STUDIES IN RESPONSE TO NITROGEN

The residual effects of 59, 118 or 177 kg N/ha applied to the primary growth of a ryegrass sward were measured in two successive regrowths as yields of fresh matter (FM), DM and digestible organic matter (DOM). The first regrowths (RGl) harvested on 12 June followed primary growth (PG) harvests 8, 12, 16, 23, 29, 45 and 57 days after applying N on 16 Apr. The second regrowths (RG2) were harvested on 12 Aug., 62 days after RGl and 119 days after applying N. Significant residual responses were shown in both regrowths which increased the annual responses substantially. Responses to the first increment of N, averaged over dates of primary growth harvests, were raised from 70.3 kg FM, 9.2 kg DM, and 5.6 kg digestible OM/kg N applied, for the primary growth, to responses for primary growth+2 regrowths of 140.8 kg FM, 22.5 kg DM and 13.9 kg digestible OM/kg N applied. For the second increment of N, negligible or negative primary growth responses of 19.0 kg FM, –0.68 kg DM and –0.68 kg digestible OM/kg N applied became 179.7 kg FM, 25.6 kg DM and 16.4 kg digestible OM/kg N applied for the sum of the 3 growths. There were significant differences between the residual responses obtained for different dates of PG harvest. When PG was harvested 8 days after applying N, primary response was low or negligible; residual responses were high, and the total responses were 21.0 kg DM/kg N applied for the first N increment and 31.0 kg DM/kg N applied for the second. Similar effects were observed for FM and digestible OM. Residual responses to the second increment of N were greatest where primary growth was harvested 23 days after N application. Similar residual responses followed the primary growth harvest 29, 45 and 57 days after N application hut the total responses were reduced. It is concluded that the very high residual responses to the second increment of N can only he explained in terms of increased availability of soil N.     

STUDIES OF RESPONSE TO FERTILIZER NITROGEN

Fifteen out of 36 possible combinations of 3 cutting dates for hay, 3 rates of N application and 4 intervals between N application and cutting date were compared to study the effects of pre-harvest application of N on the N, P, K, Mg and Ca contents of the aftermath and the effectiveness of utilization of these elements. According to the method of calculation given by ARC (1), the control haycrop harvested on 16 June was deficient in N, Ca, P and Mg, and the aftermath which was given no further N after harvest was of low bulk, but adequate in mineral content. Earlier harvesting improved the quality of the hay, and increased the bulk and reduced the mineral content of the aftermaths. Applying 125.6 kg N/ha after harvest resulted in a satisfactory increase in bulk, plus an improved mineral content in the aftermath. Applying N before harvest resulted in increased uptake of N, K, Ca, P and Mg in the hay and in the increased percentage of N, K, and Ca in the DM of the hay. Very early application of pre-harvest N increased the percentage of Mg. The general effect of pre-harvest N on the aftermath was to reduce yield and uptake of N, K, Ca, P and Mg. Doubling the pre-harvest N raised the mineral uptake. Very early pre-harvest application resulted in low mineral uptake in the aftermath. The percentage of N, K and P in the aftermath was reduced by pre-harvest N applied at both levels and on both dates. Deferring the application of fertilizer N until 4 days after harvesting the hay crop produced the highest mineral contents in the aftermath, without reducing its bulk. Mineral uptake in the regrowths was linearly related to N uptake at 1.43 kg K, 0.34 kg Ca, 0.157 kg P, 0.006 kg Mg/kg N uptake.     

STUDIES IN RESPONSE TO NITROGEN

Regression equations have been calculated for the primary growth of a ryegrass sward as FM (fresh matter), DM, DOM and for uptake of N, K, P, Ca, Na and Mg after application of 59,118 or 177 kg fertilizer N/ha on 16 Apr. These have been used to predict changes in response with time, the responses in terms of time, the dates when specific yields of DM are attained, the different characteristics of herbages at specified yields of DM and the effects of changing harvesting interval on annual DM yield and uptake of minerals. DM and DOM show significant responses to 118 kg N/ha but no response to the next increment throughout the 57-day growth period. All other attrihutes, including FM, showed responses to 177 kg N/ha. Calculated response as days gained suggest that for short-interval grazing systems the use of even 118 kg N/ha is questionable. The reduction in annual DM production and the increase in N uptake when growth intervals are shortened are related to the form of their growth curves.     

