Effects of fertilizer application to grasslands in Greece

Grasslands in Greece are composed of a large variety of plant species, but they have relatively low productivity due to their misuse by domestic animals for thousands of years, and also to soil and climatic factors. Fertilizer application can improve productivity by affecting herbage yield, botanical composition, earliness of spring growth and quality. The application of N and P generally alters species composition and increases dry matter and crude protein yields, while the addition of K is often not effective. Also, NP fertilizer increases the in vitro digestibility while N often decreases P, Ca, Mg and Zn contents of herbage. It appears that Greek grasslands cannot utilize as much N as their temperate counterparts and that their soils are usually deficient in P. This indicates that NP fertilizer is necessary to secure increased yields with P being important in achieving a balanced grass-legume composition in the plant cover.     

Herbage production from swards containing a range of grass, forb and clover species and under extensive management

Three small plot experiments were conducted to investigate the effects of species of grass and forbs, defoliation regime, inclusion of white clover and forb blend on the herbage dry matter (DM) yield, botanical composition and mineral content of swards managed with zero fertilizer inputs. The results of all three experiments were characterized by decline in herbage production and large variations in treatment effects over the harvest period.
When sown singly with a standard grass mix the species that competed well with grasses and produced annual forb herbage yields greater than 20 t DM ha⁻¹ were black knapweed, oxeye daisy, ribwort plantain, burnet, birdsfoot trefoil, chicory, kidney vetch, red clover and white clover. When sown singly with a standard forb mix, grass species significantly affected the annual yield of total ( P <005). grass ( P <001) and forb ( P <0.001) herbage. The species that most surpressed the yield of forbs were common bent, Yorkshire fog and perennial ryegrass. Those that allowed for the highest yield of forbs were rough meadow grass, sweet vernal grass and crested dogstail. Averaged over the three harvest years, defoliation regime did not significantly affect herbage production, but the inclusion of white clover in mixtures increased the yield of grasses ( P <0.01) The use of rosette-type forb blends increased forb yield ( P <0.01), compared with erect-type blends.
The effects of treatments on herbage N and mineral contents and yields were inconsistent. However, there was some evidence to support the view that the presence of forb species in swards can result in greater contents of minerals in herbage, compared with grass-only swards.     

Influence of cutting regime and fertilizer application on the botanical composition,yield and nutritive value of herbage of wet grasslands in Central Europe

The changes in dry matter (DM) yield, botanical composition and nutritive value of herbage to ruminants of two wet grasslands, Arrhenatherum elatius grassland (Experiment 1) and a Molinia caerulea fen meadow (Experiment 2), in which a range of cutting and fertilizer treatments were imposed in 1999, were assessed after 4–7 years of treatment imposition. Both experiments had a split‐plot design with four replicates. In Experiment 1 the three main‐plot cutting treatments were two cuts with a delayed first cut, three cuts and four cuts during the growing season of each year. In Experiment 2 the cutting treatments were two cuts with a traditional harvest time, two cuts with a delayed first cut and three cuts. The four sub‐plot fertilizer treatments were an unfertilized control, application of a phosphorus and potassium (PK) fertilizer, application of a nitrogen (N) and PK fertilizer to the first cut only (N₁PK) and application of PK plus N applied to each of two, three or four cuts (N_c PK). Application of fertilizer influenced yield and botanical composition of herbage more than the cutting treatments while the opposite occurred for nutritive value of the herbage. Application of fertilizer increased the proportion of tall grasses in Experiment 1 and forbs in Experiment 2. The proportion of Equisetum palustre, present only in Experiment 1, was reduced from 0·33 to less than 0·01 by increased cutting frequency together with the NPK fertilizer treatments. In Experiment 1 diversity of vascular plants was negatively affected only by the four‐cuts treatment while on both wet grasslands other cutting and fertilizer application treatments had no effect. Changes in DM yield of herbage caused by the cutting and fertilizer application treatments were similar for both vegetation types with DM yield increased significantly by fertilizer application but only slightly or not reduced by increasing the cutting frequency. Nutritive value of herbage was positively correlated with cutting frequency and was most influenced at the first cut.     

