江苏省主要土壤的磷肥指数及适宜磷肥用量

以江苏省五种典型类型土壤为供试土壤,系统研究了不同类型土壤稻季的磷肥指数和磷临界值。研究结果表明,不同土壤类型的磷肥指数和磷临界值存在着较大的差异,其中磷肥指数表现为灰沙土>黄泥土>粉砂土>淤土>砂黄泥土,而磷临界值表现为淤土>黄泥土>砂黄泥土>灰沙土>粉砂土。并结合当地的特点,推荐了当地的适宜磷肥施用量。     

Short‐term effects of application of different rates of inorganic P and residue P on soil P pools and wheat growth

Phosphorus (P) can be added to soil as inorganic P or crop‐residue P, but little is known about how these two forms of P addition affect soil P pools and how their effect changes with the rate of P addition. A glasshouse experiment was conducted to assess the effect of inorganic P and P added as residues at different rates on (1) soil P pools at two time points: immediately after amendment and 42 d later, and (2) growth and P uptake by wheat at flowering (day 42). Three types of legume residues (faba bean young shoot, chickpea mature shoots with pods, and white lupin mature shoots without pods) were added to a loamy‐sand soil at a rate of 5 or 15 g residue kg^–1. Inorganic P was added at four different rates (3, 10, 30, and 100 mg P kg^–1) to give P‐addition rates corresponding to the total P added with the different residues at the two residue rates. Soil P pool concentrations (microbial P, resin‐P, NaHCO₃‐P, NaOH‐P, HCl‐P, and residual P) and wheat growth and P uptake (shoot and root) were measured after 6 weeks. Compared to inorganic P addition, P added with residues led to a 10%–80% greater increase in shoot biomass at the two highest P‐addition rates. Wheat P uptake was positively correlated with resin‐P and microbial‐P concentrations in residue‐P‐amended soil, but with resin‐P and NaOH‐P_i concentrations in soil amended with inorganic P. The concentration of HCl‐P decreased by up to 30% from day 0 to day 42 in the residue treatments and that of residual P decreased by about 20% in all treatments during this period suggesting that these nonlabile P pools are quite dynamic and could serve as P source for plants.     

Determining the optimum range of soil Olsen P for high P use efficiency, crop yield, and soil fertility in three typical cropland soils

Soil Olsen P level has a major influence on crop yield, efficient P utilization, and soil fertility. In this study, the optimum Olsen P range was determined from long-term (1990-2012) field experiments in three typical soil types of China under single cropping of maize or double cropping of maize and wheat. The critical soil Olsen P value for crop yield was evaluated using three different models, and the relationships among P use efficiency (PUE), Olsen P, and total P were analyzed. The agronomic critical soil Olsen P values obtained from the three models for the neutral soil of Gongzhuling and the calcareous soil of Zhengzhou were similar; however, the values from the linear-linear and linear-plateau models for both maize and wheat were substantially lower than those from the Mitscherlich model for the acidic soil of Qiyang. The PUE response change rates (linear equation slopes) under different soil Olsen P levels were small, indicating slight or no changes in the PUE as the soil Olsen P increased in all three soils. A comparison of the Olsen P levels that achieved the maximal PUE with the agronomic critical values derived from the three models indicated that the linear-plateau model exhibited the best performance. The regression equation coefficients of Olsen P response to total P decreased as follows:Zhengzhou (73 mg g^-1) > Qiyang (65 mg g^-1) > Gongzhuling (55 mg g^-1). The Olsen P level increased as the total P increased, which may result in a decrease in PUE. To achieve a relatively high crop yield, PUE, and soil fertility, the optimum Olsen P range should be 13-40, 10-40, and 29-40 mg kg^-1 at Gongzhuling, Zhengzhou, and Qiyang, respectively.     

