Sodium Fertilizer Research Articles

The double-edged sword of potassium and sodium fertilization in xylem embolism resistance of two Eucalyptus species under drought stress.

Sodium (Na+) is a beneficial element for most plants and may replace potassium (K+) in osmoregulatory process to a certain extent, increasing plant water use efficiency. Thus, understanding coordinated mechanisms underlying the combined use of K+ and Na+ in tree drought tolerance is a key challenge for forestry in dealing with productivity and water limitations. A pot experiment with three ratios of K/Na (K-supplied, partial K replacement by Na, and K-deficient plants) and two water regimes, well-watered (W+) and water-stressed (W-), was conducted on saplings of two Eucalyptus species with contrasting drought sensitivities. We evaluated the point of stomatal closure (Pgs90), xylem water potential at 12, 50, and 88% embolized xylem area (P12, P50, P88), hydraulic safety margin, leaf gas exchange (A, E, gs, and dark respiration), pre-dawn and midday leaf water potential (ΨPD and ΨMD), long-term water use efficiency (WUEL) and total dry mass. Partial K replacement by Na increased leaf gas exchange, WUEL, and total dry mass, while Pgs90, P12, P50, P88, and ΨMD decreased (were more negative), compared with plants exclusively supplied with K and K-deficient plants of both species. Fertilized plants had narrower hydraulic safety margins than K-deficient plants, indicating that these Eucalyptus species adopt the functional adaptive strategy of operating close to their hydraulic limits to maximize carbon uptake while increasing the risk of hydraulic failure under drought stress.

Groundwater hydrochemical signatures, nitrate sources, and potential health risks in a typical karst catchment of North China using hydrochemistry and multiple stable isotopes.

Nitrate pollution in aquatic ecosystems has received growing concern, particularly in fragile karst basins. In this study, hydrochemical compositions, multiple stable isotopes (δ2H-H2O, δ18Ο-Η2Ο, δ15Ν-ΝΟ3-, and δ18Ο-ΝΟ3-), and Bayesian stable isotope mixing model (MixSIAR) were applied to elucidate nitrate pollution sources in groundwater of the Yangzhuang Basin. The Durov diagram identified the dominant groundwater chemical face as Ca-HCO3 type. The NO3- concentration ranged from 10.89 to 90.45mg/L (average 47.34mg/L), showing an increasing trend from the upstream forest and grassland to the downstream agricultural dominant area. It is worth noting that 47.2% of groundwater samples exceeded the NO3- threshold value of 50mg/L for drinking water recommended by the World Health Organization. The relationship between NO3-/Cl- and Cl- ratios suggested that most groundwater samples were located in nitrate mixed endmember from agricultural input, soil organic nitrogen, and manure & sewage. The Self-Organizing Map (SOM) and Pearson correlations analysis further indicated that the application of calcium fertilizer, sodium fertilizer, and livestock and poultry excrement in farmland elevated NO3- level in groundwater. The output results of the MixSIAR model showed that the primary sources of NO3- in groundwater were soil organic nitrogen (55.3%), followed by chemical fertilizers (28.5%), sewage & manure (12.7%), and atmospheric deposition (3.4%). Microbial nitrification was a dominant nitrogen conversion pathway elevating NO3- levels in groundwater, while the denitrification can be neglectable across the study area. The human health risk assessment (HHRA) model identified that about 88.9%, 77.8%, 72.2%, and 50.0% of groundwater samples posing nitrate's non-carcinogenic health hazards (HQ > 1) through oral intake for infants, children, females, and males, respectively. The findings of this study can offer useful biogeochemical information on nitrogen pollution in karst groundwater to support sustainable groundwater management in similar human-affected karst regions.

