Clover Content Research Articles

Subterranean clover growth responded to grass suppression, phosphorus and molybdenum fertilisers in a summer dry hill environment

Pastures on the north-facing slopes of the Port Hills, Canterbury, are summer-dry, grass dominant, and have low soil phosphorous and sulphur fertility. The aim of this experiment was to improve the establishment of oversown subterranean (sub) clover by the addition of fertilizer and grass-supressing herbicide. Treatments were a factorial combination of phosphorous (0 or 60 kg P/ha, -P or +P), sulphur (0 or 50 kg S/ha, -S or +S), and molybdenum (0 or 0.06 kg Mo/ha, -Mo or +Mo), with or without autumn herbicide (plus or minus, +H or -H). Fertilisers were applied in 2021, with P and S reapplied in 2023, and herbicide applied in 2022 and 2023. Pasture yields were measured annually from 2021 to 2023. Measurements in 2021 found no fertiliser effect on total pasture yield of 3650±83 kg DM/ha that included 770±43 kg of sub clover. In 2022, P addition increased total pasture yield from 2900 to 3270 kg DM/ha. Herbicide application doubled the sub clover yield from 310 to 645 kg DM/ha and reduced grass from 1650 to 1410 kg DM/ha. In 2023, the herbicide application did not affect the total accumulated pasture yield (10180±160 kg DM/ha) but increased sub clover content from 10 to 25% and reduced the grasses from 63 to 47%, with about 4% white clover. Where herbicide was applied without fertiliser (+H), total clover yield increased from 1460 to 2930 kg DM/ha. The application of P and Mo, (i.e., +H+P+Mo treatment) increased it further to 4010 kg DM/ha. There was no yield response to +S or +Mo unless added with P. Applying herbicide or phosphorous increased total metabolisable energy from 38.5 to 42.6 GJ ME/ha and crude protein from 500 to 595 kg/ha in pastures sampled in November 2023. The treatment combination providing the highest feed quality values was +H+P+Mo. These results suggest that to optimise sub clover content of pastures on the Port Hills competing grasses must be controlled initially, followed by P fertiliser if soil tests indicate it is required along with molybdenum.

Multi-year performance of white clover oversown into eastern North Island hill country

Animal performance on summer-dry North Island hill country pastures is limited by soil fertility and the challenge of establishing and retaining a strong legume base in swards on steeper slopes. However, this can be overcome by 1. selecting legume species adapted to the various slope, aspect and soil type combinations; and 2. following well-recognised establishment and management techniques developed in the 1980s. We broadcast white clover in two large southerly aspect paddocks on Tangihanga Station, Gisborne, in the autumn of 2019. Establishment methods involved resident pasture control by hard grazing and selective herbicide to supress dominant low-fertility grasses, broadcasting at high sowing rates and trampling of seed with sheep. We followed white clover persistence and animal performance over the subsequent 5 seasons of rotational cattle grazing with heifers and steers, in comparison with adjacent unsown paddocks. The cost of establishment was c. $220/ha. White clover abundance remained high throughout the 5 years, between 25-40% of cover, compared with 7-17% in unsown paddocks. This increase in clover content of the pastures translated into both increased stocking rates and per head growth rates, with overall annual LWG increasing by 67-169% depending on season. The investment was paid back within the first year.

Estimation of botanical composition of forage crops using laboratory-based hyperspectral imaging and near-infrared spectrometer measurements

Harvested forage is the main raw feed for ruminant animals in Sweden, and is commonly cultivated in mixed stands of legume and grass species. The fraction of legume on a dry matter basis, known as botanical composition (BC) is a very important indicator of forage quality. In this study, hyperspectral imaging and near-infrared spectrometer (NIRS) based methods were used to estimate BC, to overcome the shortcomings of hand separation, which is time and resource consuming. Timothy and red clover mix samples were collected from different harvests in 2017–2019 from multiple sites in Northern Sweden and hand separated. The samples were synthetically mixed to 11 different BC levels, i.e., 0–100 % clover content. Two different instruments (Specim shortwave infrared (SWIR) hyperspectral imaging system and Foss 6500 spectrometer) were used to collect spectral data of samples milled to two levels of coarseness. Three different regression analyses: partial least squares regression (PLSR), support vector regression (SVR) and random forest regression (RFR), were used to build BC estimation models. The effects of the milling particle sizes and the different instruments on the performances of the models were compared. The data from second harvest in 2019 were used for independent validation as evaluation, and the rest of data were randomly split for model calibration (75 %) and validation (25 %). The models were iteratively run 1000 times with different splits, to check the effect from the splitting of calibration and validation datasets. Among different regression analyses, PLSR performed best, with mean Nash-Sutcliffe efficiency (NSE) for model evaluation from 0.76 to 0.87, varying for different instruments and milling sizes. Finer milling made the model accuracies slightly higher. This study developed quick and robust methods to determine the BC of timothy grass and red clover mixtures, which can provide useful information for farmers or researchers.