Nutritional quality of semi-arid grassland in western Spain over a 10-year period: changes in chemical composition of grasses, legumes and forbs

From 1987 to 1996, the nutritional quality of the main botanical components (grasses, legumes and forbs) in semi-arid grasslands in the dehesa ecosystem in western Spain was analysed. Herbage samples were collected at the end of spring, in 30 locations, at two different topographic positions (upper and lower slope zones). Herbage mass over 2 cm and proportion of botanical components were estimated and samples were analysed for crude protein, neutral-detergent fibre (NDF), hemicellulose, cellulose, lignin and in vitro dry matter digestibility (DMD). Analysis of variance revealed a significant effect of sampling year on the herbage mass, proportion of botanical components and their nutritional quality. The three botanical groups, grasses, legumes and forbs, followed similar year-to-year trends in their crude protein, cellulose and lignin contents and in vitro DMD. Herbage mass was not significantly related to any meteorological variables, suggesting that interannual variation in biomass production of botanically complex pastures cannot be explained by a single factor. However, annual precipitation was significantly related to the proportion of the botanical group that was dominant at each slope zone: grasses in the lower zone and forbs in the upper zone. In the upper zone, spring precipitation explained part of the interannual variation in the NDF, cellulose, lignin contents and in vitro DMD of the botanical components.     

Botanical composition of permanent grassland in England and Wales in relation to soil, environment and management factors

Grassland in England and Wales accounts for nearly 60% of the enclosed agricultural land and approximately 50% is at least 20 years old. Botanical composition, especially amongst older grassland, is extremely variable.
A survey of 502 grassland farms was conducted in the 1970s. Factors affecting botanical composition of individual fields have been investigated using correlation and regression analyses and swards of similar botanical composition grouped using cluster analysis. Lolium perenne, Agrostis spp. and Holcus lanatus were numerically the most important species, contributing, on average, 35%. 21% and 10%, respectively. Most older swards contained Lolium perenne and Agrostis spp. in varying proportions depending on drainage, soil fertility and management. Swards containing a significant proportion of Trifolium repens were associated with adequate drainage, good soil nutrient status, low inputs of fertilizer nitrogen and hard grazing. Of the other common species Holcus lanatus was associated with poor drainage, low soil fertility, hay cutting, short-season grazing and low fertilizer N. Festuca rubra was mainly in older swards, at higher elevations and with low fertilizer N but heavy stocking. Swards containing Rumex spp., Poa trivialis and other sown grasses were associated with mowing together with reasonably high soil fertility.     

Plant diversity effects on herbage production and compositional changes in New Zealand hill country pastures

A small‐plot field experiment on grazed hill country pastures in the North Island of New Zealand was conducted to examine the productivity and compositional characteristics of swards in response to variation in pasture species diversity. The balanced incomplete factorial design incorporated variation in location, slope, soil fertility and combinations of eight plant functional groups (C₄ grasses, annual grasses, annual legumes, perennial C₃ grasses, perennial legumes, perennial forbs, ryegrass and browntop). Net herbage accumulation and botanical composition were measured at 18 months (spring) and 24 months (autumn) after oversowing following application of a systemic herbicide. Analysis of variance indicated a significant positive relationship between the number of functional groups sown and herbage accumulation of the sown species in spring, but not with total herbage accumulation. Regression analysis showed that herbage accumulation was also affected by the identity of the functional groups. However, the statistical models indicated that pasture productivity was most strongly influenced by site factors. There was a significant negative relationship between both the number and herbage accumulation of unsown species and the number of functional groups sown, indicating a positive relationship between diversity and resistance to invasion by unsown species. A comparison of the vegetation between the plots before and after oversowing showed that those more diverse prior to sowing returned to their initial composition more rapidly, evidence that diverse vegetation was more resilient in the face of disturbance.     