Influence of fertilization and water deficit on the density and anatomical characteristics of eucalyptus grandis wood

The expansion of plantations may be compromised by climate change, altering the frequency and intensity of precipitation. This study aimed to evaluate the influence of potassium and sodium fertilization and water deficit on the apparent density property and anatomical characteristics of Eucalyptus grandis wood. Six treatments varying in fertilization and rainfall incidence were evaluated. Apparent density testing was conducted via X-ray, while the anatomical features of fibers and vessels were examined through image analysis using a polarized light microscope. Cartography was also performed to map the density variation along the trunk in longitudinal and radial directions. Trees without fertilization exhibited higher apparent density, whereas those with partial rain exclusion displayed less homogeneous wood. Overall, treatments involving potassium and sodium showed no significant difference between them and resulted in a thinner secondary wall. The results indicate that water deficit and fertilization methods significantly impact wood properties.

Distinct leaf transcriptomic response of water deficient Eucalyptus grandis submitted to potassium and sodium fertilization.

While potassium fertilization increases growth yield in Brazilian eucalyptus plantations, it could also increase water requirements, making trees more vulnerable to drought. Sodium fertilization, which has been shown to promote eucalyptus growth compared to K-deficient trees, could partially mitigate this adverse effect of potassium. However, little is known about the influence of K and Na fertilization on the tree metabolic response to water deficit. The aim of the present study was thus to analyze the transcriptome of leaves sampled from Eucalyptus grandis trees subjected to 37% rainfall reduction, and fertilized with potassium (K), sodium (Na), compared to control trees (C). The multifactorial experiment was set up in a field with a throughfall exclusion system. Transcriptomic analysis was performed on leaves from two-year-old trees, and data analyzed using multifactorial statistical analysis and weighted gene co-expression network analysis (WGCNA). Significant sets of genes were seen to respond to rainfall reduction, in interaction with K or Na fertilization, or to fertilization only (regardless of the water supply regime). The genes were involved in stress signaling, primary and secondary metabolism, secondary cell wall formation and photosynthetic activity. Our focus on key genes related to cation transporters and aquaporins highlighted specific regulation of ion homeostasis, and plant adjustment to water deficit. While water availability significantly affects the transcriptomic response of eucalyptus species, this study points out that the transcriptomic response is highly dependent on the fertilization regime. Our study is based on the first large-scale field trial in a tropical region, specifically designed to study the interaction between water availability and nutrition in eucalyptus. To our knowledge, this is the first global transcriptomic analysis to compare the influence of K and Na fertilization on tree adaptive traits in water deficit conditions.

Effects of potassium/sodium fertilization and throughfall exclusion on growth patterns of Eucalyptus grandis W. Hill ex Maiden during extreme drought periods

In Brazil, most Eucalyptus plantations are located in regions experiencing periods of water shortage where fertilizers are intensively used to achieve high productivity. Fertilization can affect water use. However, the effects of fertilization on tree growth patterns during extreme droughts periods remain unknown. A throughfall exclusion experiment was set up in Sao Paulo State-Brazil to study the effects of potassium (K) and sodium (Na) fertilization and their interaction with water supply in the growth of Eucalyptus grandis trees over an abnormal season of 6 months of extreme drought in comparison with that in normal seasons, as well as the differences in responsiveness to intra-annual meteorological variability. Arranged in a split-plot design, the factors were water supply (37% throughfall exclusion vs. no throughfall exclusion) and fertilization regime (K, Na, and control). Basal area growth was monitored by band dendrometers measurements at 14-day intervals over 2 years. Meteorological and soil water content data were also collected. K and Na fertilization increased the tree basal area by four and three-fold, respectively, during normal seasons. During a severe drought season, these positive effects were suppressed. However, K- and Na-fertilized trees achieved a similar cumulative basal area increment to that of the control trees. The 37% throughfall exclusion significantly decreased tree growth in all treatments only in the severe drought period, and these effects were stronger in K-fertilized trees. K-fertilized trees were highly responsive to intra-annual meteorological variability. Our results suggest that extreme drought has similar effects on E. grandis tree growth regardless of the K/Na fertilization regime.

