Effects of phosphorus fertilizer application rate on transformation processes of phosphorus fractions in the purple alluvial soil of a riparian zone

Effects of phosphorus(P)fertilizer application rate on soil transformation processes of P fraction are still unclear in the riparian zone.Purple alluvial soils in the riparian zone of the Three Gorges Reservoir were collected to conduct a 21-day incubation executed by two hydrological environments(drying and flooding)and ten application rates of P fertilizer.Transformation percentages of P fertilizer(TPPF)were calculated as content differences of soil P fractions between fertilizer addition and none fertilizer addition divided by soil total P increases caused by fertilizer addition.TPPF to inorganic P extracted by sodium hydroxide(NaOH-Pi)and hydrochloric acid(HCl-Pi)increase by 20.91%(9.71%)and 24.26%(40.72%)under the drying(flooding)environment.Instead,TPPF to the other fractions decrease.Phosphorus fertilizer input mainly has indirect positive and negative effects on organic P via precipitated P under the drying and flooding environments and finally has indirect positive effects on labile P(p<0.001).Percentage changes of water-soluble inorganic P(H2O-Pi)and HCl-Pi under the flooding environment are higher than that under the drying environment,and percentage changes of organic P extracted by sodium hydrogen carbonate(Na HCO3-Po)and NaOH-Pi show an opposite trend(p<0.01).?(differences in soil P fraction content between flooding and drying incubations)H2O-Pi is negatively correlated with?NaHCO3-Po,and?NaHCO3-Po is positively correlated with?NaOH-Pi(p<0.001).In conclusion,P fertilizer is transformed more into precipitated P than into other P fractions with an application rate increase.Phosphorus fertilizer input mainly increases organic P via precipitated P under the drying environment and decreases organic P via precipitated P under the flooding environment,and organic P is further transformed into labile P.With P fertilizer input,P release caused by flooding is derived from NaHCO3-Po release triggered by NaOH-Pi release.The results can be helpful for the understanding of P fertilizer migration processes from the riparian zone soil to the Three Gorges Reservoir under rain leaching and flooding.

Twice-split phosphorus application alleviates low-temperature impacts on wheat by improved spikelet development and setting

Extreme low-temperature incidents have become more frequent and severe as climate change intensifies.In HuangHuai-Hai wheat growing area of China,the late spring coldness occurring at the jointing-booting stage(the anther interval stage)has resulted in significant yield losses of winter wheat.This study attempts to develop an economical,feasible,and efficient cultivation technique for improving the low-temperature(LT)resistance of wheat by exploring the effects of twice-split phosphorus application(TSPA)on wheat antioxidant characteristics and carbon and nitrogen metabolism physiology under LT treatment at the anther interval stage using Yannong 19 as the experimental material.The treatments consisted of traditional phosphorus application and TSPA,followed by a-4℃ LT treatment and natural temperature(NT)control at the anther interval stage.Our analyses showed that,compared with the traditional application,the TSPA increased the net photosynthetic rate(P_(n)),stomatal conductance(Gs),and transpiration rate(T_(r))of leaves and reduced the intercellular carbon dioxide concentration(C_(i)).The activity of carbon and nitrogen metabolism enzymes in the young wheat spikes was also increased by the TSPA,which promoted the accumulation of soluble sugar(SS),sucrose(SUC),soluble protein(SP),and proline(Pro)in young wheat spike and reduced the toxicity of malondialdehyde(MDA).Due to the improved organic nutrition for reproductive development,the young wheat spikes exhibited enhanced LT resistance,which reduced the sterile spikelet number(SSN)per spike by 11.8%and increased the spikelet setting rate(SSR)and final yield by 6.0 and 8.4%,respectively,compared to the traditional application.The positive effects of split phosphorus application became more pronounced when the LT treatment was prolonged.

