Plots In May Research Articles

Does adding legumes to tall fescue pastures before stockpiling improve productivity and animal performance?

AbstractThe rising prices of N fertilizer led to exploring cost‐saving efforts, such as intercropping cool‐ or warm‐season legumes serving as alternative sources of N for managing fall‐stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.; TF]. We aimed to evaluate red clover (Trifolium pratense L.; RC) and sunn hemp (Crotalaria juncea L.; SH) mixed with TF as alternative sources of N for stockpiling TF to increase productivity and animal performance. The experiment was conducted in Crossville, TN, in 2020 and 2021 and consisted of TF pastures mixed with RC (TRC) or SH (TSH), and TF fertilized with urea (TU). The experiment was divided into two periods: the pre‐grazing period (stockpiling) (April–October) and the grazing period (October–December). After the stockpiling period, Black Angus beef (Bos taurus) steers were used for the grazing period. The study evaluated the botanical composition, herbage mass (HM), nutritive value, steer average daily gain (ADG), and net returns (NR). The TRC pastures had a greater proportion of legumes compared to TSH plots in May, October, November, and December of both years. There were no differences among treatments for the total HM and nutritive value in 2020; however, in 2021, TU had greater HM at the beginning of the grazing period and greater average crude protein values compared to the other treatments. In both years, there were no differences among treatments for ADG or NR. Therefore, producers can make the same profit considering the beef steer price and the cost of conventional and alternative N sources.

Vegetation cover and carbon pool loss assessment due to extreme weather induced disaster in Mandakini valley, Western Himalaya

Sendai Framework for 2015-2030 emphasises on the damage and loss assessment needs and its ecosystem level impacts. We have assessed the loss of forest cover and phytomass/carbon pool in the natural forest ecosystems lost due to extreme weather conditions leading flash floods and landslides during Kedarnath tragedy on June 17, 2013 in Mandakini Valley, Uttarakhand in Western Himalaya. We used high resolution satellite IRS LISS IV (5.8 m spatial resolution) of pre-disaster (2012) & post-disaster (2013). Since lost vegetation cannot be ground inventoried, a new approach was developed wherein we used pre-disaster spectral characteristics to identify sample locations in nearby and adjacent to affected areas. We laid 45 geotagged sample plots in May 2014 on both side of the 37 landslide affected areas within a distance of 2 km from river-bed for primary data collection. Above ground biomass and Carbon was estimated using standard protocols and used species-specific volumetric equations and wood density. Above ground biomass varied from 18.05t/ha in Alpine Scrub to 252.95 t/ha in Subtropical forests. Assuming that the biomass increment and spectral properties would not change significantly, we applied several vegetation indices to get best regression model with biomass. We found NDVI (2014) with coefficient of determination (R2) of 0.893, SE± 0.038 with linear function as the best for geospatial modelling of the biomass for pre-flood 2013 and post-flood 2014 situations. Coefficient of determination (R²) between estimated vis-à-vis modelled biomass was 0.8643. It is found that there is a net loss of 52,055.80 tonnes of forest biomass and 24,466.14 tonnes of carbon due to landslides and flash floods. The maximum biomass/carbon was lost in the sub-tropical forests. The loss of forest cover was maximum in subtropical forests.

Soil Amendments Affect Soil Health Indicators and Crop Yield in Perennial Strawberry

