Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization an...Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P –1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.展开更多
采用钼蓝比色法测定甜樱桃中还原型VC含量,探讨了此方法的最佳测定条件。结果表明,钼蓝比色法的最大吸收峰为850 nm,5%硫酸溶液和5%钼酸铵溶液的最佳用量分别为1.50 m L和3.00 m L,最适反应时间为14 min,在此条件下测得R2为0.998 7。优...采用钼蓝比色法测定甜樱桃中还原型VC含量,探讨了此方法的最佳测定条件。结果表明,钼蓝比色法的最大吸收峰为850 nm,5%硫酸溶液和5%钼酸铵溶液的最佳用量分别为1.50 m L和3.00 m L,最适反应时间为14 min,在此条件下测得R2为0.998 7。优化后的测定方法变异系数小于5%,平均回收率为98.52%,还原型VC含量在0.00-0.12 mg/50 m L内呈良好的线性关系。该方法准确、快速、稳定,适合少量和批量样品的测定。用此法测得天水甜樱桃样品中的还原型VC的平均含量为2.032 mg/100 g。展开更多
文摘Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P –1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.
文摘采用钼蓝比色法测定甜樱桃中还原型VC含量,探讨了此方法的最佳测定条件。结果表明,钼蓝比色法的最大吸收峰为850 nm,5%硫酸溶液和5%钼酸铵溶液的最佳用量分别为1.50 m L和3.00 m L,最适反应时间为14 min,在此条件下测得R2为0.998 7。优化后的测定方法变异系数小于5%,平均回收率为98.52%,还原型VC含量在0.00-0.12 mg/50 m L内呈良好的线性关系。该方法准确、快速、稳定,适合少量和批量样品的测定。用此法测得天水甜樱桃样品中的还原型VC的平均含量为2.032 mg/100 g。
