急傾斜地カンキツ園の機械化体系に関する研究

The objective of this research is to develop a mechanized production system which enables to reduce hours as well as improve the working conditions for steep sloping citrus orchards that are located on the slope steepness 15 to 25ﾟ. During the research the following activities were performed : (1) Investigation on the present situation of citrus production and a mechanized production system for steep sloping orchards. (2) Development of fundamental techniques required for a mechanized production system. (3) Evaluation on reducing hours and hardness of work by a mechanized production system. (4) Analyzing the process of selecting operation systems for citrus production. 1. Present situation of citrus production and a mechanized production system. Citrus orchards with the largest quantities among in Japanese fruit industries, are remarkably spread in steep sloping land. Since steep sloping orchards are well-drained, exposed to sunshine, and well ventilated, farmers can grow sweet citrus fruits that fetch a high price. However, the mechanization of such orchards has been lagging behind because the use of machinery is difficult and sometimes even dangerous due to the steep gradients and high-density planting. As a result, farmers had to tend their orchards by hand, spending long hours stooped over their trees. Moreover, farming is facing growing problems due to the shortage of efficient farmers associated with increase of farmer's average age and decrease of the number of young people. Therefore the abandoned orchards are increasing. To cope with these problem, a new mechanized production system is in great demand for farmers. To mechanize steep sloping orchards, it is primarily necessary to construct passages for agricultural machines. The construction of wide farm roads or paths to allow the passage of large sized machines is not suitable on steep sloping orchards because the construction costs are high and there is a risk of landslide. Furthermore, the total yield from the orchards decreases because many trees have been cut to make space for machinery. Therefore, a walking-type machinery production system (WMPS) which needs narrow farm paths will be adopted for steep sloping orchards. The fundamental designs of the WMPS are as following ; 1) The basic specification of machines ; (a) The operator does not ride on the machine, but walk behind it. (b) Use of crawler treads, rather than wheel. (c) The machine has a very small turning circle. (d) Overall width of machine is less than 1.0 m. 2) The design of construction farm path ; (a) Width of path is 1.0 to 1.3 m. (b) Gradient of path is less than 15ﾟ. (c) Layout is rib pattern which the connection path acts as a backbone, while working paths are located laterally to connection path. 2. Development of fundamental techniques for WMPS. 1) Low cost pavement of farm path To allow machines to travel smoothly, a low-cost cement aggregate pavement using soil from the orchards itself instead of gravel and sand brought in from outside was developed. The cement is mixed with a coagulant powder, water, and soil, and smooth down the surface. (1) The optimum mixing ratio of soil, cement, and coagulant in pavement materials is 100 : 13 : 0.3, respectively. Pavement depth is 7 - 10 cm. This pavement is considered to be enough for machines of WMPS. (2) This pavement can be carried out using such as rotary tiller and power sprayer. The farm path is constructed at a rate of 25 m2/h with a team of five workers. 2) Mechanization of pest and disease control In order to reduce the works of pest and disease control, an air-blast sprayer was developed. The sprayer has crawler treads with a pivot turning mission. It is equipped with a power sprayer and an axial fan, and emits a fine and dense chemical mist. The operator can direct the spray precisely onto the target by controlling the direction of a fan drum, that can be adjusted freely between 35ﾟ upward 20ﾟ downward. This sprayer has a liquid chemical tank with the capacity of 300 l. (1) This sprayer can be adapted to the farm paths for WMPS. Air turbulence associated with the fan drum swinging automatically shakes the leaves of trees, so that chemical spray adheres to both sides of leaves. (2) The deposit ratio was about 90% on both side application in one row of trees or two row of zig-zag trees. The working efficiency was 15 a/h, which showed about 33% reduction of working hours. The use of the sprayer enabled to improve the labor intensity required for pesticide application by comparison with the power sprayers with long hoses. 3) Mechanized fertilizer application In order to improve the work of fertilizer application, a fertilizer spreader for side dressing which was a mounted type fertilizer unit attached on the bed of the transporter was developed. The capacity of the hopper of the fertilizer is 100 l. Granular or pellet type fertilizer metered through an auger attached the bottom of the hopper is led to a discharge pipe and blown out with air from a centrifugal fan. Mounting and unmounting the unit on the bed of transporter are easy operation, because of the transporter's hydraulic lift system. (1) This machine can be adapted to the farm paths for WMPS. The maximum discharged capacity is 25 kg/min and the width of application is 4.6 - 5.0 m. (2) Fertilizer can be applied at a rate of 100 to 150 kg/10a with a working efficiency of 45 a/h. The labor intensity required for fertilizer application was obviously reduced by the use of this spreader. 