To assess the effects of savanna afforestation on soil phosphorus (P) transformations in eastern Horqin Sandy Land, China, P fractions and phosphomonoesterase activities were examined in two soil horizons (0-5 cm a...To assess the effects of savanna afforestation on soil phosphorus (P) transformations in eastern Horqin Sandy Land, China, P fractions and phosphomonoesterase activities were examined in two soil horizons (0-5 cm and 5-20 cm) under a savanna and an adjacent 30-year-old Mongolian pine (Pinus sylvestris L. vat. mongolica Litv.) plantation on a P-deficient semi arid sandy soil. The results showed that all soil P fractions and phosphomonoestcrase activities decreased with soil depth at both sites except that labile organic P under the plantation was constant with soil depth, In contrast to savanna, soils trader Mongolian pine plantation had lower phosphomonoesterase activities and concentrations of all P fractions (with an exception of Al-P), lower proportions of organic P and Ca-P in total P, and higher proportions of labile P, Al-P and Fe-P in total P. These results suggested that P transformations mainly occurred in surface soils, and P recycled through litterfall was the most important source of plant available P. Mongolian pine afforestation enhanced the bioavailability of both organic P and Ca-P. simultaneously reduced soil P pools. indicating that protection of forest floor and P fertilization are necessary to maintain the sustainable functioning of Mongolian pine plantations.展开更多
The aim of this study was to investigate the role of rhizosphere organic phosphorus (P) in soil P supply in semiarid forests and the effects of tree species on rihizosphere organic P. We examined organic P fractions...The aim of this study was to investigate the role of rhizosphere organic phosphorus (P) in soil P supply in semiarid forests and the effects of tree species on rihizosphere organic P. We examined organic P fractions in rhizosphere and bulk soils of mono-specific Simon poplar (Populus simonii) and Mongolian pine (Pinus sylvestris var. mongolica) plantations in a semiarid sandy soil of Horqin Sandy Land in Northeast China. Total organic P (TPo) accounted for 76% of total P across the two stands. The concentration of organic P (Po) fractions decreased in the order of NaOH-Po〉Res-Po〉HCI-Po〉NaHCO3-Po in both plantations. The concentration of NaHCO3-Po was 38% and 43% lower in rhizosphere soil than in bulk soil in Simon poplar and Mongolian pine plantations, respectively. In contrast, total P, TPo and NaOH-Po significantly accumulated in rhizosphere soil in Simon poplar plantations, but no change in Mongolian pine plantations. Soil recalcitrant organic P fractions were positively correlated with soil organic carbon. The results suggest that rhizosphere labile organic P was an important source of plant-available P in this semiarid region, but the dynamic of rhizosphere recalcitrant organic P fractions varied with tree species and was correlated to organic carbon dynamics.展开更多
The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatia...The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatially by sequential chemical extraction according to the scheme proposed by Psenner et al. (Psenner, 1985) and its modified version respectively. The ammonium chloride extracted 3%—7% of the total reactive phosphorus (Tot-RP), while the distilled water extracted less(<3%). These two forms of P were significantly higher at the most eutrophic stations(I and IV). The sum of BD-RP(reductant soluble P) and NaOH-RP extracted accounted for 57%—81% of Tot-RP, which could play significant roles in P cycling. The percentages of HCl-extractable RP in the sediments of station III, however, were usually much more than those of other stations, which could reflect the original geochemistrical characteristics and trophic status of the sediments. It was noted that the sediment RP in different fractions varied in different months studied.展开更多