Soil P fractions in a volcanic soil chronosequence of Central Mexico and their relationship to foliar P in pine trees

Phosphorus (P) is a major plant nutrient, however, its availability in volcanic ash soils is presumed to be small, due to its specific sorption on short‐range order minerals. We analyzed distinct P fractions in volcanic ash soils of different age (60 to > 100,000 y BP) under pine forests in Central Mexico to investigate their changes along a chronosequence of Regosols, Andosols, and Lixisols, and to evaluate if P availability limits tree growth at any particular stage. Top soil and subsoil samples were first analyzed by the Tiessen and Moir method, which failed to extract exhaustively “organic” and “occluded P”, and “P associated with apatite”. Therefore, we modified the fractionation scheme by including a “recalcitrant organic P” fraction obtained from the difference between P determined in air‐dried subsamples and subsamples burned at 300°C; P adsorbed to short‐range order minerals was assessed in an extraction with NH₄‐oxalate, and P in primary minerals by subtracting the sum of all other fractions from total P contents determined by XRF. This we did after discovering that primary P occurred in the form of fluorapatite included in plagioclase, volcanic glass or olivine. We also measured P contents in pine needles and related these with the “mobile soil P” fractions. The results show that “organic P” reaches maximum contents in 10,000‐y old soil, as does P associated with short‐range order minerals, while P occluded into crystalline oxides increases constantly over time. After 100,000 y, 31% of total P still remains in the form of primary P in A horizons. “Mobile P” was constant > 40 mg kg^?1 in Regosols and Andosols and related positively with foliar P contents, which were within adequate nutritional ranges. Only in Lixisols small “mobile P” concentrations in soil correspond with inadequate P contents in pine needles.     

Rice-residue biochar influences phosphorus availability in soil with contrasting P status

ABSTRACT

Thermo-chemical conversion of crop residues to produce biochar is an emerging strategy in the context of sustainable phosphorous (P) use and residue management. An incubation study for 90 d was conducted to investigate the effects of rice-residue biochar (0, 10, 20 and 40 g kg^?1) in combination with inorganic-P (KH₂PO₄) (0, 25 and 50 mg kg^?1) on phosphorous availability in medium- and high-P status soils. Increasing biochar addition rates alone or in combination with inorganic-P resulted in a significant increase in P pools, i.e. plant available P or Olsen-P (from 8 to 132 mg kg^?1 in medium-P and 15 to 160 mg kg^?1 in high-P soils), microbial biomass P and various mineral-bound inorganic-P fractions in the order (Ca-P > organic-P > Al-P > loosely held/soluble-P > Fe-P > reductant soluble-P). Further, lower phosphatase activity (19–50%) with increasing rates of biochar addition in both soils elucidates the ability of biochar to act as a long-term source of available P in the experimental soils. The results demonstrate that rice-residue biochar can directly or indirectly enhance the status of available P in soils and hence can be used as a beneficial amendment to meet the crop P demand.     

Variation of soil P and other nutrients in a long-term grazed grassland P experiment field

Field-scale variation of soil phosphorus (P) information is very important for P fertilizer application and its soil sampling design in grassland. A total of 108 soil samples were collected from a long-term (41 years) grazed grassland P experiment field at Teagasc, Johnstown Castle, Wexford, Ireland, in March 2009. There were six P treatments (P0-0, P0-30, P15-15, P15-5, P30-30, and P30-0) since 1968, with changes since 1999. Each treatment had 6 replicate plots (a total of 36 plots, 3 soil samples per plot). The samples were analyzed for available (Morgan’s) P, potassium (K), magnesium (Mg), lime requirement (LR), and pH. The highest mean available P concentration was found in the P30-30 (30 kg P ha^?1 pre- and post-1998) plots, and the lowest mean available P concentration was found in the P0-0 (no P fertilizer since 1968) plots. Significant differences of mean P, Mg, LR, and pH values in different treatments were observed. There was a positive proportional effect for both the 36 plots and the 6 treatments for the P data: the local standard deviation increased with the increase of local mean. The proportional effect should be considered in order to optimize sampling design. Fewer samples can reflect soil P status in fields with low soil P levels, while more attention should be paid to the fields with high P levels in order to reduce environmental consequences of uniform applications.     