Research on Yield and Quality of Hybrid Rice under Efficient Application Amount of Phosphorus and Potassium

[Objective] Application of P and K was not reasonable in southwest rice producing area, with no effective method for guiding application of P and K. This study aimed to conduct experiments with the same N application and different P and K application in different ecological points, to explore a scientific and efficient management method of P and K nutrients and provide guidance for application of P and K in rice production. [Method] Hybrid rice Chuanxiang9838 was used as experimental material to study the relationship among application amount of P and K, utilization rates of P and K, rice yield and rice quality in seven ecological points of four provinces （municipalities） including Sichuan, Chongqing, Yunnan and Guizhou. The application amount per hectare of P was 37.5, 75, 112.5 and 150 kg, respectively; the application amount per hectare of K was 45, 135 and 180 kg, respectively. A total of 10 treatments were set for split-plot design with three replications. [Result] Yield of Chuanxiang9838 significantly varied in different experimental locations and under different levels of P and K, interaction of ecological point and different P and K treatments varied significantly. Yield had reached the maximum in ecological point of Yunnan Binchuan and in treatment with application of N 150 kg P 75 kg K 90 kg. Efficient utilization rates of P and K varied in each ecological point, efficient application amount of P and K in Sichuan Dongpo, Sichuan Luxian, Guizhou Xiaohe and Chongqing Yongchuan was the same, while that in Sichuan Guanghan, Sichuan Zhongjiang and Yunnan Binchuan was different. The main objective of high-yield rice production was to increase the number of effective panicles per hectare and seed setting rate. Rice quality was clustered into 2 categories by locations and 6 categories by treatments. [Conclusion] Prediction models of efficient application of P and K in rice production were established, which provided guidance for high-yield rice production and rational and efficient utilization of P and K in southwest rice area.

Study on Absorption Law of Nitrogen,Phosphorus and Potassium and Proper Nitrogen Application in Chuanxiangyou 9838 under No-tillage Cultivation

The aim of the study is to investigate the absorption laws of nitrogen, phosphorus, and potassium, and proper nitrogen application in Chuanxiangyou 9838 under no-tillage cultivation. Five nitrogen application treatments were designed to analyze the absorption laws of N, P and K, and to discuss the effects of different N fertilizer application amounts on yield and yield composition factors of Chuanxiangyou 9838. The results showed that gross nutrient absorption in Chuanxiangyou 9838 was greatly varied at different developmental stages under rice-rape rotation with no-tillage. The maximum N absorption in Chuanxiangyou 9838 appeared at jointing stage followed by heading stage, thirdly the tillefing stage ; the P absorption in Chuanxiangyou 9838 presented the consecutively slight increase during seedling stage and mature stage ; the K absorption in Chuanxiangyou 9838 was mainly conducted from jointing stage to heading stage, during which K absorption accounts for 73.4% of the total absorption in whole developmental stage. Consequently, N fertilizer should be applied earlier （ before jointing stage）, P fertilizer is suitable as base fertilizer and application of K fertilizer should be preferably conducted at early-middle period. When the yield reached 11 t/hm^2, the optimal N application amount in Chuanxiangyou 9838 was about 165 kg/hm^2.

Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.

Effects of Phosphorus Application in Different Soil Layers on Root Growth, Yield, and Water-Use Efficiency of Winter Wheat Grown Under Semi-Arid Conditions

Deep phosphorus application can be a usefull measure to improve crops＇ performance in semi-arid regions, but more knowledge of both its general effects and effects on specific crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus（P） application at different soil layers on root growth, grain yield, and water-use efficiency（WUE） of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars： one drought-sensitive（Xiaoyan 22, XY22） and one drought-tolerant（Changhan 58, CH58）. The four P treatments were no P（control, CK）, surface P（SP）, deep P（DP）, and deep-band P application（DBP）. CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments（DP and DBP） than under SP, clearly showing that deep P placement had beneficial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight（RW） and root length（RL） in deep soil layer（30-100 cm） were closely positively correlated with grain yield and WUE of CH58（but not XY22）, highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars（r=0.94, P〈0.001）. In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.

