Turning stability analysis of a 12-kW self-propelled riding-type automatic onion transplanter to ensure user safety

The lateral turning stability analysis of the self-propelled riding-type upland crop machinery is an important issue as the cultivation lands are usually uneven, and cause severe work-related injuries, even death. In this study, the lateral turning stability of a 12-kW self-propelled riding-type automatic onion transplanter was analyzed for ensuring the operator’s safety during transplanting operation. To evaluate turning stability, the center of gravity (CG) of the developed onion transplanter was determined theoretically. Then, a simulation was carried out to identify the lateral turning stability angles using the RecurDyn software, and the results were validated through tests. Rollover angles in the loaded and unloaded conditions were also checked. The statistical significance of the replications was determined by a one-way analysis of variance (ANOVA). According to the physical dimensions of the onion transplanter, the mathematical rollover angle was 34.5°. The average simulated rollover angles were 43.9°. Due to the symmetrical structure, a 4.5° turning difference was observed between the right and left side turning, and a 3° angle difference was occurred due to the variation of load conditions. The rollover angles fulfilled the ISO (International Organization for Standardization) standard. The findings of this study would be helpful for the manufacturers to ensure operator safety during the upland crop machinery operation in uneven and sloped lands.

Effects of Furrow Height and Amount of Manure Compost on the Growth, Yield, and Quality of Organically Grown Green Asparagus

A two-season field trial was carried out in the Upland Crop Experiment Field of the Faculty of Agronomy, Vietnam National University of Agriculture (VNUA) to assess the effects of three furrow heights (20, 35, and 50cm) and three manure compost levels (15, 25, and 35 tons ha-1) on the growth, yield, and quality of green asparagus (Asparagus officinalis L.) grown organically. The experiments were arranged in a randomized completely block design (RCBD) with three replications. The results showed that the harvested yield was highest (11.3 and 25.1 quintals ha-1 in the 2019 autumn and 2020 spring season, respectively) in the treatment with a furrow height of 35cm and compost level of 35 tons ha-1 in both seasons, and explained by the increased spear diameters and number of spears per plant in this treatment when the furrow height and compost level were increased. Additionally, the chlorophyll content, water loss, and dry matter weight of the spears also increased when the furrow height and compost level increased. The obtained quality of the spears under organic management at the furrow height of 35 cm and compost level of 35 tons ha-1 was higher than the other treatments with higher reducing sugars, vitamin C, and Brix values, while the residue nitrate contents of all the treatments were lower than the allowed safety threshold.

Subsidence of rice paddy and upland crop fields in Shinotsu Peatland, Hokkaido, Japan

Agricultural land use on peatlands inevitably causes ongoing land surface subsidence resulting in a reduction of productivity. In addition, oxidation of the peat substrate associated with subsidence is responsible for greenhouse gas emission with the ensuing consequence for global climatic stability. A concept of “paludiculture”, the utilisation of wet or rewetted peatlands for agriculture, has been proposed in European countries to avoid further subsidence and greenhouse gas emission. However, few studies have documented a long-term record of subsidence through agriculture in wet peatlands such as paddy fields for rice cultivation. In this study, we measured the subsidence rates of peatland in rice paddy use and compared them to the rates in peatland with upland crop cultivation. The average subsidence between 2006 and 2016 for the paddy plots was 3.6±1.9 cm (± SE) and significantly less than that of 25.6±1.7 cm for the upland plots, and the subsidence reduced linearly as the period of paddy use increased. These results suggest that paddy use of peatlands can effectively reduce subsidence. Our results will encourage the use of peatlands with a wet environment as one of the valid options for future peatland management in terms of mitigation of land subsidence and peat loss.

Time Tracking of Different Cropping Patterns Using Landsat Images under Different Agricultural Systems during 1990–2050 in Cold China