In this article,we study the following fractional(p,q)-Laplacian equations involving the critical Sobolev exponent:(Pμ,λ){(−Δ)s 1 p u+(−Δ)s 2 q u=μ|u|q−2 u+λ|u|p−2 u+|u|p∗s 1−2 u,u=0,inΩ,in R N∖Ω,whereΩ⊂R N i...In this article,we study the following fractional(p,q)-Laplacian equations involving the critical Sobolev exponent:(Pμ,λ){(−Δ)s 1 p u+(−Δ)s 2 q u=μ|u|q−2 u+λ|u|p−2 u+|u|p∗s 1−2 u,u=0,inΩ,in R N∖Ω,whereΩ⊂R N is a smooth and bounded domain,λ,μ>0,0<s 2<s 1<1,1<q<p<Ns 1.We establish the existence of a non-negative nontrivial weak solution to(Pμ,λ)by using the Mountain Pass Theorem.The lack of compactness associated with problems involving critical Sobolev exponents is overcome by working with certain asymptotic estimates for minimizers.展开更多
Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely c...Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely considered as a cost-effective management strategy to relieve this situation;however, how such cessation influences P speciation and concentrations in a bulk soil and colloidal fractions and whether decreasing P concentration might maintain soil fertility remain unclear. In this study, the effects of long-term fertilization(ca. 40 years) and short-term cessation of fertilization(ca. 16 months) on inorganic, organic,and colloidal P in lime concretion black soil were investigated using P sequential fractionation and31P nuclear magnetic resonance spectroscopy. After long-term fertilization, available P, dicalcium phosphate, iron-bound P, orthophosphate monoesters, and orthophosphate diesters increased significantly, but soil p H decreased by ca. 2.8 units, indicating that long-term fertilization caused soil acidification and P accumulation and changed P speciation markedly. In contrast, short-term fertilization cessation increased soil p H by ca. 0.8 units and slightly reduced available and inorganic P. Available P after fertilization cessation was 22.9–29.8 mg kg-1, which was still sufficient to satisfy crop growth requirements. Additionally, fertilization cessation increased the proportions of fine colloids(100–450 nm, including nontronite and some amorphous iron oxides) and drove a significant release of iron/aluminum oxide nanoparticles(1–100 nm) and associated P with orthophosphate and pyrophosphate species. In summary, short-term fertilization cessation effectively alleviated soil acidification and inorganic P accumulation, while concomitantly maintaining soil P fertility and improving the potential mobilization of P associated with microparticles.展开更多
The forms of phosphorus(P)in animal manure and peat are different from synthetic P fertilizers and will affect soil P fractions when they are used as P amendments.Effects of chicken manure(CMB)and peat(PB)derived bioc...The forms of phosphorus(P)in animal manure and peat are different from synthetic P fertilizers and will affect soil P fractions when they are used as P amendments.Effects of chicken manure(CMB)and peat(PB)derived biochars(CMB and PB)alone or in combination with P fertilizer(KH_(2)PO_(4))and rock phosphate(RP)on plant/soil health and soil P fractions in an acidic ultisol were examined with greenhouse pot experiments.The total P rate was constant at 120 mg kg^(−1) in all treatments.Soil P fractions,P uptake,and maize growth were determined after 56 days.Application of CMB combined with P fertilizer or alone significantly increased soil pH,water extractable and relatively labile P,dry matter yield of maize,chlorophyll contents in maize leaves,while decreasing the Fe and Al binding P.Moreover,sole application of CMB and PB showed greater effects than application of P fertilizer alone regarding plant growth and P fractionation.Integration of syn-thetic inorganic P sources with CMB or sole application of CMB is more beneficial than application of inorganic P sources to improve plant growth and P availability.展开更多