Composition of Proteins Associated with Red Clover (Trifolium pratense) and the Microbiota Identified in Honey.

The nutritional composition of honey is determined by environmental conditions, and botanical and geographical origin. In addition to carbohydrates, honey also contain pollen grains, proteins, free amino acids, and minerals. Although the content of proteins in honey is low, they are an important component that confirms the authenticity and quality of honey; therefore, they became a popular study object. The aim of the study was to evaluate protein content and composition of monofloral red clover and rapeseed honey collected from five different districts of Lithuania. Forty-eight proteins were identified in five different origin honey samples by liquid chromatography. The number of red clover proteins identified in individual honey samples in monofloral red clover honey C3 was 39 in polyfloral honey S22-36, while in monofloral rapeseed honey S5, S15, and S23 there was 33, 32, and 40 respectively. Aphids' proteins and lactic acid bacteria were identified in all honey samples tested. The linear relationship and the strongest correlation coefficient (r = 0.97) were determined between the content of Apilactobacillus kunkeei and Apilactobacillus apinorum, as well as between the number of faba bean (Vicia faba) pollen and lactic acid bacteria (r = 0.943). The data show a strong correlation coefficient between the amount of lactic acid and aphid protein number (r = 0.693). More studies are needed to evaluate the relationship between the pollination efficiency of red clover by bees and the multiplicity of red clover proteins in honey protein, as well as microbiota diversity and the influence of nature or plant diversity on the occurrence of microbiota in honey.

Plasma treated cattle slurry with modest fertilizer effect on grass.

Abstract Plasma-based nitrogen enrichment of organic fertilizers is a process that utilizes plasma technology and electricity to infuse liquid biobased fertilizers with atmospheric Nitrogen (N), doubling plant-available N content. The final product is labeled as Nitrogen-Enriched Organic Fertilizer (NEO). This study investigates and compares the applicability of NEO against conventional fertilizers in grass production during 2020-2023 across two regions in Norway. Regarding different fertilizers' N efficacy, in the trials featuring only grasses, applying 210 kg N ha -1 in NEO yielded dry matter (DM) and N yield comparable to those achieved with 149 and 154 kg N ha -1 in mineral fertilizer, respectively. Besides, the untreated cattle slurry and mineral fertilizer combination containing 210 kg N ha -1 resulted in a DM and N yield equivalent to 178 and 180 kg N ha -1 in mineral fertilizer. In the grass-clover mixture trials, NEO and mineral fertilizers reduced the clover content, significantly influencing the overall yield. Merging the results from all trials (2021-2022), it was found that given identical N-min content, standalone mineral fertilizer, and the untreated slurry and mineral fertilizer combination resulted in ~19% and ~28%, and ~14% and ~13.5% higher DM and N yields than NEO, respectively. Further, NEO provided ~9% and ~25% higher DM and N yields than untreated slurry. Notably, NEO's N-min content was nearly double that of untreated slurry (210 vs. 107 kg N ha -1 ). Nonetheless, a supplementary trial (2023) employing different NEO variants with reduced nitrite and elevated nitrate levels returned more promising results than those examined in prior years. Still, ~9% and ~6% less DM and N yield than mineral fertilizer with identical 210 kg N ha -1 content. Our findings suggest that although a considerable N fraction of NEO did not translate to yields compared to other fertilization treatments, and given that NEO is an evolving product, the NEO's enhanced performance in the final study year highlights the necessity for continued research and optimization to fully unlock and utilize the potential advantages of NEO in future agriculture.

