Ignacio F. López

The influence of topography and pasture management on soil characteristics and herbage accumulation in hill pasture in the North Island of New Zealand

The aim of this study was to examine long-term effects of fertiliser and livestock management and micro-topographical variation on soil physical and chemical characteristics and herbage accumulation on a hill site in the southern North Island of New Zealand.Paddocks subjected to high fertility-high stocking rate (HH) and low fertility-low stocking rate (LL) treatments dating back to 1975 were used. Soil samples were taken from three slope categories (0–12 ° low slope, LS; 13–25 ° medium slope, MS; >25° high slope, HS) from HH and LL and a range of soil chemical and physical features were assessed. Herbage accumulation (green matter and dead matter) was measured over 12 months on each microsite.Greater differences in soil and herbage features, such as unsaturated hydraulic conductivity (Kunsat), bulk density (BD), water holding capacity (VSM), soil compressibility (SC), total soil nitrogen (Total-N), Olsen-P and green dry matter accumulation (GDMA), were measured across slope categories than between management treatments, possibly because slope effects on soils would have operated over longer periods of time than the fertiliser-stocking rate contrasts. Increasing slope decreased GDMA on the site, as well as Total-N, Olsen-P, VSM and SC, but increased Kunsat, BD and soil rebound after compression (SR). Slope, VSM, Kunsat, SC, BD and Total-N were the soil variables with largest influence on differentiation between microsites. Olsen-P and SR were less important. Green dry matter accumulation was strongly influenced by slope, soil VSM and Kunsat, and to a lesser extent by soil Total-N and Olsen-P.

Herbage production, nutritive value and grazing preference of diploid and tetraploid perennial ryegrass cultivars (Lolium perenne L.).

The objective of this study was to determine, under the soil and climatic conditions of Southern Chile, the effect of the ploidy of perennial ryegrass (Lolium perenne L.) cultivars on herbage production, nutritive value, grazing preference and utilization of pasture produced. This study was conducted in southern Chile, Valdivia Province, and was evaluated for 3 years. The tetraploid cultivars used were Quartet (4n), Gwendal (4n), Pastoral (4n) and Napoleon (4n). The diploid cultivars were Anita (2n), Jumbo (2n), Aries (2n), and Yatsyn 1 (2n). When the average sward height reached 20 cm, all plots were simultaneously grazed by dairy cows for a period of 24 h. Before and after grazing, sward height, dry matter availability and nutritive value were evaluated. Grazing preference was visually assessed every 5 min for a period of 2.5 h after the afternoon milking. During the 3-year period 20 grazing events were evaluated. A randomized complete block design, with eight cultivars and three replicates, was used. Diploid

Sward and tiller growth dynamics of Lolium perenne L. as affected by defoliation frequency during autumn

A mini-sward study was undertaken between January and September 2008 in Valdivia, Chile, to quantify and compare changes in the herbage production, growth dynamics and nutritive quality of a Lolium perenne sward during autumn in response to different nitrogen (N) application regimes and defoliation frequencies. The N levels used in the present study corresponded to the equivalent of an autumnal application of 0, 25 or 75 kg N/ha. The defoliation frequency was based on leaf regrowth stage, and corresponded to the time taken for 1.5, 2.5 or 3.5 leaves per tiller to expand. The growth dynamic measurements were also related to temperature. The results showed that the level of N had no effect on the studied variables. Plants defoliated at the 3.5-leaf stage showed a higher herbage production, higher tillering and a more balanced nutritional profile than plants cut at the 1.5-leaf stage. The defoliation interval had no effect on leaf elongation or leaf appearance. The leaf elongation rate was linearly related to the mean daily temperature (P < 0.01), and the accumulated leaf and tiller number showed a significant linear relationship (P < 0.01) with the thermal time expressed as growing degree days. From the defoliation frequencies tested here, we can conclude that the best time for grazing L. perenne swards during autumn is at the 3.5-leaf stage due to a higher herbage production, higher tillering rate, more balanced nutritive quality and higher reserve levels of the plant, which provide a more favourable background for subsequent growth.

