INTRODUCTION The insoluble phosphates which can not be directly absorbed by plants are the mai forms of inorganic phosphate in soil. These kinds of phosphates can be solubilized by several species of bacteria which ar...INTRODUCTION The insoluble phosphates which can not be directly absorbed by plants are the mai forms of inorganic phosphate in soil. These kinds of phosphates can be solubilized by several species of bacteria which are widely spread in soil especially in rhizosphere where70% of the bacteria are capable of solubilizing inorganic phosphate. Many researchers re-展开更多
A new inorganic phosphorus (IP) fractionation scheme developed by Jiang and Gu was used in an incubation experiment to investigate the transformation of applied P in a calcareous fluvisol. The results show that after ...A new inorganic phosphorus (IP) fractionation scheme developed by Jiang and Gu was used in an incubation experiment to investigate the transformation of applied P in a calcareous fluvisol. The results show that after addition of common superphosphate (CSP), the Ca2-P in the soil decreased gradually and transformed largely to the less available Fe-P, Al-P and Ca8-P, rather than to the unavailable forms of Ca10-P and O-P. The different IP fractions ranked in the following order with respect to the increment by addition of CSP after 120 days of incubation: Fe-P> Al-P>Ca8-P>Ca2-P. After addition of pig manure, the content of Ca2-P in the soil increased rapidly at first and then decreased slowly, and the amount of different IP fractions accumulated after 120 days of incubation ranked in the following order: Ca2-P > Fe-P > Ca8-P > Al-P. Evidently, the variation in content of Ca2-P and the order of increase in different IP fractions in incubation induced by application of pig manure were quite different from that of CSP. The increase in IP fractions in the incubation of broad bean green manure (BBGM)for 120 days was in the rank of Fe-P > Ca2-P > Ca8-P > Al-P; but because organic phosphorus (OP) of BBGM degraded relatively slowly, the increment in IP fractions was lower than that of pig manure. Wheat straw was difficult to mineralize and induced a strong biological fixation of soil P, resulting in a decrease of the content of Ca2-P, even Ca8-P, Fe-P and Al-P.展开更多
Inorganic fertilizer NPK （nitrogen, phosphorus and potassium） （S） 25：5：5：5 is generally recommended for optimum yield and quality of tea （Camellia sinensis）. Non-judicious use of this inorganic fertilizer how...Inorganic fertilizer NPK （nitrogen, phosphorus and potassium） （S） 25：5：5：5 is generally recommended for optimum yield and quality of tea （Camellia sinensis）. Non-judicious use of this inorganic fertilizer however acidifies the soils and pollutes the environment. Integrated soil fertility management （ISFM） which involves the combined use of organic and inorganic fertilizer is recommended for improved crop yield and soil health. An experiment was carried out to determine the effect of enriching cattle manure with different ratios of inorganic fertilizers （OM： NPKS at ratios 1：2 and 1：4）, and rates on soil nutrient status, nitrogen uptake and yield of tea in the east of Rift Valley, Kenya. Enriching manures and organic manure up to a rate of 150 kg N/ha increased the level of P mature leaf. A higher N and K level in the mature leaf was observed when NPKS was applied at higher rates. In the soil, fertilizer rate up to 150 kg N/ha showed higher pH and K where organic manure and enriched manures were applied while NPKS treatment showed higher P content throughout the soil depths. Enriching organic manures with inorganic fertilizers increased yield significantly.展开更多
Soluble phosphate fertilizers have been preferably used in plant crop production. The cost of applying conventional water soluble phosphate fertilizer is high in developing countries since their manufacturing requires...Soluble phosphate fertilizers have been preferably used in plant crop production. The cost of applying conventional water soluble phosphate fertilizer is high in developing countries since their manufacturing requires importing high grade rock phosphate （RP）. As a result, the use of indigenously available low-grade RP is gaining importance globally. In this study, experiments were carried out using clayey loamy alkaline soil to evaluate the agronomic efficiency of fine sized low grade RP with inorganic nitrogen fertilizers and it was further compared with that of soluble phosphate fertilizer （di-ammonium phosphate）, Cicer arietinum was the test crops subjected to treatments of absolute control, di-ammonium phosphate and low grade RP with varying concentrations of ammonium sulphate or ammonium nitrate. The experiments were conducted during 2012-2013 in the bid to study the growth rate and the biomass of the crop. Tests were also performed to determine the residual effects of the fertilizers on the crops. The results revealed that the combined use of low grade RP and ammonium sulphate or ammonium nitrate, at 16 kg N/ha, resulted in an agronomic efficiency, in terms of biomass of plants, comparable to that of di-ammonium phosphate and was found to be a more attractive management option for resource-poor farmers.展开更多
基金Projcct supponcd by the National Natural science Foundation of China.
