| Direct seeding rice are all exposed on the soil surface in southern area,and would suffer bird disasters,rat disasters,rain erosion,sun exposure,low temperatures,etc,thus would influence the whole seedlings and uniform growth of populations.Rice direct seeding synchronous covering soil can effectively solve the above problems,and the technology has been widely used in the northern dry direct seeding area.However,the paddy field is different from the dry land with the higher soil moisture content and stronger fluidity,so the higher requirements would be proposed for designing the mechanical direct seeding synchronous covering soil device in the southern rice area.The fusion experiment of agricultural machinery and agronomy was conducted to develop a mechanical direct seeding synchronous pendulum type covering soil device in this study,to solve the adverse effects of south direct seeding rice seed exposed on the mud surface,It is of great practical significance to improve the direct seeding rice emergence rate in southern rice area,improve the ability of direct seeding rice to resist risks,and promote the wide application of rice direct seeding technology.The main contents and conclusions were as follows:1)Determination of the optimal covering soil thickness for mechanical direct seedingIn order to find out the optimal covering soil thickness of the southern rice mechanical direct seeding,the early rice Zhongjiazao 17,Lingliangyou 722 and medium rice Huanghuazhan and Tianyouhuazhan were used as experimental varieties,the seedling emergence rate,seedling quality of different varieties and sowing dates on direct seeding rice were investigated with different covering soil thicknesses in the field experiment.The results show that the optimal covering soil thickness would be more beneficial for the seedling emergence rate of direct seeding rice,and does not significantly affect the emergence response rate and seedling quality,and the optimal covering soil thickness range was 5mm,no more than 10 mm.The results could provide experimental basis for developing the rice mechanical direct seeding synchronous covering soil device in southern rice area.2)Overall design of the pendulum type covering soil deviceBased on the furrowing and ridging rice direct seeding technology proposed by the Luo Xiwen academician team of South China Agricultural University,the optimal coveringsoil thickness of direct seeding rice was obtained as the key parameter from the field experiment,and a rice mechanical direct seeding synchronous pendulum type covering soil device was designed,the covering soil process of the pendulum type covering soil device was analyzed to establish the model,so the mathematical model of soil transport,soil cover,pendulum trajectory and leak rate of the covering soil device was established to determine the structural parameters,and the distance between the center of fixed shaft with the bottom of the cover plate was 185 mm,the length of cover plate was 400 mm.3)Covering soil performance test of the pendulum type covering soil deviceTaking the thickness and uniformity of the covering soil as the evaluation index,the covering soil performance test of the pendulum type covering soil device was introduced.The results showed that the actual leakage rate was the smallest when the structure of the cover plate was 50% hollow area under the different soil moisture content and forward speed,cleared the affecting factors sequence of covering soil uniformity was the type of the cover plate structure,the forward speed,and the soil moisture content,and the regression equation of the covering soil thickness was established with the 0.895 fitness,and the regressive relationship is extremely significant,it can provide a basis for the evaluation and prediction of the covering soil thickness.Thus the seeding synchronous mechanical covering soil test was carried out,and the results showed that the rice emergence rate was stable after the mechanical cover by the pendulum type covering soil device. |
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