Влияние сидерального удобрения в последействии на урожайность и качество зерна ячменя

Влияние сидерального удобрения в последействии на урожайность и качество зерна ячменя

Sodium fertilization increases termites and enhances decomposition in an Amazonian forest.

Added Na was used to determine whether litter decomposition and associated fungal biomass and termites are limited by Na availability in a lowland tropical rainforest at Yasuni, Ecuador. This is a partial test of the "sodium ecosystem respiration" (SER) hypothesis that posits Na is critical for consumers but not plants, that Na shortfall is more likely on highly weathered soils inland from oceanic aerosols, and that this shortfall results in decreased decomposer activity. We fertilized 4 x 4 m plots twice a month for a year with quantities of Na comparable to those falling on a coastal tropical rainforest. Decomposition rates of four substrates were consistently higher on +NaCl plots by up to 70% for cellulose, and 78%, 68%, and 29% for three woods of increasing percentage lignin. The density of termite workers averaged 17-fold higher on +NaCl plots; fungal biomass failed to differ. After controlling for temperature and precipitation, which co-limit gross primay productivity (GPP) and ecosystem respiration (ER), these results suggest that Na shortfall is an agent enhancing the storage of coarse woody debris in inland tropical forests.

Sodium as an element increasing nitrogen productivity – a case study on sugar beet

The objective of the study was to evaluate the effect of sodium-enriched nitrogen fertilizers against the background of pre-sowing sodium fertilization on sugar beet productivity, including technological quality of taproots. A field experiment, completed in 2001-2003, consisted of two main factors: (i) pre-sowing sodium application (0, 30 kg Na ha–1 in the form of NaCl), (ii) a set of nitrogen fertilizing variants, composed of two sub-levels: one consisting of four nitrogen rates (0, 90, 120, 150 kg N ha –1 ) and the other one comprising three chemical N fertilizer forms [(i) ammonium nitrate, 34%, AN, (ii) mixture of ammonium and sodium nitrates, 26%N + 6% Na (ASN1), (iii) mixture of ammonium and sodium nitrates, 21%N + 13% Na (ASN2)]. Depending on a nitrogen rate, the fertilizers were applied on two or three dates. The first N rate was applied only as ammonium nitrate. The in-season application of nitrogen and sodium as the 2 nd and the 3 rd rate of nitrogen allowed for discrimination of sodium rates, ranging from 0 to 44.2 kg Na ha –1 . The effect of soil applied sodium was significant in the 2nd and 3rd year of study. The highest yields of taproots and sugar, despite changeable weather conditions, were harvested on the 120 kg N ha –1 treated plot. The response of sugar beet plants to in-season applied sodium was varied and depended on soil available sodium content and the course of weather during the growing season. The strongest response occurred in 2003, characterized by both the lowest amount of available soil sodium and shortage of water. The necessity of sodium application, as a nutritional factor increasing yields of taproots and sugar, was clearly demonstrable under low soil sodium content (< 5 mg kg –1 soil). Then, the optimum rate of in-season applied Na in the form of ASN1 ranged from 14.8 to 29.5 kg Na ha –1 . The available sodium content, from 10 to 12 mg kg –1 soil, defined the upper limit of sodium fertilizer application. At that sodium fertility level, 7.4 kg Na ha–1 should not be exceeded. The highest unit N productivity, as attributed to the 90 kg N ha –1 treatment, responded positidr hab. Przemys³aw Bar³og, Chair of Agricultural Chemistry and Environmental

Effects of sodium and sulphur fertilisers on the concentrations of nitrate and potentially toxic elements (PTEs) in water leached from permanent pasture