4) System analysis on harvesting operation This verse shows the comparison between two types of transporters carrying different numbers of containers, 6 and 10, for harvesting. They are used on a narrow path on a steep sloping orchard in order to improve the harvesting operation. Since the harvesting operation of fruits is a complex system influenced by a capacity of the transporter, the transporting distance, and the number of workers, we applied a systems analysis method of building a computer model and simulating the operation. The model was programmed by Visual Smalltalk, which is known as an object-oriented programming environment. The results of the computer simulation were summarized as follows. (1) Not all the bigger type transporter with 10 containers had higher efficiency than the one with 6, in case of a 20a field lot with a wide road enough for a light track in a common sloping orchard. (2) In the cases, which require long transportation over 100 m to a light track, the bigger type transporter gives a slightly higher efficiency. (3) Introduction of additional labors brings a drastic reduction in harvesting time. 3. Evaluation on reducing hours and hardness of works by WMPS To confirm the advantages of WMPS, we set up a model orchard in an actual farmer's orchard with a mean slope gradient of 25ﾟ at Yoshida town, Ehime prefecture. The model orchard of 1.0 ha was improved by adopting the developed farm path system. The working path was placed at an interval of every two rows, with a path density of 1.2 km/ha. Field experiments were conducted to determine the labor intensity of each operation and the yearly working hours by comparison with a conventional production system for four years. Investigations of yield and selling pricefor the model orchard were also performed to evaluate the productivity compared with the area average. The results of investigation were summarized as follows. 1) The process for improving by the construction of paved farm path with 1.0 to 1.3m width and under 15ﾟof gradient was shown. The rate of removed trees for the construction of the path was only 6.5-11.3 % . The improvement of citrus steep sloping orchards for the WMPS didn't cause yield reduction in spite of some thinning of citrus trees. 2) The WMPS using an air-blast sprayer, a lift transporter and a side distributor were proposed for steep sloping orchards. The tests showed that WMPS enabled to reduce yearly working hours by 35% as well as improve the working conditions without a decline the quality of fruits and yield. These results indicate that the introduction of this system enabled to avoid hard manual labor required for the maintenance of orchards on steep sloping orchards and extended the scale of farm operation. 4. Analyzing the process of selecting an operation system for citrus production In order to make a guideline for selecting an appropriate operation system for citrus production in sloping orchards, the decision support system, which was based on the Analytic Hierarchy Process method, was developed by using the Visual Smalltalk. The process of decision making by using the support system was shown. The three types of production systems, which are a facility type, a riding machinery type and the WMPS were analyzed. The facility type is composed mostly of sprinkler pipelines and monorail transport lines. The riding machinery type is constituted mainly of a speed sprayer and a light truck. The WMPS is composed of an air-blast sprayer and a crawler type transporter in the main. The hierarchical structure concerned with decision making process was constructed, and then the following results were obtained through the survey on orchard managers by using the decision support system. 1) To select the appropriate one from the three production systems, the connection roads to orchards and the gradients of fields should be considered. 2) The works of chemical application and transportation are especially demanded to rationalize. 3) Managers having comparatively a large household scale in gentle sloping areas select the riding machinery type. The facility type is selected by managers having comparatively a large household scale in steep sloping areas and having the demand financial supports. Managers having a smaller household scale in steep sloping areas select the WMPS.

書誌情報

近畿中国四国農業研究センター研究報告
en : BULLETIN of THE NATIONAL AGRICULTURAL RESEARCH CENTER for WESTERN REGION

巻 1, p. 1-48, 発行日 2002-03-01

出版者

独立行政法人農業技術研究機構近畿中国四国農業研究センター

ISSN

収録物識別子タイプ

ISSN

収録物識別子

1347-1244

DOI

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2023-05-15 15:10:37.128385

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