水肥一体化施磷对滴灌玉米磷素、磷素营养及磷肥利用效率的影响

【目的】在新疆大规模的节水滴灌农业生产中,根据作物不同生育阶段对磷素营养吸收特性,按比例通过水肥一体化以水施磷是满足作物磷素营养需求、减少磷的固定及提高磷肥利用效率的有效途径。【方法】本文在田间条件下设置不施磷 (CK)、固体磷酸二铵60%基施+40%追施(T1)、液体磷酸60%基施+40%追施(T2)、液体磷酸全部追施(T3)处理,研究了不同磷肥及施肥方式对滴灌玉米磷素吸收、产量及磷肥利用率的影响。【结果】液体磷酸全部追施处理可显著提高玉米的生物量、穗粒数和千粒重 (P0.05),玉米产量达20622 kg/hm2,其产量比CK、磷酸二铵60%基施+40%追施和液体磷酸60%基施+40%追施处理分别提高了37%、25%、10%;在抽雄期和成熟期不施磷对照、T1、T2、T3处理的玉米吸磷量分别为14.0、22.7、21.0、18.3 kg/hm2 和 68.4、77.8、87.2、91.9 kg/hm2,在成熟期全部追肥处理植株的吸磷量显著高于其他处理,说明磷肥随水追施可显著改善玉米磷素营养(P0.05);T1、T2、T3处理磷肥利用率（REP）和农学效率（AEP）分别为16.6%、32.6%、40.6% 和 7.9 kg/kg、22.7 kg/kg、40.6 kg/kg,T3处理的REP和AEP分别比其它处理提高了8个百分点~24个百分点和17.9~32.7 kg/kg,液体磷酸全追可显著提高磷肥利用效率 (P0.05)。【结论】液体磷肥100%以追肥的方式随水滴施可显著改善玉米生育中后期的磷素营养并提高产量。提高石灰性土壤玉米对磷肥的吸收利用效率,磷肥利用率可达40.6%。     

Assessing soil P fractions changes with long-term phosphorus fertilization related to crop yield of soybean and maize

Long-term P Fertiliser application increases soil phosphorus (P) labile fractions, which can be associated with crop P uptake and grain yield and are useful to improve fertilizer recommendations. Research aims were to evaluate in long-term experiments with different P Fertiliser application in a Mollisol and a Vertisol: (a) the changes of soil P fractions and (b) the relationship between soil P fractions with long-term P Fertiliser application, with accumulated apparent P budget, grain P, total P uptake, soybean (Glycine max L.Merr.) and maize (Zea mays L.) grain yield. Soil P fractions were measured after 1 and 9 year since the beginning of the long-term experiments. Experiments included an initial Fertiliser application rate of 200 kg P ha⁻¹ and annual P Fertiliser application rate of 36 kg P ha⁻¹. Bray1-P, total, organic, and inorganic P in fine (<53 μm) and coarse (>53 μm) (CF) soil fractions, and in NaHCO₃ extract were measured. Initial P Fertiliser application increased inorganic and total P fractions. However, Bray1-P, total P in NaHCO₃ extract and in the CF were the fractions that most increased with continuous long-term P Fertiliser application in both sites. In the Mollisol, maize grain yield was unrelated to long-term P Fertiliser application. In the Vertisol, total P in NaHCO₃ extract, and total and organic P in the CF were more closely related to soybean grain yield than Bray1-P. We proposed soil P indices of labile inorganic and organic P that showed close relationships with soybean grain yield and may be useful to improve the diagnosis of P soil fertility.     

Effect of P fertilizer reduction regime on soil Olsen-P, root Fe-plaque P, and rice P uptake in rice-wheat rotation paddy fields

In agricultural systems, it is vital to use limited yet optimal phosphorus(P) resources, because excessive P fertilizer application leads to the accumulation of P in soil, increasing the risk of environmental pollution and causing the waste and exhaustion of P resources. In a rice-wheat rotation system, omitting P fertilizer application in the rice-growing season is a good alternative;however, how this P fertilization reduction influences changes in P in the soil-root-aboveground system is unclear. In this study, after a seven-year rice-wheat rotation at the Yixing(YX) and Changshu(CS) sampling sites, China, compared with P fertilization in rice-and wheat-growing seasons(PR+W), reduced P fertilization(no P fertilizer application in either season, P0;P fertilization only in wheat-growing seasons, PW;and P fertilization only in rice-growing seasons, PR) did not result in substantial variation in crop biomass. The PW treatment did not reduce crop total P, root iron(Fe)-plaque P, and soil Olsen-P at three stages of rice growth(seedling, booting, and harvesting stages) at the YX and CS sites. In contrast, concentrations of soil Olsen-P, aboveground crop total P, and root Fe-plaque P decreased in the P0 treatment by 45.8%–81.0%,24.6%–30.9%, and 45.6%–73.4%, respectively. In addition, a significant negative correlation was observed between the root Fe-plaque P and crop biomass at the two sites. Significant positive correlations were also observed between root Fe-plaque P and root total P, crop total P, and soil Olsen-P. In addition, the results of a redundancy analysis revealed that soil alkaline phosphatase(ALP) played a major role in the supply of P in soil, and was closely associated with root Fe-plaque P. The results of this study will enhance the understanding of the changes in P in the soil-root-aboveground system, particularly under P fertilizer reduction regimes.     