AbstractThe concentrations of nitrate and potentially toxic elements (PTEs) are reported in water leached from a perennial ryegrass pasture to which isonitrogenous quantities of sodium nitrate, ammonium nitrate or ammonium sulphate fertilisers had been applied in an experiment lasting 2 years. The experimental design allowed a comparison of the immediate effects of sodium nitrate in the grazing season in which the fertiliser was applied with the residual effects of applying it in the previous year. Leachate composition was monitored from December of the first year to August of the second year. Sodium fertiliser reduced the concentrations of cadmium in soil and leachate, but it increased lead concentration in soil and reduced it in leachate. Sulphur fertiliser had no effect on any PTE. Nitrate concentration in leachate increased towards the end of the winter to almost reach the EU legal limit in water and then declined during the spring and summer. Sodium fertiliser applied in either but not both years reduced nitrate concentration. Sulphur fertiliser had varied effects on nitrate concentration in leachate depending on the timing of sodium fertiliser application. When applied at the same time as sodium fertiliser, sulphur fertiliser decreased nitrate concentration, but when applied to areas that had received sodium fertiliser in the previous year, it increased nitrate concentration. It is suggested that sodium fertiliser residues may have long‐term effects on leachate nitrate concentration that determine the impact of sulphur fertilisers. It is concluded that sodium fertilisers may reduce the concentrations of at least two PTEs, cadmium and lead, in ground water and that the effects of sulphur fertilisers are dependent on the sodium status of the soil.© 2002 Society of Chemical Industry

Effects of applying sodium and sulphur fertilisers on the concentrations of elements in water leached from permanent pasture

AbstractThe element composition of water leached from a perennial ryegrass pasture to which isonitrogenous quantities of sodium nitrate, ammonium nitrate or ammonium sulphate fertilisers had been applied in an experiment lasting 2 years is described. The experimental design also allowed a comparison of the immediate effects of sodium nitrate in the grazing season in which the fertiliser was applied with the residual effects of applying it in the previous year. Applying sodium fertiliser in either 1992 or 1993, but not both years, increased the concentrations of sodium, potassium, magnesium, calcium and cobalt and reduced those of phosphorus and molybdenum in leachate. The application of sulphur fertiliser reduced the concentrations of zinc, copper, iron and molybdenum in leachate. It also reduced the concentrations of sodium, potassium and magnesium, but only when sodium fertiliser was applied in 1992, and not when it was applied in 1993. It is concluded that sulphur fertiliser reduces the leaching of trace elements from the soil and that, in the long term, sodium fertiliser can amplify the effect of applying sulphur fertiliser. Sodium fertiliser in moderate quantities increased the leaching of the major divalent cations but reduced the phosphorus and molybdenum concentrations in leachate.© 2002 Society of Chemical Industry

The Effect of Applying Sodium Fertilizer on the Rate of Digestion of Perennial Ryegrass and White Clover Incubated in Rumen Liquor, with Implications for Ruminal Tympany in Cattle

A high herbage K:Na ratio increases the risk of ruminal tympany in cattle, which may relate to digestion rate. Experiment 1 examined whether in vitro digestibility of ryegrass was affected by NaCl fertilizer or by Na concentration in artificial saliva. Fertilizer Na increased grass digestibility, but Na in artificial saliva decreased it, probably due to the energy cost of sodium exclusion from bacteria. Increased herbage digestibility with fertilizer Na is therefore not due to additional Na, but may relate to increased water-soluble carbohydrates.Experiment 2 examined whether NaCl fertilizer applied at 35 or 70 kg Na ha−1to ryegrass and white clover affected in vitro gas production. Sodium fertilizer increased maximum gas output from grass and rate of production, confirming the increase in grass digestibility recorded previously, but in clover it had the opposite effect, thereby potentially reducing ruminal tympany in cows fed a high legume diet.