铜与锌对茶树生育特性及生理代谢的影响Ⅲ．施铜对茶树体内铜及其他矿质元素吸收的影响

###################################     

STUDIES OF RESPONSE TO FERTILIZER NITROGEN

The uptake of N was measured in 2 successive regrowths harvested on 12 June and 13 Aug. following harvests of primary growths 8, 12, 16, 23, 29, 45 and 57 (12 June) days after applying N at 59, 118 or 177 kg N/ha on 16 Apr. Residual responses were obtained to both increments of N, leading to high apparent recoveries of fertilizer N, especially to the higher increment. This increased availability of soil N when high rates of N are applied is shown to vary with date of harvest of primary growth, reaching a maximum equivalent to 151% apparent fertilizer N recovery 23 days after N application. In the second regrowth, percentage N in the herbage showed a negative response to N applied to the primary growth. This appears to reflect a reduction in available soil N brought about by its increased availability and uptake in primary growth and first regrowth. The possibilities of improving the efficiency of fertilizer N by exploiting soil N are considered against the possible reduction in available N for future regrowths.     

Removal of mineral nutrients by red clover varieties

K, P, Ca and Mg contents and uptakes are reported from total herbage of plots sown with six varieties of red clover harvested three times a year for 3 years. K, P and Mg contents were above those reported as critical for growth; values for Ca were lower than quoted ranges which suggested that growth might have been affected by either deficiency of Ca or low pH. Hungaropoly was characterized by relatively low K and P and high Ca contents. Maximum uptakes in red clover total herbages over 3 years were 1198 kg ha^?1 K (Hera), 112 kg ha^?1 P (Hera), 494 kg ha^?1 Ca (Hungaropoly) and 104 kg ha^?1 Mg (Mars). Results were compared with those found for S101 perennial ryegrass, harvested on a similar system and receiving similar fertilization with uptakes of 759 kg ha^?1 K, 100 kg ha^?1 P, 200 kg ha^?1 Ca and 46 kg ha^?1 Mg, by expressing accumulating uptakes and inputs as linear regression equations. The better varieties of red clover, Hera, Hungaropoly, Mars and S123 show rates of DM accumulation similar to S101 perennial ryegrass and similar uptake rates of K and P but higher rates of uptake of Ca and Mg. The levels of application of K and P used in the experiment seem to be more than adequate but attention to the Ca status may be required to sustain high-yielding red clover swards.     

Response of permanent and reseeded grassland to fertilizer nitrogen. 2. Effects on concentrations of Ca, Mg, K, Na, S, P, Mn, Zn, Cu, Co and Mo in herbage at a range of sites

The concentration of mineral elements in herbage from permanent swards of mixed species composition (predominantly Agrostis spp., Holcus lanatus, Festuca rubra, Lolium perenne, Poa spp., etc.) was compared with that from sown perennial ryegrass ( Lolium perenne ) at two fertilizer rates (0 and 300kg N ha⁻¹ year⁻¹, both with P and K) and with L. perennel Trifolium repens (at 0 N with P and K). The investigation was conducted over four years at sixteen contrasting sites in England and Wales. Herbage samples for mineral analysis were taken at first and fourth harvests (May and August) each year from plots under 4-weekly cutting. There was a wide degree of variation between sites, particularly for concentrations of Ca, Mg, Na and all trace elements analysed. Herbage from L. perenne reseeds had significantly higher concentrations of Ca, Mg, Na, Co and S, but K, Mo, Zn, Cu and P were generally lower than in the permanent swards. L. perennel T. repens swards had the highest concentration of major cations, but trace element levels were generally intermediate between those for 0 N permanent and L. perenne swards. Fertilizer N reduced concentrations of Ca, Mn, Mo and S, and increased Mg, Na and Zn, with no consistent effects on K, Co and Cu. Herbage at harvest 4, compared with harvest 1, had higher Ca, Mg, Na, Mn, Zn and S. Permanent and L. perenne swards responded similarly to fertilizer N and between harvest dates. Results are discussed in relation to previous reports of botanical and fertilizer effects on mineral concentrations, and the mineral requirements of livestock. Changes in mineral concentration resulting from reseeding permanent swards are considered unlikely to increase mineral-related livestock disorders, and in many cases could be beneficial, though problems might arise on sites where some elements, e.g. Cu and Mg, are low.     