Role of Nutrient Management in Yield, Quality and Nutrient Content of Egyptian Clover (Trifolium alexandrinum L.) Under Calcareous Soil Conditions

Nutrient management is vital for maximizing forage crop yield and economic viability; however, improper application can result in decreased yield and quality. Therefore, two seasonal experiments were conducted during the winter seasons of 2022-2023 and 2023-2024 to examine the impact of varying nitrogen, phosphorus and potassium (NPK) levels, along with the foliar application of zinc, on the forage yield and nutrient content of Egyptian clover or berseem (Trifolium alexandrinum L.) grown in calcareous soil conditions (>36% CaCO3). The experiment consisted of eight treatments, including two NPK levels (50% and 100% of the recommended dose) and two forms of Zn (Zn NPs and Zn Edta at 0.2 and 0.5% as foliar sprays), compared with the control (without treatment). Results showed that NPK full dose (100%) or in combination with Zn NPs significantly improved fresh and dry weight by an average of 67%, and 80%, respectively, across all cuts. Whereas, the highest protein percentage in berseem forage occurred with 50% NPK and foliar Zn NPs. Protein yield per unit area was highest with 100% NPK and foliar Zn NPs in the second and third cuts. Furthermore, Zn NPs boosted manganese (Mn) levels in the 2nd cut but decreased them in the 3rd cut. Iron (Fe) and Mn were mostly in normal ranges, but zinc was often below normal levels. Overall, Zn NPs increased forage yields. The results of translocation factor (TF) for micronutrients from the soil to berseem plants showed that TF values were > 1 for all micronutrients except for Cu in several instances in the 2nd cut in such calcareous soil. Furthermore, micronutrient translocations were arranged in the following order Cu < Zn <Mn <Fe in the 2nd and 3rd cuts. Our study suggested that there is a beneficial role of correcting Zn deficiency under calcareous soil conditions which is reflected on berseem yield and quality and nutrient status. Thus, using ZnO NPs along with the full recommended dose of NPK is a suitable approach to enhance berseem crop yield and quality in calcareous soil.

Reducing dietary protein and supplementation with starch or rumen-protected methionine and its effect on performance and nitrogen efficiency in dairy cows fed a red clover and grass silage–based diet

The increasing cost of milk production, in association with tighter manure N application regulations and challenges associated with ammonia emissions in many countries, has increased interest in feeding lower crude protein (CP) diets based on legume silages. Most studies have focused on alfalfa silage, and little information is available on low-CP diets based on red clover silage. Our objectives were to examine the effects of dietary CP content and supplementing a low-CP diet with dietary starch or rumen-protected Met (RPMet) on the performance, metabolism, and nitrogen use efficiency (NUE; milk N output/N intake) in dairy cows fed a red clover and grass silage-based diet. A total of 56 Holstein-Friesian dairy cows were blocked and randomly allocated to 1 of 4 diets over a 14-wk feeding period. Diets were based on red clover and grass silages at a ratio of 50:50 on a dry matter (DM) basis and were fed as a total mixed ration, with a 53:47 ratio of forage to concentrate (DM basis). The diets were formulated to supply a similar metabolizable protein (MP) content, and had a CP concentration of either 175 g/kg DM (control [CON]) or 150 g/kg DM (low-protein [LP]), or LP supplemented with either additional barley as a source of starch (LPSt; +64 g/kg DM) or RPMet (LPM; +0.3 g/100 g MP). At the end of the 14-wk feeding period, 20 cows (5 per treatment) continued to be fed the same diets for a further 6 d, and total urine output and fecal samples were collected. We observed that dietary treatment did not affect DM intake, with a mean of 21.5 kg/d; however, we also observed an interaction between diet and week with intake being highest in cows fed LPSt in wk 4 and CON in wk 9 and 14. Mean milk yield, 4% fat-corrected milk, and energy-corrected milk were not altered by treatment. Similarly, we found no effect of dietary treatment on milk fat, protein, or lactose content. In contrast, milk and plasma urea concentrations were highest in cows fed CON. The concentration of blood plasma β-hydroxybutyrate was highest in cows receiving LPM and lowest in LPSt. Apparent NUE was 28.6% in cows fed CON and was higher in cows fed any of the low-protein diets (LP, LPSt, or LPM), with a mean value of 34.2%. The sum of milk fatty acids with a chain length below C16:0 was also highest in cows fed CON. We observed that dietary treatment did not affect the apparent whole-tract nutrient digestibility of organic matter, N, neutral detergent fiber, and acid detergent fiber, with mean values of 0.785, 0.659, 0.660, and 0.651 kg/kg respectively, but urinary N excretion was approximately 60 g/d lower in cows fed the low-CP diets compared with CON. We conclude that reducing the CP content of red clover and grass silage-based diets from 175 to 150 g/kg DM while maintaining MP supply did not affect performance, but reduced the urinary N excretion and improved NUE, and that supplementing additional starch or RPMet had little further effect.