Legacy phosphorus in calcareous soil under 33 years of P fertilizer application: Implications for efficient P management in agriculture

Phosphorus (P) fertilizers have long been applied in agriculture. However, the influence of long-term P addition on the evolution of soil P fertility and legacy P characteristics have not been well-documented. Herein, literature data were collected from the Chinese National Knowledge Infrastructure Database (CNKI) to explore the evolution of soil P fertility after 33 years of application of P fertilizer; different soil samples were collected from cropland and adjacent uncultivated land to analyse the distribution of P fractions at different soil depths (0–0.8 m) using Guppy's sequential P extraction method. We found that soil Olsen-P significantly increased by 3.6-fold (from 7.2 mg kg⁻¹ in 1981 to 25.9 mg kg⁻¹ in 2013) after 33 years of P application, while total P increased slightly. The ratios of inorganic P fractions in cropland to those uncultivated land followed NaHCO₃-P (1.47) > NaOH-P (1.38) > resin-P (1.37) > residue-P (1.17) > HCl-P (1.11), suggesting that long-term P addition contributed more to labile and moderately labile P rather than non-labile P. Moreover, a principal component analysis could distinguish between cropland and uncultivated land, indicating that long-term application of P fertilizer changed soil P characteristics. Compared to uncultivated land, soil NaHCO₃-P in cropland was closely associated with soil organic C, total nitrogen and carbonate. Collectively, our findings highlight that soil legacy P was notably increased after long-term of P application, and a large portion of the applied P remained in labile and moderately labile forms. Therefore, soil legacy P can be recommended as a useful P management tool.     

Effect of organic,inorganic, and combined organic and inorganic P fertilization on plant P uptake and soil P pools

Phosphorus (P) is a limited resource, and its efficient use is a main task in sustainable agriculture. In a 6‐year field experiment on a loamy‐sand soil poor in P, the effects of organic, inorganic, and combined organic‐inorganic fertilization on crop yield, P uptake into grain, and soil properties (organic matter [OM] content, pH, water‐extractable P [P_w], double lactate–extractable P [P_dl], oxalate‐extractable P [P_ox], P‐sorption capacity [PSC], and degree of P saturation [DPS]) were investigated for the maritime climate in northeast Germany. Nine treatments were compared: a control treatment without fertilizer application, two organic fertilizers (cattle manure [CM] and biowaste compost [BC]; applied at a rate of 30 t ha^–1 in autumn 1998 and 2001), application of triple‐superphosphate (TSP; applied once a year either in autumn or in spring to evaluate the effects of application date), and combinations of organic and inorganic fertilizations. Several winter and spring crops (oilseed rape, barley, wheat) were cultivated according to good agricultural practice. The 6 year–average yield and P uptake were significantly higher for fertilized plots than for nonfertilized plots. Although the combination of organic × inorganic fertilizers resulted in higher soil P contents, significant yield increases were only found when organic fertilization was combined with TSP in spring. Small effects of P supply on yield in some years indicate that plant‐available soil P (despite of low P_dl values) was sufficient for crop growth. Phosphorus supply affected soil P_dl and P_w more than the parameters measured in the oxalate extract (P_ox, PSC, DPS). In general, periodically applied cattle manure and biowaste compost had the same effect on yield, P uptake, and soil P status as annually applied soluble mineral P.     

Can P NMR spectroscopy be used to indicate the origins of soil organic phosphates?

