不同磷水平配施生物炭对土壤磷有效性

生物炭在提高土壤磷素有效性及促进作物生长方面具有显著作用,但其效果因土壤类型不同存在较大差异。试验以赤红壤(pH 4.91)和褐土(pH 7.24)为供试土壤,设置3种磷肥水平(0、30、90 kg P·hm^-2,分别以不施磷、低磷、高磷表示)配施稻秆生物炭(0、4%)的大豆盆栽试验,研究了不同磷水平下配施生物炭对土壤磷有效性、磷酸单酯酶活性和植株磷吸收的影响。结果表明: 不同磷水平配施生物炭显著提高了两种土壤的速效磷和全磷含量,且低磷水平添加生物炭处理速效磷增幅最大,在赤红壤和褐土的增幅分别为192.6%和237.1%。与低磷相比,赤红壤中低磷配施生物炭处理的碱性磷酸单酯酶活性显著增加78.9%,活性有机磷含量降低39.3%,同时显著促进了植株生长与磷吸收;生物炭添加显著降低了褐土活性有机磷含量,但不同处理对土壤磷酸单酯酶活性和植株生长无显著影响。土壤活性有机磷含量与速效磷含量均呈显著负相关。综上,生物炭对土壤磷有效性的作用因土壤类型和磷肥水平差异而不同,其在赤红壤上对植株生长和磷吸收的促进效应强于褐土,且在低磷条件下效果更佳。本研究为生物炭在减施磷肥和促进大豆磷吸收,特别是在赤红壤上的应用提供了科学依据。     

A comparison of phosphorus and nitrogen transfer between plants of different phosphorus status

Summary This study has two objections: (1) to compare transfers of phosphorus (³²P) with nitrogen (¹⁵N) from undefoliated and defoliated mycorrhizal P-rich plants to an adjacent mycorrhizal plant and (2) to determine whether the improved nutrient status of a plant growing with a nutrient-rich plant is due primarily to movement of nutrients from roots of its nutrient-rich neighbor (= nutrient transfer) or to reduced nutrient uptake by its nutrient-rich neighbor (=shift in competition). Two plants of Plantago lanceolata were grown in a three-pot unit in which each of their root systems were split, with part in the central shared pot and part by themselves in an outside pot. There were three treatments: (1) no added P; (2) P added in the outer pot to only plant, termed the donor plant, since it might provide P to the companion plant, acting as a receiver; and (3) as in the previous treatment but the P-fertilized donor plant was also clipped. To encourage the formation of hyphal links between roots of the different plants, transfers were determined when root length densities were high (90 to 130 cm cm^-3 soil) and when 56 to 85% of the root length was infected with vesicular-arbuscular mycorrhizae. Phosphorus fertilization enhanced P but not N movement within donor plants. Regardless of treatment, N transfer from donor to receiver plants was an order of magnitude greater than P transfer and in amounts that could potentially affect plant nutrition in very infertile soils. Phosphorus transfer was very small in any of the treatments. Although P fertilization and clipping improved P status of receiver plants, P transfer was not indicated as the main reason for the improved nutrition. A shift in competition between donor and receiver plants was likely the major factor in the shift in nutrition of the receiver plants.     

长期施肥对石灰性土壤磷素肥力的影响 Ⅰ.有机质、全磷和速效磷

在陕西关中黄土区连续23年进行了不同施肥、小麦玉米轮作定位试验,研究了0～100cm土层土壤有机质、全磷、速效磷含量变化.结果表明,长期单施化肥或有机肥与化肥且配施均可增加耕层(0～20cm)土壤有机质含量.长期施用厩肥并配施化肥处理对土壤总磷库及无机磷库、速效磷的贡献大于玉米秸秆处理.长期单施化肥可增加土壤全磷、无机磷和速效磷含量,增加幅度低于厩肥和休闲处理,与秸秆处理对全磷、速效磷含量的影响效应相近.23年的不同施肥处理,与无肥处理相比,其理土壤磷素增量在0～100cm土壤剖面中的分布特点是:全磷增量剖面分布可为3层———耕层(0～20cm)为显著累积层,20～60cm土层为微增-亏损层,60～100cm土层为轻度累积层.速效磷增量剖面分布趋势与全磷增量分布趋势基本相同,仅在60～100cm土层累积较弱.     