Sodium fertilizer application to pasture. 10. A comparison of the responses of dairy cows with high and low milk yield potential

Current recommendations for the intake of sodium of lactating dairy cows are related to milk yield. A study was conducted to compare the responses of cows of high and low milk production potential to the application of sodium fertilizer to grazed perennial ryegrass pasture. The application of sodium fertilizer increased the intake of herbage dry matter (DM), the time that cows spent grazing and the biting rate. It also increased the concentration of sodium, magnesium and calcium in herbage and decreased the concentration of potassium. Applying sodium fertilizer increased milk yield and milk fat concentration and decreased somatic cell count in the milk of cows of low‐production potential only, whereas it increased persistency of milk production in the cows of high‐production potential. The concentration of lactose in milk increased in both groups after the application of sodium fertilizer. It is concluded that the optimum dietary sodium concentration for grazing cows does not increase with milk yield, and that most immediate advantage will be gained from increasing the sodium concentration in herbage for low‐yielding cows.

Effects of sodium fertilizers and supplements on milk production and mammary gland health.

A series of experiments was conducted to investigate the effects of sodium fertilizers and supplements on the milk production and mammary health of dairy cows. In Expt 1, where sodium fertilizer was applied to productive pastures consisting mainly of the natrophile perennial rye-grass, the herbage sodium content and the milk yield of cows was increased and milk somatic cell count (SCC) reduced. In Expt 2, which used pastures containing less productive, natrophobic grasses and broad-leaved plants in Estonia, sodium fertilizer did not increase herbage sodium content and did not affect milk production or composition. In Expt 3 the sodium content of the diet of individually tethered cows was increased from 1 to either 6 or 11 g/kg dry matter (DM) by adding salt to their restricted feed allowance, and the cows' milk yield was increased by the high level of sodium supplement and milk SCC were reduced by both levels of sodium supplement. The calcium and magnesium status of cows was improved by the sodium supplement. In Expt 4 a low level of supplementary salt was included in the ration of tethered cows to increase the sodium content of the diet from 2 to 3.6 g/kg DM. No effects on milk yield or SCC were found, but the sodium supplement reduced Staphylococcus aureus contamination of the milk, but not the proportion of milk samples infected with Escherichia coli. It was concluded that the optimum dietary sodium concentration for maximum milk yield was greater than the published requirements, and that substantial increases in sodium intake above current requirements also reduced milk SCC.

A comparison of the responses of dairy cows with high and low milk yield potential to the application of sodium fertilizer

Tabulated sodium requirements of dairy cows, such as those of the Agricultural Research Council (ARC, 1980), are all based on milk yield. The principle for this is the apparent homeostatic control of sodium concentration in the milk of cattle, with sodium loss in milk being approximately proportional to milk yield. However, there is evidence that low yielding cows respond more than high-yielding cows to a sodium supplement when grazing lucerne with a low sodium content (Joyce and Brunswick, 1975), and the present study therefore investigated the effect of dairy cow milk yield potential on the response to the application of a fertilizer containing sodium.

Sodium fertilizer application to pasture. 9. The effects of combined or separate applications of sodium and sulphur fertilizers on herbage composition and dairy cow production

An experiment was conducted to examine the response of herbage grazed by dairy cows to sodium fertilizer applied with or without sulphur fertilizer. The residual effects of applying sodium fertilizer in the previous year were also evaluated. The application of sodium or sulphur fertilizer did not affect herbage growth or height, but the application of sulphur fertilizer increased crude protein content of herbage. The increase in sodium content with application of sodium fertilizer was small, but was greater when sodium fertilizer had also been applied in the previous year. Herbage potassium was increased when sodium fertilizer was applied in the year of the experiment, but only if sodium had not been applied in the previous year. Application of sulphur fertilizer increased herbage sulphur content and reduced the contents of boron, chromium, molybdenum and nickel. Cows grazing pasture that had received sodium fertilizer had increased milk yields and the content of lactose in milk, whereas those grazing pasture that had received sulphur fertilizer application had reduced milk yields and the content of milk fat.

