Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure...Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use （ETc） under no soil stress treatment using gravimetric sampling. In the second season （SS）, the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point （PWP）. The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration （ET0） was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were： 0.46, 0.49, 0.53 and 0.60; for the initial stage： 0.69, 0.78, 0.88 and 0.97; for the development stage： 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage： 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.展开更多
With the advancement of agricultural mechanization,soil compaction has become a serious environmental problem.Soil compaction can increase soil bulk density and firmness,reduce porosity and permeability,and deteriorat...With the advancement of agricultural mechanization,soil compaction has become a serious environmental problem.Soil compaction can increase soil bulk density and firmness,reduce porosity and permeability,and deteriorate soil structure,ultimately inhibit sugar beet growth and reduce both root yield and sugar content.However,few farmers recognize the link between soil compaction and these adverse effects.Soil compaction has a cumulative effect,with significant differences observed in the vertical range of compaction accumulation.The most significant soil compaction occurs in the topsoil of 0-10 cm,and the influence depth can reach 70 cm,but it is small in deep soil,and the inflection point is at a soil depth of 10 cm.The degree of soil compaction is related to soil type,water content,tractor shaft load,tyre type,tyre pressure and operation speed,etc.Therefore,in the production process of sugar beet,it is advisable to avoid high-humidity operations,use low pressure tyres,reduce the number of tractor-units passes over the farmland,and implement agricultural and agronomic measures to minimize soil compaction.These practices will help protect the soil environment and ensure sustainable production of sugar beets.展开更多
文摘Crop coefficients （Kc） of sugar beet were determined for accurate calculation of water requirements （CWR） and better irrigation water management. Three irrigation treatments were used during two seasons to measure actual crop water use （ETc） under no soil stress treatment using gravimetric sampling. In the second season （SS）, the method was modified to target 8 temporal points during crop growth for smooth calculation of ETc under sufficient moisture supply to avoid the distortion that was created by the continuous gravimetric sampling after, before and during each irrigation cycle on the experimental plots. Water was stopped when each targeted sampling point was reached using large plots where intensive sampling continues until the crop reaches severe water stress or permanent wilting point （PWP）. The actual crop water use was extracted from the soil moisture depletion curve which allowed the identification of two clear segments. The first segment indicated crop water use during no water stress while the change of the slope indicated the beginning of the water stress. The reference crop evapotranspiration （ET0） was determined on daily basis using appropriate weather data that coincides with the ETc measurement and consequently the crop Kc were calculated. The results showed that the method used during the SS is easy and provides a better understanding of actual crop water use and better estimation of crop Kc. The calculated 10-day Kc values for sugar beet under heavy cracking clay soil conditions were： 0.46, 0.49, 0.53 and 0.60; for the initial stage： 0.69, 0.78, 0.88 and 0.97; for the development stage： 1.05, 1.11, 1.13, 1.11 and 1.04; for mid-season stage and for late season stage： 0.92, 0.74 and 0.60. Yield and other sugar related parameters were also presented for the two seasons.
基金Supported by China Agriculture Research System(Sugar Crops)of Ministry of Agriculture and Rural Affairs and Ministry of Finance(CARS-170601)Natural Science Foundation of Heilongjiang Province(C201239).
文摘With the advancement of agricultural mechanization,soil compaction has become a serious environmental problem.Soil compaction can increase soil bulk density and firmness,reduce porosity and permeability,and deteriorate soil structure,ultimately inhibit sugar beet growth and reduce both root yield and sugar content.However,few farmers recognize the link between soil compaction and these adverse effects.Soil compaction has a cumulative effect,with significant differences observed in the vertical range of compaction accumulation.The most significant soil compaction occurs in the topsoil of 0-10 cm,and the influence depth can reach 70 cm,but it is small in deep soil,and the inflection point is at a soil depth of 10 cm.The degree of soil compaction is related to soil type,water content,tractor shaft load,tyre type,tyre pressure and operation speed,etc.Therefore,in the production process of sugar beet,it is advisable to avoid high-humidity operations,use low pressure tyres,reduce the number of tractor-units passes over the farmland,and implement agricultural and agronomic measures to minimize soil compaction.These practices will help protect the soil environment and ensure sustainable production of sugar beets.