Sodium fertilizer application to pasture. 4. Effects on mineral uptake and the sodium and potassium status of steers

Mineral availability and status in body tissues was examined with four rumen-fistulated steers arranged in a Latin-square change-over design. The steers were fed perennial ryegrass herbage from a pasture fertilized with four Na treatments: 0 (Nil), 32 (Low), 66 (Medium) or 96 (High) kg Na ha^-1 yr^-1. Na fertilizer increased herbage contents and intakes of Na, Mg and Ca but did not affect intakes of K, P and S. Herbage K:Na and K:(Ca+Mg) decreased in direct proportion to the amount of Na fertilizer applied. With increasing dietary Na intake, the Na content of saliva increased and the K content decreased. There was an increase in Na and a reciprocal decrease in K contents of rumen fluid with increasing dietary Na. Blood plasma Na contents were greater when the Na-treated herbages were fed than in the Nil treatment. There was no effect of treatment on blood plasma K content. Increasing dietary Na increased urinary Na but did not affect urinary K. Faecal mineral concentrations of Na, Ca, P and S were increased by increasing dietary Na, whereas K content was reduced and the Mg content was unaffected. There was no difference between treatments in the proportion of mineral rapidly solubilized, except Na which increased with increasing dietary Na content. The fractional rate of degradation was greater for Na, K, and Mg than for Ca and P. Based on effective solubilization, minerals were ranked in the order K > (Mg = Na) > Ca > P, and treatments were in the order Medium > (High = Low) > Nil. Increasing Na intake increased Ca but not P or Mg availability and increased the uptake of all three minerals.     

Effects of application of nitrogen fertilizer on concentrations of P, K, S, Ca, Mg, Na, Cl, Mn, Fe, Cu and Zn in perennial ryegrass/white clover pastures in south-western Victoria, Australia

Effects of timing and rate of N fertilizer application on concentrations of P, K, S, Ca, Mg, Na, Cl, Mn, Fe, Cu and Zn in herbage from perennial ryegrass/white clover pastures were studied at two sites in south-western Victoria, Australia. Nitrogen fertilizer (0, 15, 25, 30, 45 and 60 kg ha^–1) was applied as urea in mid-April, early May, mid-May, early June and mid-June 1996 to pastures grazed by dairy cows. At Site 1, N fertilizer resulted in a linear increase in P, K, S, Mg and Cl concentrations in herbage and a linear decrease in Ca concentration. For all times of application, concentrations of P, K, Ca, Mg and Cl in herbage increased by 0·0048, 0·08, −0·010, 0·0013 and 0·053 g kg^–1 dry matter (DM) per kg N applied respectively. For S concentration, maximum responses occurred in mid-May (0·012 g kg^–1 DM per kg N applied). At Site 2, N fertilizer resulted in a linear increase in P, S and Na concentrations in herbage, a linear decrease in Ca concentration and a curvilinear increase in K and Cl concentration. The maximum responses for P, S and K concentrations in herbage occurred for the N application in mid-June and were 0·015, 0·008 and 0·47 g kg^–1 DM per kg N applied respectively. For Cl concentration, the maximum response occurred for the N application in early June and was 0·225 g kg^–1 DM per kg N applied. Overall, applications of N fertilizer up to 60 kg ha^–1 did not alter herbage mineral concentration to levels that might affect pasture growth or animal health.     