Yield performance and optimal nitrogen and phosphorus application rates in wheat and faba bean intercropping

Yield performance in cereal and legume intercropping is related to nutrient management,however,the yield response of companion crops to nitrogen(N)input is inconclusive and only limited efforts have focused on rationed phosphorous(P)fertilization.In this study,two multi-year field experiments were implemented from 2014-2019 under identical conditions.Two factors in a randomized complete block design were adopted in both experiments.In field experiment 1,the two factors included three planting patterns(mono-cropped wheat(MW),mono-cropped faba bean(MF),and wheat and faba bean intercropping(W//F))and four N application rates(N0,0 kg N ha^(-1);N1,90 and 45 kg N ha^(-1) for wheat and faba beans,respectively;N2,180 and 90 kg N ha^(-1) for wheat and faba beans,respectively;and N3,270 and 135 kg N ha^(-1) for wheat and faba beans,respectively).In field experiment 2,the two factors included three P application rates(P0,0 kg P_(2)O_(5) ha^(-1);P1,45 kg P_(2)O_(5) ha^(-1);and P2,90 kg P_(2)O_(5) ha^(-1))and the same three planting patterns(MW,MF,and W//F).The yield performances of inter-and mono-cropped wheat and faba beans under different N and P application rates were analyzed and the optimal N and P rates for intercropped wheat(IW)and MW were estimated.The results revealed that intercropping favored wheat yield and was adverse to faba bean yield.Wheat yield increased by 18-26%,but faba bean yield decreased by 5-21% in W//F compared to MW and MF,respectively.The stimulated IW yield drove the yield advantage in W//F with an average land equivalent ratio(LER)of 1.12.N and P fertilization benefited IW yield,but reduced intercropped faba bean(IF)yield.Nevertheless,the partial LER of wheat(pLER_(wheat))decreased with increasing N application rates,and the partial LER of faba bean(pLER_(faba bean))decreased with increasing P application rates.Thus,LER decreased as N input increased and tended to decline as P rates increased.IW maintained a similar yield as MW,even under reduced 40-50% N fertilizer and 30-40% P fertilizer conditions.The estimated optimum N application rates for IW and MW were 150 and 168 kg ha^(-1),respectively,and 63 and 62 kg ha^(-1) for P_(2)O_(5),respectively.In conclusion,W//F exhibited yield advantages due to stimulated IW yield,but the intercropping yield benefit decreased as N and P inputs increased.Thus,it was concluded that modulated N and P rates could maximize the economic and ecological functions of intercropping.Based on the results,rates of 150 kg N ha^(-1) and 60 kg P_(2)O_(5) ha^(-1) are recommended for IW production in southwestern China and places with similar conditions.

Assessment of Long-Term Compost Application on Physical, Chemical, and Biological Properties, as Well as Fertility, of Soil in a Field Subjected to Double Cropping

The aim of this article was to assess the influence of long-term application of compost on the physical, chemical, and biological properties, as well as the fertility, of soil in a field subjected to double cropping (paddy rice and barley), mainly by integrating previous studies of the effects of compost and manure on soil qualities. Continuous compost application, especially at a high level (30 Mg·ha-1·y-1), into the double cropping soils increased the activities of organic C-, N-, and P-decomposing enzymes and the contents of organic C, total N, and microbial biomass N, as well as the cation exchange capacity, thereby contributing to the enhancement of soil fertility. Also, the compost application increased the degree of water-stable soil macroaggregation (>0.25 mm), which was correlated significantly (r > 0.950, p < 0.05) with the contents of hydrolyzable carbohydrates (with negative charge) and active Al (with positive charge), and resulted in the modification of soil physical properties. Furthermore, the application increased the amount of soil organic matter, including humic acid with a low degree of darkening and fulvic acid, and contributed to C sequestration and storage. Physical fractionation of soil indicated that about 60% of soil organic C was distributed in the silt-sized (2 - 20 μm) aggregate and clay-sized (<2 μm) aggregate fractions, while about 30% existed in the decayed plant fractions (53 - 2000 μm). The results obtained unambiguously indicate that long-term application of compost can improve soil qualities in the field subjected to double cropping, depending on the amount applied.