Predicitng yield of irrigated red clover (Trifolium pratense L.) pastures in response to temperature.

Two datasets from red clover monoculture pastures grown in Lincoln, New Zealand, were analysed to generate coefficients to predict red clover yield. The mean annual production of established red clover was 17.0±0.48 t DM/ha, with a maximum mean growth rate of 125±9.36 kg DM/ha/day (spring Year 2). In the establishment year irrigated red clover grew at a constant rate of 7.30±0.14 kg DM/ha/°Cd (Tb = 3 °C) throughout the year. In contrast, there was a splitline linear response in Years 2 and 3, which differed between years and decreased after the second week of January. Specifically, the growth rate in Phase 1 was 7.70±0.38 kg DM/ha/°Cd in Year 2, which was 16% higher than the 6.60±0.28 kg DM/ha/oCd in Year 3. The difference probably reflected increased competition from weed grasses as red clover content declined from >95% to ~75% of total annual yield. After January, red clover grew at 3.05±0.35 kg DM/ha/°Cd, in both years. This lower rate occurred in the mid-January-July period, and probably reflected a change in partitioning of assimilate to red clover roots in response to a decreasing photoperiod. The coefficients reported here for red clover need to be validated from other datasets. However, they provide easily transferable coefficients that can be used to estimate red clover yield under nonlimiting conditions for other locations. These could be integrated into feed budgeting software to assist onfarm decision making.

Clover Dry Matter Predictor Based on Semantic Segmentation Network and Random Forest

As a key animal feed source, the dry matter content of clover is widely regarded as an important indicator of its nutritional value and quality. The primary aim of this study is to introduce a methodology for forecasting clover dry matter content utilizing a semantic segmentation network. This approach involves constructing a predictive model based on visual image information to analyze the dry matter content within clover. Given the complex features embedded in clover images and the difficulty of obtaining labeled data, it becomes challenging to analyze the dry matter content directly from the images. In order to address this issue, a method for predicting dry matter in clover based on semantic segmentation network is proposed. The method uses the improved DeepLabv3+ network as the backbone of feature extraction, and integrates the SE (Squeeze-and-Excitation) attention mechanism into the ASPP (Atrous Spatial Pyramid Pooling) module to enhance the semantic segmentation performance, in order to realize the efficient extraction of the features of clover images; on this basis, a regression model based on the Random Forest (RF) method is constructed to realize the prediction of dry matter in clover. Extensive experiments conducted by applying the trained model to the dry matter prediction dataset evaluated the good predictor performance and showed that the number of each pixel level after semantic segmentation improved the performance of semantic segmentation by 18.5% compared to the baseline, and there was a great improvement in the collinearity of dry matter prediction.

Tactical use of gibberellic acid and nitrogen fertiliser to improve production of perennial ryegrass and white clover swards

The timing and frequency of exogenous gibberellic acid (GA) application was explored in a cut-and-carry small plot experiment using irrigated Canterbury swards. GA applications (8 g GA/ha/application) replaced urea applications (25 kg N/ha/application) over multiple harvests in late winter, early spring and autumn. Timing and number (1, 2 or 3 applications) of GA application occurred in combinations to test the effect of early (August and February), delayed (September and March) or late (October and April) application of GA. Annual herbage yield was 14.6, 18.3 and 18.3±0.40 t DM/ha/y for the three controls (0, 250 kg N/ha/y and 250 kg N/ ha/y + 80g GA/ha/y respectively). Clover content varied with treatment and time of year and was more abundant in low N treatments. There was a positive relationship between N fertiliser rate and annual herbage yield. There was no relationship between increasing GA rate and annual yield, though there was evidence of annual yield improvements, associated with frequent GA application under low (100 kg N/ha/y) or moderate (150 kg N/ha/y) N fertiliser. In late winter, delaying a single application of GA into spring improved N use efficiency (P<0.01). Tactical use of GA, in place of N fertiliser, can be used to maintain herbage yield.

