Interaction of phosphorus and molybdenum in relation to uptake and utilization of molybdenum,phosphorus, zinc,copper and manganese by rice

Summary The effect of phosphorus and molybdenum alone and combined, on the uptake and utilization of Mo, Mn, Zn, Cu and P by rice (Var. IR-579) was studied in the greenhouse at varying levels of Mo (0, 2.5 and 5.0 ppm) and (0,100 and 200 ppm). Application of P increased the dry matter yield of shoot and root. Combined application of P and Mo increased the dry matter yield of shoot. Application of Mo increased the concentration of Mo and P in shoot. Applied P caused an increase in the concentration of Mo, Zn and P in shoot. Combined application of P and Mo resulted in an increase in concentration and uptake of Mo in shoot.     

Interaction of phosphorus and molybdenum and the availability of zinc,copper, manganese,molybdenum and phosphorus in waterlogged rice soil

Summary Laboratory incubation experiments were conducted with low-land rice soil to study the effect of applying three different levels of molybdenum (0, 2.5 and 5.0 ppm) and phosphorus (0, 100 and 200 ppm), in all possible combinations, on the changes in available Mo, P, Mn, Zn and Cu in soil. The results showed that application of Mo at both the levels increased the content of extractable Mo and P but decreased those of Cu and Mo in soil whereas application of Mo at higher level only increased the content of extractable Zn in soil. Application of P at both the levels decreased the content of extractable Mo, Mn and Cu but increased that of P whereas it showed an inconsistent effect on the extractable Zn content in soil. The P × Mo interaction effect was found to be beneficial for the content of P, Mo and Zn only. During the initial period of incubation all elements except Cu recorded an increase but with the progress of incubation period the content of all the elements except Mn gradually declined.     

Effect of algal growth on the availability of phosphorus,iron and manganese in rice soils

Summary Laboratory experiments were conducted to study the effect of algal growth on the change of (I) pH, (II) available phosphorus and (III) solubility of iron and manganese content in five waterlogged alluvial rice soils of West Bengal, India. The results showed that the algal growth initially caused an increase in the soil pH, which later declined to the original value in some of the soils. The available phosphorus content decreased upto 90 days of their growth and began to increase towards the later period of incubation. The drastic fall of water soluble plus exchaneable manganese content of the soils due to algal growth was accompanied by similar increase in reducible manganese content. No appreciable change in water soluble plus exchangeable ferrous iron content was encountered but theN-NH₄OAC(pH 3) extractable iron due to algal growth progressively decreased with the progress of the incubation period.     

Effect of phosphorus and zinc on the growth and phosphorus,zinc, copper,iron and manganese nutrition of rice

Summary A greenhouse experiment was conducted to study the effect of phosphorus and zinc application, in three lowland alluvial rice soils (Haplustalf) on the growth of rice and the concentration of phosphorus, zinc, copper, iron and manganese in shoots and roots. The results showed that application of phosphorus and zinc significantly increased the dry matter yield of shoots, grains and roots. Application of phosphorus caused a decrease in the concentration of zinc, copper, iron and manganese both in shoots and roots. Application of zinc also similarly lowered the concentration of phosphorus, copper and iron, but increased that of manganese in shoots and roots. The decrease in the concentration of the elements in the shoots was not due to dilution effect or to the reduced rate of translocation of the elements from the roots to tops. This has been attributed more to the changes in the availability of the elements in soil resulting from the application of phosphorus and zinc.     

Availability of iron,manganese, zinc and phosphorus in submerged sodic soil as affected by amendments during the growth period of rice crop

Summary Effect of amendments, gypsum (12.5 tonnes/ha), farmyard manure (30 tonnes/ha), rice husk (30 tonnes/ha) and also no amendment (control) on the availability of native Fe, Mn and P and applied Zn in a highly sodic soil during the growth period of rice crop under submerged conditions was studied in a field experiment. Soil samples were collected at 0, 30, 60 and 90 days of crop growth. Results showed that extractable Fe (1N NH₄OAC pH 3) and Mn (1N NH₄OAC pH 7) increased with submergence upto 60 days of crop growth but thereafter remained either constant or declined slightly. Application of farmyard manure and rice husk resulted in marked improvement of these elements over gypsum and control. Increases in extractable Mn (water soluble plus exchangeable) as a result of submergence and crop growth under different amendments were accompanied by corresponding decreases in easily reducible Mn content of the soil. Application of 40 kg zinc sulphate per hectare to rice crop could substantially raise the available Zn status (DTPA extractable) of the soil in gypsum and farmyard manure treated plots while the increase was only marginal in rice husk and control plots indicating greater fixation of applied Zn. Available P (0.5M NaHCO₃ pH 8.5) behaved quite differently and decreased in the following order with crop growth: gypsum>rice husk>farmyard manure>control.     

