179 The Effect of Sward Type on the Performance of Co-grazed Cattle and Sheep

A farmlet study was established to evaluate the effect of four sward types on the performance of heifers and lambs co-grazing: a perennial ryegrass only sward (PRG) receiving 170 kg N/ha each year; a permanent pasture (PP) receiving 135 kg N/ha each year; a six species mix (2 grasses, 2 legumes, 2 herbs) at 70 kg N/ha each year (6SP); and a 12 species mix (3 grasses, 4 legumes and 5 herbs) at 70 kg N/ha each year (12SP). Each farmlet (9 ha) was rotationally grazed with 20 dairy cross heifers (13 months old) and 22 ewes plus lambs from April to November 2020. Heifers and lambs were finished for slaughter from herbage only diets. Heifers were weighed monthly and drafted for slaughter on three occasions when their estimated fat class on the EUROP grid scale reached 3-. Lambs were weighed fortnightly and drafted for slaughter at 42 kg [lambing to weaning (July 7th)], 44 kg (weaning to September) and 46 kg (after September 1st) to obtain a target carcass weight of 21 kg. Average daily gain (ADG) was higher for heifers grazing the 6SP sward (1.13 kg/day) than the PRG (0.99 kg/day) or PP swards (1.03 kg/day; P < 0.05). Kill out percentage (KO%) was higher for heifers grazing the 12SP sward (48.9%) compared to the PP sward (47.2%; P < 0.01). Lamb ADG was higher for lambs grazing the 6SP sward (0.38kg/day) compared to lambs grazing either the PP (0.32kg/day) or the PRG sward (0.29kg/day) (P < 0.01). Lamb KO% was higher for lambs grazing the 12SP sward (49.4%) compared to those grazing the PRG (45.7%) and the PP swards (44.5%; P < 0.01). Lambs grazing the 6SP sward had reduced days to slaughter (109) compared to lambs grazing the PP (137) and PRG (149) swards (P < 0.01). In conclusion, co-grazing multispecies swards improved overall heifer and lamb performance.

PSXIV-21 Performance of hair lambs maintained on stockpiled permanent pasture mixed with Cleome gynandra L. at multiple stocking densities

Stockpiled forage may extend the grazing season for sheep, reducing feeding costs. Additionally, internal parasites are a problem in sheep managed under grazing conditions. Plants high in phenolic compounds have potential to reduce parasite problems. Cleome gynandra is one such plant that has traditionally been used to treat worms in humans. Thirty-six Katahdin × Dorper lambs (38.8 ± 0.7 kg) were used to investigate the effect of stockpiled forages on lamb performance at different stocking densities: (i) 23 lambs/ha (LOW), (ii) 46 lambs/ha (MED), and (iii) 92 lambs/ha (HIGH). To test C. gynandra for anthelmintic properties, lambs were assigned to (i) permanent pastures (PP), and (ii) PP inter-seeded with C. gynandra (CL). The LOW lambs had the highest ADG (83.8 ± 10.5 g/day), MED lambs were intermediate (48.4 ± 11.6 g/day) and HIGH lambs were lowest (11.0 ± 10.6 g/day; P < 0.001). Lamb BCS did not differ between stocking densities or pasture types (P > 0.10). Fecal egg counts did not differ (P > 0.10) between pasture treatments. In conclusion, stockpiled forages may extend the grazing season for yearling lambs in Southern California. The lack of effect on parasite egg counts may be attributed to grazing C. gynandra at mature stage when nutritional and medicinal values were at their lowest. Future research can clarify the economics of grazing stockpiled forages for sheep at different stages of production, and nutritional effect of C. gynandra on carcass quality.