Sodium fertilizer application to pasture. 8. Turnover and defoliation of leaf tissue

The effects of application of sodium fertilizer on the turnover and defoliation of leaf tissue were investigated in a perennial ryegrass (Lolium perenne) pasture grazed by dairy cows. Eight plots were allocated to treatments either with or without sodium fertilizer, with the former receiving 32 kg Na ha–1 applied in five applications of NaNO3 over the grazing season. An equivalent amount of nitrogen was given to the controls as ammonium nitrate, the application of which was reduced in the sodium treatment to equate nitrogen fertilizer applications for the two treatments. In nine periods between April and September, marked tillers were recorded to measure leaf turnover, leaf lamina growth and specific leaf weight and, when combined with tiller density measurements, gave an estimate of herbage flux for the sward. The defoliation and net growth of the marked tillers were monitored at 3‐day intervals and the data were combined with tiller density and specific leaf weight data to determine the intake of the expanding, penultimate and oldest live leaf laminae. Sodium fertilizer application did not affect the rate at which leaves appeared, but it retarded their rate of disappearance. The extension rate and the specific weight of green laminae were both increased by sodium fertilizer application and therefore the net gravimetric growth rate was increased. Tiller density was not affected by sodium fertilizer application and hence the estimated herbage growth and net herbage flux were increased by sodium fertilizer application. Application of sodium fertilizer did not affect lamina length, and in both treatments the penultimate laminae were approximately twice as long as expanding and oldest live laminae. Defoliation frequency decreased from the expanding to the oldest live laminae in the control treatment without sodium. Sodium fertilizer application increased the frequency of defoliation of the oldest live leaf and also increased the length of the expanding leaf that was defoliated. For penultimate leaf laminae sodium fertilizer application reduced the defoliation frequency and length of foliage grazed. The dry‐matter (DM) intake of the oldest live laminae was increased by the application of sodium fertilizer. It is concluded that sodium fertilizer application increases net herbage growth both by increased extension rate of leaf laminae and specific leaf weight and by delayed laminae senescence, and that it increases herbage DM intake by increasing the defoliation frequency of the oldest live leaf laminae.

Effects of sodium fertiliser on the distribution of trace elements, toxic metals and water-soluble carbohydrates in grass and clover fractions

The distribution of trace elements, toxic metals and water-soluble carbohydrates was examined in the leaves, stems and inflorescences of perennial ryegrass and white clover, with and without sodium fertiliser. Copper and manganese were observed in both species to concentrate in the leaves and stems and iron and molybdenum in the leaves. In clover, nickel concentrated in the inflorescence. Differences in mineral concentrations between fractions were related to the mobility of the metal and its function in the plant. Sodium fertiliser approximately doubled the cadmium content of the leaves, stems and inflorescences of both species, reflecting cadmium mobilisation from the soil. The sodium fertiliser also reduced the zinc, copper, manganese and iron contents of grass but not clover and increased the molybdenum content of clover but not grass. Water-soluble carbohydrates were increased by sodium in grass but decreased in clover. Differences between the two species appeared to relate to nitrogen fixation by clover but not grass. © 1999 Society of Chemical Industry

The effects of mild water stress and soil type on the responses of grass and clover to sodium fertilizer

The effect of mild water stress on the response of herbage grown in sandy or loam soils to sodium nitrate fertilizer has been investigated. Sodium nitrate was applied at the equivalent of 32 kg Na ha−1 to perennial ryegrass and white clover grown in pots with sand, loam and mixed soils and irrigated daily. One half of the pots were subjected to water stress by withholding irrigation water for three days each week. Water stress reduced herbage yield but did not affect the response to sodium fertilizer, except that the ash concentration of grass was increased only when water stress was applied as well as sodium fertilizer. The sodium fertilizer increased herbage sodium concentrations and decreased calcium and magnesium concentrations. It also increased the potassium concentration in clover and in herbage grown in sandy but not loam or mixed soils. Clover and grass had similar sodium and magnesium concentration, but clover contained more nitrogen, potassium and calcium than grass. Therefore, under the conditions of this experiment, the increase in herbage sodium concentration with sodium fertilizer was consistent and not affected by water stress, soil type or herbage species. Changes in herbage potassium concentration, however, were inconsistent, which detracts from the value of sodium fertilizer for reducing hypomagnesaemia in ruminants. © 1999 Society of Chemical Industry

