The productivity and response to inorganic fertilizers of species-rich wetland hay meadows on the Somerset Moors: nitrogen response under hay cutting and aftermath grazing

The productivity and response to fertilizer nitrogen (N) was measured in herb-rich wetland hay meadows within a Site of Special Scientific Interest (SSSI) in Somerset, UK. Output from hay cut after 1 July each year and from beef production at aftermath grazing was measured over a total of 4 years.
Total utilized metabolizable energy (UME) output averaged from 40·6 GJ ha⁻¹ year⁻¹ without fertilizers to 61·7GJha⁻¹ at 200kgNha⁻¹ (N-200), the highest rate used, with about two-thirds of this output from hay. N response was markedly curvilinear above about 50kgN ha⁻¹, but data from a concurrent experiment suggested that the comparatively low replacement rates of P and K applied were limiting at higher N rates. When hay cutting was delayed until early August in a wet year, yield response to N was lost because fertilized swards had passed a peak in yield several weeks before harvest.
Compared with other published data, the results suggest that output and response to N is not constrained by the diversity of the flora or the damp conditions. The data will help to estimate the financial implications for farmers of restricted or zero fertilizer use within SSSIs and the wider Environmentally Sensitive Areas.     

The influence of cutting date and previous fertilizer treatment on the productivity and botanical composition of species-rich hay meadows on the Somerset Levels

The effects on productivity, botanical and chemical composition of cutting species-rich hay meadows in Somerset on four different dates between late May and early September in two consecutive years, were measured. Plots that had received 200 kg N ha⁻¹ year⁻¹ with low levels of P and K for the previous 5 years were compared with plots that had previously received no fertilizer.
Previous fertilizer treatment increased metabolizable energy (ME) production only with cutting in May. Dry-matter (DM) yield increased significantly with date of cutting until August, whereas ME value declined correspondingly. There was no difference in either yield or quality of herbage cut between August and September. ME output per hectare increased very significantly between May and July, but showed no further change between cutting dates.
Botanical diversity was reduced by cutting in May after 1 year and by cutting in either May or September after 2 years, and was greatest with cutting in August. The dominance of Holcus lanatus on previously fertilized plots increased after cutting in either May or September. The contribution to vegetation cover of species that regenerate primarily by seed, including annuals, was greatly influenced by cutting date in preceding years, whereas species that regenerate vegetatively were not affected.     

氮磷钾肥对大豆脂肪含量的效应

采用正交回归旋转设计方法，建立了氮、磷、钾肥对大豆脂肪含量的综合作用模型。根据该模型探讨氮、磷、钾肥对大豆脂肪含量影响的规律。氮、磷、钾肥对大豆脂肪含量的单因素效应、二因素互作效应受到其它因素水平的影响。氮肥对脂肪含量的影响均为增加效应，增加速度随着氮肥编码值增高而加快。磷肥和钾肥对脂肪含量的作用有正有负。获得绥农14号大豆品种21.5%以上的脂肪含量，相应的施肥措施为：施N量为0.07～0.13 g/kg，施P2O5量为0.11～0.37 g/kg，施K2O量为0.04～0.10 g/kg，采用这个比例施肥有95%的可能使大豆品种绥农14的脂肪含量高于21.5%。     

A von Liebig response function to nitrogen and phosphorus for hay production from irrigated pastures

Permanent pasture in the Po Valley of Italy was the site of a pluriannual experiment (1975–81) to observe the effects on hay production of N and P fertilizer applications well above those normally recommended. A split-plot design with a randomized complete block arrangement of the whole-plot factor with 5 levels of N and the subplot factor with 3 levels of P was chosen for the experiment. The maximum rate of N application was 800 kg ha^?1 while the corresponding rate for P was 87.3 kg ha^?1. Principal species in the sward were orchard grass (Dactylis glomerata L.), perennial ryegrass (Lolium perenne L.), common velvetgrass (Holcus lanatus L.) and white clover (Trifolium repens L.). This field was irrigated according to customary techniques during summer months and cut five limes each year. Yields were analysed by means of a response function of the linear and plateau type which incorporates von Liebig's Law of the Minimum, it was found that this function represents the hay response very well with respect to N. In fact, beyond 390 kg ha ^?1 applied N the response is negligible up to 800 kg ha^?1, the maximum rate tested in this experiment. The optimal rate of applied N decreased consistently over the years from 390 to 260 kg ha^?1. At these unusually high levels of fertilization hay production increased about 60–80% compared with normal practices. The estimation of the von Liebig response function requires mathematical programming knowledge. The estimates obtained are maximum likelihood estimates. The practical importance of estimating and using this response function lies in its ability to achieve the maximum response with the minimum amount of fertilizers among all other admissible response functions. Hence, its adoption for making fertilizer recommendations would save farmers money and limit chemical pollution to the environment.     