Organic and inorganic fertilization compared in a natural Mediterranean grassland

The effect of goat slurry on species composition and herbage production as compared to inorganic fertilizer was studied in a natural grassland dominated by warm and cool season perennial grasses in Macedonia, Greece. Goat slurry was applied in early spring every 1 or 2 years at a rate of 40 t ha^-1 being equivalent to about 160 kg N ha^-1 and 100 kg, P₂O₅ ha^-1. Inorganic fertilizer was also broadcast in early spring at a rate of 80 kg N ha^-1 and 100 kg P₂O₅ ha^-1 every 2 years. Measurements of the basal cover of the dominant species or groups of species and herbage yields were taken for 6 years at the end of the growing period in June, while in the seventh year the experiment was grazed with goats. It was found that goat slurry improved species composition more than the inorganic fertilizer by depressing the less palatable warm season grasses and favouring the subdominant cool season grasses and legumes. Goat slurry significantly increased herbage yields in most of the years. It is suggested that the optimum rate of goat slurry is 40 t ha^-1 every 2 years as this encourages plants most preferred by goats.     

Frequency of defoliation of native and naturalized species of the Flooding Pampas (Argentina)

This study describes the effect of herbage mass of species on defoliation patterns in a multispecies temperate–subhumid natural grassland of the Flooding Pampas at low, medium and high sward herbage mass [761  ±  8·7, 989  ±  137 and 1591  ±  44·0 kg green dry matter (DM) ha^–1 respectively] maintained by continuous grazing of cattle at variable stocking rates. Four native and naturalized warm-season species were studied: the grasses Cynodon dactylon , Leersia hexandra and Paspalum dilatatum and the legume Lotus tenuis . Sward state of the four species was described in terms of sward surface height, herbage biomass and the number of individual grass tillers and legume stems per unit area. The defoliation pattern was monitored twice-weekly during an experimental period of 3 weeks on permanently marked individual plants. Proportions of individual plants defoliated and the ranking of species selected differed among sward treatments and species. The results showed that the density of the species was a major factor determining the pattern of species defoliation and suggest that, in continuously grazed mixtures, the pattern of defoliation might be more dependent on the abundance of a species in the plant community than on species preferences. The results show the importance of considering this structural characteristic of swards in understanding the process of species selection by large herbivores in multispecies vegetation.     

马铃薯块茎淀粉含量与叶片、茎秆干物率关系的研究

以内薯7号和克新1号原种为试验材料,采用两品种3个施肥处理二裂式裂区试验设计,通过田间试验和室内分析测定,对生育期间马铃薯块茎淀粉含量与叶片、茎秆干物率的关系进行了初步研究,结果表明:马铃薯块茎淀粉含量在块茎形成时便表现出品种特性;块茎淀粉含量与叶片、茎秆干物率呈显著正相关;增施肥料可降低茎秆干物率和块茎淀粉含量,影响马铃薯的加工品质。     

Productivity of mixtures of Italian ryegrass and red clover

Two red clover ( Trifolium pratense ) cultivars, Red Head (tetraploid) and Kuhn (diploid), were sown at a seed rate of 13 kg ha⁻¹ either alone or in mixture with Italian ryegrass ( Lolium multiflorum ) cv. RvP sown at seed rates of 10, 15, 20 or 30 kg ha⁻¹. RvP was also sown alone at a seed rate of 30 kg ha⁻¹ and received nil or 300 kg ha⁻¹ fertilizer a⁻¹ fertilizer N. All plots were established using the barley cultivar Midas sown at a seed rate of 100 kg ha⁻¹ as a nurse crop.
Neither clover cultivar nor ryegrass seed rate significantly influenced either dry matter harvested or botanical composition over the 3 harvest years. On average over all years the grass-clover mixtures produced 75% of the yield of the N-fertilized RvP, 125% of the clover monocultures and 225% of the unfertilized RvP. The red clover contribution to the total dry matter harvested of the mixtures averaged 45–60%. The dry matter concentrations of the mixtures were considerably higher than those of the pure clover stands. In the third year yields were markedly reduced in comparison with those in the first and second years.
It was concluded that Italian ryegrass can be a suitable companion grass for red clover. Its superior yielding capacity over other grasses such as perennial ryegrass or timothy under a conservation management can be coupled to advantage with red clover to give a sward which Is essentially stable, at least over a 2- to 3-year cropping period, although giving slightly reduced yields in the third year. Italian ryegrass-red clover mixtures, without the use of fertilizer N, can produce high DM yields of good quality herbage.     

