Four testing methods using canon exchange membrane (CEM), ammonium acetate, ASI (0.25 mol L-1 NaHCO3+0.01 mol L-1 EDTA +0.01 mol L-1 NH4P) and 1.0 mol L-1 boiling nitric acid, respectively, were used to evaluate soil ...Four testing methods using canon exchange membrane (CEM), ammonium acetate, ASI (0.25 mol L-1 NaHCO3+0.01 mol L-1 EDTA +0.01 mol L-1 NH4P) and 1.0 mol L-1 boiling nitric acid, respectively, were used to evaluate soil available K. The soil K tested by CEM was significantly correlated with that by the other (conventional) methods (r2=0.43**~0.95***). The soil K tested by CEM saturated with NH4HCO3 (15 min extraction) was most closely correlated with that by the other methods (2 =0. 60***~0.95***). Potassium availability, as predicted by soil test, was comparable to actual K uptake by canola and wheat grown on the soils in growth chamber. Regression analyses showed that plant K uptake was more closely correlated with K extracted by CEM (r2=0.56***~0.81***) than that by the conventional methods (r2=0.46***~;0.81***), most closely correlsted with that by NH4HCO3-saturated CEM for 15 min (r2=0.81***), and worst correlated with that by HNO3 (r2=0.45**~0.72***).展开更多
In order to find out the effects of long-term no-tillage operation on soil available phosphorus and available potassium in the loess plateau, a suitable high-yield and high-efficiency tillage technology system was est...In order to find out the effects of long-term no-tillage operation on soil available phosphorus and available potassium in the loess plateau, a suitable high-yield and high-efficiency tillage technology system was established. In the Changwu loess plateau agri-ecological experiment station of the Northwest A&F University of Changwu County, Shaanxi Province, the no-tillage experimental field for three consecutive years was selected. In September 2015, no-tillage, tillage, and rotary tillage were carried out before winter wheat was sowed. After the harvest of winter wheat in 2016, the contents of available phosphorus and available potassium in 0-30 cm soil layer under three tillage methods were analyzed. The results showed that in the 0-30 cm soil layer, the soil available phosphorus and available potassium decreased with the increase of the soil depth in the three tillage methods. The content of available phosphorus and available potassium in 10-20 cm soil layer and 20-30 cm soil layer decreased by 16.07%, 32.74%, 15.54% and 27.08%, respectively, and there were significant differences ( P <0.05). Under different tillage methods, the soil available phosphorus content in the 0-10 cm soil layer significantly reduced by 11.31% compared with no-tillage. The soil available potassium content under tillage and rotary tillage significantly reduced by 6.16% and 4.97%, respectively ( P <0.05). Compared with no-tillage, the soil available phosphorus content in the 20-30 cm soil layer significantly reduced by 18.12%. The soil available potassium content under tillage and rotary tillage methods significantly reduced by 17.17% and 9.22%, respectively ( P <0.05). Therefore, in the long-term no-tillage dry loess plateau, it is necessary to conduct proper tillage or rotary tillage.展开更多
Xuancheng City is the dominant tobacco-planting area of Anhui province due to the high quality of the tobacco leaves. However, the potassium content in the tobacco leaves shows a gradual decreasing trend in recent yea...Xuancheng City is the dominant tobacco-planting area of Anhui province due to the high quality of the tobacco leaves. However, the potassium content in the tobacco leaves shows a gradual decreasing trend in recent years, which may be attributed partly to the possible low potassium content in topsoil of tobacco-planting farmland. Therefore, the content data in the year of 2005-2007 of rapidly available potassium (RA-K) of 7730 topsoil samples mainly under double rice rotation or wheat/rice-rice rotation at that time and the content data of slowly available potassium (SA-K) and RA-K of 124 typical topsoil samples in the year of 2015 under tobacco-rice rotation were used and compared in order to disclose the status of topsoil potassium and to provide a guidance for reasonable potassium fertilization in Xuancheng. The results showed that in 2005-2007 RA-K content ranged from 1 mg·kg-1 to 844 mg·kg-1 with an average of 68 mg·kg-1, and 82.7% of topsoil samples were insufficient in RA-K (-1). Comparatively in 2015 SA-K content ranged from 230 mg·kg-1 to 1340 mg·kg-1 with an average of 595 mg·kg-1, and 13.7% of soil samples were insufficient in SA-K (-1);RA-K content ranged from 46 mg·kg-1 to 352 mg·kg-1 with an average of 134 mg·kg-1, and 25.8% of soil samples were insufficient in RA-K (-1). The above data show that RA-K content has increased gradually in farmland topsoil mainly due to fertilization since 1980s, particularly to farmland under tobacco-rice rotation, but insufficient RA-K in topsoil is still widely and serious for farmland under double rice rotation or wheat/rice-rice rotation. Under tobacco-rice rotation, RA-K insufficiency usually occurred in the farmlands which plant tobacco less than 3 years, indicating more potassium fertilizer should be applied.展开更多
文摘Four testing methods using canon exchange membrane (CEM), ammonium acetate, ASI (0.25 mol L-1 NaHCO3+0.01 mol L-1 EDTA +0.01 mol L-1 NH4P) and 1.0 mol L-1 boiling nitric acid, respectively, were used to evaluate soil available K. The soil K tested by CEM was significantly correlated with that by the other (conventional) methods (r2=0.43**~0.95***). The soil K tested by CEM saturated with NH4HCO3 (15 min extraction) was most closely correlated with that by the other methods (2 =0. 60***~0.95***). Potassium availability, as predicted by soil test, was comparable to actual K uptake by canola and wheat grown on the soils in growth chamber. Regression analyses showed that plant K uptake was more closely correlated with K extracted by CEM (r2=0.56***~0.81***) than that by the conventional methods (r2=0.46***~;0.81***), most closely correlsted with that by NH4HCO3-saturated CEM for 15 min (r2=0.81***), and worst correlated with that by HNO3 (r2=0.45**~0.72***).