Pasture yield responses and nitrogen leaching losses from rolling downland grazed by sheep in the South Island of New Zealand

ABSTRACT A sheep grazing trial on rolling downland in East Otago was conducted from 2004 to 2007 to measure the effect of increasing rates of nitrogen (N) fertiliser on pasture yield and N leaching losses. For fertiliser rates ranging from 100 to 500 kg N/ha/yr, the efficiency of response averaged 20 kg DM/kg N and increased up to 300 kg N/ha/yr. Pasture yield averaged 12,680 kg DM/ha/yr in the control plots and peaked at 21,000 kg DM/ha/yr at 300 kg N/ha/yr. Clover content was significantly depressed by N use, declining from approximately 15% for the control to 2% when 200 kg N/ha/yr or more was applied. Leaching losses of 8–30 kg N/ha/yr at 100 and 200 kg N/ha/yr measured using mini-lysimeters were only slightly more than the control but increased up to 116 kg N/ha/yr at 500 kg N/ha/yr. The results from this site suggested that up to 100–200 kg N/ha/yr can be applied to produce more pasture on rolling downland grazed by sheep with only a small increase in N leaching losses.

Multispecies swards outperform perennial ryegrass under intensive beef grazing

Decreasing reliance on fertiliser Nitrogen (N) is key to enhancing the sustainability of pasture-based agricultural systems. This study assesses the effect of sward type on annual and seasonal herbage dry-matter (DM) production potential, sown species and unsown species contribution to herbage DM under an intensive dairy-calf to beef system. Three sward types were investigated in a farmlet experiment: Lolium perenne (LP; 205 kg N ha-1 a-1); L. perenne-Trifolium repens (LP-TR); multispecies sward consisting of L. perenne, Phleum pratense, T. repens, Trifolium pratense, Cichorium intybus and Plantago lanceolata (MSS). L. perenne-T. repens and MSS each received 92 kg N ha-1 a-1. Herbage samples were collected for DM production and botanical composition determination at each grazing. Further quadrat sampling was undertaken on three occasions per grazing season (early-, mid- and late-season), to enumerate the unsown species composition of swards and changes in bare ground. Over the course of the two-year study, LP, LP-TR and MSS produced annual herbage DM yields of 9950, 10,650 and 12,600 kg DM ha-1 a-1 respectively, despite reducing fertiliser N application to LP-TR and MSS by 55% compared to LP. The average proportional contribution of grass species to MSS’ herbage DM remained constant, the clover content of MSS increased, while the herb content decreased from 2020 to 2021. Seasonally, the proportional contribution of L. perenne and P. lanceolata to MSS’ herbage DM declined as the grazing season progressed, the contribution of T. repens and T. pratense increased and that of P. pratense and C. intybus remained similar. In LP-TR, T. repens’ proportional contribution to herbage DM increased from 2020 to 2021, while L. perenne’s proportional contribution declined. Seasonally, the proportional contribution of L. perenne to the herbage DM of LP-TR declined as the grazing season progressed, while the proportion of T. repens’ increased. The contribution of dead plant material to herbage DM increased across all swards in the second year but did not differ between sward types. Sward type did not affect the proportional contribution of unsown species by functional group to herbage DM. These results demonstrate that under a relatively-intensive beef grazing system, MSS receiving reduced N compared to LP monocultures, and the same N compared to LP-TR swards, produce more herbage DM, and do not have a greater weed (unsown species) burden. Overall, our findings demonstrate the potential of MSS to ‘produce more while using less’, a key requirement of sustainable grazing systems.

Productivity of fodder agrocenoses in the Northern territories of the Arkhangelsk region

