and plots being on marginal land, among other factors, increased tree planting density. Age had a negative effect on both allocation of land to woodlots and tree density, whereas farm size had an inverted U-shaped relationship with both decisions. These results suggest that wider expansion of A. decurrens-based plantation systems could be achieved through improving extension, credit access and road infrastructure to connect small-scale farmers to markets and finance.

Analyzing the runoff response to soil and water conservation measures in a tropical humid Ethiopian highland

Abstract: Different soil and water conservation (SWC) practices have been implemented in many drought-prone parts of Ethiopia since the 1980s. We assessed the effect of SWC practices on runoff response and experimentally derived and tested the validity of the runoff curve number (CN) model parameter for the tropical humid highland climate of the Kasiry watershed in northwestern Ethiopia. We recorded daily rainfall and runoff depth from 18 runoff plots (30 m long × 6 m wide) representing the five main land-use types with various SWC practices and two slope classes (gentle and steep). CN values were derived using the lognormal geometric mean CN procedure. Runoff was significantly less from plots with SWC measures, with average reductions of 44 and 65% observed in cultivated and non-agricultural lands, respectively. Runoff on plots representing non-agricultural land was relatively accurately predicted with the derived CN method, but predictions were less accurate for plots treated with a SWC practice. We concl...

Genetic Tracing of Jatropha curcas L. from Its Mesoamerican Origin to the World

Abstract: Jatropha curcas L. (Jatropha), a shrub species of the family Euphorbiaceae, has been recognized as a promising biofuel plant for reducing greenhouse gas emissions. However, recent attempts at commercial cultivation in Africa and Asia have failed because of low productivity. It is important to elucidate genetic diversity and relationship in worldwide Jatropha genetic resources for breeding of better commercial cultivars. Here, genetic diversity was analyzed by using 246 accessions from Mesoamerica, Africa and Asia, based on 59 simple sequence repeat markers and eight retrotransposon-based insertion polymorphism markers. We found that central Chiapas of Mexico possesses the most diverse genetic resources, and the Chiapas Central Depression could be the center of origin. We identified three genetic groups in Mesoamerica, whose distribution revealed a distinct geographic cline. One of them consists mainly of accessions from central Chiapas. This suggests that it represents the original genetic group. We found two Veracruz accessions in another group, whose ancestors might be shipped from Port of Veracruz to the Old World, to be the source of all African and Asian Jatropha. Our results suggest the human selection that caused low productivity in Africa and Asia, and also breeding strategies to improve African and Asian Jatropha. Cultivars improved in the productivity will contribute to expand mass commercial cultivation of Jatropha in Africa and Asia to increase biofuel production, and finally will support in the battle against the climate change.

Assessment of agricultural drought in rainfed cereal production areas of northern China

Abstract: Agricultural drought assessment is an important tool for water management in water-scarce regions such as Inner Mongolia and northeastern China. Conventional methods have difficulty of clarifying long-term influences of drought on regional agricultural production. To accurately evaluate regional agricultural drought, we assessed the performance of drought indices by constructing a new assessment framework with three components: crop model calibration and validation, drought index calculation, and index assessment (standard period setting, mean value and agreement assessments). The Environmental Policy Integrated Climate (EPIC) model simulated well of county-level wheat and maize yields in the nine investigated counties. We calculated a major crop-specific index yield reduction caused by water stress (WSYR) in the EPIC crop model, by relating potential and rainfed yields. Using 26 agricultural drought cases, we compared WSYR with two meteorological drought indices: precipitation (P) and aridity index (AI). The results showed that WSYR had greater agreement (85 %) than either the precipitation (65 %) or aridity index (68 %). The temporal trend of the indices over the period 1962–2010 was tested using three approaches. The result via WSYR revealed a significant increase in the trend of agricultural drought in drought-prone counties, which could not be shown by the precipitation and aridity indices. Total number of dry year via WSYR from 1990s to 2000s increases more sharply than via P or AI. As shown by WSYR, the number of dry years in northeastern China and Inner Mongolia is generally increasing, particularly after the 2000s, in the western part of the study area. The study reveals the usefulness of the framework for drought index assessment and indicates the potential of WSYR and possible drought cases for drought classification.