Comparative studies of the influence of sward conditions on the ingestive behaviour of cows and sheep

Separate groups of non-lactating cows and wether sheep grazed at similar herbage allowances for two successive 5-d periods on swards that had previously been grazed frequently or infrequently with the intention of creating differences in canopy structure. Measurements were made of sward structure and composition, ingestive behaviour and diet composition. The preliminary treatments had little effect upon either sward conditions or animal behaviour.
Herbage mass was reduced from 4020 kg dry matter (DM) ha⁻¹ to 3290 kg DM ha⁻¹ on average over a 5-d grazing period as a consequence of the relatively low grazing pressure imposed. This resulted in a mean decline in intake per bite of 28%, and the changes for cattle and sheep did not differ significantly. However, there was a marked difference in the other behavioural responses of the two species; in the sheep biting rate fell and grazing time increased with declining herbage mass, particularly in the sward previously grazed infrequently, whereas the changes in the cattle were small.
Differences in the botanical composition of the herbage eaten by cattle and sheep were minor, but there was a small but consistent advantage to the sheep in the digestibility of the herbage eaten.
In the first of the two periods the variation in surface height after grazing was substantially greater for sheep-grazed than for cattle-grazed swards, indicating more patchy grazing by the sheep.
Estimates of daily herbage organic matter (OM) intake calculated from ingestive behaviour variables were high (means 38 and 32 g (kg LW) ⁻¹ for cattle and sheep respectively) and usually declined substantially over a grazing period.     

Soil chemical properties,plant species composition,herbage quality,production and nutrient uptake of an alluvial meadow after 45 years of N,P and K application

Little is known about the long-term effects of mineral N, P and K application on the nutritional status of mown alluvial grasslands. We asked how long-term fertilizer application affected soil chemical properties, plant species composition, herbage production, nutrient concentrations in soils and plants and balance of nutrients. Six treatments (control, PK, N50PK, N100PK, N150PK and N200PK) were investigated at the Černíkovice Experiment (Czech Republic) established in 1966 on an Alopecurus pratensis meadow, using annual application rates of 50, 100, 150 and 200 kg N, 40 kg P and 100 kg K ha⁻¹. Data were collected and analysed for 2007, 2008 and 2009. Although fertilizers had been applied over 45 years, differences in soil chemical properties between fertilization treatments were small. The legumes Lathyrus pratensis and Trifolium repens responded highly positively to PK application, and tall grasses, A. pratensis in particular, to NPK application. Herbage quality was high in terms of content of major nutrients, and its chemical properties varied considerably between treatments, cuts and years. Mean annual herbage yield ranged from 6·1 in the control to 9·7 t ha⁻¹ in the N200PK treatment. Herbage production was N-limited in 2007 and 2009, but not in 2008. Seasonal N agronomical efficiency ranged from 4·2 to 22·9 kg of DM herbage per kg of applied N. The herbage N:P and N:K ratios did not reflect the actual response of herbage production to N application. A negative balance between N applied and N removed in harvested herbage was recorded in all treatments. We concluded that in highly productive alluvial grasslands, mineral-rich soils can respond weakly to N, P and K application, fertilizer application modifies plant species composition and herbage production is not N-limited in all years. Nutrient ratios must be interpreted with caution for the estimation of nutrient limitation.     

THE SIMULATION OF ANIMAL RETURNS IN GRASSLAND EXPERIMENTATION

An experiment was carried out on a grass/white-clover sward at North Wyke to evaluate the use of mixtures of inorganic and organic nutrient sources to simulate the nutrient effect of animal excreta, both with and without overall PK fertilizer. Grazing with sheep and the return of excreta from caged sheep both increased herbage yields, as did artificial return treatments. Artificial return treatments giving 75% of the nutrient level returned by excreta gave yields comparable with grazing. The effect of the simulated return treatments was not influenced by PK application. Grazing gave a very different botanical composition to that from the treatments in wbich natural or simulated excreta were returned to cut swards. Mixtures simulating excreta may replace the nutrient effect of the grazing animal, but not its physical effect, in some forms of grassland experimentation. They are not recommended for fertilizer trials.     