不同施磷量对春油菜产量和土壤磷素平衡的影响

青海省东部春油菜主产区的土壤速效磷含量高、磷肥施用量大、磷肥利用率低。研究不同施磷量对春油菜的生长、磷素吸收和利用、土壤磷素平衡的影响,可为该地区春油菜田养分高效管理提供科学依据,对保障青藏高原农业可持续发展具有重要意义。本研究于2017和2018年在青海省互助县开展了田间试验,设置0、30、60、90、120 kg P₂O₅·hm^-2 5个磷肥施用量,测定了不同处理春油菜的产量、磷素吸收与利用、籽粒含油率等。结果表明: 2017年施磷量60 kg·hm^-2处理的油菜籽粒产量、成熟期地上部磷素累积量和产油量均显著高于不施磷处理,但施磷量超过60 kg·hm^-2后,籽粒产量和产油量不再增加;2018年施磷量对春油菜籽粒产量、成熟期地上部磷素累积量和产油量均无显著影响。两年度的磷肥表观利用率均很低,平均为6.7%。施用磷肥条件下土壤均有不同程度的磷素盈余,施磷量低于60 kg·hm^-2时盈余量较低。综合考虑春油菜产量、产油量、磷肥表观利用率和土壤磷素表观平衡,在青海省东部春油菜区,推荐施磷量为60 kg·hm^-2。     

长期施肥对石灰性土壤磷素肥力的影响Ⅰ．有机质、全磷和速效磷

在陕西关中黄土区连续23年进行了不同施肥、小麦-玉米轮作定位试验。研究了0～100cm土层土壤有机质、全磷、速效磷含量变化．结果表明,长期单施化肥或有机肥与化肥且配施均可增加耕层(0～20cm)土壤有机质含量．长期施用厩肥并配施化肥处理对土壤总磷库及无机磷库、速效磷的贡献大于玉米秸秆处理．长期单施化肥可增加土壤全磷、无机磷和速效磷含量,增加幅度低于厩肥和休闲处理,与秸秆处理对全磷、速效磷含量的影响效应相近．23年的不同施肥处理,与无肥处理相比,其理土壤磷素增量在0～100cm土壤剖面中的分布特点是：全磷增量剖面分布可为3层——耕层(0～20cm)为显著累积层,20～60cm土层为微增一亏损层,60～100cm土层为轻度累积层．速效磷增量剖面分布趋势与全磷增量分布趋势基本相同,仅在60～100cm土层累积较弱．     

长期施磷对玉米-小麦轮作系统作物产量和磷素吸收及土壤磷积累的影响

本研究利用位于河北省保定市的7年田间定位试验,探讨了4个磷水平(不施磷、70%优化施磷、优化施磷、130%优化施磷)对玉米-小麦轮作系统作物产量的影响,分析了作物磷素吸收和磷肥利用效率以及土壤磷盈亏的变化。结果表明: 长期(7年)施磷能够显著提高玉米和小麦产量及磷素吸收量,且玉米和小麦产量与磷素吸收量随着施磷量的增加均呈现先上升后下降的抛物线变化趋势。各施磷水平下玉米季磷肥利用率高于小麦季,小麦季磷肥累积利用率呈现下降趋势,下降速率表现为优化施磷>70%优化施磷>130%优化施磷;玉米季磷肥累积利用率均呈现上升趋势,上升速率表现为优化施磷>70%优化施磷>130%优化施磷。长期不施磷条件下土壤表观磷盈亏量和累积磷盈亏量都表现为亏缺状态,施磷条件下土壤磷表现为盈余,且施磷量越高,累积年限越长,土壤磷盈余量越高。河北潮土在秸秆还田条件下小麦施磷量在105～150 kg·hm^-2,玉米施磷量在63～90 kg·hm^-2时,既能保证作物高产,又能使磷肥利用率保持在较高水平,减少磷素在土壤中的累积,降低环境风险。     

Effect of mycorrhizal inoculation and soluble phosphorus fertilizer on growth and phosphorus uptake of pearl millet

