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Zhen Wang - One of the best experts on this subject based on the ideXlab platform.
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Effects of drip system uniformity and nitrogen Application Rate on yield and nitrogen balance of spring maize in the North China Plain
Field Crops Research, 2014Co-Authors: Zhen WangAbstract:Abstract The effects of drip system uniformity and nitrogen Application Rate on spring maize growth, nitrogen uptake, yield, yield components, nitrogen agronomic efficiency, and apparent nitrogen loss were investigated through field experiments to modify the current design and evaluation standards for drip system uniformity. The experiments were conducted in the North China Plain during two growing seasons of spring maize ( Zea mays L.) in 2011 and 2012 using 27 experimental plots of 30 m long and 3 m wide. Three Christiansen uniformity coefficients ( CU ) of 59, 80, and 97% and three levels of nitrogen applied at 0, 120, and 210 kg ha −1 were tested. The results demonstRated that the drip system uniformity had an insignificant effect on plant growth, plant nitrogen uptake, yield, yield components, nitrogen agronomic efficiency, and apparent nitrogen loss at a significance level of p −1 did not reach a statistical significance. In the subhumid region of the North China Plain where irrigation only accounts for 21–23% of the precipitation during the growing season of maize, a drip system uniformity that is lower than the values recommended by the current standards might be used to reduce the installation and operation costs of drip irrigation systems. Using a nitrogen Application Rate that is lower than the conventional values (e.g., 210 kg ha −1 ) is a promising practice to reduce nitrogen losses while maintaining an acceptably high level of yield.
Louis B. Best - One of the best experts on this subject based on the ideXlab platform.
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Effects of Application Rate on avian risk from granular pesticides
Environmental Toxicology and Chemistry, 1998Co-Authors: Tamara R. Stafford, Louis B. BestAbstract:Fensulfothion was formulated on silica granules to evaluate the relationship between avian risk of adverse effects from granular pesticides and granule availability. Captive house sparrows (Passer domesticus) were offered the granular pesticide in bands on soil surfaces at Application Rates of 50, 100, 200, 400, 800, 1,200, 1,600, or 2,000 LD50/ft 2 . Individual pesticide granules were formulated with 1/2 the LD50 for house sparrows (0.3 mg/kg). Bird behavior, survival, and brain cholinesterase activity were used to assess pesticide exposure. A significant negative correlation between brain ChE activity and the natural logarithm of Application Rate indicated that the relationship between avian risk and granule availability was asymptotic rather than linear. Thus. the assumption, implicit in the LD50/ft 2 risk index, that the potential exposure of birds to granular pesticides increases as granule availability increases may result in overestimates of risk to birds from granular pesticides, particularly at higher granule Application Rates.
Hongbin Liu - One of the best experts on this subject based on the ideXlab platform.
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identifying critical nitrogen Application Rate for maize yield and nitRate leaching in a haplic luvisol soil using the dndc model
Science of The Total Environment, 2015Co-Authors: Yitao Zhang, Hongyuan Wang, Shen Liu, Qiuliang Lei, Jian Liu, Limei Zhai, Tianzhi Ren, Hongbin LiuAbstract:Abstract Identification of critical nitrogen (N) Application Rate can provide management supports for ensuring grain yield and reducing amount of nitRate leaching to ground water. A five-year (2008–2012) field lysimeter (1 m × 2 m × 1.2 m) experiment with three N treatments (0, 180 and 240 kg N ha− 1) was conducted to quantify maize yields and amount of nitRate leaching from a Haplic Luvisol soil in the North China Plain. The experimental data were used to calibRate and validate the process-based model of Denitrification–Decomposition (DNDC). After this, the model was used to simulate maize yield production and amount of nitRate leaching under a series of N Application Rates and to identify critical N Application Rate based on acceptable yield and amount of nitRate leaching for this cropping system. The results of model calibration and validation indicated that the model could correctly simulate maize yield and amount of nitRate leaching, with satisfactory values of RMSE-observation standard deviation ratio, model efficiency and determination coefficient. The model simulations confirmed the measurements that N Application increased maize yield compared with the control, but the high N Rate (240 kg N ha− 1) did not produce more yield than the low one (120 kg N ha− 1), and that the amount of nitRate leaching increased with increasing N Application Rate. The simulation results suggested that the optimal N Application Rate was in a range between 150 and 240 kg ha− 1, which would keep the amount of nitRate leaching below 18.4 kg NO3−-N ha− 1 and meanwhile maintain acceptable maize yield above 9410 kg ha− 1. Furthermore, 180 kg N ha− 1 produced the highest yields (9837 kg ha− 1) and comparatively lower amount of nitRate leaching (10.0 kg NO3−-N ha− 1). This study will provide a valuable reference for determining optimal N Application Rate (or range) in other crop systems and regions in China.