The relationship between organic P status of 4 soils, 20 microorganisms isolated from these soils (2 bacteria and 3 fungi for each soil) and 13 dominant plant species of typical natural ecosystems of these soils was evaluated. The soils used were represented by two pairs with different ratios of monoester and diester P, and of DNA and other diester P. A Dystric Podzoluvisol and an alpine Umbric Leptosol were characterized by a relatively high proportion of diester P including much DNA P, while a Calcic Chernozem and subalpine Umbric Leptosol had lower proportion of diesters containing relatively less DNA P. The proportions of P compounds in bacteria and plants were very similar on average, based on the monoester to diester P ratio and on the proportions of different diesters in alkaline extract, whereas fungi contained considerably higher proportions of monoesters and polyphosphates, and a higher proportion of phospholipids in the diester fraction. The results showed that the P_org composition of NaOH extracts from different soils was more similar to the composition of extracts from different groups of microorganisms. There was no clear correspondence between soil and microbial diester P proportion and composition. A high proportion of polyphosphate P including pyrophosphate P in soil extracts indicates a significant contribution of fungal P compounds in the soil while the monoester to diester P ratio, and DNA to non-DNA P ratio should be used with caution to interpret the origins of soil P_org. The relative contributions of microorganisms and plants to monoester and diester P in soils is only partially understood.     

Availability of P from 32P-labelled endogenous soil P and 33P-labelled fertilizer in an alkaline soil producing cotton in Australia

Yield responses of irrigated, field‐grown cotton to phosphorus fertilizer application in Australia have been variable. In an attempt to understand better this variability, the distribution of fertilizer P within soil P fractions was identified using ³²P and ³³P radioisotopes. The soil chosen, an alkaline, grey, cracking clay (Vertosol), was representative of those used for growing cotton in Australia. Chang and Jackson fractionation of soil P from samples collected within 1 h of application indicated that 49, 7 and 13% of the P fertilizer was present as 0.5 m NH₄F, 0.1 m NaOH and 1 m H₂SO₄ extractable P, respectively. Over 89% of the P fertilizer was recovered as Colwell extractable P in these samples, suggesting that the majority of these reaction products was in a highly plant‐available form. Fertilizer‐P remained in an available form within the band 51 days after application, and 68% of the applied fertilizer‐P was recovered as Colwell‐P (1071 mg kg^?1). The Colwell‐P concentration in the band was 35 times that in the unfertilized soil. Thus, the variability in crop response to P fertilizer application in these soils is not a consequence of fertilizer‐P becoming unavailable to plants. These results confirm the suitability of the Colwell (1963) sodium bicarbonate extraction method for measuring available P in these soils.     

湖南省油菜施磷效应及土壤速效磷丰缺指标研究

为研究施磷对油菜的产量及经济效益的影响,并建立湖南省油菜种植体系土壤速效磷的丰缺指标,于2005～2008年在湖南省油菜主产区布置51个磷肥肥效田间试验.结果表明,油菜施磷具有明显的增产效应及增收效果.施磷较不施磷增产51～1265 kg/hm2,平均429 kg/hm2,平均增产率为45.9%,每千克P2O5增加5....     

不同磷浓度对土壤吸附锌特性的影响

通过等温吸附试验,研究了不同磷浓度条件下水、旱田两种土壤吸附锌的规律,结果表明:在本试验条件下,以Freundlich方程拟合土壤对锌的吸附等温线的效果最好;不同磷浓度条件下,同一土壤的吸附等温线方程参数k和n均没有显著的变化;不同磷浓度对土壤吸附锌的量没有显著影响。因此,磷锌拮抗的原因可能不是施磷加强了土壤对锌的吸附作用。     

小麦生长期间施肥后土壤微生物生物量C和P的变化

A pot experiment was carried out with a clay loam in a green house.The results showed that soil microbial biomass C increased with the application of organic manure at the beginning of the experiment and then gradually decreased with declining of the temperature .The soil biomass C increased at the tillering stage when the temperature gradually increased,and rose to the highest value at the anthesis stage,being about 554.9-794.4mg C kg^-1,The applicatio of organic manure resulted in the highest increase in biomass C among the fertiliztion treatments while that of ammonium sulphate gave the lowest At the harvest time the soil biomass C decreased to the presowing level. Like the soil biomass C the amount of biomass P was increased by the incorporation of organic manure and was the highest among the treatments,with the values of the check and ammonium sulphate treatments being the lowest ,Meanwhile,the changing patterns of the C/P ratio of soil microbial biomass at stages of wheat growth are also described.     