Effect of lime,phosphorus and mycorrhizal fungi on growth,nodulation and nitrogen fixation by white clover (Trifolium repens) grown in UK hill soils

Summary The responses of white clover (cv NZ Grasslands Huia grown in four UK hill soil types) to additions of lime and P, to inoculation with Rhizobium and mycorrhizal fungi, and to differences in soil water status were assessed in pot and field experiments. With a deep peat soil in pots, shoot production, nodulation and N fixation by clover were increased by 160, 130 and 85% respectively following inoculation with mycorrhiza, but in the field, despite a doubling of root infection, there was no response in growth. On a brown earth soil in the field inoculation with one endophyte (Glomus mosseae L1) out of four tested depressed production of white clover shoots by 42% but enhanced that of leeks (Allium porrum) by 50%; the others were without effect. With dry peaty podzol and brown earth soils in pots, clover shoot production was highest with added P when a water holding capacity of 80% was maintained, but roots from the latter had only 2.6 compared to 68 nodules per plant from the former. Further work is required to explain poor nodulation in the brown earth soils.     

Influence of phosphorus and zinc fertilizers on the uptake of P and Zn by corn plants grown in highly calcareous soils

Summary The influence of heavy applications of P (100, 200 and 400 ppm P) and Zn (12.5 and 25 ppm) fertilizers on their extractabilities, availabilities and uptake by corn grown in highly calcareous soil was investigated.A significant increase was found in the levels of (NH₄)₂CO₃-EDTA-extractable Zn either by Zn-applications alone or together with P. The amounts of NaHCO₃-extractable P were also increased with P additions and the influence of Zn applications was not clear.Phosphorus application generally increased the plant dry weight. In the soils treated with P and Zn fertilizers, that increase was mostly related to P rather to Zn.In the soils not treated with Zn, P additions increased Zn uptake by the plants. On the other side, in the soils treated with Zn, P additions decreased Zn uptake.Phosphorus concentration in the whole plant and/or in the different plant parts was increased by P application without being significantly affected by Zn addition. The plants showed greater response to 12.5 ppm Zn application than to 25 ppm.Plants grown for 4 weeks contained lower amounts of Zn relative to those grown for 8 weeks. The influence of plant age on P content was not as clear as occurred with Zn.     

P、Zn在小麦细胞内的积累、分布及交互作用的研究

报道了小麦无性系细胞在含有3个P水平(0.5、1.5、3.5mmol·L^-1)和2个Zn水平(0、60μmol·L^-1)的M.S培养液中,细胞对P、Zn的积累、分布特性及交互作用的研究.P和Zn在细胞内的积累分别随外施P、Zn浓 度的提高而提高.与缺Zn比较,加Zn处理能抑制培养7d细胞中P的含量.营养液中0.5～1.5mmol·L^-1 P能促进细胞的含Zn量,但高P处理即抑制细胞的含Zn量.小麦细胞壁固定了细胞83.9%～88.3%的P,而外施P浓度越高,则细胞壁中P分配的比例越大.在供Zn条件下,细胞壁截留了细胞中一半以上的Zn(52.0～60.5%).小麦液泡中P和Zn的含量较少,分别为2.2%～3.8%和10.6%～30%.     