Heavy metal chemistry in soils received long-term application of organic wastes

This study was carried out to understand the long-term effect of organic waste treatment on the fate of heavy metals originated from the organic wastes, together with examination of changes in soil properties. For this, the soils received three different organic wastes (municipal sewage sludge, alcohol fermentation processing sludge, pig manure compost) in three different rates (12.5, 25, 50 ton/ha/yr) for 7 years (1994 - 2000) were used. To see the long-term effect, plant growth study and soil examination were conducted twice in 2000 and 2010, respectively. There was no additional treatment of organic wastes for post ten years after ceasing organic waste treatment for seven years. Soil examination conducted in 2010 showed decreases in soil pH, EC, total nitrogen, organic matter, available phosphorus, exchangeable cations and heavy metal contents in all soils received organic wastes compared to the results obtained in 2000. Speciation of heavy metals in soil through sequential extraction showed that organically bound Cu was the dominant species in all treatment and exchangeable Cu was increased in the plots treated with municipal sewage sludge and alcohol fermentation processing sludge. organically bound Ni increased from 25% - 30% to 32% - 45% in 2010 inall treatment while Pb showed increase in carbonate form in all treatments. Zn existed mainly as sulfide and residual forms, showing increases in organically bound form in all treatment during post ten years.

Study on the Application of Gibberellin for the Spectrophotometric Determination of Arsenic,Phosphorus,Silicon and Germanium

In the media of 0.66,0.96, 2. 16 and 0.54 mol/L ofH2SO4,the heteropoly acids of As,P.Si and Ge are separately reduced to corresponding heteropoly blues by gibberellin, which exhibit maxirnum absorptions at 835, 820, 810 and 805 nm with molar absorptivities of 2.64x104, 2.54x104 3.51x104 and 2.25x104 L.mol-1'cm-1 and linear ranges of 0-30,0-15,0-10 and 0-30 μg/25mL, The method was applied to the determinations of As, P and Si in alloyed steel.

On the long-term joint distribution of characteristic wave height and period and its application

By analysing the scatter diagrams of characteristic the wave height H and the period T on the basis of instrumental data from various ocean wave stations, we found that the conditional expectation and standard deviation of wave period for a given wave height can be better predicted by using the equations of normal linear regression rather than by those based on the log- normal law. The latter was implied in Ochi' s bivariate log-normal model(Ochi. 1978) for the long-term joint distribution of H and T. With the expectation and standard deviation predicted by the normal linear regression equations and applying proper types of distribution, we have obtained the conditional distribution of T for given H. Then combining this conditional P(T / H) with long-term marginal distribution of the wave height P(H) we establish a new parameterized model for the long-term joint distribution P(H,T). As an example of the application of the new model we give a method for estimating wave period associated with an extreme wave height.

Impact of Long-Term Fertilization on Phosphorus Status in Black Soil

A twelve-year field trial was carried out to determine the impact of long-term fertilization on phosphorus (P) distribu- tion in the soil profile, P balance, and the transformation and availability of soil P in a black soil (Phaeozem, FAO). Under a wheat-soybean-corn rotation, during twelve years where no fertilizer was applied, crops removed 60 and 81 mg P kg-1 soil in the control and NK treatment, respectively. About one third of the P absorbed by crops was originated from organic P. Ca2-P, Cag-P, Al-P and Fe-P were the main forms of inorganic P absorbed by crops. The surplus P from fertilization remained in the 0-20 cm soil layer and increased with the application rate of P. The combined application of NP or NPK increased available P to a lesser extent than the combined application of PK. Fertilizer P had mainly transformed to the Al-P, Fe-P, Ca2-P, and Cas-P forms. By using the P budget (X), changes in total P (Y1) and available P (Y2) in soils under the current cropping system could be predicted by the equations: Y1 = 0.02 + 1.01X and Y2 = 2.08 + 0.15X.