Soil amendments with varying carbon:nitrogen (C:N) ratios [grass clippings, wheat (Triticum aestivum), straw, sawdust] were pre-plant incorporated into 12 × 15-ft field plots at ≈4 tons/acre in fall and then planted to perennial strawberry (Fragaria ×ananassa) the following spring and grown 4 years. These amendments were intended to alter soil biological activity as measured by a suite of soil tests referred to as “soil health indicators” which, in turn, were hypothesized to affect strawberry plant growth and yield. In addition, plots were either tilled deeply or shallowly to determine if intensity of tillage affected soil health indicators. After the first and second years, amendments were reapplied between rows and soil and plant variables continued to be monitored. Soil respiration was consistently higher in plots with higher C:N amendments, with up to a 189% increase in respiration in sawdust-amended plots over unamended plots. The respiration rate was highest in sawdust-amended shallow-tilled plots; however, in most cases, tillage depth had no effect on other soil or plant variables. Potentially mineralizable N was higher in sawdust-amended plots in May both years, but not throughout the rest of the season. Soil moisture and pH were 21% and 2% higher, respectively, between the rows of strawberries than within the rows by September of the planting year, and remained that way throughout the next year. Neither the C:N ratio of the soil nor the foliar nutrient concentration of strawberry leaves was affected by the C:N ratio of the amendments. Most significantly, plant density and yield were depressed up to 42% and 26%, respectively, by planting into straw-amended soil, but planting into other amendments did not have this effect. After the second fruiting year (the third growing season), only straw was incorporated into half of the plots after harvest to mimic winter straw mulch incorporation, and yield was measured again the following spring. However, incorporation of straw between rows after plants were established did not affect yield. This study corroborates the general recommendation to avoid new strawberry plantings in locations that were recently planted to strawberry, as old fields likely harbor pathogens and contain undecomposed straw residue from previous years’ mulching that could depress yield. Despite differences in soil health indicators between amendment and tillage treatments, yield differences were not correlated with them. These observations suggest that alternative soil health indicators may be better suited for perennial strawberry.

Influences of one-year red clover ley management on subsequent cereal crops

A field experiment of one-year leys was established at Moreton-in-Marsh, Gloucestershire, UK (NGR SP 217 323) with six combinations of red clover, perennial ryegrass and cocksfoot and two fallow control plots in May 2010 to determine the effects of ‘cut and remove’ cropping three times or ‘cut and mulch’ once annually on biomass yield and nitrogen (N) accumulation. The effect of fertility building leys on grain yield and quality were studied in two subsequent cereal crops. There was no evidence during the ley fertility building phase that red clover monoculture (RC) had a strong positive effect on grass productivity when in mixtures, irrespective of the cutting system. In cut/mulch, the red clover/ryegrass/cocksfoot (RCRGCF) mixture had least dry matter and N yields of all red clover-based leys. In the arable phase, all red clover-based leys gave subsequent winter wheat grain yields comparable to those of best conventional management. The cutting system had an effect only on red clover/ryegrass (RCRG) and ryegrass (RG). Maximum grain yield of winter wheat occurred after mulching of RCRG. For spring wheat, the preceding sown species or the cutting system had no effect on grain yield, partly due to preceding wet weather. RC consistently had greater grain protein in both subsequent winter and spring wheat. Growing short-term RC as a fertility-building forage crop could significantly improve grain protein content in both winter and spring wheat, regardless of management. RC could potentially be of economic importance, especially in low input stockless farming, where N supplementation may be limited.

Effects of Targeted Grazing and Prescribed Burning on Community and Seed Dynamics of a Downy Brome (Bromus tectorum)–Dominated Landscape

AbstractDowny brome (Bromus tectorumL.)—dominated communities can remain as stable states for long periods, even with frequent disturbance by grazing and fire. The objective of this study was to determine the effectiveness of using targeted cattle grazing and late-season prescribed burning, alone and in combination, to reduceB. tectorumseed bank input and seed bank density and thus alter aboveground community dynamics (species composition) on aB. tectorum–dominated landscape in northern Nevada. Cattle removed 80 to 90% of standing biomass in grazed plots in May of 2005 and 2006 whenB. tectorumwas in the boot (phenological) stage. Grazed and ungrazed plots were burned in October 2005 and 2006. The combined grazing–burning treatment was more effective than either treatment alone in reducingB. tectorumseed input and seed bank density, and in shifting species composition from a community dominated byB. tectorumto one composed of a suite of species, withB. tectorumas a component rather than a dominant. This study provides a meso-scale precursor for landscape-scale adaptive management using grazing and burning methodologies.