文摘In order to find out the effects of long-term no-tillage operation on soil available phosphorus and available potassium in the loess plateau, a suitable high-yield and high-efficiency tillage technology system was established. In the Changwu loess plateau agri-ecological experiment station of the Northwest A&F University of Changwu County, Shaanxi Province, the no-tillage experimental field for three consecutive years was selected. In September 2015, no-tillage, tillage, and rotary tillage were carried out before winter wheat was sowed. After the harvest of winter wheat in 2016, the contents of available phosphorus and available potassium in 0-30 cm soil layer under three tillage methods were analyzed. The results showed that in the 0-30 cm soil layer, the soil available phosphorus and available potassium decreased with the increase of the soil depth in the three tillage methods. The content of available phosphorus and available potassium in 10-20 cm soil layer and 20-30 cm soil layer decreased by 16.07%, 32.74%, 15.54% and 27.08%, respectively, and there were significant differences ( P <0.05). Under different tillage methods, the soil available phosphorus content in the 0-10 cm soil layer significantly reduced by 11.31% compared with no-tillage. The soil available potassium content under tillage and rotary tillage significantly reduced by 6.16% and 4.97%, respectively ( P <0.05). Compared with no-tillage, the soil available phosphorus content in the 20-30 cm soil layer significantly reduced by 18.12%. The soil available potassium content under tillage and rotary tillage methods significantly reduced by 17.17% and 9.22%, respectively ( P <0.05). Therefore, in the long-term no-tillage dry loess plateau, it is necessary to conduct proper tillage or rotary tillage.
文摘Xuancheng City is the dominant tobacco-planting area of Anhui province due to the high quality of the tobacco leaves. However, the potassium content in the tobacco leaves shows a gradual decreasing trend in recent years, which may be attributed partly to the possible low potassium content in topsoil of tobacco-planting farmland. Therefore, the content data in the year of 2005-2007 of rapidly available potassium (RA-K) of 7730 topsoil samples mainly under double rice rotation or wheat/rice-rice rotation at that time and the content data of slowly available potassium (SA-K) and RA-K of 124 typical topsoil samples in the year of 2015 under tobacco-rice rotation were used and compared in order to disclose the status of topsoil potassium and to provide a guidance for reasonable potassium fertilization in Xuancheng. The results showed that in 2005-2007 RA-K content ranged from 1 mg·kg-1 to 844 mg·kg-1 with an average of 68 mg·kg-1, and 82.7% of topsoil samples were insufficient in RA-K (-1). Comparatively in 2015 SA-K content ranged from 230 mg·kg-1 to 1340 mg·kg-1 with an average of 595 mg·kg-1, and 13.7% of soil samples were insufficient in SA-K (-1);RA-K content ranged from 46 mg·kg-1 to 352 mg·kg-1 with an average of 134 mg·kg-1, and 25.8% of soil samples were insufficient in RA-K (-1). The above data show that RA-K content has increased gradually in farmland topsoil mainly due to fertilization since 1980s, particularly to farmland under tobacco-rice rotation, but insufficient RA-K in topsoil is still widely and serious for farmland under double rice rotation or wheat/rice-rice rotation. Under tobacco-rice rotation, RA-K insufficiency usually occurred in the farmlands which plant tobacco less than 3 years, indicating more potassium fertilizer should be applied.