Effects of 42-year long-term fertilizer management on soil phosphorus availability, fractionation,adsorption–desorption isotherm and plant uptake in flooded tropical rice

Soil phosphorus(P) fractionation, adsorption, and desorption isotherm, and rice yield and P uptake were investigated in flooded tropical rice(Oryza sativa L.) following 42-year fertilizer and manure application. The treatments included low-input [unfertilized control without N, P, or K(C0N0)], farmyard manure(FYM)(C1N0), NP(C0NP), NPK(C0NPK), FYM + NP(C1NP), and high-input treatment, FYM + NPK(C1NPK). Grain yield was increased significantly by 74%over the control under the combined application of FYM + NPK. However, under low- and high-input treatments, yield as well as P uptake was maintained at constant levels for 35 years.During the same period, high yield levels and P uptake were maintained under the C0 NP, C0 NPK,and C1 NPK treatments. These are unique characteristics of a tropical flooded ecosystem, which is a self-sustaining system for rice production. The Fe–P fraction was highest compared to the Ca–P and Al–P fractions after 42 years of fertilizer application and was significantly higher under FYM + NPK treatment. The P adsorption capacity of soil was highest under the low-input treatment and lowest under long-term balanced fertilization(FYM + NPK). In contrast, P desorption capacity was highest under NPK and lowest in the control treatment. Long-term balanced fertilization in the form of FYM + NPK for 42 years lowered the bonding energy and adsorption capacity for P in soil but increased its desorption potential, increasing P availability to the plant and leading to higher P uptake and yield maintenance.

Effect of long-term fertilization on phosphorus fractions in different soil layers and their quantitative relationships with soil properties

Investigating the dynamics and distribution of soil phosphorus(P) fractions can provide a basis for enhancing P utilization by crops. Four treatments from a 29-year long-term experiment in black soil with maize cropping were involved in this study: no fertilizer(CK), inorganic nitrogen and potassium(NK), inorganic nitrogen, phosphorus, and potassium(NPK), and NPK plus manure(NPKM). We analyzed soil P fractions in different soil layers using a modified Hedley sequential method. The long-term NPKM treatment significantly increased total P by 0.6–1.6 times in the different soil layers. The Olsen-P concentration far exceeded the environmental threshold for soil Olsen-P(50.6 mg kg) in the NPKM treatment in the 0–60 cm soil profile. Moreover, the concentrations and proportion of labile and partially labile inorganic P(Pi) fractions(i.e., Na HCO-extracted Pi, Na OH-extracted Pi, and dilute HClextracted Pi) to the sum of all P fractions(Pt) in the 0–60 cm soil profile were higher in the NPKM treatment than in the NPK treatment, indicating that manure could promote the transformation of non-labile into more labile forms of P in soil, possibly by manure reducing P fixation by soil particles. Soil organic matter, Mehlich-3 extractable iron(Fe), and organic-bound aluminum were increased by fertilization, and were the main factors influencing the differences in the P fractions in the 0–20 cm soil layer. Soil mineral components, i.e., free Fe oxide and Ca CO, were the main factors influencing the P fractions in the subsoil. The soil P transformation process varied with soil layer and fertilization. Application of manure fertilizer can increase the labile(Olsen) P concentrations of the various soil layers, and thus should reduce the mineral P fertilizer requirement for crop growth and reduce potential environmental damage.