文摘INTRODUCTION The insoluble phosphates which can not be directly absorbed by plants are the mai forms of inorganic phosphate in soil. These kinds of phosphates can be solubilized by several species of bacteria which are widely spread in soil especially in rhizosphere where70% of the bacteria are capable of solubilizing inorganic phosphate. Many researchers re-
文摘A new inorganic phosphorus (IP) fractionation scheme developed by Jiang and Gu was used in an incubation experiment to investigate the transformation of applied P in a calcareous fluvisol. The results show that after addition of common superphosphate (CSP), the Ca2-P in the soil decreased gradually and transformed largely to the less available Fe-P, Al-P and Ca8-P, rather than to the unavailable forms of Ca10-P and O-P. The different IP fractions ranked in the following order with respect to the increment by addition of CSP after 120 days of incubation: Fe-P> Al-P>Ca8-P>Ca2-P. After addition of pig manure, the content of Ca2-P in the soil increased rapidly at first and then decreased slowly, and the amount of different IP fractions accumulated after 120 days of incubation ranked in the following order: Ca2-P > Fe-P > Ca8-P > Al-P. Evidently, the variation in content of Ca2-P and the order of increase in different IP fractions in incubation induced by application of pig manure were quite different from that of CSP. The increase in IP fractions in the incubation of broad bean green manure (BBGM)for 120 days was in the rank of Fe-P > Ca2-P > Ca8-P > Al-P; but because organic phosphorus (OP) of BBGM degraded relatively slowly, the increment in IP fractions was lower than that of pig manure. Wheat straw was difficult to mineralize and induced a strong biological fixation of soil P, resulting in a decrease of the content of Ca2-P, even Ca8-P, Fe-P and Al-P.
文摘Inorganic fertilizer NPK （nitrogen, phosphorus and potassium） （S） 25：5：5：5 is generally recommended for optimum yield and quality of tea （Camellia sinensis）. Non-judicious use of this inorganic fertilizer however acidifies the soils and pollutes the environment. Integrated soil fertility management （ISFM） which involves the combined use of organic and inorganic fertilizer is recommended for improved crop yield and soil health. An experiment was carried out to determine the effect of enriching cattle manure with different ratios of inorganic fertilizers （OM： NPKS at ratios 1：2 and 1：4）, and rates on soil nutrient status, nitrogen uptake and yield of tea in the east of Rift Valley, Kenya. Enriching manures and organic manure up to a rate of 150 kg N/ha increased the level of P mature leaf. A higher N and K level in the mature leaf was observed when NPKS was applied at higher rates. In the soil, fertilizer rate up to 150 kg N/ha showed higher pH and K where organic manure and enriched manures were applied while NPKS treatment showed higher P content throughout the soil depths. Enriching organic manures with inorganic fertilizers increased yield significantly.
文摘Soluble phosphate fertilizers have been preferably used in plant crop production. The cost of applying conventional water soluble phosphate fertilizer is high in developing countries since their manufacturing requires importing high grade rock phosphate （RP）. As a result, the use of indigenously available low-grade RP is gaining importance globally. In this study, experiments were carried out using clayey loamy alkaline soil to evaluate the agronomic efficiency of fine sized low grade RP with inorganic nitrogen fertilizers and it was further compared with that of soluble phosphate fertilizer （di-ammonium phosphate）, Cicer arietinum was the test crops subjected to treatments of absolute control, di-ammonium phosphate and low grade RP with varying concentrations of ammonium sulphate or ammonium nitrate. The experiments were conducted during 2012-2013 in the bid to study the growth rate and the biomass of the crop. Tests were also performed to determine the residual effects of the fertilizers on the crops. The results revealed that the combined use of low grade RP and ammonium sulphate or ammonium nitrate, at 16 kg N/ha, resulted in an agronomic efficiency, in terms of biomass of plants, comparable to that of di-ammonium phosphate and was found to be a more attractive management option for resource-poor farmers.