Yao Bao-quan - One of the best experts on this subject based on the ideXlab platform.
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Fertilizer Response and Optimum Application Rate of NPK on Sweet Potato
Fujian Journal of Agricultural Sciences, 2007Co-Authors: Yao Bao-quanAbstract:The NPK fertilizer response and its optimum Application Rate on sweet potatoes was studied by field experiments in Fujian.The results showed that on average,the Application of N,P,and K on sweet potatoes increased yield by 27.2%,15.8%,and 26.4%,respectively.The Rates of the increase were N KP.The weight ratio of big-medium to small sweet potato was 6.7 in a NPK balanced fertilization.It was significantly higher than the N,P or K deficient controls.The output/input ratio of N and K fertilizers was higher in the summer sweet potatoes than in the autumn crop.However,the P fertilizer's ratio was higher in the autumn.The optimum Application Rate for N was 168 kg·hm-2,48 kg·hm-2 for P2O5,and 168 kg·hm-2 for K2O,in the ratio of 1∶0.3∶1.0 on summer sweet potatoes.For the autumn crop,the optimum Application Rate was 174 kg·hm-2 for N,57 kg·hm-2 for P2O5,and 200 kg·hm-2 for K2O,in the ratio of 1∶0.3∶1.2.But obviously,the optimum Application Rate depends largely on the soil type and its fertility.The NPK balanced fertilization increased yield by 14.9% and net income 3600 yuan per hectare over the traditional practice in a higher yield farmland,or increased yield by 12.0% and income by 2200 yuan per hectare in a medium-low yield farmland.
Richard L. Snyder - One of the best experts on this subject based on the ideXlab platform.
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Modification of water Application Rates and intermittent control for sprinkler frost protection
Transactions of the ASABE, 2018Co-Authors: Lu Yongzong, Zhao Chen, Richard L. SnyderAbstract:Abstract. To validate the feasibility of an automated frost protection sprinkler system, a sprinkler irrigation system with an optimal water Application Rate was designed, constructed, and tested in a tea field. A modified calculation model of the water Application Rate was provided by simulation with different values of airflow velocity, air temperature, air humidity, and spray water temperature. An intermittent control stRategy was provided using a modified model that included the start and stop time of the system and adjustment of the water Application Rate. Tea field experiments were conducted to evaluate the effect of frost protection based on this control stRategy during frost night events. The results showed that a variable water Application Rate was better suited for frost protection, and the modified intermittent control automatically regulated the water Application Rate. In early spring and winter heavy frost nights, the canopy temperature (Tc) of the irrigated area remained above -1.2°C and 0°C, respectively, which is higher than the critical damage temperature for tea plants. The Tc of the irrigated area was approximately 2.8°C higher than that of a non-irrigated area. Moreover, the irrigated area with the modified model had a slower temperature rise after sunrise compared with the non-irrigated area, which was beneficial for frost protection. This sprinkler control stRategy is an effective frost protection method that could be applied for in tea fields in the Yangtze River region. The calculation and simulation procedure of the water Application Rate would be applied for constructing sprinklers for different micrometeorological environments. Keywords: Frost protection, Intermittent control, Spraying water temperature, Sprinkler irrigation system, Tea, Water Application Rate.