Interaction of soil microbial communities and phosphorus fractions under long-term fertilization in paddy soil

Understanding the impact of biological activities on the soil phosphorus(P)distribution under long-term fertilizer application can facilitate better soil P fertility management.Therefore,the primary objectives of this study were to investigate the effect of long-term(since 1981)fertilizer application on the soil P fractions and microbial community and to evaluate correlations between the microbial community structure and P distribution.The following treatments were implemented in a long-term field trial:no fertilization(CK),inorganic N and K(NK),inorganic P and K(PK),inorganic N,P and K(NPK)and manure+NPK(MNPK)fertilization.The study showed that the soil pH,soil organic carbon and total and available N and P concentrations were considerably higher in the MNPK treatment than in the CK treatment.The soil microbial biomass C,N and P concentrations were also significantly higher in the MNPK treatment than in the CK treatment.Among fertilization treatments,theβ-1,4-glucosidase,α-1,4-glucosidase,urease,acid phosphatase and phosphodiesterase activities were the highest in the MNPK treatment.Compared to inorganic fertilization,the MNPK treatment increased the labile soil P fractions and decreased the residual soil P concentration.Continuous fertilization significantly affected the soil microbial composition.The total phospholipid fatty acid(PLFA)concentrations in the NK,PK,NPK and MNPK treatments were 23.3,43.1,48.7 and 87.7%higher,respectively,than in the CK treatment.A significant correlation was observed between the microbial community and soil P fractions.Moreover,the aggregated boosted tree(ABT)model showed that among the various soil biochemical properties,the total PLFA concentration was the factor that most influenced the active P pool,accounting for 35.4%of the relative influence of all soil biochemical properties examined.These findings reveal that combined manure and inorganic fertilizer application is a better approach than applying inorganic fertilizer alone for sustaining long-term P fertility by mediating soil biological activity.

Effects of Long-term Fertilization on Phosphorus Accumulation and Migration in Purple Soil

Based on a long-term location test lasting for 20 years, the accumulation and migration of phosphorus in purple soil was studied. The results showed that P2Os input in paddy-upland rotation was 120.0 kg/（ hm2 · a） （a conventional level of phosphorus application）, and P had a surplus of 53.9 kg/（hm2 · a）. Phosphorus accumulating in soil increased available phosphorus （Olsen-P） content, and the positive correlation between P changing balance and Olsen-P change in wheat-rice rotation was extremely significant. The mixed application of organic fertilizer and chemical P fertilizer can speed up accumulation of available phosphorus in soil. Olsen-P content in all treatments with P fertilizer was higher in 0 -60 cm soil than that of treatments without P fertilizer, and Phosphorus applied in surface soil moved to soil at a depth of 60 cm, increasing risk of P leakage and loss. The migration of phosphorus in soil is affected by P input, type of organic fertilizer and planting method. The quantities of phosphorus moving down increased with the increase of P input, and the application of pig manure can lead to migration of phosphorus in soil more easily compared with straw. The migration of phosphorus from soil to water mainly occurred in the first ten days after rice was transplanted, and paddy field drainage should not be conducted in the first 30 days after rice was transplanted.

Effects of Long-term Located Fertilization on Evolution of Available Phosphorus and Phosphorus Pool in Shandong Fluvo-aquic Soil

This study was conducted to investigate the effects of long-term located fertilization on soil phosphorus,the changes of soil available phosphorus(OlsenP),the evolution of soil total phosphorus(TP)and the ratio change of Olsen-P to TP(PAC)by 33-year fertilization experiments in winter wheat-summer maize rotation system in Shandong fluvo-aquic soil.Eight treatments were designed as no fertilization(CK),nitrogen fertilizer(N),nitrogen and phosphate fertilizer(NP),nitrogen and potassium fertilizer(NK),phosphate and potassium fertilizer(PK),nitrogen-phosphate-potassium fertilizer(NPK),reduced NPK fertilizer(N(15)PK),and increased NPK fertilizer(N_(25)PK).Meanwhile,eight organic fertilizer-added treatments were designed based on the application of inorganic fertilizer the same as the above ones.The results showed that TP,Olsen-P and PAC of treatments added with organic fertilizer were higher than those without organic fertilizer,and those of the treatments applied with phosphate fertilizer were higher than those of no phosphate fertilizer.With the increase of years,soil P pool decreased due to crop absorption,nutrient loss and morphological transformation and other causes under the treatments of without and only phosphate fertilizer,while remained stable under the treatments added with organic fertilizer.The PAC values were generally lower in fluvo-aquic soil,and it could be improved by the application of organic fertilizer.On the whole,the application of chemical phosphate fertilizer combined with organic fertilizer could improve the phosphorus content in soil and ensure the supply of phosphorus nutrition.This study would provide scientific basis for fertilization management and soil fertility in fluvo-aquic soil.