Nutritive value, in vitro fermentation and methane production of perennial pastures as affected by botanical composition over a growing season in the south of Chile

Permanent pastures have been shown to produce similar herbage masses and nutrient contents to perennial ryegrass pastures. To the best of our knowledge, little research has been conducted on the ruminal fermentation of permanent pastures. Our objective was to evaluate the effect of botanical composition of four perennial pastures during a growing season in the south of Chile [winter, September 2010 ‘S1’; spring, November 2010 ‘S2’; and summer, January 2011 ‘S3’]: on in vitro fermentation products using a batch culture system. The perennial pastures studied included: permanent (PP), permanent fertilised (PFP) and renovated pastures (Lolium perenne and Trifolium repens pasture ‘RGWC’; Bromus valdivianus, Dactylis glomerata, Holcus lanatus, L. perenne and T. repens ‘MIXED’). There were strong interactions between pasture type and regrowth period for true organic matter, nitrogen (N) and neutral detergent fibre digestibility; total gas and volatile fatty acid (VFA) production; ammonia and microbial N. In general, all pasture treatments showed a high true organic matter digestibility (>800 g/kg), and tended to decrease in S3. In vitro fermentation of PFP and RGWC produced the highest total VFA concentration during S1 and S2, and no differences among pastures were observed in summer. Propionate proportion of total VFA was affected by pasture type and regrowth period, being higher for RGWC and S1, respectively. In vitro microbial N was higher for MIXED in S1, and PFP in S2 and S3. No pasture and regrowth period effects were observed for methane production and its proportion of total gas production. These results indicate that the in vitro fermentation products of a permanent fertilised pasture reach similar levels to those obtained from a sown pasture, and thus may be considered as a sustainable alternative for grazing livestock systems.

Short-term effects of different pasture improvement treatments on the physical quality of an andisol

Abstract The improvement of degraded pastures is important for increasing pasture herbage mass and animal production in southern Chile. While research has normally focused on how animal treading affects soil compaction, no major work has yet been done to define the impact of pasture improvement managements on soil physical functions, particularly when the initial situation is a degraded pasture. Thus, the aim of this study is to define the short-term effects of different pasture improvement managements on the physical quality and related processes of a volcanic ash soil. Four treatments were defined: two tilled, fertilized and seeded plots (T1 and T2), one non-tilled and non-fertilized plot (T3) and one non-tilled and fertilized plot (T4), all of which were compared to the initial situation of a highly degraded pasture (IS). Undisturbed soil samples were collected (1-10 cm) and the volumetric water content and temperature was continuously monitored at the 10 cm depth. The short-term effects of pasture improvement managements on soil physical quality and related processes differed in relation to the treatment method. As compared to the non-tilled plots, the aggregate destruction after tillage induced an increase in the water holding capacity, but a decrease in the air capacity and pore-continuity values due to grazing. The physical quality assessed by the S-Index reflected a good soil structural quality (S > 0.035). The tilled plots presented a higher S-Index as compared to the non-tilled plots, which is related to a slightly lower mechanical strength and larger water holding capacity. The latter also increased due to tillage and was positively correlated to pasture yields during the first intensive soil drying. Soil temperature differences between treatments were assessed and can be related to the higher water contents in the tilled plots and the presence of broad-leaf species in the non-tilled pastures. Finally, in order to properly understand how the implementation of pasture improvement managements affects the soil physical quality and related processes, long-term studies are required.

Plant functional groups in a heterogeneous environment

Abstract Species membership of plant functional groups and the relationship to soil variables were studied in two paddocks with long‐term differentiated management in New Zealand hill country. The microrelief of the paddocks contained three slope classes (low, medium, and high) with contrasting soil variables. Soil variables (unsaturated hydraulic conductivity, bulk density, volumetric soil moisture, total soil porosity, field volumetric soil moisture, soil compression, soil rebound, and air permeability), botanical composition and herbage mass accumulation were determined. Analysis of variance, cluster analysis, simple correlation analysis and canonical variate analysis were performed on the data. Seven functional plant groups were determined. High fertility grasses and Lolium perenne were strongly affected by changes in the level of soil variables. Low fertility species appeared to be affected indirectly by soil variables, as they were poor competitors when availability of soil resources was high. Some species (e.g., Agrostis capillaris) were indifferent to changes in the levels of available resources due to soil characteristics. Species and functional groups colonised the evaluated sites according to the soil resources. Species and functional groups were shown to have the capability to respond positively to soil resources, adjusting their growth according to the varying circumstances. The relationship between plant functional groups and field condition, a grazing management concept that measures the deviation from some ideal ecological state, was also examined. Results suggested that field condition and plant functional groups are complementary concepts in grassland dynamic analyses.