Summary Six mycorrhizal fungi were tested as inoculants for pearl millet (Pennisetum americanum Leeke) grown in pots maintained in a greenhouse. VAM fungi varied in their ability to stimulate plant growth and phosphorus uptake. Inoculation withGigaspora margarita, G. calospora andGlomus fasciculatum increased shoot drymatter 1.3 fold over uninoculated control. In another pot trial, inoculation withGigaspora calospora andGlomus fasciculatum resulted in dry matter and phosphorus uptake equivalent to that produced by adding phosphorus at 8 kg/ha.The influence of inoculatingGigaspora calospora on pearl millet at different levels of phosphorus fertilizer (0 to 60 kg P/ha) as triple superphosphate in sterile and unsterile alfisol soil was also studied. In sterile soil, mycorrhizal inoculation increased dry matter and phosphorus uptake at levels less than 20 kg/ha. At higher P levels the mycorrhizal effect was decreased. These studies performed in sterilized soil suggest that inoculation of pearl millet with efficient VAM fungi could be extremely useful in P deficient soils. However, its practical utility depends on screening and isolation of fungal strains which perform efficiently in natural (unsterilized) field conditions.     

Co-effect of phosphorus and cadmium interaction on fraction distribution and accumulation of phosphorus in mangrove-sediment system

Mangrove [Kandelia obovata (S. L.)] seedlings were cultivated in rhizoboxes under different rates of phosphorus (P) and cadmium (Cd) level. The speciation distributions of P both in the rhizosphere and non-rhizosphere sediments were examined using sequential extraction procedures. P contents in different K. obovata (S.L.) tissues were also determined. Results showed that considerable differences existed in P speciation distribution between rhizosphere and bulk sediments. A higher proportion of iron-bound phosphate (Fe-P) was found in the rhizosphere sediments, while a relatively higher concentration of exchangeable phosphate (Ex-P) and Aluminum-bound phosphate was found in the bulk sediments. P accumulation in plant tissues was significantly positively correlated to Ex-P and Fe-P. Results indicated that root activities play an important role in the P cycling. And the coexistence of P and Cd induced higher P accumulation in mangrove plants. It is suggested that the root-induced chemical and biological changes in the rhizosphere environment play an important role in enhancing the bioavailability of soil P.     

Effects of phosphorus and calcium to phosphorus consumption ratio on mineral metabolism and cardiometabolic health

Phosphorus is a common additive used in food processing that is typically consumed in excess of the recommended daily allowance; however, our knowledge of its effects on health, in the context of normal renal function, is limited. Unlike phosphorus, calcium intake is generally less than recommended, and it has been hypothesized that the calcium to phosphorus ratio may be partly responsible for the proposed negative health consequences. Therefore, this study sought to determine the effects of increased phosphorus additive intake, in the context of high calcium consumption, on endocrine markers of mineral metabolism and cardiometabolic health. An outpatient feeding study was performed in which healthy adults were fed a run-in control diet for 2 weeks followed by a phosphorus additive enhanced diet with supplemental calcium to an approximate ratio of 1 (experimental diet) for 2 weeks. Blood and urine samples were collected, and participants had brachial flow-mediated dilatation measured, with analyses comparing follow-up measures to baseline. Two weeks of experimental diet increased serum fibroblast growth factor 23 concentrations but lowered body weight and serum leptin; however, other phosphorus responsive factors such as osteopontin and osteocalcin did not increase. A complementary study in male mice also demonstrated that the regulation of known dietary phosphorus responsive factors was mostly abrogated when dietary calcium was raised in parallel with phosphorus. In conclusion, the study identifies weight, leptin and insulin as responsive to dietary phosphorus and that certain aspects of the systemic phosphorus response are attenuated by a corresponding high calcium intake.     

蚯蚓活动对红壤磷素主要形态及有效磷含量的影响

通过盆钵生物试验和采用Hedley磷素分级方法研究了秉氏环毛蚓(Pheretima pingi)对红壤磷素主要形态和红壤有效磷含量的影晌.结果表明,在蚯蚓和有机物料(稻草、花生秸、油菜秸)的共同作用下,经过100d培养后土壤有效磷含量显著提高.统计分析结果表明,花生秸接种蚯蚓处理与不接种蚯蚓处理和油莱秸接种蚯蚓处理与不接种蚯蚓处理之间的土壤有效磷含量差异均达显著水平.采用Hedley磷素分级法测得的树脂磷由原土的痕量增加到10.5～17.8 mg·kg^-1,NaHCO₃溶解态磷由原土的14.5 mg·kg^-1增加到23.5～53.6 mg·kg^-1,微生物细胞磷由原土的1.0 mg·kg^-1增加到6.8～9.7 mg·kg^-1,土壤有机磷含量由原土的37.9 mg·kg^-1增加到50.7～59.3 mg·kg^-1,而土壤中活性最低的残留磷含量则有所降低.蚯蚓活动对红壤磷素具有较强的活化作用.     

