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Soil testing is widely adopted as an essential diagnostic tool for identifying soil nutrient factors that limit sustained crop production. A systematic approach for rapid soil testing and fertilizer recommendation has been introduced and widely used in China by Agro Services International (ASI), USA. To verify the usefulness and reliability of the ASI method in soil testing and fertilizer recommendation in comparison with other commonly used traditional soil testing methods, 294 soil samples from major agricultural regions and soil types in China with a wide range of soil pH, from 5.1 to 8.9, were taken and analyzed for available phosphorus (P) and potassium (K) by the ASI multielement extraction solution and selected traditional methods, Olsen extractant for P, ammonium acetate (NH4OAc) extractant for K, and multielement extractant Mehlich 3 for P and K. Also, 46 soils were selected from northern China regions for a greenhouse trial with sorghum seedlings to determine if the soil testing values correlate...

Potash resources in China are very scarce. It is especially important to correctly evaluate the potential potassium‐supplying power of soils in northern China in order to use soil potassium sufficiently and potash fertilizer properly. Regional differences in crop yield responses to long‐term potassium application in northern China were determined in this study. Twenty‐five representative soil samples from 13 provinces, municipalities, and autonomous regions of major agricultural regions in northern China were collected from the surface layer (0–20 cm) before crop seeding in 1993. A soil potassium‐depletion study was carried out in a pot experiment with successive planting of corn seedlings for 10 harvests in the 25 soils. Since 1993, field trials on wheat and corn response to long‐term potassium application were conducted at the fixed sites of HLJ‐SC (Shuangcheng of Heilongjiang), JL‐LFZ (Liufangzi of Jilin), HB‐XJ (Xinji of Hebei), SX‐LF (Linfen of Shanxi), QH‐NKY (Nongkeyuan of Qinghai), and XJ‐CJ (Chan...

A pot experiment was conducted to determine the effects of potassium (K) application on volatile compounds, taste compounds, and firmness of fresh tomato fruits. Each pot was filled with 8 kg of clean sand. The experiment consisted of six K application rates with 0, 1.25, 2.5, 5.0, 10.0, and 20.0 mmol K L−1 in the nutrient solution. Volatile compounds, soluble sugars, soluble solids, titratable acidity, and firmness of fresh tomato fruits were measured. The results show that the concentrations of 3-methylbutanal, 1-penten-3-one, hexanal, cis-3-hexenal, 2-methyl-4-pentenal, trans-2-hexenal, 2E-4E-hexadienal, 6-methyl-5-hepten-2-one, phenylacetaldehyde, phenylethanol, soluble sugars, and soluble solids tended to increase at first and then decrease between 0 to 10.0 mmol K L−1. K application rate obtaining the highest values of the concentrations ranged from 1.4 to 3.0 mmol K L−1, with the exception of cis-3-hexenal (1.1 mmol K L−1), phenylacetaldehyde (4.5 mmol K L−1), and phenylethanol (4.8 mmol K...