Sodium fertilizer application to pasture. 1. Direct and residual effects on pasture production and composition

Results are given on the effect of sodium (Na) fertilizer applied as NaNO₃ in five application sat 0 (Nil), 32 (Low) or 64 (High) kg Na ha ^-1yr^-1 and the residual effect of sodium chloride(NaCl) fertilizer applied in the previous year on the growth rate and the chemical composition of herbage cut at fortnightly intervals over the grazing season. Na fertilizer at Low and High rates increased herbage Na contents by 20 and 40% respectively. Magnesium (Mg) content in herbage was increased at Low Na fertilizer application rate but there was no difference between the Nil and the High Na treatments. Calcium (Ca) content was increased in proportion to Na fertilizer level. Potassium (K) content of Nil Na herbage exceeded that of Low and High, but there was no effect of treatment on total harvested K yields. The contents of phosphorus (P), sulphur (S), true protein (TP) and modified acid detergent fibre (MADF) in herbage were not affected, but the dry matter digestibility (DMD) was increased with increasing Na fertilizer level. Applying Na fertilizer at the Low and High levels gave similar increases in water-soluble carbohydrates (WSC) and ash contents and decreased crude protein (CP) and non-protein nitrogen (NPN) contents. Net herbage accumulation(fresh and dry weight) was increased by 15 and 26% at the Low and High Na fertilizer application rates respectively. NaCl fertilizer residues from the previous year increased herbage Na, DM, DMD and WSC contents, reduced K contents and did not affect Ca, P, S, CP, TP and NPN contents. Residues from Na fertilizer decreased MADF and ash contents at the Low and High Na application rates. The main and residual effects of Na fertilizer were generally maximal in early season and diminished as the season progressed, with many of the effects eliminated by late season. Proportionally 0·70 of Na applied was recovered in the first two grazing seasons after application. The effects of Na fertilizer on mineral ratios are also described, together with the implications for animal health.     

Lime and phosphorus influence Kennebec potato yield and chemical composition

An experiment conducted in 1970 and 1971 with Kennebec potatoes on a Typic Cryothod near Willow Creek in Alaska compared the effects of seven P rates, with and without lime, on yields and chemical content of foliage and tubers. Each P increment increased plant vigor, foliage and tuber yields, P percentage in both foliage and tubers, K, Ca, and Sr concentration in the foliage and tubers, K, Ca, and Sr concentration in the foliage, and N, P, K, Ca, and Mg uptake by both foliage and tubers. The higher P rates depressed the A1 and Fe concentration in the foliage and the Ba in the tubers. Additions of high rates of P also tended to increase available P in the soil. Lime application decreased soil acidity, increased plant vigor, practically eliminated physiological leaf necrosis, and increased Ca and depressed Mn and Zn concentrations of both foliage and tubers. Lime further depressed the concentrations of A1, Ba, B, Cu, Fe, and Sr in the foliage and the Ba of the tubers. The uptake of N, P, K, Ca, Mg, and Na were also increased with lime applications because yields were greatly increased. Comparison of Ca/Mn and Mn/Fe ratios with those of another researcher (5) suggested a possible Mn toxicity. The concentrations of N and Cr in both foliage and tubers, and the amount of P, K, Na, A1, B, Cu, Fe, and Sr in the tubers were not influenced significantly by lime.     

INTERACTIONS BETWEEN FIRST AND SECOND APPLICATIONS OF FERTILIZER NITROGEN AND IMPLICATIONS IN EFFICIENCY OF NITROGEN USE

DM yield and N uptake data are presented from primary growth and two successive regrowths of perennial ryegrass treated with combinations of three N treatments for the primary growth viz. 0, 50 and 100 kg N/ha (PN) and four N treatments applied for the second growths, viz. 0, 33, 66 and 100 kg N/ha (SN). Primary growth gave a response of 24·2 kg DM/kg applied N to PN50 with only a further l±0 kg DM/kg applied N from the second PN increment. A significant interaction between PN and SN treatments was shown in second growth. The residual DM response to PN was highest at SN0 and reduced as the level of SN was raised. Substantially greater residual responses to PN treatments were shown in the third growth. Third growth DM responses to SN treatments were high. High apparent recovery of fertilizer N reached 111% of primary N where SN66 followed PN50. High available soil N is partly responsible for both high apparent recovery of N and high DM response. The latter appears to be associated with inclusion of growths given no fertilizer N so that the full residual effects of fertilizer N and ‘priming’ of available soil N can be realised.     

