Michihisa Iida

Geostatistical analysis of soil chemical properties and rice yield in a paddy field and application to the analysis of yield-determining factors

Abstract To obtain basic information for rational site-specific soil management for rice production, spatial variability of soil chemical properties and grain yield of rice was evaluated in a 50 m × 100 m paddy field. One hundred surface soil samples were collected from each of the 5 m × 10 m plots before puddling to investigate the spatial variability of their chemical properties: pH, EC, total C content, total N content, C/N ratio, contents of mineralizable N, inorganic N, available P, exchangeable Ca, Mg, K, and Na. Grain yield was also measured at harvest for the corresponding 100 plots. Geostatistical analysis was carried out to examine their within-field spatial variability using semivariograms, and multivariate analysis was also carried out to evaluate yield-determining factors. Geostatistical analysis of the soil properties indicated a high to moderate spatial dependence for all the properties except for the inorganic N content. The ranges of spatial dependence were about 20–30 m for the pH, EC, total C content, total N content, content of exchangeable Na, about 40 m for the contents of available P, mineralizable N, exchangeable Ca and Mg, and about 50–60 m for the C/N ratio and content of exchangeable K. Grain yield showed a moderate spatial dependence with a range of about 50 m. The results of spatial dependence enabled to prepare kriged maps of the soil properties and yield to compare their spatial distribution in the field. Multivariate analysis further showed, in combination with geostatistics, that the soil chemical properties contributed significantly to the yield as yield-determining factors and explained as much as 65% of the spatially structured or non-random variation of the yield. In conclusion, the possible benefit of site-specific soil management or precision agriculture was demonstrated even in an almost flat paddy field.

Geostatistical Analysis of Yield, Soil Properties and Crop Management Practices in Paddy Rice Fields

Abstract We examined the possible benefit of rational site-specific crop management practices in 17 paddy fields located in an area of 2.0 ha for the prevalence of precision agriculture methods on a cooperatively managed large-scale farm in Sakurai, Nara Japan. Data on grain yield, soil physicochemical properties and farmers crop management practices were collected in each paddy field. Unhulled rice yield was estimated at a resolution of 5m ą 5m in an area of 1.2 ha using a yield-monitoring combine. The spatial distribution of the variations for the collected data was characterized using geostatistical procedures. The kriged map of the unhulled rice yield drawn from the results of geostatistical analysis indicated the potential value of rational site-specific crop management using the yield-monitoring combine. The ratio of spatially structured variation to the total variation of brown rice yield, that is, the controllable proportion to total variation, was 75.4%. Each yield component i.e., the number of spikelets per square meter, filled-spikelet percentage and 1000-grain weight contributed 33.7%, 54.7% and 11.6%, respectively, to brown rice yield. These three yield components combined contributed to 96.5% of the brown rice yield variation. The agronomic factors (soil fertility factor, early growth factor, N dressing and uptake factor) contributed 79.7%, 52.1% and 41.8%, respectively, to the variation of these three yield components. Therefore these agronomic factors accounted for 58.1% of the total variation of the brown rice yield and 77.1% (i.e. 58.1% out of 75.4%) of the spatially structured variation of the brown rice yield. This controllable proportion may be a criterion for the prevalence of site-specific crop management in large-scale farm management in general, although only one case study was conducted.

Design and control of a heavy material handling manipulator for agricultural robots

In this paper, we propose a manipulation system for agricultural robots that handle heavy materials. The structural systems of a mobile platform and a manipulator are selected and designed after proposing new knowledge about agricultural robots. Also, the control systems for these structural systems are designed in the presence of parametric perturbation and uncertainty while avoiding conservative results. The validity of both the structural and control systems is confirmed by conducting watermelon harvesting experiments in an open field. Furthermore, an explicit design procedure is confirmed for both the structural and control systems and three key design tools are clarified.