In situ rumen degradation kinetics as affected by type of pasture and date of harvest

Botanical composition affects the nutritive value and nutrient degradation kinetics of pastures. However, there is little information about pastures composed of various species. The present study was conducted to evaluate in situ degradation kinetics of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) of a naturalized non fertilized pasture (NNF), naturalized fertilized pasture (NF), sown pasture with Lolium perenne L. and Trifolium repens L. (RGWC), and sown pasture with Bromus valdivianus Phil., Dactylis glomerata L., Holcus lanatus L., L. perenne and T. repens (MIXED); at three dates of harvest (early-spring, mid-spring and autumn). Duplicate bags were incubated in the rumen of three cannulated cows for 2, 4, 8, 12, 24 or 48 h. Zero-hour bags were washed with water. Ruminal degradation was evaluated according to exponential models with or without lag phase. Pasture chemical composition showed on average low DM, high CP and digestible organic matter (DOMD). Degradation parameters of DM, CP and NDF exhibited strong pasture type*date of harvest interactions. In general, high potential degradability and fractional degradation rates of DM, CP and NDF were observed. Nutrient supply was generally higher for RGWC and NF, especially compared with NNF during autumn. Naturalized fertilized pastures supply similar amounts of nutrients to grazing cattle as sown pastures. However, it is necessary to consider other variables that determine the productive performance such as DM intake and rumen fermentation products.

Behavior of grazing European wild boar (Sus scrofa) in a semi-extensive production system

S.M. Hodgkinson, F. Matus, and I.F. Lopez. 2013. Behavior of grazing European wild boar (Sus scrofa) in a semi-extensive production system. Cien. Inv. Agr. 40(1):193-199. In the semi-extensive farming systems that are used to raise European wild boar in countries such as Chile, the behavior of the animals in paddocks has not been studied and is important for managing the system. The objective of the present study was to determine the proportion of time that grazing wild boar spent on different activities and the distribution of these activities during the day. The study was conducted in paddocks containing Cynodon dactylon, Lolium perenne and Poa pratensis. A total of 35 purebred European wild boars with a liveweight (average + SEM) of 37.4 + 1.11 kg with noserings were used in the study. The animals were in the paddocks from 08:30 h until 16:30 h, after which they had free access to a commercial diet for one hour and were kept in a barn until the following day. The activity of each animal was observed every 5 minutes throughout the grazing period, with the activities categorized as grazing, rooting (either with the snout or foot), walking, running, playing, lying down, drinking or other activities. Overall, throughout the grazing time, the animals spent 26% of their time grazing, 17% rooting, 7% walking, 3% playing, 2% drinking and 44% lying down. When the animals entered the paddock in the morning, they grazed intensively, as 74% of observations were of grazing during the first half hour. Gradually the observations of grazing decreased, reaching the lowest number between 12:00 and 12:30 h, when only one animal was observed to graze at one timepoint. The number of animals observed lying down gradually increased over the morning. In the afternoon, the proportion of animals grazing gradually increased, reaching a maximum of 27% of animals grazing at 15:00 h. Over an 8-hour period with access to pasture, European wild boar spent a significant amount of time grazing (26%). The intensity of grazing was high when they first entered the paddock and decreased gradually over the next four hours, increasing slightly again toward the end of the 8-hour period.

Phenotypic variability in Holcus lanatus L. in southern Chile: a strategy that enhances plant survival and pasture stability.

Holcus lanatus L. can colonise a wide range of sites within the naturalised grassland of the Humid Dominion of Chile. The objectives were to determine plant growth mechanisms and strategies that have allowed H. lanatus to colonise contrasting pastures and to determine the existence of ecotypes of H. lanatus in southern Chile. Plants of H. lanatus were collected from four geographic zones of southern Chile and established in a randomised complete block design with four replicates. Five newly emerging tillers were marked per plant and evaluated at the vegetative, pre-ear emergence, complete emerged inflorescence, end of flowering period, and mature seed stages. At each evaluation, one marked tiller was harvested per plant. The variables measured included lamina length and width, tiller height, length of the inflorescence, total number of leaves, and leaf, stem, and inflorescence mass. At each phenological stage, groups of accessions were statistically formed using cluster analysis. The grouping of accessions (cluster analysis) into statistically different groups (ANOVA and canonical variate analysis) indicated the existence of different ecotypes. The phenotypic variation within each group of the accessions suggested that each group has its own phenotypic plasticity. It is concluded that the successful colonisation by H. lanatus has resulted from diversity within the species.

Sustainable Pasture Improvement in the South of Chile

To alleviate the soil pasture growth constraints, farmers have being directing their attention to four areas of pasture improvement: soil fertility, grazing, plant species and broad leaf species control. The level of fertilizer input depends on the potential production of the soil at site level, soil nutrients that constraint plant growth thus requires to be increased and pasture attributes indicators of pasture condition, such as botanical composition, species density and pasture herbage mass and height. The application of nitrogen (N), phosphorus (P), potassium (K), lime and other micronutrients are based on soil laboratory testing results.4