Effects of plant spacing and fertilizer level on forage yield and chemical composition of hybrid Urochloa cv. Mulato II grass during the first 150 days of growth under irrigation supplementation, in Chagni Ranch, Awi Zone, Ethiopia

A study was conducted to evaluate the effects of plant spacing and N fertilizer application on dry matter yield and chemical composition of Urochloa hybrid cv. Mulato II grass for the first 150 days after planting. A factorial experiment with 3 urea fertilizer levels (0, 50 and 100 kg/ha) and 4 spacings between plants and rows (20 × 20, 30 × 40, 40 × 60 and 50 × 80 cm) with 3 replications was used. Data collected were dry matter yield (DMY), leaf:stem ratio and chemical analyses, i.e. crude protein (CP), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) concentrations. Results indicated that DMY, leaf:stem ratio, CP%, NDF% and ADF% were significantly (P<0.05) affected by interactions between plant spacing and fertilizer level. However, ash and ADL were significantly (P<0.05) affected only by main effects. The highest DMYs (9.18 t/ha and 8.93 t/ha) were recorded for narrowest plant spacing (20 × 20 cm) with higher urea fertilizer level (100 kg/ha) and narrowest plant spacing (20 × 20 cm) with medium urea fertilizer level (50 kg/ha), respectively. CP% ranged from 14.6 to 20% and leaf:stem ratio from 1.12 to 1.82:1. Similar studies need to be conducted over longer periods to determine to what extent these findings relate to performance over the life of a permanent pasture.

The Distribution of Soil Micro-Nutrients and the Effects on Herbage Micro-Nutrient Uptake and Yield in Three Different Pasture Systems

Pasture micro-nutrient concentrations are often deficient for herbage productivity and the health of livestock. The aim of this study was to investigate soil and herbage micro-nutrient content and the effects on yield on the three pasture systems of the North Wyke Farm Platform (NWFP): high-sugar grass + legume mix minus nitrogen (N) fertilizer (blue/HSG + L); permanent pasture plus N fertilizer (green/P + N); high-sugar grass plus N fertilizer (red/HSG + N). The locations with high soil total micro-nutrient concentrations had a greater slope and higher soil organic matter (SOM) content. Herbage micro-nutrient concentrations were often greater at the locations with high soil total micro-nutrient concentrations. The concentration and uptake of nearly all micro-nutrients was greatest in the herbage of the green/P + N system, which had the highest SOM content, whereas they were often lowest in the red/HSG + N system, which had the lowest SOM and the highest yield, indicating biomass dilution of micro-nutrients in the herbage. At the locations with high soil micro-nutrient concentrations, yield was higher than at locations with low micro-nutrient concentrations, and was equal across the three pasture systems, regardless of fertilizer N treatment. Variation in micro-nutrient uptake/yield in the blue grass–legume system was predominantly explained by the soil molybdenum (Mo) concentration, possibly relating to the requirement for Mo in biological nitrogen fixation. There was, therefore, a trade-off in ploughing and re-seeding for higher yield, with the maintenance of SOM being important for herbage micro-nutrient content.

The interactive effect of land-use and soil depth on microbial activity during drying and rewetting – an experimental and computational investigation

&lt;p&gt;The alternation of drought periods and rainfall events, intensified by climate change, has huge impacts on carbon cycle dynamics. Changes in soil moisture induce significant releases of CO&lt;sub&gt;2&lt;/sub&gt; from soils to the atmosphere. This phenomenon, known as the Birch effect, is accompanied by drastic changes in the microbiology as well. Based on the response patterns of microbial growth and respiration to the rewetting of dry soil, two different types have been identified. Microbial communities either respond immediately after rewetting and start increasing growth in a linear way (so-called &amp;#8220;type 1&amp;#8221; response), or they recover growth after a lag phase preceding an exponential increase (&amp;#8220;type 2&amp;#8221; response). The reasons behind the different responses, including how harsh the drought is perceived by the communities and what history of moisture conditions they were subjected to, are not yet fully resolved. Moreover, most studies focus on the top few centimeters of soil and the effect of depth and the contribution of deeper soils to the overall dynamics have been largely overlooked.&lt;/p&gt;&lt;p&gt;In order to investigate the influence of depth on microbial dynamics during drought and rainfall events, taking into account land-use, we performed a set of laboratory experiments that were also used to parameterize and validate numerical modelling-based analysis of the ecology driving soil biogeochemistry. We collected soil samples from permanent pasture and tilled and cropped arable fields at two different depths (0-5 cm and 20-30 cm). We then subjected them to a week of air drying followed by rewetting to optimal moisture, and measured respiration, bacterial growth and fungal growth at high temporal resolution.&lt;/p&gt;&lt;p&gt;The patterns were significantly different between soil types, showing type 1 responses in arable soils and type 2 responses in pasture soils. The type 1 responses in arable soils were also characterized by a higher carbon use efficiency after the rewetting perturbation. Moreover, the deeper microbial communities were relatively more affected by the drying and rewetting experiment than the respective shallow ones. Taken together, these results suggested that the drying and rewetting event was perceived by soil microbial communities as a stronger disturbance in the pasture soils, and at deeper depths, as illustrated by more sensitive microbial responses.&lt;/p&gt;&lt;p&gt;We then incorporated these laboratory data into a soil microbial model (EcoSMMARTS) and identified the depth- and community-specific differences in osmolyte regulation, necromass turnover, and cell residue activity as the microbial mechanisms potentially explaining the observed patterns. These findings provide insights into soil-climate feedback from different ecosystems, where intensively used arable soils were more resilient than permanent pasture soils and stored larger amounts of carbon due to a higher fraction of microbial growth to respiration under climate change scenarios. The capacity of microbial communities to adapt and regulate soil carbon dynamics is not uniform through the soil profile nor across management practices, therefore indicating a need for future studies incorporating depth and especially land-use which has the strongest effect on microbial activity during soil drying and rewetting.&lt;/p&gt;

