中国黄土高原における農作業体系 ４．平均的農家の年間労働時間配分の推定

Abstract

The survey of customary farm practices for improving the cropping system in Guyuan Prefecture of Ningxia Autonomous Region, which is located at the western part of the Loess Plateau in China, was carried out, This work has been conducted as a part of the research project on the “Fundamental study of the establishment of grasses and crops on the Loess Plateau in China” sponsored by the Ministry of Education, Science and Culture, Japan. In this paper, we discussed the characteristics of the distribution of yearly work hours which were estimated from the work hours for a 10 day period in the cultivation of each crop where crop rotation occured1) Using statistics of the village investigated, it was estimated that the mean cultivated acrege and the mean number of labor of each farm were 2.6ha and 3 persons, respectively. The mean yearly hour of farm labor and of draft animal use for a farm were 1918.5 and 666.1 hours, respectively. We found that there were three busy farming seasons in a year. The first season was in middle- and late-May owing to weeding. The second season was from late-July to early-August, when spring wheat and flax were harvested, followed to field plowing after harvest of wheat and pea. The third season, which was the busiest farming season, was in late-September, when plowing and carring and application of organic fertilizer in the field were achieved.2) Through all our papers (Parts from 1 to 4), the following things were pointed out.(1) In order to prevent soil erosion on the Loess Plateau, it is important to stop crop cultivation on steep slopes and to establish grassland there. However, this results in reduction of the cultivated acreage, and necessity of increase in crop yields on the flat land. Based on our observations and field trials, we consider an increase in the soil water and fertilization application might be the key facters for increasing crop yields.(2) In customary farm practices, farmers have made a great effort to break the crust formed on the soil surface with repeated sharrow plowing, and to harvest rainfall water into the soil during the summer season. On the other hand, this farm practice caused the formation of very hard plow sole in the fields. To solve this problem, it is suggested that subsoiling will be able to increase crop yields due to the increase in water retention and expansion of the root zone for crop growth.(3) Organic fertilizer, which contains a high percentage of soil, is the main fertilizer. It needs long working hours to carry and spread in the field. For reducing work hours, we recommend that determining a reasonable percentage of soil in the fertilizer is important. At present the amount of chemical fertilizer applied is small. So, we suggest that in order to increase crop yield, it is necessary to increase the application amount of phosphoric and nitrogenous fertilizers.(4) Because of inefficient threshing practice using a stone made roller, waste and quality loss of grains during temporal storage seemed to be large. We suggest that a foot pedal thresher, which is usually used in other parts of China, should be introduced to rectify the loss.(5) Farmers need the aid of children and old forks for hand hoe weeding. We recommend to introduce a highly efficient hand weeder for the release from such grueling work.