The effects of sodium and potassium fertilizers on the grazing behaviour of dairy cows

Sodium fertilizer has been observed to increase the grazing time of dairy cows kept on pastures of restricted availability, but it is unclear whether this is a behavioural response to changes in pasture composition or whether it is an indirect effect of a reduction in herbage availability caused by increased cow production and appetite. Sodium fertilizer was applied in an experiment utilising tall pasture and low stocking rates so that availability would not be restricted. Cows on the pasture with sodium fertilizer still had longer grazing times than those on pasture where no sodium fertilizer had been applied. They had more feeding bouts but bout length was reduced, and they had faster biting and walking rates while grazing. They ruminated for longer, with a faster chewing rate, and spent longer standing idle and less time lying idle. They had longer drinking bouts but a similar number of them, compared to the cows on pasture without sodium. The fixed and variable energy costs of grazing and drinking bouts were estimated, these being the energy requirements for activities that are independent and dependent of bout duration, respectively. It is proposed that for grazing bouts the low ratio of fixed costs (getting up and lying down) to variable costs (standing and walking) favoured an increase in bout number to increase the grazing time of cows grazing pasture fertilised with sodium. For drinking bouts, the high ratio of fixed costs (getting up, lying down, standing and walking to the trough) to variable costs (standing at the trough) favoured bout elongation to increase the drinking time of cows grazing pasture fertilised with sodium. A second experiment with unrestricted herbage availability between morning and afternoon milking compared the grazing response to sodium and potassium fertilizers with a control where no fertilizer was applied. Grazing time was increased most by sodium and a smaller response occurred with potassium. The proportion of herbage that was rejected by the cows decreased with sodium and to a lesser extent potassium. It is concluded that changes in herbage composition with sodium fertilizer increase feeding and drinking by the grazing dairy cow, with the increase in feeding being achieved by increased bout number but reduced bout length, and the increase in drinking being by increased bout length.

The effect of introducing timothy, cocksfoot and red fescue into a perennial ryegrass sward and the application of sodium fertilizer on the behaviour of male and female cattle

The effects on cattle grazing behaviour of introducing the three novel species into a perennial ryegrass pasture were examined in a Latin Square design. Castrated male and entire female cattle of similar age were grazed on plots of perennial ryegrass only (treatment 1), perennial ryegrass and timothy (treatment 2), perennial ryegrass, timothy and cocksfoot (treatment 3) and perennial ryegrass, timothy, cocksfoot and red fescue (treatment 4). Perennial ryegrass had the greatest nutritional value, with a high crude protein and low MADF content, whereas cocksfoot and red fescue had high MADF contents. The introduction of timothy had no effects on grazing behaviour. When cocksfoot was additionally included, the cattle grazed for longest on the cocksfoot plots and total grazing time and the time spent ruminating both increased. When red fescue was additionally included with the other three species it was mostly avoided. When they did graze the red fescue, the cattle had slow biting and walking rates and reduced lateral head movement, suggesting greater selectivity. Mean treatment herbage height was increased in treatments three and four because cocksfoot and red fescue were taller than the other two species. Sodium fertilizer increased the sodium concentration of all species but particularly perennial ryegrass and cocksfoot. The grazing time was only increased by sodium for these two species, and the rates of biting and walking during grazing were also increased, suggesting that sodium reduced selectivity. Male cattle had faster biting and walking rates than female cattle and extended lateral head movement during grazing. It is concluded that perennial ryegrass, timothy and cocksfoot were more acceptable to cattle than red fescue. There was an increase in acceptability of the natrophilic species, perennial ryegrass and cocksfoot, when sodium fertilizer was applied, suggesting that sodium content partly determines herbage acceptability.