Analysis of the Spatial Variation of Soil Salinity and Its Causal Factors in China’s Minqin Oasis

Abstract: Land salinization and water resource deterioration negatively affect irrigated agriculture in arid and semiarid areas by limiting the area of arable land and reducing crop yields. The spatial variation of soil salinity is affected by many factors, and their interactions are complex. In this study, we utilized grey relational analysis to evaluate the factors that affect soil salinity in China’s Minqin Oasis and the interactions among them and then ranked the significance of their impacts on soil salinity for different land use and cover types. The data used in this study include data obtained from soil chemical analyses based on field sampling in 2015 and hydrological data obtained from local government agencies. We found that the main factors that affect soil salinity in the region’s sparse grassland are groundwater salinity and vegetation cover; the least important factor was the distance to the nearest irrigation canal. For cropland, the most important factors were the distance to irrigation canals and hydrological factors. By accounting for these factors, it should be possible to manage the region’s limited natural water and soil resources more efficiently, while allowing remediation of existing salinized land and helping to maintain sustainable agriculture in this arid land.

Effects of spatiotemporal heterogeneity of forage availability on annual range size of Mongolian gazelles

Abstract: We analyzed the effects of forage amount and its spatiotemporal heterogeneity on the annual range size of Mongolian gazelles by tracking 20 gazelles over a wide range of their distribution in Mongolia and by applying the normalized difference vegetation index (NDVI). Annual ranges were separated into four regions. The maximum individual annual range size was more than 40 times the minimum (range: 900–37 000 km2). Annual range size was increased with increasing forage amount and spatial heterogeneity and seasonal change in forage amount. Many tracked gazelles changed their range locations between summer and winter, and these ranges occupied only small parts of their annual ranges. The smaller annual range size in the areas with smaller forage amount was explained by the smaller seasonal change and spatial heterogeneity of forage amount. Knowledge of such variations of movements and environments in a continuous distribution can improve our understanding of movement ecology.

Effects of substituting alfalfa hay for concentrate on energy utilization and feeding cost of crossbred Simmental male calves in Gansu Province, China

Abstract: From August to September 2015 (trial 1 [T1]) and September to November 2015 (trial 2 [T2]), the effects of replacing concentrate feed (C) with alfalfa hay (AH) on the daily gain (DG), dietary energy utilization status and the economic advantage of AH feeding for growing beef cattle were studied in crossbred male Simmental calves (n = 18) in Gansu Province, China. The target DG was set as 1 kg for both trials. Animals in each trial were allocated to a conventional feeding group (CTRL), a low-level AH feeding group (LA), and a high-level AH feeding group (HA). In a one-way-layout design, they were fed iso-energetic experimental diets comprising harvested corn stover (CS) and C (T1-CTRL, T2-CTRL), diets replacing 22% (T1-LA) or 44% (T1-HA) of the quantity of C for T1-CTRL with AH, and diets replacing 13% (T2-LA) or 25% (T2-HA) of the quantity of C for T2-CTRL with AH. Measurements of feed intake and DG, respiration and metabolism trials were performed for 49 and 41 days in T1 and T2, respectively. Average DG did not reach the target value for HA in T1 and CTRL in T2. Energy metabolizability was slightly greater for CTRL than for LA and HA in T1 and significantly greater for CTRL than for the other groups in T2. There was no marked difference in energy metabolizability between LA and HA in both trials. Dietary substituting AH for C did not impair the feed intake of the animals, but it did not improve feed efficiency. In terms of economic feasibility, low-level AH inclusion in the diets of growing beef cattle appeared more profitable at the 1-kg DG level as compared with CTRL and high-level AH inclusion, and should be practiced in the drylands of Gansu Province, China.

Habitat Fragmentation by Railways as a Barrier to Great Migrations of Ungulates in Mongolia

Abstract: Mongolia’s Gobi-Steppe Ecosystem is the largest grassland in the world and the habitat of long-distance movement ungulates, such as the Mongolian gazelle (Procapra gutturosa) and the Asiatic wild ass (Equus hemionus). The international railway between Russia and China bisects this habitat, and there has been concern that it may impede the movements of wild ungulates. We tracked ungulate movements on both sides of the Ulaanbaatar–Beijing Railway, and found that most of the tracked animals never crossed the railway. The construction of additional railways to permit mining projects in the area is therefore a further threat to maintaining the great migrations of ungulates across Mongolia.