The studies were conducted in 2019-2021 in the conditions of the northern part of the Arkhangelsk region. The aim of the research is to study perennial agrophytocenoses consisting of promising cereals and legumes to improve the fodder base in the conditions of northern regions. Herbage grasses of 3 years of life formed from various combinations of cereals and legumes were studied, their productivity and participation of components of grass mixtures in the formation of yields were determined. Meteorological conditions varied during the years of the study. In 2019 and 2020, the growing seasons were excessively wet (hydrothermal coefficient (HTC) 1.80 and 1.76), in 2021, the period was noted as quite wet (HTC 1.38). It was found that in the 1st year of life the formation of green mass yield is due to the legume component. At the same time, 73% of red clover and 59-67% of alfalfa are contained in the structure of the crop. Later in the phytocenosis there is a decrease in the participation of leguminous grasses in the yield, in the 3rd year the content of red clover was 15- 20%, alfalfa fell out of the herbage. The herbage, consisting of reed fescue and red clover, stood out as the most productive. Two-cuts use of this agrophytocenosis allows for the first 2 years of intensive use to get from 10.71 to 11.41 t/ha of dry matter, 114.12-129.01 GJ/ha of exchange energy and 1.43- 1.51 t/ha of crude protein. Reed fescue stands out as the most promising crop. When alfalfa falls out of the herbage, the experiment variant with reed fescue is superior to the control variant in dry matter yield and exchange energy yield.

Estimation of Nutritive Value and Protein Degradability of Trifolium Repens and Poa Pratensis as the Dominant Pasture Species, Under Simulated Rotational Grazing

Summary A cutting trial was conducted to determine the nutritional value, crude protein (CP) fractions distribution and CP ruminal degradability of white clover (Trifolium repens L.) and Kentucky bluegrass (Poa pratensis L.) as the dominant species of permanent grassland. The legume and grass herbage was obtained in the field experiment carried out on pasture throughout a spring growth season where rotational grazing was simulated using three consecutive cuts, which were compared. The fractionation of CP, according to Cornell Net Carbohydrate and Protein System (CNCPS v6.5), was used to predict protein degradability of the legume and grass forage. A significant (p <0.05) lowering of the CP content in the legume and grass herbage was found, while NDF (neutral detergent fiber) and ADF (acid detergent fiber) significantly increased (p <0.05) as the spring growth season progressed. A significant decrease (p <0.05) of fractions A1 and A2 was noted in the legume and grass herbage, with a significant (p <0.05) increase of CP fractions B2 and C as the vegetation season progressed. A higher rumen degradable protein (RDP) content (p <0.05) of white clover and Kentucky bluegrass herbage was obtained in the first harvest, compared with the second and third one. Significantly larger values (p <0.05) of net energy were observed in the white clover and Kentucky bluegrass forage obtained from the first cut, compared with later regrowths, and white clover was characterized by a higher energy content of 12.4–33.1% (dry matter basis), relative to Kentucky bluegrass.

A Retrospective Analysis of White Clover (Trifolium repens L.) Content Fluctuation in Perennial Ryegrass (Lolium perenne L.) Swards under 4 Years of Intensive Rotational Dairy Grazing

The objective of this study was to examine fluctuations in white clover (Trifolium repens L.) content in perennial ryegrass (Lolium perenne L.) swards within a high nitrogen (250 kg N/ha) input grazing dairy system. The data came from a larger, overall system experiment within which all management and growing condition variables were categorised each year for the 40 paddocks that contained perennial ryegrass-white clover swards, over four growing years. Within that study, eight perennial ryegrass cultivars were examined, each sown individually with two white clover cultivars in a 50:50 mix of ‘Chieftain’ and ‘Crusader’. To determine management associations and meteorological patterns with white clover content and rate/direction of change, separate generalised linear models were used to analyse each individual management or meteorological variable. Paddocks with high white clover contents were associated with lower pre- and post-grazing sward heights, lower pasture cover over the winter period and shorter over-winter period. Perennial ryegrass cultivars with lower pre- and post-grazing height, lower pre-grazing pasture mass and pasture yield removed, all retained more white clover in their swards. Soil fertility remained a key factor that affected white clover persistence influencing the degree of responses in all treatments, particularly soil phosphorus (P) levels. Beyond this, higher white clover contents and lower rates of white clover decline were associated with paddocks that received lower rainfall, had higher soil moisture deficits and received more radiation into the base of the sward, particularly around the time of grazing.