The concentration and components of manure phosphorus(P)are key factors determining potential P bioavailability and runoff.The distribution of P forms in swine,poultry and cattle manures collected from intensive and e...The concentration and components of manure phosphorus(P)are key factors determining potential P bioavailability and runoff.The distribution of P forms in swine,poultry and cattle manures collected from intensive and extensive production systems in several areas of China was investigated with sequential fractionation and a simplified two-step(NaHCO3-NaOH/EDTA)procedures.The mean total P concentration,determined by the sequential fractionation procedure of intensive swine,poultry and cattle manure,expressed as g·kg–1,was 14.9,13.4 and 5.8 g·kg–1,respectively,and 4.4 g·kg–1 in extensive cattle manure.In intensive swine,poultry and cattle manure about 73%,74%and 79%of total P,respectively,was bioavailable(i.e.,P extracted by H2O and NaHCO3)and 78%in extensive cattle manure.The results indicated the relative environmental risk,from high to low,of swine,poultry and cattle manure.There is considerable regional variation in animal manure P across China,which needs to be considered when developing manure management strategies.展开更多
In this paper, a robust fractional order fuzzy P + fuzzy I + fuzzy D (FOFP + FOFI + FOFD) controller is presented for a nonlinear and uncertain 2-1ink planar rigid manipulator. It is a nonlinear fuzzy controller...In this paper, a robust fractional order fuzzy P + fuzzy I + fuzzy D (FOFP + FOFI + FOFD) controller is presented for a nonlinear and uncertain 2-1ink planar rigid manipulator. It is a nonlinear fuzzy controller with variable gains that makes it self- adjustable or adaptive in nature. The fractional order operators further make it more robust by providing additional degrees of freedom to the design engineer. The integer order counterpart, fuzzy P + fuzzy I + fuzzy D (FP + FI + FD) controller, for a comparative study, was realized by taking the integer value for the fractional order operators in FOFP + FOFI + FOFD controller. The performances of both the fuzzy controllers are evaluated for reference trajectory tracking and disturbance rejection with and without model uncertainty and measurement noise. Genetic algorithm was used to optimize the parameters of controller under study for minimum integral of absolute error. Simulation results demonstrated that FOFP + FOFI + FOFD controller show much better performance as compared to its counterpart FP + FI + FD controller in servo as well as the regulatory problem and in model uncertainty and noisy environment FOFP + FOFI + FOFD controller demonstrated more robust behavior as compared to the FP + FI + FD controller. For the developed controller bounded-input and bounded-output stability conditions are also developed using Small Gain Theorem.展开更多
基金This work was supported by Innovation Research Project of Chinese Academy of Sciences (KZCX3-SW-418), National Natural Science Foundation of China (30471377) and sustentation project of the Institute of Applied Ecology of Chinese Academy of Sciences (SLYQY0409).
文摘To assess the effects of savanna afforestation on soil phosphorus (P) transformations in eastern Horqin Sandy Land, China, P fractions and phosphomonoesterase activities were examined in two soil horizons (0-5 cm and 5-20 cm) under a savanna and an adjacent 30-year-old Mongolian pine (Pinus sylvestris L. vat. mongolica Litv.) plantation on a P-deficient semi arid sandy soil. The results showed that all soil P fractions and phosphomonoestcrase activities decreased with soil depth at both sites except that labile organic P under the plantation was constant with soil depth, In contrast to savanna, soils trader Mongolian pine plantation had lower phosphomonoesterase activities and concentrations of all P fractions (with an exception of Al-P), lower proportions of organic P and Ca-P in total P, and higher proportions of labile P, Al-P and Fe-P in total P. These results suggested that P transformations mainly occurred in surface soils, and P recycled through litterfall was the most important source of plant available P. Mongolian pine afforestation enhanced the bioavailability of both organic P and Ca-P. simultaneously reduced soil P pools. indicating that protection of forest floor and P fertilization are necessary to maintain the sustainable functioning of Mongolian pine plantations.