The development of response to fertilizer nitrogen in the first regrowth of perennial ryegrass

The experiment was undertaken to examine the interactions between yield responses to secondary applications of fertilizer N and length of regrowth interval following three levels of primary N. A sward of S24 perennial ryegrass received all combinations of three fertilizer treatments, nil, 50, and 100 kg ha^-1 N for primary growth harvested on 21 May and four treatments, nil, 33, 66 and 100 kg ha^-1 N for the second growth harvested 2, 3, 4, 5, 6 or 7 weeks later.
Cubic equations of growth were derived from the yields of dry matter and both the direct response to secondary N and the residual responses to primary N increased as regrowths developed. A positive residual effect to increasing primary N was obtained at the three lower levels of secondary N for weeks 4–7 but a negative response was obtained with the highest level of secondary N. The implications are discussed in terms of target responses and yields and the growth interval required to attain these targets.     

STUDIES OF RESPONSE TO FERTILIZER NITROGEN

The effects of 59, 118 or 177 kg N/ha were measured on 7 occasions from 8 to 57 days after application to a perennial ryegrass sward in terms of changes in composition. The first increase Dt of N significantly raised percentages of CP, non-protein N, K, P, Ca, Na and Mg and significantly depressed percentages of DM, OM and OM digestihility. The second increment of N resulted in a further rise in the percentages of CP, true protein, non-protein N, K, P, Ca, Na and Mg; the percentages of DM and OM were further depressed but OM digestihility was not significantly depressed. Percentages of P and Na showed increased responses for the more mature herbage; while percentage non-protein N showed a more marked response in younger herbage. As herbage matured percentages of OM and Na rose, the latter only from days 16 to 45. All other attributes showed falling percentages to levels which could be inadequate for a 500 kg dairy cow yielding 15 kg milk. CP percentage reached this critical level (1.4% N) at days 37, 45 or 56 given 59, 118 or 177 kg N/ha; P percentage became critically low (< 0.36%) at days 27, 35 or 38, respectively; Mg percentage fell to the critical level (0.12%) at days 23, 35 and 46. Na percentage showed the reverse trend, being deficient (< 0.13%) in the earliest samples and becoming satisfactory from days 23 or 27 at 118 and 177 kg N/ha but it remained inadequate at 59 kg N/ba.     

香草兰营养特性的研究

对海南不同生产水平的香草兰种植园植株的养分调查分析,及Ｎ,Ｐ,Ｋ,Ｃａ,Ｍｇ肥料的盆栽试验,研究香草兰的营养特性。结果表明,香草兰植株养分的吸收量以Ｋ〉Ｃａ〉Ｎ〉Ｍｇ〉Ｐ,叶片以Ｃａ〉Ｋ〉Ｎ〉Ｍｇ〉Ｐ;结果植株养分吸收量Ｎ：Ｐ：Ｋ：Ｃａ：Ｍｇ＝１．００：０．２４,１．３９：１．１８：０．４８,盆栽幼苗Ｎ：Ｐ：Ｋ：Ｃａ：Ｍｇ＝１．００：０．１０：１．３８：１．２３：０．３３;高产园植株Ｃａ,Ｐ含量极     

施肥对番木瓜植株叶柄养分含量的影响

采用L18(37)正交设计,探讨氮、磷、钾、镁、硼肥配施对EksokaⅡ品种番木瓜(Carica papaya Linnaeus)植株叶柄养分含量的影响.结果表明:施氮肥对植株叶柄含氮量的影响最大,其次为施磷、钾和硼肥.施镁肥则影响最小;施氮肥能明显提高叶柄中的含氮量,但当施氮量达35g/株·次时,效果不显著;施磷、钾肥有降低叶柄中含氮量的趋势.施磷肥对植株叶柄含磷量的影响最大,其次为施镁和钾肥,施硼和氮肥的影响最小,磷肥、硼肥施用量与叶柄中含磷量之间无明显的变化规律.施钾和镁肥对植株叶柄含钾量的影响最大.其次为施磷肥,施氮肥和硼肥的影响最小;在施钾肥25～45g/株·次的范围内,能显著提高植株叶柄中的含钾量.施氮和钾肥对植株叶柄含镁量的影响最大,其次为施镁肥和磷肥,施硼肥的影响最小;施氮肥能提高叶柄中的含镁量,但当施氮量达35g/株·次时,增量已不显著;施钾肥有降低叶柄含镁量的趋势,当施肥量达45 g/株·次时,叶柄中的含镁量显著下降.施镁肥对植株叶柄含硼量的影响最大,其次为施磷肥,施氮肥、硼肥和钾肥的影响最小:施磷肥15、25 g/株·次时,叶柄中的含硼量相同,但当施用量达35g/株·次时,叶柄中的含硼量则显著上升.镁肥施用量不宜过大,当施用量≥0.53g/株·次时,会造成叶柄中的氮、磷、钾、镁、硼含量下降.     