Effects of the different rates of urease and nitrification inhibitors on gaseous emissions of ammonia and nitrous oxide, nitrate leaching and pasture production from urine patches in an intensive grazed pasture system

Minimizing nitrogen (N) losses via ammonia (NH 3) and nitrous oxide (N 2O) emissions into the atmosphere and nitrate (NO 3 −) leaching into surface and ground waters from intensively grazed pastures is essential for environmental protection worldwide. Applying urease inhibitor such as N-(n-butyl) thiophosphoric triamide (nBPT) or (Agrotain) and nitrification inhibitor dicyandiamide (DCD) to grazed pastures has the potential to mitigate such N losses. A lysimeter/mini plot experiment, using Paparua silt loam soil near Lincoln, Canterbury New Zealand, was conducted to quantify these N losses during May 2007 to July 2008. The nine treatments were: cow urine only applied at an equivalent rate of 600 kg N ha −1, urine + DCD at 5 kg ha −1, urine + DCD at 7 kg ha −1, urine + DCD at 10 kg ha −1, urine + double inhibitor (DI), i.e. both Agrotain and DCD applied at 1 L ha −1 and 7 kg ha −1, respectively (or 1:7 of v/w basis), urine + DI (1:10), urine + DI (2:7), urine + DI (2:10) and the control (no urine). These treatments were randomly applied to one set of lysimeters or mini plots in May as autumn and then to another set of lysimeters or mini plots in August as spring applications. Additional nine lysimeters received DCD only at rates equivalent to 5, 7 and 10 kg ha −1 in autumn to see if DCD has any effect on NO 3 − leaching and pasture production and N uptake from non-urine patches in autumn. Gaseous emissions of NH 3 and N 2O, NO 3 − leaching and pasture production and N uptake varied with the types and rates of the applied inhibitors during the two seasons. DCD applied at 7 and 10 kg ha −1 rates with urine was more effective than its lower rate of 5 kg ha −1 and reduced N 2O emissions by 37–53% (autumn) and 47% (spring), NO 3 − leaching losses by 57–55% (autumn) and 26–10% (spring) compared with urine alone. However DCD increased NH 3 emissions by 41% and 18% compared with urine alone treatment after autumn and spring, respectively. DCD applied at higher rates also increased pasture dry matter by 9% and 12% and N uptake by 12% and 6% after autumn and spring applications, respectively. However DCD applied at different rates without urine in autumn had no such effect on either NO 3 − leaching or pasture dry matter yield or N uptake. The DI at 1:7 ratio was more effective than the higher rates of DI and DCD in reducing losses of NH 3 (48% and 51%), N 2O (55% and 63%) and NO 3 − leaching (56% and 42%) as well as increasing pasture production (13% and 17%) and N uptake (7% and 18%) compared with urine alone treatment in autumn and spring, respectively. These results suggest that applying Agrotain + DCD at a ratio of 1:7 (v/w) may provide the best option for both mitigating N losses and improving pasture production in intensively grazed systems.

The formation of rubber particles in developing cortical parenchyma of Parthenium argentatum plants exposed to the low temperatures of fall and winter of the Chihuahuan Desert

In this paper we have examined rubber particle formation in cortical parenchyma cells of guayule ( Parthenium argentatum Gray) plants exposed to the low temperature of the fall and winter of the Chihuahuan Desert that stimulates rubber formation. Plants were transplanted to field plots in May in Ft. Stockton, TX. In September most of the cortical parenchyma in cross-sections 3 cm from the stem tips and from the base of the stems were mature, containing a central vacuole, tonoplast and a parietal cytosol with chloroplasts, mitochondria, peroxisomes and a few rubber particles. In 8-month-old plants examined in January many of the cortical parenchyma cells 3 cm from the stem tip were immature and completely filled with cytosol containing a high population of rubber particles. At this stage of development there was a thickened secondary cell wall but no central vacuole, tonoplast or parietal cytosol and all the rubber particles were formed in the central cytosol. In the cortical parenchyma in early stages of central vacuole development, by the coalescing of microvacuoles, the rubber particles were located in the developing central vacuole and in the cytosol being appressed toward the cell wall. In 8-month-old plants in January, the cortical parenchyma at the base of the stems was more mature than cells near the stem tips. These cells showed a later stage of development of a central vacuole from microvacuole fusing and contained a high population of mixed sizes of rubber particles and a thin layer of parietal cytosol containing chloroplasts, mitochondria and rubber particles with a partly developed tonoplast. There was clear evidence of the fusion of small rubber particles with other rubber particles that may represent a mechanism for the growth of rubber particles.