基金funded by the National Natural Science Foundation of China (41373087, 30800887)the State Key Laboratory of Forest and Soil Ecology (LFSE2013-11)
文摘The aim of this study was to investigate the role of rhizosphere organic phosphorus (P) in soil P supply in semiarid forests and the effects of tree species on rihizosphere organic P. We examined organic P fractions in rhizosphere and bulk soils of mono-specific Simon poplar (Populus simonii) and Mongolian pine (Pinus sylvestris var. mongolica) plantations in a semiarid sandy soil of Horqin Sandy Land in Northeast China. Total organic P (TPo) accounted for 76% of total P across the two stands. The concentration of organic P (Po) fractions decreased in the order of NaOH-Po〉Res-Po〉HCI-Po〉NaHCO3-Po in both plantations. The concentration of NaHCO3-Po was 38% and 43% lower in rhizosphere soil than in bulk soil in Simon poplar and Mongolian pine plantations, respectively. In contrast, total P, TPo and NaOH-Po significantly accumulated in rhizosphere soil in Simon poplar plantations, but no change in Mongolian pine plantations. Soil recalcitrant organic P fractions were positively correlated with soil organic carbon. The results suggest that rhizosphere labile organic P was an important source of plant-available P in this semiarid region, but the dynamic of rhizosphere recalcitrant organic P fractions varied with tree species and was correlated to organic carbon dynamics.
文摘The bioavailability of phosphorus in lake sediment mainly depends on its forms. Therefore, reactive phosphorus (RP) pool of the sediment in a shallow eutrophic lake(Donghu Lake) was determined seasonally and spatially by sequential chemical extraction according to the scheme proposed by Psenner et al. (Psenner, 1985) and its modified version respectively. The ammonium chloride extracted 3%—7% of the total reactive phosphorus (Tot-RP), while the distilled water extracted less(<3%). These two forms of P were significantly higher at the most eutrophic stations(I and IV). The sum of BD-RP(reductant soluble P) and NaOH-RP extracted accounted for 57%—81% of Tot-RP, which could play significant roles in P cycling. The percentages of HCl-extractable RP in the sediments of station III, however, were usually much more than those of other stations, which could reflect the original geochemistrical characteristics and trophic status of the sediments. It was noted that the sediment RP in different fractions varied in different months studied.
基金National Natural Science Foundation of China(11501252 and 11571176)。
文摘In this article,we study the following fractional(p,q)-Laplacian equations involving the critical Sobolev exponent:(Pμ,λ){(−Δ)s 1 p u+(−Δ)s 2 q u=μ|u|q−2 u+λ|u|p−2 u+|u|p∗s 1−2 u,u=0,inΩ,in R N∖Ω,whereΩ⊂R N is a smooth and bounded domain,λ,μ>0,0<s 2<s 1<1,1<q<p<Ns 1.We establish the existence of a non-negative nontrivial weak solution to(Pμ,λ)by using the Mountain Pass Theorem.The lack of compactness associated with problems involving critical Sobolev exponents is overcome by working with certain asymptotic estimates for minimizers.
基金supported by the National Natural Science Foundation of China (No. 41907063)the Foundation of Modern Agricultural Innovation Center, Henan Institute of Sun Yat-sen University, China (No. N2021-002)。
文摘Long-term excessive application of mineral fertilizer has led to soil acidification and phosphorus(P) accumulation, increasing the risk of P loss and environmental pollution, and cessation of fertilization is widely considered as a cost-effective management strategy to relieve this situation;however, how such cessation influences P speciation and concentrations in a bulk soil and colloidal fractions and whether decreasing P concentration might maintain soil fertility remain unclear. In this study, the effects of long-term fertilization(ca. 40 years) and short-term cessation of fertilization(ca. 16 months) on inorganic, organic,and colloidal P in lime concretion black soil were investigated using P sequential fractionation and31P nuclear magnetic resonance spectroscopy. After long-term fertilization, available P, dicalcium phosphate, iron-bound P, orthophosphate monoesters, and orthophosphate diesters increased significantly, but soil p H decreased by ca. 2.8 units, indicating that long-term fertilization caused soil acidification and P accumulation and changed P speciation markedly. In contrast, short-term fertilization cessation increased soil p H by ca. 0.8 units and slightly reduced available and inorganic P. Available P after fertilization cessation was 22.9–29.8 mg kg-1, which was still sufficient to satisfy crop growth requirements. Additionally, fertilization cessation increased the proportions of fine colloids(100–450 nm, including nontronite and some amorphous iron oxides) and drove a significant release of iron/aluminum oxide nanoparticles(1–100 nm) and associated P with orthophosphate and pyrophosphate species. In summary, short-term fertilization cessation effectively alleviated soil acidification and inorganic P accumulation, while concomitantly maintaining soil P fertility and improving the potential mobilization of P associated with microparticles.