根表铁氧化物胶膜对水稻吸收Zn的影响

采用营养液培养方法研究了水稻根表形成的铁氧化物胶膜对水稻吸收Ｚｎ的影响．结果表明,在有Ｆｅ２＋的嫌气环境中,由于根际氧化作用水稻根表会形成红色的铁氧化物胶膜,根表的铁氧化物胶膜影响水稻对Ｚｎ的吸收．铁膜数量较少时,由于对Ｚｎ的富集作用有限,其对水稻Ｚｎ的吸收虽有促进作用,但不明显．随着根表铁膜数量的增加,这种促进作用也相应增加,并且在铁膜数量增加到一定值时,对水稻吸收Ｚｎ的促进作用达到最大．而后,随着铁膜数量的进一步增加,铁膜反而阻碍水稻对Ｚｎ的吸收,成为水稻吸收Ｚｎ的障碍层．在此过程中,水稻的根分泌物,特别是其中的植物铁载体对覆有铁膜水稻根系吸收Ｚｎ有促进作用．这种促进作用随铁膜数量的增加而逐渐减弱．因此,根表铁氧化物胶膜对水稻吸收Ｚｎ并不总是起促进作用,其作用的方向和程度取决于铁膜的数量．     

磷氮在水田湿地中的迁移转化及径流流失过程

水稻田湿地系统是我国东南部高产农业区的主要土地利用类型,是我国特有的景观结构．在巢湖六叉河小流域进行的野外实验结果表明,这一湿地系统的水塘、水沟和水稻田都能有效地截留来自村庄、森林地和旱地的磷氮非点源污染物．实验同时研究了磷氮物质从水稻田中的径流流失方式和机理,结果发现磷氮物质从水稻田中的径流流失量与水稻田持水量、施肥量、降雨量、水稻生长过程和水稻田排水堰高度等因素有关,并提出了一个模型计算磷氮径流流失量,表明在施肥情况下的磷氮流失量分别高达０．６９和１１．２ｋｇ·ｈｍ－２,是最大的潜在非点源污染．     

Copper nutrition of wheat in relation to nitrogen and phosphorus fertilization

Summary In a pot culture study, copper addition to soil increased the crop yield only in presence of nitrogen. The latter increased the utilization of both native as well as applied copper but more that of applied. It also minimised the adverse effect of applied phosphorus on copper utilization. Phosphorus at the rate 45 ppm had the tendency of decreasing copper uptake by wheat if applied without nitrogen or with its low level.     

Relative effectiveness of various types and methods of zinc application on rice and maize crops grown in calcareous soil

Summary Application of zinc sulphate mixed with compost/poultry manure proved to be equivalent to the effect of dipping the seedling roots in 4% ZnO suspension with respect to rice yields but Zn-amended organic manures were superior to other treatments with regards to total Zn uptake. A marked residual effect of soil applied treatments was recorded on the succeeding maize crop. Application of poultry manure alone was about one and a half times more effective than compost alone in increasing the rice and maize grain yields. Poultry manure surpassed compost in increasing zinc uptake by the crops and at the same time it built up more available Zn in soil than compost for the following crop. The magnitude of yields and Zn uptake response were magnified when zinc sulphate was applied along with organic manures. Application of 25 kg zinc sulphate/ha alone had the same effect as 50 quintals poultry manure alone or 12.5 kg zinc sulphate applied with 50 quintals compost/ha with respect to crop yields. A significant positive correlation was, recorded in both the crops between Zn concentration in grain or straw and their respective yields.     

氮锌硒肥配合施用对白三叶的固氮作用与氮转移的影响

在湖北省宜昌县百里荒草场山地黄棕壤上配合施用氮锌硒肥,研究其对混播白三叶,混播黑麦草及单播黑麦草的干重及混播白三叶的固氮作用和氮转移的影响,试验结果表明：（1）氮锌硒肥配合施用,混播黑麦草的干重均高于相应处理的单播黑麦草,混播牧草和单播黑麦草重最高的处理都是N46Zn0Se5,其干重辚25．38 g／盆和19．93g/盆。（2）施氮对混播白三叶,混播黑麦草及单播黑麦草的生长有明显的促进作用,施锌,硒对混播白三叶,混播黑麦草及单播黑麦草的生长作用不明显。（3）混播白三叶氮素的主要来源是固氮作用,占全氮产量的57．6000％－77．258％。（4）混播白三叶固定氮的转移量只占混播黑麦草的全氮产量的0．316％－12．251％,通过正交方差分析发现,适量氮肥（N30mg/kg)促进固定氮的转移,高量氮肥（N46mg/kg)抑制固定氮的转移。     