Development of a Mobile Grading Machine for Citrus Fruit

A mobile grading machine for citrus fruits has been developed to collect crop information such as fruit yield, diameter, and sugar content of fruits of each tree part. It consists of a mobile mechanism, a differential global positioning system, a fruit conveyer system, a color camera for machine vision, a NIR spectrometer, and a personal computer for control and database. Preliminary field tests were conducted to investigate basic performance of this machine in a mandarin orange orchard. Using the collecting data of fruit yield and diameter and sugar content of fruit, crop information maps of each tree part was made. These maps indicated that each tree part has large variability of yield, size, and sugar content of fruit.

Development of an End-Effector for a Tomato Cluster Harvesting Robot

Abstract An end-effector was developed for a tomato cluster harvesting robot. This end-effector can harvest not individual fruits but a whole fruit cluster to improve the robots harvest efficiency. Experiments for harvesting tomato clusters were conducted in a high-density plant training system. According to a harvesting algorithm, the end-effector was able to perform well, even when target peduncle orientations were not given. Although the success rate of harvesting tomato clusters was 50 %, it is considered that this rate would improve if an end-effector is used for the high-wire tomato plant training systems in Dutch systems where the node lengths of plants are long enough to loosely hold the main stems.

Measurement and Analysis of Side-Slip Angle for an Articulated Vehicle

Abstract Experiments to measure the side-slip angle of an articulated vehicle were conducted using a wheel loader equipped with displacement, global positioning system (GPS), and fibre-optic gyro (FOG) sensors. In addition, a constant circular turn of the articulated vehicle in a horizontal plane was simulated using equations of motion for a vehicle with no tractive force. The cornering stiffness between tire and unpaved ground was determined by comparing the experimental and simulation results.

Variable Rate Fertilizer Applicator for Paddy Field

A prototype of variable rate granular applicator for paddy field was constructed in this research. Variable rate application of nitrogen fertilizer was demonstrated in a field experiment by using the applicator. A 0.5 ha paddy field of Minami-Hikari variety was treated with a uniform rate basal nitrogen application. At top dressing the half with variable rate application consumed 12.8% less of the nitrogen-potassium fertilizer than that of the half with uniform rate application. Grain yield in dry basis of both halves showed similar average yields of 7.29 t/ha. This experiment shows the possibility of applying variable rate fertilization in rice cultivation for maintaining high yield with minimum variability and shows a variable rate applicator design.

Development of “STORK”, a watermelon-harvesting robot

Recently, the production of heavy fruit and vegetables has been decreasing in Japan because strenuous labor is require to harvest them. A robot would allow them to be harvested more easily. We have developed the robot “STORK” to harvest watermelons. STORK has a low mass and a long working range. The position accuracy and repeatability of the manipulator, the required vacuum, and the allowance for position error of the vacuum pad were tested.

Heavy material handling manipulator for agricultural robot

This paper presents a manipulator which is able to handle heavy materials for agricultural applications. The characteristics of agricultural operation are discussed and extracted. As the manipulator for handling heavy materials is analyzed using kinematic indices, the parallel type manipulator is shown to be superior to the other manipulators (i.e. the polar coordinate type, articulated type and cylindrical coordinate type manipulators). A parallel type manipulator has therefore been designed and developed. The robotic harvesting experiment was carried out using the parallel type manipulator in a watermelon field.

Application of Image Processing Technology for Unloading Automation of Robotic Head-Feeding Combine Harvester*

Abstract The automation of agricultural work is expected to solve several of Japans agriculture problems and help farmers. It has now become necessary to maintain the sustainability of national agricultural production. Thus, we have been trying to develop a robotic combine harvester. While attempts have been made to develop robotic combine harvester and a few prototypes can run and automatically harvest rice and wheat, the unloading task, in which grains are unloaded through the harvesters auger into a grain container on a truck, has not yet been automated. This paper presents a method that uses machine vision to position the harvesters spout at an appropriate point over the grain container on a truck. Experimental results show that this method has sufficient accuracy.