Effect of nitrogen,phosphorus, and potassium fertilizers on yield components and specific gravity of potatoes

Netted Gem potatoes were grown at four levels of N, three of P, and two of K fertilizer in metal lysimeters protected from rain by an automatic shelter. The first two increments of N fertilizer, 200 and 400lb/acre (224 and 448 kg/ha), successively increased yields by increasing the number of tubers produced. The first increment also increased the average tuber weight. With 800 lb N/acre (896 kg N/ha), tuber yield and grade of potatoes were reduced from those of the 400-lb/acre (448-kg/ha) treatment becuase the average weight per tuber was reduced. P fertilizer increased yield by increasing the average tuber weight. The increased yield due to N and P fertilizers was almost entirely in the form of Canada No. 1 potatoes. K fertilizer did not affect number or weight of tubers in this high-K soil.     

氮磷钾肥施用对甘蓝型春油菜产量及肥料利用效率的影响

利用大田试验研究了氮、磷、钾肥对青海省互助县种植的甘蓝型春油菜产量、养分吸收量和肥料利用效率等指标的影响。结果表明,氮肥和磷肥对春油菜(甘蓝型杂交油菜青杂2号)籽粒产量的提高有显著作用,钾肥的影响相对较小;与不施肥对照相比,氮、磷、钾肥的施用可显著促进成熟期春油菜地上部N、P、K素累积量(P<0.05);不同肥料的春油菜农学利用率分别为5.3kg/kg N、5.6kg/kg P2O5和1.7kg/kg K2O;肥料表观利用率分别为N 33.6%、P2O5 7.8%和K2O 52.0%, N、P、K肥对油菜籽产量的偏生产力分别为28.0kg/kg N、46.7kg/kg P2O5和26kg/kg K2O。青海省互助县种植条件下,当春油菜产量水平在3 504kg/hm2时,NPK配施条件下每生产100kg籽粒需要吸收N、P2O5、K2O量分别为4.6kg、2.0kg和5.6kg,氮磷钾比为1:0.43:1.21。油菜生产实践中实现高产目标需同时关注地力培肥和平衡施肥两方面。     

氮磷钾肥施用对油菜产量及养分吸收利用的影响

为油菜科学施肥提供依据,利用当前推广的6个油菜品种秦优11号（QY11）、中农油2008（ZNY2008）、中油杂11号（ZYZ11）、湘油17（XY17）、浙油601（ZY601）和沪油杂1号（HYZ1）,在大田试验条件下研究了氮、磷、钾肥施用对油菜产量及氮、磷、钾素吸收利用的影响,并比较了不同品种对施肥响应的差异。结果显示,相同施肥处理下不同品种籽粒产量差异显著,不施N（PKB）、不施P（NKB）、不施K（NPB）及NPK全施（NPKB）处理下品种间最大差异分别为385、244、759和720kg/hm2,变异系数分别为18.1%、25.5%、16.4%和11.0%。氮、磷、钾施用可显著提高各品种产量和相应养分积累量,NPKB处理相比PKB、NKB及NPB处理分别增产1 101～2 012、1 681～2 459和293～1 567kg/hm2,N、P、K积累量分别增加63.0～113.2、17.2～23.8和94.1～166.3kg/hm2。不同品种氮、磷、钾肥利用率也存在显著差异。同一品种对氮、磷、钾的响应一致,其中秦优11号对氮、磷、钾肥施用的敏感程度均大于其它品种,湘油17耐低氮、低磷和低钾的能力均高于其它品种。     

The effect of straw mulch on nitrogen,phosphorus and potassium uptake and use in hybrid rice

Paddy and Water Environment - To optimize straw application and understand the effects of straw mulch and straw nutrient release on rice nutrient uptake, we investigated the effects of two types of...     