Effects of targeted cattle grazing on fire behavior of cheatgrass-dominated rangeland in the northern Great Basin, USA

We evaluated the effectiveness of using targeted, or prescribed, cattle grazing to reduce the flame length and rate of spread of fires on cheatgrass (Bromus tectorum)-dominated rangeland in northern Nevada. Cattle removed 80–90% of B. tectorum biomass during the boot (phenological) stage in grazed plots in May 2005. Grazed and ungrazed plots were burned in October 2005 to assess fire behavior characteristics. Targeted grazing reduced B. tectorum biomass and cover, which resulted in reductions in flame length and rate of spread. When the grazing treatments were repeated on the same plots in May 2006, B. tectorum biomass and cover were reduced to the point that fires did not carry in the grazed plots in October 2006. Fuel characteristics of the 2005 burns were used to parameterize dry-climate grass models in BEHAVE Plus, and simulation modeling indicates that targeted grazing in spring (May) will reduce the potential for catastrophic fires during the peak fire season (July–August) in the northern Great Basin.

Early-Season Aerial Adult Colonization and Ground Activity of Pea Leaf Weevil (Coleoptera: Curculionidae) in Pea as Influenced by Tillage System

The pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), is an important pest of pea, Pisum sativum L., in northern Idaho. Previous research revealed greater relative pea leaf weevil abundance and feeding damage in peas grown using conventional-tillage compared with no-tillage practices. However, the effects of tillage practices on early season colonization and activity by the pea leaf weevil on pea are not fully understood. Aerial traps and pitfall traps were used to assess adult colonization and relative density of adult pea leaf weevil into conventional-tillage and no-tillage pea in northern Idaho during 2005 and 2006. Feeding damage to the crop also was evaluated. During both years, aerial traps captured more pea leaf weevil in May, when crop establishment and early growth occurred, than in later months. Significantly more adult pea leaf weevils were captured in aerial traps in conventional-tillage than in no-tillage plots in May of both years. Significantly more pea leaf weevil were captured in pitfall traps in conventional-tillage plots than in no-tillage plots during the period immediately after peak aerial adult colonization in late May and early June. Crop feeding damage was significantly greater in conventional-tillage than in no-tillage plots in late May and early June. The patterns suggest that more adult pea leaf weevil colonize conventional-tillage pea than no-tillage pea. Pea plants in conventional-tillage emerged earlier and were larger than those in no-tillage during the pea leaf weevil colonization period, possibly accounting for the differences in colonization rates. This leads to greater early season pea leaf weevil infestation of conventional-tillage plots at a critical period for pea development that might ultimately influence crop yield.

Early-season aerial adult colonization and ground activity of pea leaf weevil (Coleoptera: Curculionidae) in pea as influenced by tillage system.

The pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), is an important pest of pea, Pisum sativum L., in northern Idaho. Previous research revealed greater relative pea leaf weevil abundance and feeding damage in peas grown using conventional-tillage compared with no-tillage practices. However, the effects of tillage practices on early season colonization and activity by the pea leaf weevil on pea are not fully understood. Aerial traps and pitfall traps were used to assess adult colonization and relative density of adult pea leaf weevil into conventional-tillage and no-tillage pea in northern Idaho during 2005 and 2006. Feeding damage to the crop also was evaluated. During both years, aerial traps captured more pea leaf weevil in May, when crop establishment and early growth occurred, than in later months. Significantly more adult pea leaf weevils were captured in aerial traps in conventional-tillage than in no-tillage plots in May of both years. Significantly more pea leaf weevil were captured in pitfall traps in conventional-tillage plots than in no-tillage plots during the period immediately after peak aerial adult colonization in late May and early June. Crop feeding damage was significantly greater in conventional-tillage than in no-tillage plots in late May and early June. The patterns suggest that more adult pea leaf weevil colonize conventional-tillage pea than no-tillage pea. Pea plants in conventional-tillage emerged earlier and were larger than those in no-tillage during the pea leaf weevil colonization period, possibly accounting for the differences in colonization rates. This leads to greater early season pea leaf weevil infestation of conventional-tillage plots at a critical period for pea development that might ultimately influence crop yield.