氮、磷和钾肥对菜用大豆籽粒产量和主要矿质元素积累的影响

以大豆专用型品种南农9610为材料,研究了温室大棚条件下,氮、磷和钾肥不同肥料水平对菜用大豆籽粒产量和主要矿质元素含量的影响.结果表明:适量增施氮、磷和钾肥均可明显提高大豆籽粒产量,但施肥过多则降低产量.氮肥和磷肥对菜用大豆籽粒中氮有明显促进作用,磷和钾肥对籽粒磷有促进作用,氮、磷、钾肥对籽粒钾含量均具有明显的促进作用,而钾肥对籽粒中氮含量、氮对籽粒中磷含量具有负作用.施氮使籽粒中Mg、Mn和Fe的含量和积累量先上升再下降;而籽粒中Ca则在低氮时大幅度下降,此后逐渐回升;施磷和钾使Mg、Mn、Fe和Ca含量先上升再下降.     

氮磷钾肥对稻米铁、锌、铜、锰、镁、钙含量和产量的影响

 采用田间试验，在四川省西昌市用两个水稻品种研究了氮、磷、钾肥施用量对稻米中铁、锌、铜、锰、镁、钙含量和产量的影响。结果表明，稻米中铁、锌、铜、锰、镁、钙含量均随着施氮量增加先上升后下降，滇屯502的铁、锌、铜、锰、镁、钙含量和产量都以施用90 kg/hm2 N最高，稻谷产量以施用180 kg/hm2 N最高；而合系39的铁、锌、铜、锰、镁、钙的含量以施用180 kg/hm2 N最高，稻谷产量以施用270 kg/hm2 N最高，说明供试籼型品种滇屯502对氮肥的敏感性较粳型品种合系39强；磷肥明显降低了稻米中铁、铜、锰、钙的含量和产量，适量增施磷肥有利于增加稻米中镁的含量和产量；适量施用钾肥有利于提高稻米中铁、锌、铜、锰含量和产量，两供试品种铁、锌、铜、锰含量均以90 kg/hm2 K2O时最高，而钾肥明显降低了稻米中镁、钙的含量和产量。     

云南亚麻高产栽培数学模型研究

本试验研究了亚麻品种阿里安在秋播条件下的密度、氮、磷、钾肥施用量及氮肥施用时期五个主要可控栽培因子与原茎产量之间的效应关系及其数学模型。获取相应的农艺措施；优选出最佳农艺措施：密度2008株／666．7m^2、尿素24．05kg/666．7m^2、普钙39．3kg／666．7m^2、硫酸钾2．7kg/666．7m^2、尿素施用适期是底肥5％、枞形前期25％、枞形末期70％。     

不同品种椰子凋落叶的营养成分分析

测定6个不同品种椰子凋落叶中的营养成分。结果表明,6个品种椰子凋落叶的叶柄中C、N、P、K、Na、Ca、Mg、Mn、Zn营养元素之间差异显著,其中Fe和Cu含量差异不显著;小叶中,C、N、P、K、Na、Ca、Mg、Fe、Mn、Zn营养元素之间差异显著,其中Cu含量差异不显著。同时,小叶中的C、N、Fe、Mn、Zn含量高于叶柄,而叶柄中的P、K、Na、Ca、Mg含量高于小叶。