The effects of nitrogen and phosphorus fertilizer application on herbage yield of natural pastures

This study was carried out in a natural pasture in Van province of Turkey between the years of 2004 and 2005 to determine the effects of nitrogen and phosphorus fertilization on herbage yield. The study was performed in randomized block with three replications. 0, 4, 8, 16 kg da(-1) nitrogen and 0, 6, 12 kg da(-1) phosphorus applications were examined. The effects of different nitrogen and phosphorus fertilizer applications on plant height, green herbage and crude protein yield were significant for both years. Depending on the increasing nitrogen and phosphorus applications, significant increases were in green herbage, hay and crude protein yields. According to results, differences between 8 and 16 kg da(-1) doses of nitrogen and 6 and 12 kg da(-1) doses of phosphorus applications were insignificant. In the first year, in terms of nitrogen applications, the highest green herbage, hay and crude protein yield (1423.1, 263.3 and 29.2 kg da(-1)) were obtained from 8 kg N da(-1), in the second year, the highest values (1426.1, 602.7 and 67.8 kg da(-1)) were obtained from 16 kg N da(-1) application. As for the phosphorus applications, in the first year, the highest green herbage yield was 1142.2 kg da(-1) at the 6 kg P2O5/da application, hay and crude protein yields (218.2, 23.1 kg da(-1)) were recorded from 12 kg P2O5/da application. In the second year, the highest green herbage, hay and crude protein yields were (1335.8, 549.6 and 66.1 kg da(-1)) determined at the 12 kg P2O5/da application.     

The effect of date of primary growth harvest and levels of nitrogen and potassium fertilizers on the dry matter production of timothy (Phleum pratense)

Scots timothy was harvested three times a year for 3 years under four harvesting patterns and at all combinations of three levels of application of nitrogen and four of potassium. Harvesting patterns, H1, H2, H3 and H4, comprised cutting primary growth on 27–29 May or 14, 28 or 42 d later followed by cutting a first regrowth 8 weeks afterwards and a second regrowth on 15–16 October. N treatments, N0, N1 and N2, involved annual totals of 0,108 and 216 kg ha^-1 N in three equal doses. K treatments, K0, K1, K2 and K4, involved annual totals of 0, 54, 108 and 216 kg ha^-1 K also in three equal doses. Mean herbage DM yields in successive years were 8·90, 9·54 and 9·61 t ha^-1 containing92·4%, 93·1% and 94·5% timothy, respectively. Systems H3 and H4 had 24% higher yields than H1 and H2. The superiority of the late systems derived from higher yields of primary growth. Mean response to 108 kg ha^-1 N at 36·7 kg DM per kg N was significantly higher than the response to an additional 108 kg ha^-1 N. Response in primary growth to successive increments of 36 kg ha^-1 N averaged 53·9 and 27·5 kg DM per kg N. The first regrowth gave linear responses up to 72 kg ha^-1 N. The possibility is discussed of more effective use of N by increasing the proportion applied to regrowth. Response to K was low except in the third year when there was a marked response at N2. It was calculated that to maintain soil potash it is necessary to apply 23·9, 47·7 and 86·6 kg ha^-1 fertilizer K for each harvest at N0, N1 and N2 respectively.     

The effect of irrigation rates and nitrogen and phosphorus fertilizers on fiber characteristics of Gossypium hirsutum L. cotton

This article reports the estimated relationships between fiber properties of the Acala 4–42 cultivar and N- and P-fertilizers and irrigation. Increasing water rates in the range of 4200–7200 m³/ha weakened the tensile strength of the fibers and increased their fineness; the regression of maturity, length and uniformity ratio was curvilinear: positive on initial rates and negative on those exceeding 5800 m³/ha. N-fertilizer favorably affected all fiber properties determined: fineness and upper quartile length throughout the rate range tested but strength, mean length and uniformity ratio only up to 250–500 kg ammonium sulfate per ha. The most favorable effect of P-fertilizer was in considerably increasing the length uniformity ratio; it also increased length and fineness but suppressed the maturity index.     