Integrating Narcissus-derived galanthamine production into traditional upland farming systems

Alzheimer’s disease (AD) is a disorder associated with progressive degeneration of memory and cognitive function. Galantamine is a licenced treatment for AD but supplies of the plant alkaloid that it is produced from, galanthamine, are limited. This three-year system study tested the potential to combine Narcissus-derived galanthamine production with grassland-based ruminant production. Replicate plots of permanent pasture were prepared with and without bulbs of Narcissus pseudonarcissus sown as lines into the sward. Two different fertiliser regimes were imposed. The above-ground green biomass of N. pseudonarcissus was harvested in early spring and the galanthamine yield determined. In the second harvest year a split-plot design was implemented with lines of N. pseudonarcissus cut annually and biennially. All plots were subsequently grazed by ewes and lambs and animal performance recorded. Incorporation of N. pseudonarcissus into grazed permanent pasture had no detrimental effects on the health or performance of the sheep which subsequently grazed the pasture. There was no consistency to the effects of fertiliser rates on galanthamine yields. There was no difference in overall galanthamine yield if N. pseudonarcissus was cut biennially (1.64 vs. 1.75 kg galanthamine/ha for annual combined vs biennial cuts respectively; s.e.d = 0.117 kg galanthamine/ha; ns). This study verified the feasibility of a dual cropping approach to producing plant-derived galanthamine.

Soil carbon market-based instrument pilot – the sequestration of soil organic carbon for the purpose of obtaining carbon credits

Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha–1 year–1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha–1 year–1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.

Stock and indices of carbon management under different soil use systems

The aim of this study was to evaluate the stock of total organic carbon (TOC) and to perform the physical-granulometric fractionation of soil organic matter (SOM) in different management systems (MS). Three MS and one reference area of Native Forest (NF) were studied, and the three systems were sugarcane (SC), permanent pasture (PP) and no-tillage system (NTS). Soil samples were collected in the 0–0.05, 0.05–0.10, 0.10–0.20-m layers. Soil density (Sd), TOC, stratification index (SI), carbon stock (StockC), variation in StockC (∆StockC), carbon content of particulate organic matter (C-POM) and mineral organic matter (C-MOM), carbon stock index (CSI), lability (L), lability index (LI), and carbon management index (CMI) were determined. The MS presented higher Sd than the NF area. The NF area had higher TOC contents in the first layers, reaching 25.40 g kg-1 in the 0–0.05-m layer, with the PP area having higher values than the NF in the 0.10–0.20-m layer. The NF area showed the highest levels of C-POM (15.25 g kg-1) and C-MOM (10.15 g kg-1) in the first layer. In the 0.10–0.20-m layer, the PP and NTS systems were superior to the others. Regarding the C-MOM content, SC and PP showed higher levels in the 0.10–0.20-m layer. The highest CMI values were observed in the NTS and PP areas in the 0.10–0.20-m layer. The MS increased the Sd and reduced the TOC levels. The different MS modified the POM fraction, and the MOM fraction was most impacted by the SC area. The lability of the SOM was altered by the MS in the most superficial layers.