PSXI-15 Evaluation of low-lignin alfalfa ‘Hi-Gest® 360’ on the Canadian prairies: productivity, nutrient profile, and rumen degradation kinetics

The study was conducted at Saskatoon, SK, Canada in the Dark Brown soil zone (52°07′N,106°38′W), to compare low-lignin Hi-Gest®360 alfalfa (Hi-Gest; Medicago sativa L.) to a conventional alfalfa (AC Grazeland) under two cutting regimes. Each cultivar was seeded in 2017 as both a monoculture and binary mixture (binary; Hi-Gest+HB and Grazeland+HB) with AC Success hybrid bromegrass (HB). Plot size was 1.2m×6m with 4 rows. Three years (2018–2020) result suggested that the first cut DMY was 1695±241 and 2151±276 kg/ha for the Hi-Gest and Grazeland, respectively. Hi-Gest had greater (P < 0.05) TDN (68.4 vs. 66.6%, DM basis), NEm (1.7 vs. 1.6 Mcal/kg), IVNDFD48: (42.9 vs. 37.8%), but lower second cut DMY (1288 vs. 1560 kg/ha), ADF (26.3 vs. 28.7%), NDF (34.7 vs. 36.6%), compared to AC Grazeland. Under two cutting, Hi-Gest was numerically lower in total DMY (2983 vs. 3712 kg/ha; P = 0.114) relative to Grazeland. In first cut forage, Hi-Gest also was numerically lower in ADL (5.9 vs. 6.5%; P = 0.57) relative to AC Grazeland. Hi-Gest was similar (P = 0.15) with AC Grazeland in effectively degradable dry matter (EDDM; 622 g/kg DM), effectively degradable CP (EDCP; 689 g/kg CP). Hi-Gest alfalfa had greater (P = 0.05) effectively degradable neutral detergent fiber (EDNDF; 19% more; 340 vs. 285 g/kg NDF) relative to AC Grazeland alfalfa. In binary system, Hi-Gest+HB had (P = 0.02) greater EDCP (12% more; 526 vs. 468 g/kg CP), and numerically greater EDNDF (4.4% more; 259 vs. 248 g/kg NDF; P = 0.10) but had similar EDDM (409 g/kg DM) relative to Grazeland+HB mixture. Each percentage unit increase in alfalfa ADL concentration decreased EDNDF by 2.3 percentage units (EDNDF, % NDF = 46.0–2.93×ADL, % DM, r2=0.26, P < 0.01). Although Hi-Gest yielded less (~25% less) than AC Grazeland, Hi-Gest had greater nutritive value compared to AC Grazeland; differed little for yield and quality in binary mixture, suggesting Hi-Gest can be a viable alternative legume for western Canadian prairies.

Pigeon pea (Cajanus cajan) fodder cutting management in the Guinea Savanna Agro-Ecological Zone of Ghana

This study evaluated the effect of cutting regime on biomass yield and nutrient composition of pigeon pea (Cajanus cajan (L) Millsp.) fodder in the Guinea Savanna Agro-Ecological Zone of Ghana. Three cutting regimes (12, 16 and 20 Week After Planting [WAP]) in RCBD were imposed on Cajanus cajan at both initial establishment and regrowth. At each harvest, biomass yield was estimated after which samples of the fodder were separated into leaf and stem botanical fractions for chemical composition and in vitro digestibility. Cutting regime significantly affected plant height, number of branches and stem diameter in both the initial establishment and regrowth. Biomass yield was significantly affected by cutting regime in the initial establishment but not the regrowth. The biomass yield was highest in the harvest at 20WAP (6515kgDM/ha) while 12WAP (3175 kg/ha) recorded the lowest biomass yield in the initial establishment. All chemical composition parameters were significantly affected by cutting regime and botanical fractions except hemicellulose in the initial establishment. Cutting regime also significantly affected DM, CP and ash concentrations in the regrowth with botanical fraction significantly (P < 0.05) influencing CP, NDF, ADF and ash. The highest CP was obtained in the leaf fraction harvested at 12 WAP and 20 WAP in the initial establishment and regrowth respectively. Cutting regime, botanical fraction and their interaction were significant in gas produced at 24 h, SCFA and ME in both the initial establishment and regrowth stages. In conclusion, harvest at 20WAP produced the highest biomass yield but lower CP in the initial establishment whiles in the regrowth, harvest at 20WAP produced higher biomass yield, CP and ME.

Size Effect of CeO2 Particle On Nanoscale Single-Asperity Sliding Friction

The size of abrasive particle has a great impact on the fundamental friction behavior and mechanical properties of the abrasive during ultra-precision polishing performance. Here, the size effect of the tribological behavior and mechanical properties of CeO2 single abrasive were studied. Experimental results show that the size effect plays a role on coefficient of friction (COF) of each regime in single-asperity sliding friction, especially in ploughing and cutting regimes. The residual depth of the scratch and COF both decrease with the increase of the CeO2 tip radius. These results relate to the mechanical properties of CeO2 nanoparticles. We found that the effective modulus increases with the decrease of abrasive size, which corresponds to the size effect of the single-asperity sliding friction experiment.