A review of legume research and extension in New Zealand (1990–2022)

Legumes have underpinned transformational change on New Zealand sheep and beef farms over the last 30 years. This was through an emphasis on ewe nutrition based on lucerne or red clover dominant pastures, and increased use of subterranean and white clovers on uncultivatable hill country. Pre- and post-weaning lamb growth rates have increased, and enabled earlier slaughter of heavier lambs. The farm systems results include greater numbers of hoggets mated, higher lambing percentages and greater ewe efficiency (kg lamb weaned/kg ewe mated). Extension packages to support legume use have compared growth rates of resident and legume-based pastures, economic analyses of successful farms and management packages for the most appropriate legume in different environments. Over the same period, the dairy industry rapidly expanded in cow numbers and area onto flat irrigated land on the Canterbury Plains. The nitrogen deficiency of perennial ryegrass was overcome by a linear increase in nitrogen fertiliser use. Environmental concerns from this intensification has led to a legislated nitrogen cap of 190 kg/ha.year. This, coupled with a recent trebling in urea price, has returned attention to increasing the white clover content of these pastures. Nitrogen applications can be minimised by using diverse pastures sown with a legume, herb and <8 kg/ha of perennial ryegrass. Work on other legumes, including annuals and those with condensed tannins, has to date failed to increase their use in most pastoral settings, with the exception of the perennial lupin which is adapted to high-aluminium soils in the South Island High Country.

Changes in sward structure, plant morphology and growth of perennial ryegrass–white clover swards over winter

White clover (Trifolium repens L.) is at a disadvantage to perennial ryegrass (Lolium perenne L.; PRG) due to its limited cold tolerance and low growth rates at colder temperatures, which can affect subsequent spring herbage dry matter (DM) availability. The effect of PRG ploidy on white clover morphology and growth over winter, and its subsequent recovery in spring and the following growing season, is poorly understood. The objective of this study was to compare the effect of white clover inclusion and PRG ploidy on sward structure, plant morphology and growth of PRG–white clover swards over winter. Four swards (diploid PRG only, tetraploid PRG only, diploid PRG–white clover and tetraploid PRG–white clover) were evaluated over a full winter period (November–February) at a farmlet scale. The PRG ploidy had no effect on herbage DM production, white clover content or tissue turnover (P > 0.05) over winter. However, white clover inclusion caused a significant decrease in herbage DM production (P < 0.001; −254 kg DM/ha) and tiller density (P < 0.001; −1,953 tillers/m2) over winter. Stolon mass was not affected by PRG ploidy (P > 0.05); however, stolon length and number of leaves per stolon were affected by PRG ploidy (P < 0.05). Including white clover in PRG swards can alter winter sward dynamics, potentially causing difficulties in subsequent spring management and performance due to the reduced over-winter growth rate when compared with PRG.

Short-Term Effects of Irrigation with Wastewater from Treatment Plant on the Development and Some Metal and Metalloid Contents of White Clover (Trifolium repens L.) + Kentucky Bluegrass (Poa pratensis L.) Mixture

Bu çalışmada, ak üçgül (Trifolium repens L.) ve çayır salkım otu (Poa pratensis L.) bitkilerinden oluşan karışımın, Türkiye-Van Edremit İleri Biyolojik Atık Su Arıtma Tesisi çıkış suyunun farklı konsantrasyonları ile sulanması konusu ele alınmıştır. Bu kapsamda, araştırma; atık suyun, bitkilerin ayrı ayrı ve karışım gelişimine etkisinin araştırılması amacıyla yürütülmüştür. Ayrıca, atık suyun toprak ve bitkide bazı metal ve metaloid içeriği üzerine kısa vadeli etkilerinin belirlenmesi de amaçlanmıştır. Çalışmada, denemeler 2018 yılında iklim odasında saksılarda tesadüf parselleri deneme desenine göre üç tekrarlamalı olarak yürütülmüştür. Araştırmada uygulamalar; % 100 saf su kontrol (100S), % 25 atık su + % 75 saf su (25A75S), % 50 atık su + % 50 saf su (50A50S) ve % 75 atık su + % 25 saf su (75A25S) şeklinde yapılmıştır. Araştırma sonuçlarına göre, bitki boyu her biçimde atık su uygulama miktarına bağlı olarak artış göstermiş olup; en yüksek bitki boyu ortalaması ak üçgülde 10.70 cm ile 75A25S, çayır salkım otunda 11.42 cm ve 11.21 cm ile sırasıyla kontrol ve 75A25S uygulamasından elde edilmiştir. Ak üçgülün yaş ve kuru ağırlığı atık su uygulamalarına bağlı olarak artmış, çayır salkım otunda ise atık su uygulamalarının etkisi görülmemiştir. Bitkilerin ve hasat sonrası toprağın metal ve metaloid içeriği uygulamalara bağlı olarak genelde artmıştır. Çayır salkım otunda molibden (Mo), ak üçgülde ise bakır dışında incelenen metal ve metaloid içerikleri 75A25S uygulamasında en yüksek değerlere ulaşmıştır. Hasat sonrası toprakta Mo, kurşun ve kadmiyum içeriğinde bir değişiklik olmamış, ancak diğer metal ve metaloid içerikleri artmıştır. Hasat sonrası alınan toprak örneklerinde atık su uygulamaları ile pH değerinde bir düşüş olduğu belirlenmiştir. Atık su uygulama konsantrasyonları arttıkça toprağın elektriksel iletkenlik değerinde de artış belirlenmiştir. Bu sonuçlar ışığında, kullanılan atık suyun bitki büyüme ve gelişmesi üzerine olumlu etkileri belirlenmiş ancak toprak üzerine etkileri için uzun süreli çalışmalara ihtiyaç olduğu kanısına varılmıştır.

