Guozhong Zhang

Design of a pneumatic feed mechanism for precision rice hill-drop drilling machine

Rice is the most important food crop in China. The techniques for high yield and labor –saving have become the trend of rice production in China. Precision hill-drop drilling is one of the major representative techniques for rice production. In order to promote and improve this technique, a pneumatic feed mechanism for precision rice hill-drop drilling machine was designed. Experiments were conducted to investigate the working principle of the grouped holes on the sucking disk under negative pressure airflow. Three varieties of rice seeds were used in the experiments, including Indica hybrid Peizataifeng, Japonica hybrid E3, and Dianrui408. Three small holes were set in each of the eight hole groups which were uniformly distributed on the seed-sucking disk with a 130mm diameter. Relationships between the number of seed sucked by grouped holes, and the negative pressure, the shape of sucking holes were studied at a disk rotation speed of 8rpm without seed clearing device. Results showed that seed number sucked by each hole group exhibited a significant negative exponential relationship with the negative pressure airflow, when the negative pressure increased from 1.05kpa to 4.65kpa.The sucked seed amount differed among different rice varieties, while the sucking characteristic was similar. In addition, the sucking probability of grouped holes was the conditional probability based on the sucking probability of a single hole, with an approximately exponential relationship. Precision multi-seed suction for rice could be achieved with the design of grouped holes on a pneumatic feed mechanism for precision rice hill-drop drilling machine.

Effects of Precision Rice Hill-drop Drilling on Methane Emission from Paddy Field

Agricultural practices contribute to emissions of the methane (CH4). The objective of this study was to evaluate the effects of precision rice hill-drop drilling (PRHDD) technology on CH4 emission from a flooded rice field in Guangzhou, China, over the second growing season using closed static chamber techniques in situ. The results showed that the CH4 influx was significantly reduced in paddy fields treated by PHDD as compared with the non-precision rice controls, especially during the earlier rice nutritional growth stages. Methane influx level from PRHDD field (1.54 mg•m-2•h-1) was significantly decreased by 24.8% as compared with manual seedling broadcasting (MSB, 2.05 mg•m-2•h-1), and by 35.0% as compared with mechanical transplanting (MCT, 2.37 mg•m-2•h-1). In conclusion, this study showed the precision rice hill-drop drilling technology could effectively reduce the emission of CH4 in the rice paddy field, which could be ecological evidences for its further spreading in the world.