基金This study was supported by the National Key Research and Development of China(No.2016YFD0200302).
文摘The forms of phosphorus(P)in animal manure and peat are different from synthetic P fertilizers and will affect soil P fractions when they are used as P amendments.Effects of chicken manure(CMB)and peat(PB)derived biochars(CMB and PB)alone or in combination with P fertilizer(KH_(2)PO_(4))and rock phosphate(RP)on plant/soil health and soil P fractions in an acidic ultisol were examined with greenhouse pot experiments.The total P rate was constant at 120 mg kg^(−1) in all treatments.Soil P fractions,P uptake,and maize growth were determined after 56 days.Application of CMB combined with P fertilizer or alone significantly increased soil pH,water extractable and relatively labile P,dry matter yield of maize,chlorophyll contents in maize leaves,while decreasing the Fe and Al binding P.Moreover,sole application of CMB and PB showed greater effects than application of P fertilizer alone regarding plant growth and P fractionation.Integration of syn-thetic inorganic P sources with CMB or sole application of CMB is more beneficial than application of inorganic P sources to improve plant growth and P availability.
基金financially supported by the National Key R&D Program of China (2017YFD0200200 and 2017YFD0200202)
文摘The concentration and components of manure phosphorus(P)are key factors determining potential P bioavailability and runoff.The distribution of P forms in swine,poultry and cattle manures collected from intensive and extensive production systems in several areas of China was investigated with sequential fractionation and a simplified two-step(NaHCO3-NaOH/EDTA)procedures.The mean total P concentration,determined by the sequential fractionation procedure of intensive swine,poultry and cattle manure,expressed as g·kg–1,was 14.9,13.4 and 5.8 g·kg–1,respectively,and 4.4 g·kg–1 in extensive cattle manure.In intensive swine,poultry and cattle manure about 73%,74%and 79%of total P,respectively,was bioavailable(i.e.,P extracted by H2O and NaHCO3)and 78%in extensive cattle manure.The results indicated the relative environmental risk,from high to low,of swine,poultry and cattle manure.There is considerable regional variation in animal manure P across China,which needs to be considered when developing manure management strategies.
文摘In this paper, a robust fractional order fuzzy P + fuzzy I + fuzzy D (FOFP + FOFI + FOFD) controller is presented for a nonlinear and uncertain 2-1ink planar rigid manipulator. It is a nonlinear fuzzy controller with variable gains that makes it self- adjustable or adaptive in nature. The fractional order operators further make it more robust by providing additional degrees of freedom to the design engineer. The integer order counterpart, fuzzy P + fuzzy I + fuzzy D (FP + FI + FD) controller, for a comparative study, was realized by taking the integer value for the fractional order operators in FOFP + FOFI + FOFD controller. The performances of both the fuzzy controllers are evaluated for reference trajectory tracking and disturbance rejection with and without model uncertainty and measurement noise. Genetic algorithm was used to optimize the parameters of controller under study for minimum integral of absolute error. Simulation results demonstrated that FOFP + FOFI + FOFD controller show much better performance as compared to its counterpart FP + FI + FD controller in servo as well as the regulatory problem and in model uncertainty and noisy environment FOFP + FOFI + FOFD controller demonstrated more robust behavior as compared to the FP + FI + FD controller. For the developed controller bounded-input and bounded-output stability conditions are also developed using Small Gain Theorem.