Response of irrigated dry-seeded rice to nitrogen and phosphorus in a semi-arid environment

Summary Under semi-arid conditions, three field experiments were conducted at Gezira Research Station to determine response of irrigated dry-seeded rice (Oryza sativa L. var IR 2053-206-1-3-6) to addition of nitrogen and phosphorus fertilizers. The experimental treatments included the factorial combinations of seven levels of nitrogen applied as urea and four levels of phosphorus applied as super phosphate. Plant growth and grain yield were significantly and progressively increased with the rise in the levels of added nitrogen and phosphorus. However, response to added phosphorus was restricted by the applied level of nitrogen. The responses of grain yield to nitrogen and phosphorus levels are given by quadratic regression equations. Without addition of nitrogen or phosphorus grain yield averaged 1.52 t/ha compared to 6.07 t/ha with addition of the optimal levels (160 kg N plus 35 kg P/ha). The high potential for rice production in semi-arid environment is evidently restricted by addition of relatively high rates of nitrogen and phosphorus.     

Effect of zinc fertilization on the mineral nutrition of rices differing in tolerance to zinc deficiency

Summary The effects of four Zn levels on the electrochemical and chemical properties of the soil solution, and on the growth and mineral nutrition of two rice varieties (IR26 and IR34) differing in tolerance to Zn deficiency were studied in the greenhouse using Zn-deficient soils from two locations. A similar experiment was conducted in culture solution to check how Zn addition affects translocation of other nutrients.In both soil and culture solution, plant Zn concentrations alone was not enough to account for varietal tolerance to Zn deficiency. Comparison of nutrient to Zn and shoot to root ratios of nutrients was more useful in determining the possible mechanism of varietal tolerance. IR 34 appeared to tolerate the disorder due to its lower Zn requirement, more efficient Zn translocation and ability to maintain lower Fe/Zn, Cu/Zn, Mg/Zn and P/Zn ratios in the shoot than the more susceptible variety, IR26. This was shown to be due to decreased translocation of Fe, Mg and P to shoots and decreased absorption of Cu by the root in IR34 in culture solution studies. Adding Zn further reduces translocation or absorption of these nutrients and depending on the nutrient supply of the soil, could cause deficiencies or mineral imbalances, especially of Fe, Cu, and P.These observed varietal differences regarding Zn requirement and the interaction of Zn with absorption and translocation of plant nutrients necessitates revision of recommendations for Zn fertilization. There is an inevitable need for Zn application in severely Zn-deficient soils regardless of rice variety. But on marginally Zn-deficient soils especially those low in Fe, Cu, or P, Zn fertilization is not advisable when resistant rice varieties are used.     

The effect of nitrogen and phosphorus addition on the growth,reproduction, and nutrient dynamics of two ericaceous shrubs

Summary Aboveground growth, reproduction, and foliar nitrogen and phosphorus contents of two ericaceous shrub species were compared over two seasons in (a) an undisturbed shrub bog (pocosin), and (b) a factorial fertilization design in which three levels each of nitrogen and phosphorus were added in all possible combinations. One species, Zenobia pulverulenta, is deciduous whereas the other species, Lyonia lucida, is evergreen. In the nutrient-poor undisturbed pocosin the two species exhibited similar foliar nitrogen and phosphorus concentrations and aboveground growth rates. Neither species flowered. In response to nutrient-addition Zenobia increased growth rates more than Lyonia. Foliar phosphorus concentrations of both species increased in response to enhanced phosphorus availability. in the first season neither species flowered in any treatment. In the second season Zenobia flowered only in the fertilized plots, with the most flowering in the high phosphorus treatments. I conclude that, by virtue of high growth rates and efficient use of nutrients and despite differences in leaf phenology and morphology, both Lyonia and Zenobia are successful in a competitive community under conditions of extremely low phosphorus availability. However, unlike Lyonia, Zenobia can take advantage of temporarily increased nutrient availability, which occurs following fire in the pocosin, to increase growth and reproduction.     