Rapid cropland reclamation is underway in Cold China in response to increases in food demand, while the lack analyses of time series cropping pattern mappings limits our understanding of the acute transformation process of cropland structure and associated environmental effects. The Cold China contains different agricultural systems (state and private farming), and such systems could lead to different cropping patterns. So far, such changes have not been revealed yet. Based on the Landsat images, this study tracked cropping information in five-year increments (1990–1995, 1995–2000, 2000–2005, 2005–2010, and 2010–2015) and predicted future patterns for the period of 2020–2050 under different agricultural systems using developed method for determining cropland patterns. The following results were obtained: The available time series of Landsat images in Cold China met the requirements for long-term cropping pattern studies, and the developed method exhibited high accuracy (over 91%) and obtained precise spatial information. A new satellite evidence was observed that cropping patterns significantly differed between the two farm types, with paddy field in state farming expanding at a faster rate (from 2.66 to 68.56%) than those in private farming (from 10.12 to 34.98%). More than 70% of paddy expansion was attributed to the transformation of upland crop in each period at the pixel level, which led to a greater loss of upland crop in state farming than private farming (9505.66 km2 vs. 2840.29 km2) during 1990–2015. Rapid cropland reclamation is projected to stagnate in 2020, while paddy expansion will continue until 2040 primarily in private farming in Cold China. This study provides new evidence for different land use change pattern mechanisms between different agricultural systems, and the results have significant implications for understanding and guiding agricultural system development.

WATER USE EFFICIENCY OF RICE-BASED UPLAND CROP PRODUCTION SYSTEMS IN FLOOD-AFFECTED CHAU PHU DISTRICT, AN GIANG PROVINCE, VIET NAM

Retaining abundant flood water and later using it as crop irrigation water is an issue for the flood-prone area in the Mekong Delta of Viet Nam. The present study aimed to determine an appropriate rice-based upland crop production practice with high water use efficiency and hence the feasibility of retaining flood water for agricultural use in the flood area in the Mekong Delta. On-farm studies were carried out in Chau Phu district of An Giang province from January 2012 to July 2015. Chilli, maize, rice were used as the proxy crops. Crop irrigation water quantity was monitored, and crop yields and economic inputs and outputs were recorded. Results showed that maize or chilli grown on the paddy field were more water-efficient than rice cropping grown alone. Double maize and chilli cropping and rotational rice and maize or chilli cropping required an irrigation water volume of 3,341 m3/ha and 3,686 m3/ha, respectively, compared to 4,289 m3/ha for the commonly-applied double rice cropping. For financial water use efficiency, each cubic meter of water used for crop irrigation yielded a net value of output of 10,950 $VN with double maize and chilli cropping , 6,370 $VN with rotational rice and maize or chilli and 2,790 $VN with double rice cropping practice. These results need to be validated with more farmers’ fields to evaluate the feasibility of the promising crop production systems in larger scale.

Empirical Estimation of the Spatial Sediment Transport Capacity Coefficient Using the Rain Erosivity Factor and SWAT Model Results in the Han River Basin, South Korea

The ratio of sediment delivery is a critical and uncertain factor in model-based assessments of the total sediment yield of watersheds that results from the transport of sediment produced by soil erosion. This study estimates the watershed-scale distribution of sediment yield at a spatial resolution of 1 km by 1 km through evaluating the rain erosivity (R) factor of the Revised Universal Soil Loss Equation (RUSLE) in the Han River basin (34,148 km2) of South Korea over 14 years (2000~2013) using 1-minute data from 16 rainfall gauging stations. For this study, the Water and Tillage Erosion Model/Sediment Delivery Model (WATEM/SEDEM) sediment delivery algorithm is adopted. This algorithm is based on R, the soil erodibility factor K, the length-slope factors LS of RUSLE, and the transport capacity coefficient KTC. The average 1-minute value of R for the basin is estimated to be 3,812 MJ/ha · mm/year. To determine the 1-km grid-based transport capacity coefficient (KTC; generally given from 0.01 to 100) for the transport capacity (TC) equation used in the estimation of sediment transport with WATEM/SEDEM algorithm, the TC results from 181 subwatersheds ranging in area from 75.4 km2 to 281.5 km2 obtained using the Modified Universal Soil Loss Equation (MUSLE) implemented in the Soil Water Assessment Tool (SWAT) are used. A comparison of the suspended solids (SS) simulated using SWAT with the observed values at 7 locations yields an average coefficient of determination R2 of 0.72. Using the SWAT TC, the spatial KTC is determined in each subwatershed. These values range from 0.16 to 112.58, and the average value for the whole basin is 12.58. To permit general estimation of KTC values, multiple regressions are performed using the characteristic watershed factors of watershed slope, watershed area, the K factor of MUSLE, upland crop area (%), and paddy field area (%). A multiple regression equation of KTC with watershed area, K factor, and upland crop area (%) is derived. This equation yields an R2 of 0.76 when compared to the KTC values evaluated using SWAT. The KTC can be determined using information on watershed scale, soil and land use.