Identifying the critical phosphorus balance for optimizing phosphorus input and regulating soil phosphorus effectiveness in a typical winter wheat-summer maize rotation system in North China

Phosphorus(P)is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield.Excessive P fertilizer application is widespread in agricultural production,which not only wastes phosphate resources but also causes P accumulation and groundwater pollution.Here,we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency(PUE).A 12-year field experiment with P fertilization rates of 0,45,90,135,180,and 225 kg P_(2)O_(5)ha^(-1)was conducted to determine the crop yield,PUE,and soil Olsen-P value response to P balance,and to optimize the P input.Annual yield stagnation occurred when the P fertilizer application exceeded a certain level,and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P_(2)O_(5)ha^(-1).A critical P balance range of 2.15-4.45 kg P ha^(-1)was recommended to achieve optimum yield with minimal environmental risk.The critical P input range estimated from the P balance was 95.7-101 kg P_(2)O_(5)ha^(-1),which improved relative yield(>90%)and PUE(90.0-94.9%).In addition,the P input-output balance helps in assessing future changes in Olsen-P values,which increased by 4.07 mg kg^(-1)of P for every 100 kg of P surplus.Overall,the P balance can be used as a critical indicator for P management in agriculture,providing a robust reference for limiting P excess and developing a more productive,efficient and environmentally friendly P fertilizer management strategy.

Long-Term Animal Feeding Trial of the Refined Konjac Meal Ⅰ. Effects of the Refined Konjac Meal on the Calcium and Phosphorus Metabolism and the Bone in Rat

Effects of refined konjac meal (RKM) on the calcium and phosphorus metabolism and bone parameters were observed in rats of both sexes fed with food containing 1% of RKM for 18 months. A comparable group of rats fed on basic diet only was used as a control.Results obtained indicate that all the measured parameters (serum calcium and phosphorus level, femur weight and its calcium and phesphorus content, and the osteometry of the tibia) showed no significant difference between the experimental and the control groups.Thus there is no adverse effect either on the calcium and phosphorus metabolism or on the bone after a long-term intake at a moderate dosage.

Growth,yield,yield components,and grain qualities of groundnut(Arachis hypogaea L.)as affected by liming and phosphorus rates in southwest Ethiopia

Two field experiments were conducted in the main seasons of 2021/22 at the farmers'farm in two districts of southwest Ethiopia to investigate the effects of lime and phosphorus on groundnut yield and yield components,employing four levels of lime(0,2,4,and 6 t CaCO_(3)ha^(-1))and phosphorus(0,46,69,and 92 kg P_(2)O_(5)ha^(-1))arranged in factorial RCBD design with three replications.Data on the yield and its components were collected and subjected to an ANOVA using SAS software.The result demonstrated that plant height,number of branches,canopy spread,and shelling percentage were affected significantly by liming while effective nodule number,total peg,matured pod,and pod yield of groundnut significantly influenced by the main factors and their interactions.The combined application of 4 t lime and 46 kg P_(2)O_(5)ha^(-1)resulted in the highest number of effective nodules(147.23 plant^(-1)),total pod(72.6 plant^(-1)),mature pod(62.4 plant^(-1)),pod yield(4.49 t ha^(-1)),oil content(50.6%)and protein content(33.1%)whereas the lowest values of these parameters were seen in plots where neither lime nor phosphorus was applied.Therefore,it is advised that groundnut growers in the study areas,and similar agroecologies,apply the combination of 4 t lime and 46 kg P_(2)O_(5)ha^(-1).