The effects of lime on pasture composition and production in western Waikato hill country

A 4-year lime rate trial was established on a hill country sheep and cattle property near Te Akau to determine lime effects on pasture utilisation. Four rates of lime were applied (1.25 t/ha, 2.5 t/ha, 5 t/ha and 10 t/ha) to 2 m × 2 m plots, from which soil Al, Ca and pH, pasture grazing heights, dry matter production, pasture species composition, feed quality and brix levels were measured. Lime application reduced soil Al (14.6 to 1.1 mg/kg), and increased Ca and pH (5.0 to 6.2) over time in the highest application rate. Dry matter production responded to all rates of lime in each year, and by the fourth year it was 27% greater (1.25 t/ha treatment), 35% greater (2.5 t/ha treatment), 69% greater (5 t/ha treatment), and 97% greater (10 t/ha treatment) than in the un-limed plots. Ryegrass and subterranean clover content increased with lime rate, whereas chewings fescue and dicot weed content declined. There were no sustained differences in pasture grazing heights, feed quality or brix levels between the control and rates of lime. On this site, all rates of lime were economic to apply by truck or plane when the benefits were spread over 4 years, with the greatest cost-benefit from thelower rates of lime.

Source partitioning using N2O isotopomers and soil WFPS to establish dominant N2O production pathways from different pasture sward compositions.

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) emitted from agricultural soils and is influenced by nitrogen (N) fertiliser management and weather and soil conditions. Source partitioning N2O emissions related to management practices and soil conditions could suggest effective mitigation strategies. Multispecies swards can maintain herbage yields at reduced N fertiliser rates compared to grass monocultures and may reduce N losses to the wider environment. A restricted-simplex centroid experiment was used to measure daily N2O fluxes and associated isotopomers from eight experimental plots (7.8 m2) post a urea-N fertiliser application (40 kg N ha-1). Experimental pastures consisted of differing proportions of grass, legume and forage herb represented by perennial ryegrass (Lolium perenne), white clover (Trifolium repens) and ribwort plantain (Plantago lanceolata), respectively. N2O isotopomers were measured using a cavity ring down spectroscopy (CRDS) instrument adapted with a small sample isotope module (SSIM) for the analysis of gas samples ≤20 mL. Site preference (SP = δ15Nα - δ15Nβ) and δ15Nbulk ((δ15Nα + δ15Nβ) / 2) values were used to attribute N2O production to nitrification, denitrification or a mixture of both nitrification and denitrification over a range of soil WFPS (%). Daily N2O fluxes ranged from 8.26 to 86.86 g N2O-N ha-1 d-1. Overall, 34.2% of daily N2O fluxes were attributed to nitrification, 29.0% to denitrification and 36.8% to a mixture of both. A significant diversity effect of white clover and ribwort plantain on predicted SP and δ15Nbulk indicated that the inclusion of ribwort plantain may decrease N2O emission through biological nitrification inhibition under drier soil conditions (31%-75% WFPS). Likewise, a sharp decline in predicted SP indicates that increased white clover content could increase N2O emissions associated with denitrification under elevated soil moisture conditions (43%-77% WFPS). Biological nitrification inhibition from ribwort plantain inclusion in grassland swards and management of N fertiliser source and application timing to match soil moisture conditions could be useful N2O mitigation strategies.