Effect of timing and formulation of dicyandiamide (DCD) application on nitrate leaching and pasture production in a Bay of Plenty pastoral soil

Urine excreted from grazing animals has been identified as the main source of nitrate leaching from grazed pastures. The nitrification inhibitor dicyandiamide (DCD) has the potential to be an important tool for reducing nitrate leaching in grazed pasture systems. A mowing trial near Rotorua examined the effects of different DCD formulations, and the timing of DCD application on plant growth and leaching of urine‐N. Treatments were urine‐only or urine+DCD (either granular or liquid DCD) applied at a rate of 18 kg DCD ha‐1. The effect of timing of DCD application was tested by applying the DCD to plots in May (autumn) or July (winter) immediately after urine was applied. The application rate of the urine was equivalent to 598 kg N ha‐1 in the form of artificial urine. There was no significant effect of DCD formulation (granular versus liquid) on any N leaching or yield parameter measured in either the autumn or winter application. On average, the autumn application of DCD significantly (P < 0.001) increased pasture dry matter (DM) from urine plots (34% increase or 21 DM ha‐1). Extrapolation of treatments with or without DCD to grazed pasture, with 5% of the area affected by urine at this grazing, would equate to an annual pasture response of approximately 7%. The increased pasture growth resulted in a greater apparent recovery of urine‐N in herbage from the urine+DCD treatments compared with the urine‐only treatment over the first 98 days of the study of 64% or 103 kg N ha‐1. In contrast to autumn application, winter application of DCD did not significantly influence pasture DM yield from urine plots. Total nitrate leaching losses for the autumn‐applied urine+DCD treatments were 17% less than the urine‐only treatments, but this was not significant. Interestingly, over the short‐term (30–55 days), the autumn urine+DCD treatments showed reduced nitrate leaching losses of up to 50% (P < 0.05), but after day 84 greater amounts of nitrate were leached from the urine+DCD plots giving cumulative losses at day 159 of 217 and 263 kg nitrate‐N ha‐1 for the urine+DCD and urine‐only treatments, respectively. It was apparent that the DCD had become ineffective in inhibiting nitrification, thus allowing the conversion of ammonium to nitrate and its subsequent leaching from the root zone. In contrast to autumn, the application of DCD in winter led to a reduction in nitrate leaching from urine‐N of 62% compared to the urine‐only treatment (average of 32 versus 86 kg N ha‐1 respectively; P < 0.001). Overall, our study showed that when applied at a rate of 18 kg ha‐1 the form of DCD (granular versus liquid) used was inconsequential. However, to gain the greatest benefit from DCD use, more than one application is needed during autumn/winter to maximise the potential for reducing nitrate leaching during this key period of high drainage and N losses.

Small-Scale Distribution of the Sand Dollars Mellita tenuis and Encope michelini (Clypeasteroida, Echinodermata) off the Central Florida Gulf Coast

Small-scale distributions of Encope michelini were quantified 27 km west of Captiva Island at 20 m depth and of Mellita tenuis 7 km west of Egmont Key at 6.5 m depth and at Mullet Key at 1.5 m depth during 2005. Encope michelini were aggregated in 33.3% of three plots in March. Off Egmont Key, M. tenuis were aggregated in 100% of four plots in March but in none of three plots in Sept. At Mullet Key, M. tenuis were aggregated in 37.5% of 16 plots in May, 12.5% of 16 plots in July, and 50.0% of 16 plots in Sept. Percentage of organic content was not correlated with sand dollar distribution, except for M. tenuis off Egmont Key. The distribution pattern of both species is dynamic. The pattern at Mullet Key changed within 2 to 5 hr after initial observations in two of eight plots in May and July and in five of eight plots in Sept. It is possible that aggregation is influenced by local, short-term concentration of food below the sensitivity of measurement of organic content and that dispersal to random distribution may occur when food concentration is decreased.

