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971.
NH3 volatilization from surface-applied urea, diammonium phosphate (DAP), and calcium ammonium nitrate (CAN) was measured with chambers through which air was drawn continuously. Two sandy soils and two sandy loam soils, which had been treated with and without time for the last 25 years, were used for the experiments. The accumulated NH3 loss from CAN applied to an unlimed sandy soil was linearly related to time. For the other treatments the accumulated loss was exponentially related to time. The NH3 loss was exponentially related to the maximum soil pH of the fertilizer-amended soil, and was inversely related to the content of exchangeable H+. Due to the low cation exchange capacity of these light-textured soils the NH3 loss was not reduced as the soil CEC increased. The maximum pH after soil amendment was related to soil pH. Therefore, a model is proposed that relates the NH3 loss solely to fertilizers and soil pH. The NH3 loss was less than 5% from CAN, about 20% from DAP, and about 30% from urea, with the insignificant loss from urea applied to the unlimed sandy soil excluded. The NH3 loss from surface-applied DAP was related to the air flow rate and a transfer coefficient (K
a) was estimated. K
a increased exponentially with the flow rate. At a flow rate above 3.9 liters min–1 (20 volume exchanges min–1) no further increase was seen. 相似文献
972.
Ahmed A. Lasisi Darshani Kumaragamage 《Communications in Soil Science and Plant Analysis》2020,51(7):911-918
ABSTRACTThe effectiveness of N-(n-butyl) thiophosphoric triamide (NBPT) in reducing ammonia volatilization from urea-based fertilizers has been thoroughly investigated. However, the stability of this inhibitor during storage of NBPT treated urea and urea ammonium nitrate (UAN) needs further investigation. We compared ammonia volatilization from NBPT treated urea (360 mg NBPT kg?1 urea) and UAN (180 mg NBPT L?1 UAN) that were stored at room temperature for 6, 3 and 0 months. We measured ammonia volatilization with cylindrical chambers fitted with acid-charged discs at five times for 21 d. Total ammonia volatilization (measured as a % of applied nitrogen) was significantly greater in untreated urea and UAN (32% to 33%) than those in NBPT treated urea and UAN (6% to 12%). Reduction of ammonia volatilization was not significantly different among NBPT treated urea (73% to 81%) and UAN (63% to 73%) irrespective of storage time. This implies that farmers can mix their urea-based fertilizers with NBPT formulation 6 months prior to fertilization without compromising the ammonia volatilization reducing property of the NBPT. 相似文献
973.
Renata Matraszek 《Journal of plant nutrition》2015,38(8):1158-1195
The effect of ion exchange substrate Biona-312 addition (2 or 5%) on the macronutrients composition of butterhead lettuce cv. ‘Justyna’ plants under conditions of basic (1.5-times) and intensive (3-times concentrated Hoagland solution) mineral nutrition level was investigated. Both experimental doses of Biona-312 introduced into 1.5-times concentrated Hoagland nutrient solution [electrical conductivity (EC) 2.41–2.47 dS m?1] dropped nitrogen (N) content in roots. Simultaneously statistically proven increase in foliar concentration of total sulfur (S) as well as a decrease in phosphorus (P) and potassium (K) contents in lettuce above- and underground organs were observed. The changes in calcium (Ca) and magnesium (Mg) content were insignificant. Ion exchange substrate supplementation into 3-times concentrated Hoagland nutrient solution (EC 6.85–7.30 dS m?1), significantly elevated N and K contents in above- and underground organs, raised the foliar S content, decreased Ca and Mg contents in leaves, as well as dropped P concentration in roots and increased content in leaves. 相似文献
974.
袁荣湘 《中国农村水利水电》2003,(10):21-23,30
对高压线路新型电流差动保护的原理进行了分析,说明新型电流差动保护实际上是比较在一定时间内累积的两端电荷流动的相对方向,并用电磁场理论初步说明了其物理意义,证明了新型电流差动保护原理的正确性。文中还对新型电流差动保护实现时的整定计算方法进行了讨论,定量分析了保护判据中动作门槛值的整定计算方法,对新型电流差动保护应用于实践具有重要的意义。 相似文献
975.
以甲壳素的浓盐酸水解产物氨基葡萄糖盐酸盐为原料 ,通过阴离子交换层析法制备氨基葡萄糖硫酸盐 ,并对其的部分性质进行研究。采用本方法制备的氨基葡萄糖硫酸盐产物的氨基葡萄糖含量为 71.6 0 % ,硫酸根含量为 18.2 5 % ,氯离子含量为 0 .0 38%。经纸层析鉴定 ,以吡啶、乙酸乙酯、水和冰醋酸按体积比 5∶5∶3∶1组成的溶剂系统进行展层 ,氨基葡萄糖硫酸盐的Rf 值为 0 .36。将氨基葡萄糖硫酸盐产物的晶体重新溶解于 2 0℃水中时 ,它的比旋光度随时间的延长而下降 ,1.5h后趋于稳定 ,从 92 .1°降低至 5 6 .7°。对它的红外光谱鉴定表明 ,在波数为 330 3.9、14 15 .6、12 15 .6、1181.2、1118.7、10 93.7和 10 34.4cm-1处有特征吸收峰。通过对氨基葡萄糖硫酸盐产物的元素分析 ,碳、氢、氮和硫的含量分别为 2 9.6 3%、6 .34%、5 .39%和 6 .5 6 %。 相似文献
976.
采用不同比例的八烷基氨基酸表面修饰剂修饰红壤,研究了在单一Cd^2+和苯酚混合条件下供试土样对Cd^2+的吸附和热力学特征.目的在于探讨两性修饰剂修饰可变电荷土壤以增强对重金属离子吸附的效果。结果表明,除20℃混合条件下100%A A-8处理外.同一温度下不同修饰比例的供试土样对Cd^2+的吸附量顺序均为CK〉50%A A-8〉100%A A-8,但差异并不显著。Cd^2+的吸附具有化学吸附的升温正效应特征。苯酚的共存对Cd^2+的吸附具有减弱作用。Langmuir模型是描述Cd^2+吸附等温线的最佳模型。热力学研究结果表明供试土样对Cd^2+的吸附为熵增控制的自发性反应,表面修饰剂羧基上的负电荷点位和土壤表面上的正电荷点位的结合可能是主要的修饰机理,八烷基碳链的疏水性则是Cd^2+在供试土样表面上吸附阻力的主要形式。八烷基氨基酸不是一种较好的增强红壤吸附重金属能力的有机修饰剂。 相似文献
977.
978.
979.
The aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na+, K+, Ca2+, Mg2+), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na2CO3 and the mixture of the two salts in the same volume. All three treatments caused increases in Na+ concentration, proline content and REL and decreases in root Mg2+ and K+ content. Increased Ca2+ and antioxidase activities were observed at lower external Na+ concentrations. However, at higher external Na+ levels, decreased Ca2+ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na+ and low K+ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca2+ content in the plant under alkaline salt stress. 相似文献
980.