Root distribution and influencing factors of dry-sowing and wet-growing cotton plants under different water conditions

To study the effect of soil water and salt environment factors on the root growth of cotton under different moisture control,three different emergence water volumes(60,105,and 150 m^(3)/hm^(2)),two different frequencies(high frequency and low frequency)and one double film cover winter irrigation control treatment(CK:2250 m^(3)/hm^(2))were set up to analyze the spatial distribution patterns of soil water and salt environment and root density in dry sown and wet emerged cotton fields under diffe-rent moisture control conditions.The results show that the soil water content and water infiltration range gradually become larger with the increase of seedling water quantity,and the larger the seedling water quantity,the higher the soil water content.With the same seedling water quantity,the soil water content of the high-frequency(HF)treatment becomes obviously larger.The soil conductivity of each treatment tends to decrease gradually with the increase of seedling water and drip frequency,among which the distribution of soil conductivity of S6 treatment is closest to that of CK.With the increase in soil depth,the soil conductivity tends to increase first and then decrease.Compared with the low-frequency(LF)treatment,the high-frequency treatment shows a significantly deeper soil salt accumulation layer.The root length density(RLD)of cotton gradually increases with the amount of seedling water and the frequency of dripping.The soil layer of root distribution gradually deepens with the amount of seedling water in the vertical direction,and the RLD value in the horizontal direction is significantly greater in the mulched area than that in the bare area between films.This research can serve as a solid scientific foundation for the use of dry sowing and wet emergence techniques in cotton fields in southern Xinjiang.

Mechanism analysis and performance improvement of mechanized ridge forming of whole plastic film mulched double ridges

In order to achieve high-performance and mechanization construction standard of whole plastic mulched double ridge seedbed,and to meet its forming process and corresponding agronomic requirements of the mechanized double ridge seedbed,the key working parameters such as the speed of rotary blade group,the thickness of upturned sod and the power consumption of rotary blade group under different parameters were analyzed based on related working performance in ridge forming.Also,the test factors and their range of values were finally determined in this study.Discrete element method(DEM)simulation was applied in the numerical simulation of the mechanized ridge forming process of whole plastic mulched double ridges,and the ridge forming effect and digging resistance variation characteristics of different types of shovels were compared.Taking the forward speed of the combined machine,the penetration angle of the arc-shaped shovel and the depth of rotary tillage as independent variables,and the qualified rate of seedbed tillage as the response value,the mathematical model between the test factors and the qualified rate of the seedbed tillage was established,to explore the influence sequence of the factors on the qualified rate of seedbed tillage,and obtained the following optimal working parameters of the ridge forming device:the advancing velocity of the combined machine of 0.50 m/s,penetration angle of the arc-shaped shovel of 31°,rotary tillage depth of 140 mm,and average qualified rate 95.20%of seedbed tillage in corresponding simulation verification test.Field test showed that the average qualified rate of seedbed tillage in ridge forming device was 93.60%,which was close to that of the simulation results.The actual working condition of the sample machine was basically in line with the simulation process and could relatively precisely reflect the mechanized ridge forming mechanism of whole plastic double ridges.The results showed that the established DEM model and its parameter setting were relatively accurate and reasonable.