Productivity and Stability Relationships in Mowed Pasture Communities of Varying Species Composition

Plant species composition of most managed pasture lands tends to be dominated by one or two species, usually a perennial grass and a legume. Recent ecological research suggests that increasing this forage diversity could increase pasture productivity and stability. We conducted a 4-yr field experiment to determine whether increasing the diversity of pasture mixtures would increase yields and improve interannual yield stability. Mixtures of cool-season pasture plants ranging from one to 15 species were planted into 2.25-m2 plots in May 1998. Interannual yield variation and yield responses to mowing frequency (2- vs. 4-wk frequency) were used to evaluate stability. Forage yields averaged <400 g m−2 yr−1 in mixtures having one or two species, while mixtures with three or more species averaged >1000 g m−2 yr−1 Increasing the diversity of mixtures beyond three sown species did not consistently improve yields. Interannual yield variation was lowest in the one- and two-species mixtures, and showed no consistent relationship with increasing species diversity. The number of species planted in each mixture declined by approximately 30% from 1999 to 2001, with the mixtures becoming dominated by perennial grasses. Although limitations in our experimental design prevent us from making strong conclusions about relationships between forage diversity and pasture productivity, our findings suggest that increased forage yield and stability may be best achieved by planting two or three forage species that are well matched to specific environmental conditions rather than planting a random assemblage of forage species in a complex mixture.

Nutritive Value of Chicory and English Plantain Forage

Forage production in midsummer is a challenge for graziers in the northeastern USA. Domesticated cultivars of chicory (Cichorium intybus L.) and English plantain (Plantago lanceolata L.) are available in the USA as perennial herbs for pastures. These species have been touted as having good summer production and relatively high nutritive value. We conducted two field‐plot experiments at Rock Springs, PA, during 1997 to 2001 to evaluate the nutritive value of chicory and plantain under clipping. ‘Grasslands Puna’, ‘Lacerta’, and ‘Forage Feast’ chicory and ‘Ceres Tonic’ and ‘Grasslands Lancelot’ grazing plantain were sown in field plots in May 1997 and 1999 and harvested multiple times in 1998 (Exp. 1) and 2000 (Exp. 2). Herbage from three harvests in 1998 and two harvests in 2000 was analyzed for in vitro true digestibility (IVTD); neutral detergent fiber (NDF); and the minerals P, K, Ca, Mg, Mn, Cu, B, and Zn. Averaged for cultivars, chicory had 11% higher (P &lt; 0.05) IVTD and 6 to 20% lower (P &lt; 0.05) NDF than plantain. Concentrations of all minerals, except for Ca, were 17 to 48% higher (P &lt; 0.05) in chicory than in plantain. There were few meaningful differences in nutritive value among cultivars within chicory or plantain. Chicory and plantain are of relatively high nutritive value and could enhance the nutritional profile of mixed species pastures. The nutritive value benefits, however, must be balanced against the lack of persistence of chicory and plantain.