Co-limitation of plant primary productivity by nitrogen and phosphorus in a species-rich wooded meadow on calcareous soils

High small-scale species richness of calcareous grasslands is generally thought to result from evening of species competitive potentials by limited N availability, because of relatively low herb N/P ratios in these communities. However, P mobility is low in alkaline soils as well. We studied soil chemistry and productivity of herb and moss layers in a very diverse calcareous meadow (up to 76 vascular plant species per m²) to test the hypotheses of a co-limitation of herb productivity by both soil N and P availabilities and moss productivity primarily by P availability. The effect of nutrient supply on productivity was investigated using both a natural productivity gradient as well as fertilization experiments. We observed strong positive correlations of soil P availability and total soil N with the above-ground productivity of herb layer. A long-term fertilization experiment demonstrated that P alone and N and P together increased productivity of vascular species, and that the productivity continuously declined after cessation of fertilization with the effect of previous fertilization occasionally visible even 14 years after treatment termination. A short-term fertilization experiment further demonstrated that N and P when supplied alone increase productivity of vascular plants, suggesting that both elements were limiting. Furthermore, there was a significant interaction between N and P on productivity, indicating that simultaneous N and P supply increased productivity more than separate nutrient additions. Moss productivity was negatively associated with vascular plant productivity. In particular, N addition decreased moss productivity, but moss productivity did not decline in P addition treatments. P requirements of mosses were larger than those of vascular plants. Our data indicate co-limitation of herb productivity by both soil N and P in this highly diverse grassland, while limitation of moss productivity mainly by P. We suggest that N and P co-limitations are common in calcareous diverse grasslands, and may partly explain the extreme small-scale species diversity in these communities.     

The effect of afforestation with Scots pine (Pinus silvestris L.) of sandy post-arable soils on their selected properties. II. Reaction, carbon, nitrogen and phosphorus

Despite the extensive literature on the effect on soil properties of afforestation of former arable land, we still lack full understanding of whether the changes proceed in the same direction and at the same rate, and of how long is required to achieve a state of soil equilibrium typical of a natural forest ecosystem. Therefore, as part of a study comparing post-arable sandy soils (Dystric Arenosols) afforested with Scots pine (Pinus silvestris L.) with arable soils and soils of continuous coniferous forests, the range and direction of changes in pH, organic carbon (C_org), total nitrogen (N_tot), ammonium (N-NH₄) and nitrates (N-NO₃) in soil solution, total (P_tot) and available (P_av) phosphorus were determined. The studies were carried out in south-east Poland (51°30′-51°37′N, 22°20′-22°35′E). Ten paired sites of afforested soils (five with 14- to 17-year-old stands and five with 32- to 36-year-old stands) with adjacent cultivated fields, and five sites of continuous forest with present stands of ca. 130–150 years old were selected. Soil samples were taken from the whole thickness of master horizons and, in the case of the A horizon of the afforested soils, from three layers: 0–5 (A_0–5), 5–10 (A_5–10) and 10–20 cm (A_10–20). The cultivated soils in the Ap horizon showed higher pH (by ca. 1.0 unit), lower C_org and C:N, similar N_tot, lower N-NH₄, higher N-NO₃, higher P_tot and P_av contents compared with the Ah horizon of continuous forest soils. The results indicated decreased soil pH in the former plough layer of the afforested soils, with the greatest decrease observed in the 0–5 cm layer. In these soils, the C_org content was considerably higher in the A_0–5 layer, but lower in the two deeper layers and in the whole A horizon (0–20 cm) compared with the Ap horizon of the arable soils. The results indicate that the C_org content, after an initial phase of decline, again achieved a level characteristic of arable soils. The N_tot content in all layers of the A horizon of the afforested soils was lower than in the Ap horizon of the arable soils, and showed a reduction with stand age, especially in deeper layers. The C:N ratios in the mineral topsoil increased with stand age. N-NH₄ content increased and N-NO₃ decreased after afforestation. The P_tot and P_av contents in all layers and in the whole A horizon of the afforested soils, on stands of both ages, was lower than in the Ap of the cultivated soils. From the results, it could be concluded that, after more than 30 years of tree growth, the soils of the A horizon were still more similar to arable than to continuous forest soils with respect to C_org, P_tot and P_av. With respect to pH, N-NH₄ and N-NO₃, especially in the 0–5 cm layer, they were more similar to continuous forest soils than to cultivated soils, but with respect to N_tot and C:N ratio they were somewhere in between.