聚磷茵JPA1菌株的生长特性和聚磷条件的优化

以YG培养基为基础,考察不同条件对聚磷菌JPA1菌株生长及聚磷效率的影响。结果表明：JPA1菌株生长的对数期为3-9h,9h后进入稳定期,12h到达衰亡期。在单因素试验中,麦芽糖为JPA1菌株最适生长和聚磷的C源,最适生长温度为30-35℃,pH为8,Na＋、Ca2＋、Mg2＋、Mn2＋和K＋等离子有利于JPA1菌株的生长;最适聚磷温度为30-35℃,pH为7,Fe2＋、Na2＋、Mg2＋、Mn“和K＋等离子有利于JPA1菌株的聚磷。正交试验结果表明：JPA1菌株去磷培养基的最优组合为麦芽糖1．5g／L,温度37℃,pH6．5,装液量50mL（300mL摇瓶）;菌株最适扩增培养基为麦芽糖1．5g/L,温度37℃,pH6．5或7．5,装液量150mL（300mL摇瓶）。     

Effect of wheat phosphorus status on leaf surface properties and permeability to foliar-applied phosphorus

Aims

This study aimed to analyse the effect of phosphorus (P) nutritional status on wheat leaf surface properties, in relation to foliar P absorption and translocation.

Methods

Plants of Triticum aestivum cv. Axe were grown with three rates of root P supply (equivalent to 24, 8 and 0 kg P ha^?1) under controlled conditions. Foliar P treatments were applied and the rate of drop retention, P absorption and translocation was measured. Adaxial and abaxial leaf surfaces were analysed by scanning and transmission electron microscopy. The contact angles, surface free energy and work-of-adhesion for water were determined.

Results

Wheat leaves are markedly non-wettable, the abaxial leaf side having some degree of water drop adhesion versus the strong repulsion of water drops by the adaxial side. The total leaf area, stomatal and trichome densities, cuticle thickness and contact angles decreased with P deficiency, while the work-of-adhesion for water increased. Phosphorous deficient plants failed to absorb the foliar-applied P.

Conclusions

Phosphorous deficiency altered the surface structure and functioning of wheat leaves, which became more wettable and had a higher degree of water drop adhesion, but turned less permeable to foliar-applied P. The results obtained are discussed within an agronomic and eco-physiological context.     

Species ecological strategy and soil phosphorus supply interactively affect plant biomass and phosphorus concentration

Excess soil phosphorus often constrains ecological restoration of degraded semi-natural grasslands in Western-Europe. Slow-growing species, often target of restoration (measures), are at a disadvantage because they are outcompeted by fast-growing species. Gaining insight into the responses of plant species and communities to soil phosphorus availability will help understanding restoration trajectories of grassland ecosystems. We set up two pot experiments using twenty grassland species with contrasting growth forms (i.e. grasses versus forbs) and nutrient use strategies (i.e. acquisitive versus conservative nutrient use). We quantified the nutrient use strategy of a species based on the stress-tolerance value of the CSR framework (StrateFy et al. 2017). We grew these species (1) as monocultures and (2) in mixtures along a soil phosphorus gradient and measured the aboveground biomass and plant phosphorus concentrations. Plant phosphorus concentration generally increased with soil phosphorus supply and biomass increased with soil phosphorus supply only in conservative communities. Forbs had higher plant phosphorus concentrations compared to grasses both in monocultures and mixtures. The species’ nutrient use strategy had contrasting effects on plant tissue phosphorus concentrations, depending on soil phosphorus supply (interaction effect) and vegetation biomass (dilution effect). Our findings contribute to the knowledge required for successful ecological restoration of species-rich grasslands. Our results suggest that under specific conditions (i.e. nitrogen limitation, no dispersal limitation, no light limitation), slow-growing species can survive and even thrive under excess soil phosphorus availability. In the field, competition by fast-growing species may be reduced by increased mowing or grazing management.