Forage Yield and Persistence of Chicory and English Plantain

Graziers in the northeast USA often face forage shortages in midsummer. Chicory (Cichorium intybus L.) and English plantain (Plantago lanceolata L.) have been introduced in the USA as sumer‐active perennial herbs for pastures. We conducted two experiments at Rock Springs, PA, to evaluate chicory and plantain for yield and persistence under clipping. ‘Grasslands Puna’, ‘Lacerta’, and ‘Forage Feast’ chicory, and ‘Ceres Tonic’ and ‘Grasslands Lancelot’ plantain were sown in field plots in May 1997 (Exp. 1) and 1999 (Exp. 2). Plots were cut every 3 or 5 wk in 1998 and 1999 in Exp. 1 and every 4 wk during 2000 and 2001 in Exp. 2. Dry matter yield was determined at each harvest. Stand densities were determined in each experiment. Forage Feast chicory yielded 25% less than Puna (6000 vs. 8100 kg dry matter ha−1; P &lt; 0.05) in 1998, whereas yields of both cultivars were similar (P &gt; 0.05) in 1999 and 2000. Lacerta chicory yielded 9 to 16% less than Puna and Forage Feast in Exp. 2. Forage Feast and Puna chicory had 20 to 50% stand loss in Exp. 1 and 40 to 60% stand loss in Exp. 2. Lacerta chicory lost 80% of the stand during Exp. 2. The plantain cultivars yielded 6 to 14% less dry matter than Puna chicory in 1998 and 33 to 39% less in 2000. Both plantain cultivars, however, suffered a nearly complete loss of plants during the second winter after establishment in both experiments. Ceres Tonic and Lancelot plantain are not suited for the northeastern USA.

LAND-SNAIL DIVERSITY IN A SQUARE KILOMETRE OF CRETAN MAQUIS: MODEST SPECIES RICHNESS, HIGH DENSITY AND LOCAL HOMOGENEITY

The land mollusc fauna of 1 km 2 of Cretan maquis was surveyed by sampling fourteen 400-m 2 plots in May 2001, and by resampling six of these in February 2002. Sampling methods were designed to resemble those used in similar surveys of 1-km 2 sites in tropical rainforests in Cameroon and Sabah. A total of 27 species were recorded for the site. Slugs and a semi-slug were found only in the 2002 survey. Individual plots were very similar in species richness and composition; the richest plot contained about 85% of the fauna recorded for the whole site. Overall densities were very high. This local homogeneity contrasts with marked heterogeneity over Crete as a whole. These results are contrasted with those from tropical forests, where individual plots vary considerably in richness and composition, where densities are lower and where the total site faunas are larger. Although there are problems associated with differing amounts of sampling error between studies, this contrast is striking and some possible causes are discussed. Further work in tropical forest on limestone may elucidate this.

Relationship of tillering and morphological characteristics of two perennial ryegrass lines to “pulling” when grazed by dairy cows

The morphology and sward structural characteristics of two perennial ryegrass pipeline (pre‐commercial) selections that showed different “pulling” tolerances, were studied at Hamilton, New Zealand. Pulling was defined as the removal of clumps of ryegrass plants from the sward during grazing. One line, coded as NZA1, was less tolerant of pulling than was the other, coded as NZA3. NZA3 is now commercially available as the cultivar ‘Bronsyn’. The ryegrass lines were established in small plots in May 1994 on a silt loam and a peaty silt loam soil. Half the area of each plot received nitrogen (N) fertiliser (30 kg N ha−1) after each grazing, and tiller dynamics were monitored from September 1995 to April 1996. NZA1 had a higher leaf shear strength (6.21 versus 5.91 kg, standard error of difference (SED) = 0.087), wider leaves (3.621 versus 3.252 mm, SED = 0.0535), and a lower clump shear strength (13.4 versus 14.9 kg, SED = 0.57) than did NZA3. N fertiliser did not affect leaf shear strength, and tillering responses to N fertiliser were inconsistent. It is argued that better anchorage combined with leaves that break more easily when grazed contributed to less pulling of NZA3 than of NZA1 clumps during dry summers.