Operational nitrogen fertilizer management in dairy farming systems: identification of criteria and derivation of fertilizer application rates

Fertilizer‐nitrogen (N) management is a decisive factor in grass‐based, intensive dairy farming, as it strongly influences economic and environmental performance but little attention has been paid to providing guidance on N‐fertilizer management at an operational level to meet these criteria of performance. Essential criteria in operational N‐fertilizer management were identified as target dry matter (DM) yield of herbage, growth period per cut, herbage N concentration, N use efficiency (NUE), amounts of unrecovered N and marginal N response. Statistical relationships between fertilizer‐N application rates per cut and these criteria were derived from field experiments. These relationships were then used to explore the effects of the criteria on optimum fertilizer‐N applications. Optimum fertilizer‐N rates depended strongly on target levels for NUE, amounts of unrecovered N, growth period and DM yield of herbage. Calculations showed that target DM yield of herbage and growth period per cut are essential in estimating the effect of applied N on marginal N response, NUE and amounts of unrecovered N. The derived relationships can be used to explore the effects of changes in target levels of the criteria on optimum fertilizer‐N applications. The study showed that operational fertilizer‐N management set constraints to the decisions made at strategic and tactical management levels and vice versa.     

Effects of pasture management and fertilizer regimes on botanical changes in species‐rich mountain calcareous grassland in Central Europe

A 3‐year experiment was conducted in Central Europe to examine the effects of three managements, viz. continuous cattle grazing from April to September, mowing once in July and abandonment of grazing, and two levels of fertilizer application, no fertilizer and 400 kg ha^?1 of a NPK fertilizer, on changes in plant species composition and summer biomass of dry matter (DM) in a calcareous mountain grassland containing many plant functional types. Different managements led to changes in species composition due to species‐specific responses. Low creeping and rosette species were associated with grazing, while grasses and tall forbs correlated with mowing and abandonment of grazing, probably because of their ability to outcompete rosette species. There was a negative relationship between the number of species and above‐ground biomass and a positive relationship between number of species and below‐ground biomass, suggesting that these species‐rich communities allocate more to below‐ground organs when not grazed. The application of fertilizer had no effect on species composition but it indirectly increased competitive asymmetry for light and increased the number of plant extinctions. It is concluded that continuation of cattle grazing is an acceptable form of grassland management at the study site and that species and functional group compositions can rapidly change with changing environmental conditions such as abandonment of grazing or application of fertilizer.     

Effect of humic substances on nutrient uptake by herbage and on production and nutritive value of herbage from sown grass pastures

The effect of humic substances on the nutrient uptake, herbage production and nutritive value of herbage from sown grass pastures was studied in six field experiments. Commercial humic substances were applied in combination with mineral fertilizer or slurry, either as a solution (HF liquid; 8·3 kg humic substances ha⁻¹) or incorporated into the mineral fertilizer (HF incorporated; 3·6 to 6·4 kg humic substances ha⁻¹). A series of cuts, ranging from two to five cuts, was taken during the growing season. The general response in herbage production to application of humic substances was an increase in herbage mass of dry matter (DM) at the first cut although this was only significant in two experiments for the HF incorporated treatment. Total herbage production of DM over the growing season, however, was similar for treatments with or without application of humic substances. The overall effect of HF incorporated and HF liquid on the herbage mass of DM at the first cut across the experiments was calculated using a meta-analysis technique and it was shown that there was a significant proportional increase of 0·14 ( P  <   0·05) with the HF incorporated treatment and a non-significant increase of 0·08 with the HF liquid treatment compared to the control treatment. The nutritive value of the herbage at the first cut was similar across all treatments. In general nitrogen, phosphorus and potassium uptake at the first grass cut was higher after application of humic substances but only in one experiment was this increase statistically significant.     