Management to Promote Flowering Understoreys Benefits Natural Enemy Diversity, Aphid Suppression and Income in an Agroforestry System

Agroforestry systems, where productive trees are integrated into agricultural land, can deliver benefits to biodiversity, natural pest control, and pollination, but the effects are highly variable. Recent advances in our understanding of flower strips in agricultural systems suggest that the management of the tree row understorey could be an important contributor to this variation. Here, we compare two cutting regimes for an understorey, originally seeded with the same flower mix, in the tree rows of an apple-arable agroforestry system: (i) uncut vegetation to promote a flowering understorey, and (ii) regularly mown vegetation. We recorded the effects of management on invertebrate pests, natural enemies, and pollinators, in both the apple and arable components. Apple trees above flowering understoreys supported significantly: (i) more natural enemies early in the season, (ii) fewer aphid colonies, (iii) fewer aphid-damaged fruits, and (iv) higher pollinator visitation, compared with those above mown understoreys. In the arable crop alleys, both the taxonomic richness and Shannon diversity of ground-based natural enemies were significantly higher adjacent to flowering understoreys, compared with those adjacent to mown understoreys, early in the season. Financial modelling based on aphid damage to apples, mowing costs, and income from Countryside Stewardship grants, indicated that flowering understoreys increased farm income by GBP 231.02 per ha of agroforestry compared with mown understoreys. Our results provide the first empirical evidence that management to promote flowering understoreys in agroforestry systems can be a win-win option to improve invertebrate diversity, associated ecosystem services, and farm income.

The role of land cover, land use, and atmospheric transport for the mismatch of flowering and atmospheric pollen seasonality

&lt;p&gt;Aeroallergens contribute a major climate change impact on human health since warming favours the production and advances the release of plant pollen. This goes in line with a widely observed advance of flowering in response to increasing temperatures. However, documented plant phenological changes vary with species traits, seasons, and sites. Nevertheless, the start and end of flowering dates are known to build a solid baseline for assessing the spatial and temporal patterns in pollen calendars. A closer look at the match/mismatch of flowering and start of pollen season dates reveals considerable differences which may be also indirectly linked to climate change. In this talk, we will present three perspectives related to (1) grassland land use, cutting regimes and agri-environment measures (AEM), (2) post-season pollen transport of an alpine &lt;em&gt;Alnus &lt;/em&gt;species, as well as (3) a first climatology of pre-season long-range pollen transport to Bavaria. These selected examples underline the prominent role of land use/land cover (LULC) and pollen transport besides direct temperature mediated climate change effects on flowering for regional pollen calendars.&lt;/p&gt;

Lucerne (Medicago sativa L.) Persistence Remains Unchanged under Variable Cutting Regimes

Lucerne (Medicago sativa L.) persistence is important for farming systems in south east Australia. Defoliation of lucerne that is too frequent (arguably more than once every six weeks) reduces yield and accelerates stand decline. Three experiments were conducted in south east Australia (Burraja, New South Wales; Rutherglen and Hamilton, Victoria) to investigate different cutting regimes on lucerne persistence. At Burraja lucerne was cut 16 (lax) or 33 (severe) times over three years at different plant densities. At Rutherglen and Hamilton lucerne was cut every 21 days (short rotation), every 42 days (long rotation), when new shoots (2.5 cm long) emerged (new shoots) or cutting when new shoots emerged but allowing the lucerne to flower in autumn (new shoots flowering). It was hypothesised that the frequent cutting of lucerne would result in lower plant densities. At Burraja there was little difference between treatments at any density or assessment. At Hamilton, apart from the assessment in June 2016, there was no difference (p > 0.1) between treatments. At Rutherglen, there was no difference (p > 0.1) between treatments at any assessment although plant numbers declined in 2016 from waterlogging. The results provide evidence that lucerne has intrinsic mechanisms that protect it from cutting, often at short intervals, thus promoting its persistence over three to four-year periods.

Control of Chip Formation and Improved Chip Ejection in Drilling With Modulation-Assisted Machining

Drilling with modulation-assisted machining (MAM) superimposes a low-frequency oscillation onto the drill feed motion. The otherwise continuous cutting in the drilling process is converted into a series of discrete cutting events. The result is a discrete chip formation process and concurrent improvement in chip ejection. The discrete chip formation and ejection in drilling with MAM were investigated via systematic experiments in OFHC Cu and Ti6Al4V using a two-flute twist drill and a single-flute gun drill. Drilling thrust force and chip morphologies for various modulation conditions are examined. The continuous cutting and discrete cutting regimes of modulation-assisted drilling are compared with conditions determined by a kinematic model. The results show that chip formation in the continuous cutting regime with MAM can influence chip breakage by random fracture at thin sections of the chip, but in this regime the resulting chip size is variable and not controlled. In contrast, when MAM conditions operate in the regime of discrete cutting, the deformed chip size can be directly controlled. The ability to control the chip size improves chip ejection and drilling process stability. A set of modulation conditions for enhanced performance of chip ejection are proposed. The study shows that modulation-assisted machining offers distinct advantages as a method for deep-hole drilling applications.