Forage Yield and Persistence of Chicory and English Plantain

Graziers in the northeast USA often face forage shortages in midsummer. Chicory (Cichorium intybus L.) and English plantain (Plantago lanceolata L.) have been introduced in the USA as sumer-active perennial herbs for pastures. We conducted two experiments at Rock Springs, PA, to evaluate chicory and plantain for yield and persistence under clipping. ‘Grasslands Puna’, ‘Lacerta’, and ‘Forage Feast’ chicory, and ‘Ceres Tonic’ and ‘Grasslands Lancelot’ plantain were sown in field plots in May 1997 (Exp. 1) and 1999 (Exp. 2). Plots were cut every 3 or 5 wk in 1998 and 1999 in Exp. 1 and every 4 wk during 2000 and 2001 in Exp. 2. Dry matter yield was determined at each harvest. Stand densities were determined in each experiment. Forage Feast chicory yielded 25% less than Puna (6000 vs. 8100 kg dry matter ha−1; P < 0.05) in 1998, whereas yields of both cultivars were similar (P > 0.05) in 1999 and 2000. Lacerta chicory yielded 9 to 16% less than Puna and Forage Feast in Exp. 2. Forage Feast and Puna chicory had 20 to 50% stand loss in Exp. 1 and 40 to 60% stand loss in Exp. 2. Lacerta chicory lost 80% of the stand during Exp. 2. The plantain cultivars yielded 6 to 14% less dry matter than Puna chicory in 1998 and 33 to 39% less in 2000. Both plantain cultivars, however, suffered a nearly complete loss of plants during the second winter after establishment in both experiments. Ceres Tonic and Lancelot plantain are not suited for the northeastern USA.

Development of pea bacterial blight caused by Pseudomonas syringae pv. pisi in winter and spring cultivars of combining peas (Pisum sativum) with different sowing dates

SummaryPea bacterial blight occurred by natural infection in a field trial on peas in 1995. Disease development in the winter cultivars Rafale, Frilene and Froidure was compared with that in the spring cultivars Baccara, Conquest and Bohatyr, each sown on six dates in October, November, December, mid‐March, late March and April. Disease incidence had reached 100% plants affected in all treatments by mid‐July. Disease severity was greater in winter‐sown (October, November or December) than in spring‐sown peas of each cultivar at each assessment. Significant (P &lt; 0.05) differences in disease severity occurred between cultivars in the winter‐sown plots in May and June and the spring cultivars were affected more severely than the winter cultivars. Comparison of areas under the disease progress curves for both disease incidence and severity also showed that the winter‐sown peas were more affected by disease than spring‐sown peas and that spring cultivars were more severely affected than winter cultivars. Yield was strongly correlated with disease severity. A linear regression model suggested that, for peas sown in October, November or December, a yield loss of 0.5 tha‐1 occurred for each 10% increase in canopy area affected by pea bacterial blight.

Phosphate fertiliser residues in wheat-growing soils of the Western Downs, Queensland

Effects of repeated annual application and residual effects of past phosphorus (P) applications were studied at Billa Billa and The Gums, Queensland, on 2 Vertisols representative of a large cropping area in this region. Phosphorus was applied annually at 0, 4, 8, 12, and 25 kg/ha at sowing to each wheat crop between 1978 and 1988. Phosphorus was also applied at 25, 50, 100, 200, or 400 kg/ha as a once-only application, before wheat was sown in 1978, and was incorporated by tillage. Pot experiments were conducted each year with soil (6 kg/pot) gathered from field plots in May before wheat sowing to determine the residual value (RV) of previously applied P fertiliser under standard conditions of frequent watering. In 1979 the RV was determined in a second series of pots with a water deficit to simulate conditions of plant moisture stress that were to dominate the field experiments. The RV of P fertiliser was reduced to one-third that determined under well-watered conditions. Low residual values (8–47%) determined in the field in 1979 for P rates 25 and 50 kg/ha applied in 1978 were probably due to reduced P uptake from dry topsoil throughout which P residues were incorporated by tillage. By contrast, P applied annually at a low rate (4 or 8 kg/ha) in a band close to seeds created profitable responses when evaluated over the sequence of successive wheat crops. The bicarbonate-extractable soil test value (Pbf) on either soil fertilised annually for n years with P at a rate R (kg/ha· year) was described by the model where Pbu is the soil test value (mg/kg) of unfertilised soil.