叶面喷施调节肥对寒地水稻生长及产量形成的影响

以水稻空育131(主茎11叶)为材料,通过叶面喷施调节肥,比较了不同处理之间水稻生长及产量形成的差异,确定了适宜的调节肥施用量及喷叶期。结果表明:调节肥叶喷施用量为整个生育期氮肥用量的10%和15%更有利于提高水稻成穗率和增加平方米茎数,其中15%施用量对各节间长度的配比效果最佳;3个处理均显著提高了抽穗后15～20 d干物质积累量,其中6.1～6.5叶期喷干物质积累为最多,8.1～8.5叶期喷次之。     

钼肥对套作大豆干物质积累与分配及产量的影响

在"玉/豆"套作模式下,采用完全随机区组设计,研究钼肥干拌种对套作大豆干物质积累、分配及产量的影响。结果表明,五节期(V5)到完熟期(R8)套作大豆干物质积累总量随施钼量的增加呈先升高后降低的趋势,且都以B2(1.0g/kg)处理最高;V5期到盛花期(R2)干物质主要分配在茎秆和叶片中,钼肥处理降低了干物质在茎秆中的分配率,而增加了叶片的分配比例;R8期时干物质向荚果的分配比例最高,且随施钼量增加呈先增加后减少的趋势,而向茎秆和叶片的分配则表现为相反的趋势;施钼肥能够提高茎叶中的干物质向荚果的转移率及其对荚果的贡献率和产量,且均以B2处理最优。     

高产春大豆干物质积累与花荚形成的关系研究

为探明高产春大豆花荚期干物质积累与花荚形成的关系,田间随机区组排列法研究10个高产大豆品种(系)的花期、花荚期干物质增量分别与开花数、成荚数、产量的关系。结果表明,产量在4 527.4～5 734.2 kg·hm^-2的范围内,花期干物质增量与产量相关不显著,花荚期干物质增量与产量呈极显著正相关,总花数、总荚数均与产量呈显著正相关;花期干物质增量与开花数呈二次曲线关系,Y_1=-0.050 3X■+42.285X_1-5 312.2,R^2=0.673 9~*;花荚期的干物质增量与成荚数呈线性关系,Y_2=0.090 4X_5+419.47,R^2=0.719 4^**;开花期叶片干物质增量与开花数呈二次曲线关系,花荚期茎秆、叶片、叶柄干物质增量与成荚数均呈二次曲线关系。花期和花荚期过少或过多茎叶干物质积累量均不利于花、荚形成。花期茎叶稳健生长,荚期荚快速生长有利于增加开花数、成荚数。在花期、花荚期地上部干物质增量分别为4 373,7 801 kg·hm^-2、荚干重占33.8%,总花数为3 773.3×10~4朵·hm^-2、总荚数为1 127.3×10~4个·hm^-2,产量可达5 734.2 kg·hm^-2,其干物质成花效率、成荚效率依次为8.63朵·g^-1、1.45个·g^-1。     

Seasonal dynamics of biomass production and herbage quality of three grasslands with contrasting functional compositions

Classifying grasses into plant functional types (PFT) according to their strategy of nutrient capture (PFT A, B and b) or nutrient conservation (PFT C) is claimed to predict variability in biomass production and herbage quality in grasslands. PFT A, B and b are characterized by higher production than PFT C, with higher nutritive value, which decreases rapidly. PFT C is characterized by lower nutritive value, which remains more stable in time. The aim of this study was to quantify the consequences of PFT composition at the community level on the seasonal dynamics of biomass and herbage quality for livestock feed. We studied three grasslands located in the same area with contrasting PFT composition and classified PFT A, PFT Bb and PFT C. The dynamics of vegetation stages, dry‐matter yield and nutritive value were followed over three vegetation cycles in 2007–2008. In the first cycle, biomass accumulation was high for the PFT A and PFT Bb grasslands and the high quality of herbage declined rapidly with the reproductive development. By contrast, biomass accumulation was slow in the PFT C grassland, with a lower quality that declined slowly, consistent with the later reproductive development. For regrowth cycles, the same ranking of grasslands was observed for biomass accumulation, and differences in digestibility were similar to those observed at the beginning of the first vegetation cycle. Combining type of grassland with sum of temperature for the first cycle and regrowth days for the second and third vegetation cycles provided quantitative models of herbage biomass and quality.