The effect of fertilizer nitrogen rate, white clover variety and closeness of cutting on herbage productivity from perennial ryegrass/white clover swards

Four varieties of white clover (small-leaved cv. Aberystwyth S184. medium-leaved cv. Grasslands Huia and large-leaved cvs Linda and Olwen) were sown at 3 kg ha^-1 together with 10 kg ha^-1 perennial ryegrass cv. Talbot. Herbage productivity was measured for three harvest years, 1979-81, over four annual rates of fertilizer N (0,120,240 and 360 kg ha^-1) and two closeness of cutting treatments (80 and 40 mm from ground level). A simulated grazing regime of six cuts per year at 3- to 6-week intervals was used.
Production of total herbage DM was increased by increasing N rate; mean annual DM production ranged from 783 1 ha^-1 with no N to 11701 ha^-1 at 360 kg ha^-1 N. Mean herbage response to N (kg DM per kg N applied) was 73,90 and 108 for the three successive N increments relative to no N. Mean white clover DM production was reduced from 4 14t ha^-1 with no N to 051 t ha^-1 at 360 kg ha^-1 N.
The large-leaved clover varieties were more productive than the small- or medium-leaved varieties at all N rates. Close cutting increased total herbage and white clover by a mean annual 16% and 31%. respectively. White clover varieties did not interact with either N rate or closeness of cutting.
It is concluded that repetitive N application over the growing season is incompatible with white clover persistence and production, even with large-leaved clover varieties or with close cutting, two factors which improved clover performance in the experimental swards.     

氮磷钾追施对夏大豆产量的影响

氮肥和磷钾肥追施试验表明:适量的氮磷钾肥后移不仅能提高产量,且有一定的经济效益。增产幅度和效益的顺序为:氮肥后移>磷肥后移>钾肥后移。氮肥后移适宜比例为50%左右,宜初花期一次追施或初花期、鼓粒期二次追施;30%以上的磷钾肥可后移至初花期追施。生产上应提倡氮肥后移;在基施磷钾肥不足时,还应追施磷钾肥。     

The effect of nitrogen in cattle slurry and mineral fertilizers on nitrogen fixation by white clover

The influence of N in slurry or in mineral fertilizers on herbage yield and nitrogen fixation by white clover grown in mixed swards was investigated. Two levels of N in cattle slurry were compared with a range of mineral N fertilization. The percentage of N derived from symbiosis (% Nsym) was measured by the ¹⁵N-isotope dilution method. The measurements were made in spring 1987 in two 4-year-old field trials, and included two out of five harvests.
The % N_sym was approximately 90% without N fertilization. It decreased in response to both mineral N and N in slurry but did not fall below 63%. The sum of two harvests revealed that 51·2 kg N ha⁻¹ were fixed in the absence of N fertilization. With 75 kg mineral N ha⁻¹ or 50 m³ cattle slurry ha⁻¹, the yield of fixed N decreased to 17·2 and 24·9 kg ha⁻¹, respectively. When compared on the basis of the fertilizer effect on dry matter yield and N concentration of perennial ryegrass, the decrease in yield of N fixed due to treatment with cattle slurry was less than that due to mineral N fertilizer. This was owing to the smaller extent of the depression in the proportion of white clover in the sward when the same amount of N was applied in cattle slurry, as compared with mineral fertilizer, although % N_sym responded similarly to both types of N fertilization.     

人工生态茶园的机质和氮磷钾动态变化研究

在相同生态条件下，研究了人工生态茶园，密植免耕园，常规栽培园3种主要栽培方式对土壤肥力的影响，结果表明：人工生态茶园方式不仅能提高土壤能力，而且土壤能力有上升和富集向上的趋势，密植免耕栽培方式，土壤肥力也有提高，但较人工生态茶园栽培方式差，常规栽培方式土壤肥力有下降的趋势。     

不同氮磷钾组合搭配对佛手茶产量效应的影响初报

以茶叶目标产量为基础，以氮磷钾肥料不同组合搭配进行L9（3^4）正交试验，结果氮磷钾肥取2：1：1水平为最优化配方组合，处理4（A281C2）、处理6（A283C1）较接近最优化配方组合，但经经济效益分析，只有处理6（A283C1）单产582．00kg／667m^2，纯收入2973．59元／667m^2为最佳组合。由此认为在粘质红壤施肥，应以氮肥为主，配合施用速效磷肥，即尿素32．60kg／667m^2、钙镁磷66.18kg／667m^2、氯化钾7．50kg／667m^2，纯N14．996kg／667m^2，N：P2O5：K2O=1：0．75：013为最佳组合较合理。佛手茶是大叶品种，适量增施氮磷肥，有利于促进新梢的生长而提高产量.