不同利用方式旱地红壤水稳性团聚体及其碳、氮、磷分布特征

针对江西红壤地区不同利用方式引起的土壤质量和肥力的相应变化,研究了不同肥力水平、不同利用方式下红壤旱地水稳性团聚体含量及其养分分布规律。研究表明,荒地土壤中>5 mm水稳性团聚体含量显著高于其他利用方式,花生地和果园土壤则以0.25～0.053 mm的水稳性团聚体为主。各肥力水平下,菜地土壤中除>5 mm水稳性团聚体外,各粒级团聚体中有机碳、全氮和全磷含量均显著高于花生地、果园和荒地土壤。说明菜地土壤长期大量施肥,导致土壤碳、氮、磷养分含量均相对丰富。不同利用方式旱地红壤中,有机碳、全氮主要分布在>5 mm、5～2 mm和2～1 mm的较大粒径水稳性团聚体中。说明随着团聚体粒径增大,其有机碳含量增加,土壤全氮的消长趋势和有机碳一致。土壤全磷较均匀地分布在水稳性团聚体中,如高肥力菜地和荒地土壤各粒级团聚体中全磷含量间均无显著性差异。各利用方式旱地红壤中2～1 mm和1～0.5 mm的水稳性团聚体含量与土壤有机碳、全氮和全磷含量间均达到了极显著正相关。     

Critical Olsen P and CaCl2‐P levels as related to soil properties: results from micropot experiments

The usefulness of soil phosphorus (P) tests used in routine soil analyses is limited by the fact that a single measurement cannot encompass all P‐related factors potentially affecting plant performance. In this work, we performed micropot (15 mL) experiments to test the hypothesis that the predictive value of two common soil P tests (Olsen P and CaCl₂‐P) can be improved by considering properties commonly measured in laboratory analyses. Forty‐nine sets of soils ranging widely in properties were used for this purpose, each set consisting of samples with similar properties but differing in P status. Ryegrass and turnip were grown in a chamber for 30 days in two separate experiments and their yields at harvest recorded. The critical Olsen P and CaCl₂‐P levels, which were taken to be those corresponding to 95% asymptotic yield as calculated from data fitted to a Mitscherlich equation, were greater for turnip than for ryegrass, probably as a result of the difference in yield (49 and 160 mg dry matter/micropot on average for ryegrass and turnip, respectively) and hence in P requirements between the two species. Critical Olsen P spanned narrower ranges than critical CaCl₂‐P in both crops and is therefore seemingly the more robust of the two tests. Both critical P values exhibited moderate correlations with soil properties. Thus, critical Olsen P was (a) lower in soils with a medium pH – which is consistent with the fact that the bicarbonate solution method tends to overestimate plant‐available P in strongly acid and calcareous soils; (b) positively correlated with pH and carbonate content in calcareous soils; and (c) uncorrelated with soil properties in noncalcareous soils. On the other hand, critical CaCl₂‐P in some soil groups was negatively correlated with some properties increasing the P buffering capacity of soil (e.g. Fe oxide content). Taken together, our results suggest that routinely measured soil properties help to predict critical Olsen P better than critical CaCl₂‐P.     

不同氮肥配施方法下稻草还田短期效应研究

为探索适宜稻草还田量及配合稻草还田的N、P肥施用方法,通过盆栽试验,采用树脂法和传统化学法相结合,研究了不同N肥配施方法下稻草还田对土壤N、P养分及水稻生长的短期影响。结果表明:稻草还田短期内可降低土壤氨氮浓度,提高土壤有效磷浓度,抑制水稻生长;稻草还田的这3种效应都随稻草水平的增加而加强,但不同N肥配施下无差异。稻草还田后易引起水稻铁中毒,因此稻草还田量不宜过多;稻草还田后除需多施N、P肥外,还需通过排水等措施以解决其铁毒效应。